Houston Region Import Capacity Project

Houston Region Import Capacity Project July 25, 2013 Prepared by: CenterPoint Energy Transmission Planning

Executive Summary 3 1. Introduction 5 2. Methodology and Study Assumptions 7 2.1 Case Description 7 2.2 Methodology Description 9 3. Phase I - Study Case Analysis 10 3.1 AC Contingency Analysis Years 2015-2018 10 3.2 Houston Region Capacity Demand and Reserves Analysis 11 4. Phase II - Identification of Interconnection Options and Initial Screening 13 4.1 Description of the Interconnection Options 14 4.2 Transfer Capability Analysis 19 4.3 Preliminary Cost Estimates 20 4.4 Initial Screening of Options 21 5. Phase III Selected Interconnection Options Studies 28 5.1 Steady State Voltage Stability Analysis 28 5.2 Detailed Cost Analysis 31 5.3 AC Contingency Analysis Primary Options 35 5.4 Short Circuit Analysis Primary Options 39 6. Conclusions 41 7. References 43 Appendix A. Transfer Capability of Identified Options 44 Appendix B. Preliminary Cost Estimates of Identified Options 52 Appendix C. Detailed Cost Estimates of Selected Options 58 Appendix D. PV Analysis of Selected Options 64 2

Executive Summary CenterPoint Energy Houston Electric, LLC (CenterPoint Energy) completed projects in 2007, 2009, and 2011 that increased the import capacity into the Houston Region. However, as the load continues to grow in the Houston Region and the potential for additional generation in the region remains limited, the need for additional import capacity increases. In its Long-Term System Assessment report dated December 28, 2012, ERCOT concluded the following: The Houston Region will need at least one additional import path within the next ten years. In the Transmission Needs Analysis section of the same report, ERCOT stated the following: ERCOT observed the need for expanded import paths into the Houston Metropolitan Region in every scenario studied in the context of this LTSA. In most scenario base cases, existing import paths into Houston were overloaded within the 10-year initial planning horizon. The results from the various scenarios evaluated are consistent and clear: the Houston Region will need incremental or expanded import capacity absent a significant amount of generation development within the area. CenterPoint Energy has completed a reliability evaluation of the need for additional transmission import capability into the Houston Region. This study identified potential reliability issues beginning in 2018 with respect to ERCOT s Planning Criteria: Planning uide 4.1.1.2 (1)(b) This criterion includes the outage of any generating unit, with any other generation pre-emptively redispatched, followed by the loss of a double-circuit tower line with a length greater than 0.5 miles. This system performance criterion will not be satisfied for anticipated system conditions starting in 2018 unless additional resources are added in the Houston Region that more than offset potential unit retirements and load additions. CenterPoint Energy identified and evaluated 25 transmission interconnection options for improving import capability in the Houston Region and recommends building one of three preferred interconnection options, which are summarized below: Preferred Interconnection Options Transfer Increase (MW) New 345 kv Structure-miles ** Cost ($ MM) MW/$ MM Option 15 : Twin Oak-Zenith (including system improvements) Option 24 : Ragan Creek-Zenith* (including system improvements) 2701 117 462 5.85 1960 69 297 6.60 Option 25 : Limestone-Ragan Creek-Zenith* (including system improvements) 2532 130 532 4.76 *Ragan Creek is a future CenterPoint Energy 345 kv Switching Station to be constructed as part of the interconnection option. **New 345 kv structure-miles include a 20 percent increase from their point-to-point straight-line distances to account for uncertainty in routing. Transfer capability into the Houston Region and estimated project cost were the primary factors used when comparing alternatives. CenterPoint Energy also considered other factors, such as expandability, geographic diversity, and the ability to construct the facilities without requiring long outages of existing facilities. CenterPoint Energy s specific cost estimates were used for improvements expected to be implemented by CenterPoint Energy, and ERCOT s LTSA average costs were used for improvements of non-centerpoint Energy owned facilities. CenterPoint Energy expects that ERCOT will conduct 3

additional analyses and recommend one project. CenterPoint Energy is willing to pursue any reasonable alternative to relieve the reliability concerns. The length of time required to construct the ERCOT-designated project depends on multiple variables, including time required for ERCOT approval, routing considerations, and right-of-way acquisition. It will be challenging to complete a significant new 345 kv transmission project to address the Houston Region import constraint by 2018. There are also various factors beyond ERCOT s or CenterPoint Energy s control that could cause the reliability need to be accelerated to earlier than 2018, such as additional load growth in the Houston Region, additional retirements of Houston Region generating units, or both. Accordingly, CenterPoint Energy believes the ultimate project determined by ERCOT s independent analysis should be designated as critical to reliability for the ERCOT Region. If the ERCOT Board of Directors approves a project by November 2013 and ERCOT designates the project as critical to reliability, CenterPoint Energy would expect to target completion of the project by May of 2018. 4

1. Introduction Background Cancellation of the Fayetteville-Zenith Import Project: In July of 2009, CenterPoint Energy submitted a report to ERCOT [1] that addressed the potential need to increase the North to Houston interface transfer capacity and, to a lesser extent, the South to Houston transfer capability. In 2010, ERCOT reviewed the study on the relative merits, performed its own study [2] to verify results and review multiple alternative options, and formalized in a report their recommendation for constructing a new Fayetteville-Zenith 345 kv double-circuit transmission line and related improvements. In the report, ERCOT noted that additional import capacity into the Houston Region was not considered necessary to meet reliability criteria in the period of the analysis, which was 2014, because the load in the Houston Region could be reliably served by generation in the Houston Region and the existing import capacity. ERCOT, however, recommended the project based on economic reasons by meeting the consumer impact, or the generator revenue reduction test, included in the ERCOT Planning Charter. Initiated by HB 971 of the 82 nd Legislature in 2011, the Public Utility Commission of Texas concluded in March of 2012 that the consumer impact or generator revenue reduction test should not be used by ERCOT and amended P.U.C. Subst. R. 25.101 relating to proceedings for a certificate of convenience and necessity (CCN). As a result, CenterPoint Energy discontinued pursuing the Fayetteville Zenith import project. Current State: ERCOT s most recent LTSA analysis [3] identified that the Houston Region would need incremental or expanded import capacity absent a significant generation addition within the area. ERCOT s 2012 Report on Existing and Potential Electric System Constraints and Needs [4] asserts that in the evaluation of 2015 and 2017, three of the highest congested elements are related to importing power into the Houston Region from the north. The Houston metropolitan area, one of the major load centers in ERCOT, interconnects to ERCOT at both the 345 kv and 138 kv voltage levels. A combination of local generation and import power from external sources serves the load in the area. Nine existing 345 kv import circuits, four from the north and five from the south, are the primary transmission circuits used for importing the external power. These include: North Houston Import Circuits - Singleton Zenith 345 kv circuit 98 - Singleton Zenith 345 kv circuit 99 - Singleton Tomball 345 kv circuit 74 - Roans Prairie King 345 kv circuit 75 South Houston Import Circuits - South Texas Project Dow 345 kv circuit 18 - South Texas Project Dow 345 kv circuit 27 - South Texas Project W. A. Parish 345 kv circuit 39 5

- W.A. Parish Hillje 345 kv circuit 72 - W.A. Parish Hillje 345 kv circuit 64 CenterPoint Energy has completed an evaluation of transmission interconnection options that focuses on the need for providing sufficient import capability into the Houston Region to meet reliability requirements, the details of which are contained in this report. 6

2. Methodology and Study Assumptions 2.1 Case Description CenterPoint Energy used the ERCOT Steady-State Working roup (SSW) cases created in February of 2013 as a starting point for building the Study Cases. The ERCOT SSW load flow cases for years 2015 to 2018 were modified to include the latest information with respect to future generation to be installed in the Houston Region as described in this section Table 2-1 below lists prospective generator projects located within CenterPoint Energy s service territory that have a signed Standard eneration Interconnection Agreement (SIA). Effective February 1, 2013, ERCOT Planning uide Section 6.9 was revised to clarify that a SIA, notice to proceed, and any necessary security are required to include a prospective generator in planning models built by the SSW. The WA Parish addition is part of a post-combustion carbon capture system planned for 2015. The combustion turbine will be providing power to the grid in 2013, but by 2015 all of the power is expected to be used for carbon capture and, therefore, was not included in the Study Cases for 2015 to 2018. The Deer Park and Channel Energy Center expansions have signed a SIA, provided a notice to proceed, and provided security, so they were included in the Study Cases for analysis. Pondera signed a SIA in 2010; however, Pondera has not provided a notice to proceed nor the financial security required to proceed with interconnection facilities. Therefore, CenterPoint Energy removed the Pondera project from the Study Cases. Deepwater Energy Storage facility is an energy storage facility that can only operate for a limited time before requiring to be recharged, so it was not added to the Study Cases. Agrifos Fertilizer Inc. signed a SIA in January 2013, but had not provided a notice to proceed nor financial security at the time of the study, so it was not included in the Study Cases for analysis Table 2-1: New Resources in the Houston Region with Signed Standard eneration Interconnection Agreements as of March 15, 2013 rid Included Unit in Study eneration Modeled (MW) MW Cases Yr 2015 Yr 2016 Yr 2017 Yr 2018 WA Parish Addition 89 No 0 0 0 0 Deer Park Energy Center Addition 215 Yes 215 215 215 215 Pondera (New Plant) 1,300 No 0 0 0 0 Channel Energy Center Addition 200 Yes 200 200 200 200 Deepwater Energy Storage +/ - 40 MW No 0 0 0 0 Agrifos Fertilizer Inc. 15.4 No 0 0 0 0 Total 415 415 415 415 In 2012, several generating units in the Houston Region changed from mothball to operational status. Table 2-2 provides the generating units in the Houston Region that have been in mothball status in the 7

past or are currently in mothball status. enerating units over 50 years of age inside the Houston Region are listed in Table 2-3. Previously and currently mothballed units as well as all of the generating units greater than 50 years old were considered to be available in the Study Cases. Table 2-2: Previously or Currently Mothballed Units Unit eneration Modeled (MW) Yr 2015 Yr 2016 Yr 2017 Yr 2018 SRB_SRBT_2 13 13 13 13 SRB_SRB_1 118 118 118 118 SRB_SRB_2 174 174 174 174 SRB_SRB_3 230 230 230 230 SRB_SRB_4 230 230 230 230 BY_BY_5 406 406 406 406 APD_APD_1 138 138 138 138 BY_BYT82 58 58 58 58 Total 1367 1367 1367 1367 Table 2-3: enerating Units older than 50 years in Houston Region Bus Number Bus Name kv Pmax (MW) Id Total in-service Years Yr 2017 Yr 2018 110005 SRB_SRBT_2 13.2 13 MB 50 51 110002 SRB_SRB_1 20 118 N1 59 60 110001 SRB_SRB_2 20 174 N2 61 62 110003 SRB_SRB_3 16.5 230 N3 58 59 110004 SRB_SRB_4 16.5 230 N4 57 58 110041 THW_THWT_1 13.2 13 BS 50 51 110019 WAP_WAPT_1 13.2 13 BS 50 51 110011 WAP_WAP_1 20 169 N1 59 60 110012 WAP_WAP_2 20 169 N2 59 60 110013 WAP_WAP_3 24 258 N3 56 57 110014 WAP_WAP_4 22 552 N4 49 50 Total MWs for Units 50 Years or more in service 1387 1939 8

2.2 Methodology Description CenterPoint Energy divided the study into three phases: - Phase I: Study Case Analysis A reliability analysis was performed for years 2015 to 2018, under the existing system network configuration, for the Study Cases and for two different generation sensitivity analysis scenarios. The objective was to review system performance in serving load without additional new import projects, while satisfying ERCOT and CenterPoint Energy Planning Criteria. - Phase II: Identification of Interconnection Options and Initial Screening Following the reliability analysis performed in Phase I, 25 different interconnection options were identified and studied. The total transfer capacity provided by each option was estimated using linear transfer capability techniques. Average cost estimates, as defined by ERCOT in its latest Long Term Study from December of 2012, were determined in this phase. Some options were eliminated in this phase based on technical and cost considerations. - Phase III: Selected Interconnection Options Studies CenterPoint Energy performed a detailed cost analysis and a non-linear steady state voltage stability analysis (PV analysis) on the selected set of interconnection options remaining from the Phase II screening. Some additional options were eliminated, and an AC Contingency analysis and Short Circuit analysis were performed on the remaining primary interconnection options from which the final set of preferred interconnection options was determined. 9

3. Phase I - Study Case Analysis CenterPoint Energy evaluated the 2015 to 2018 Summer Peak ERCOT base cases with varying generation dispatches to model a range of possible North to Houston and South to Houston import scenarios. The SSW ERCOT 2015 to 2018 Base Cases were modified by taking out of service the Pondera units (1300 MW) and adding the Deer Park and Channel Energy Center expansions (415 MW total). CenterPoint Energy studied the reliability of the base cases with respect to ERCOT s Planning Criteria: Planning uide 4.1.1.2 (1)(b). This criterion accounts for taking the largest unit inside the Houston Region out of service, which is Cedar Bayou 2 (CBY2-745 MW), creating the corresponding Study Cases and performing common tower outages or the contingency loss of a transmission circuit or transformer. In addition to the Study Cases, the ERCOT Planning Criteria was used to evaluate two additional sensitivity analysis scenarios. For Scenario 1, the previously or currently mothballed units in the Houston Region dispatched in the SSW cases are removed from service. Because there is no additional generation available within the Houston Region, load is reduced outside of the Houston Region. In Scenario 2, an additional 500 MW of generation is added inside the Houston Region by increasing five existing units in the CenterPoint Energy service area by 100 MW each to simulate a net increase. Table 3-1 provides pre-contingency interface flows through the main 345 kv ties for years 2015 to 2018 for the Study Case and sensitivity analysis scenarios. Table 3-1: Pre-contingency 345 kv Ties Interface Flow Years 2015-2018 Scenarios Pre-contingency Interface Flows North to Houston Interface (MW) South to Houston Interface (MW) Yr 2015 Yr 2016 Yr 2017 Yr 2018 Yr 2015 Yr 2016 Yr 2017 Yr 2018 Study Case 3014 3188 3205 3351 2546 2613 2812 2937 Scenario 1 - Mothballed units out-of-service Scenario 2-500 MW additional generation 3754 3924 3945 4086 3075 3149 3348 3481 2753 2928 2944 3091 2358 2424 2624 2746 3.1 AC Contingency Analysis Years 2015-2018 An initial AC Contingency analysis was performed for all years for the three scenarios described above. The analysis highlights potential loading issues that may arise over the years on the most critical ties into the Houston Region. Contingency studies included ERCOT s Category B and C contingencies. Table 3-2, Table 3-3, and Table 3-4 present the results for this analysis. ERCOT s generating unit unavailability criterion (Planning uide 4.1.1.2 (1)(b)) is not satisfied in the Study in 2018 due to an overload of the emergency rating of both of the Singleton to Zenith 345 kv circuits. The Scenario 1 10

sensitivity analysis illustrates that a net decrease in generation from the Study Case, in this case previously or currently mothballed units removed from service, would lead to very high overloads. The Scenario 2 sensitivity analysis illustrates a reduction in the contingency loading of the Singleton to Zenith 345 kv circuits, below 95% of their emergency rating, with the addition of 500 MW of generation within the Houston Region. All available generation in the Houston Region was dispatched at full output to meet the modeled load levels; therefore, there is no generation dispatch available within the Houston Region to lower the import level into Houston. Table 3-2: AC Contingency Years 2015-2018 Study Case with CBY2 Off-line Emergency Loading % ** From bus ** ** To bus ** CKT Rating Yr 2015 Yr 2016 Yr 2017 Yr 2018 Contingency Description 44645 SNLTN_345 345 44900 ZENITH 345A 345 98 1450.0 95.2 95.9 100.8 TOMBALL 345 - SINLETON & KIN - ROANS PRAIRIE 44645 SNLTN_345 345 44900 ZENITH 345A 345 99 1450.0 95.3 95.9 100.8 TOMBALL 345 - SINLETON & KIN - ROANS PRAIRIE Table 3-3: AC Contingency Analysis Years 2015-2018 Scenario 1 with Mothballed Units Off-line and CBY2 Off-line Emergency Loading % ** From bus ** ** To bus ** CKT Rating Yr 2015 Yr 2016 Yr 2017 Yr 2018 Contingency Description 44645 SNLTN_345 345 44900 ZENITH 345A 345 98 1450.0 114.3 121.4 124.1 134.3 TOMBALL 345 - SINLETON & KIN - ROANS PRAIRIE 44645 SNLTN_345 345 44900 ZENITH 345A 345 99 1450.0 114.3 121.5 124.2 134.4 TOMBALL 345 - SINLETON & KIN - ROANS PRAIRIE 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 98 1137.0 95.2 97.8 99.4 BELLAIRE 345 - JEANETTA 345 CKT.64 & BELLAIRE 345 - WA PARISH 345 CKT.50 44645 SNLTN_345 to 46500 TOMBAL 345B 345 74 1924.0 96.2 102.0 103.1 108.5 SINLETON - ZENITH 345 CKT.98 & SINLETON - ZENITH 345 CKT.99 Table 3-4: AC Contingency Analysis Years 2015-2018 Scenario 2 with Additional 500 MW of eneration in the Houston Region and CBY2 Off-line Emergency Loading % ** From bus ** ** To bus ** CKT Rating Yr 2015 Yr 2016 Yr 2017 Yr 2018 Contingency Description 44645 SNLTN_345 345 44900 ZENITH 345A 345 98 1450.0 87.0 87.5 92.2 TOMBALL 345 - SINLETON & KIN - ROANS PRAIRIE 44645 SNLTN_345 345 44900 ZENITH 345A 345 99 1450.0 87.0 87.5 92.2 TOMBALL 345 - SINLETON & KIN - ROANS PRAIRIE 3.2 Houston Region Capacity Demand and Reserves Analysis Another way of assessing the reliability concerns of the Houston Region is through a Capacity, Demand, and Reserves (CDR) table showing projected resources versus projected load for the area. CenterPoint Energy performed a CDR analysis for years 2015 to 2018. The Houston Region capacity is composed of the generation resources and import capability. The generation resources exclude the largest unit, which is Cedar Bayou 2, to be consistent with the ERCOT generating unit unavailability criterion. The import capability is the contingency constrained total import capacity for the existing 138 kv and 345 kv lines connecting the Houston Region to the rest of ERCOT. Load and losses are based on the Summer Peak load flow Study Cases for years 2015 to 2018. The import capability for each year corresponds to an average of the maximum pre-contingency import into the Houston Region without overloading any element under a common tower outage calculated for years 2015 to 2018 from the Study Cases. In particular, the most limiting contingency corresponds to the loss of the Roans to Tomball double-circuit tower line. Table 3-5 provides the reserve margin for the Houston Region. A deficit between demand and capacity exists starting in 2018. Additional import capacity into the Houston Region is necessary unless timely new net resources are added in the Houston Region that more than offset potential unit retirements and unplanned load additions. 11

Table 3-5: Capacity-Demand Balance under -1 Conditions for Cedar Bayou 2 745 MW Out-of- Service Year 2015 2016 2017 2018 Peak Load (MW) 19111 19331 19525 19726 Peak Transmission Losses (MW) 291 319 330 346 Peak Demand (MW) 19402 19650 19855 20072 Installed Capacity w/o CB2 (MW) 11706 11706 11706 11706 Previously and Currently Mothballed (MW) 1367 1367 1367 1367 Average Import Capacity From 138 and 345 kv Ties (MW) 6500 6500 6500 6500 Planned Resources with Signed IA, Air Permit, and Securitized Deposit per Table 2-1 (MW) 415 415 415 415 Total Resources (MW) 19988 19988 19988 19988 Surplus/Deficit (MW) 586 338 133 (84) 12

4. Phase II - Identification of Interconnection Options and Initial Screening CenterPoint Energy identified 25 interconnection options and performed initial screening studies to improve the import capacity into the Houston Region to relieve the reliability concern identified in the Phase I 2018 Study Case. CenterPoint Energy chose the year 2018 Study Case, because the year corresponds to the highest loading of Houston Region import lines for all scenarios studied. The 25 interconnection options included either upgrading existing circuits or building new tie lines at 345 kv or 500 kv. The new tie line options included many different termination points, making them flexible for future expansion and geographically diverse. The merits of the 25 interconnection options were compared by performing a technical and cost analysis with the objective of narrowing the options to the most robust for further detailed analysis. The following section lists the 25 interconnection options that were identified along with a brief description. The options identified were based on prior analyses performed in 2009 and 2010 by CenterPoint Energy and ERCOT, economical alternatives discussed in ERCOT s 2012 Long Term analysis, and some new proposals by CenterPoint Energy for this study. CenterPoint Energy evaluated the interconnection options to determine the amount of increase in transfer capability into the Houston Region each provided. This evaluation was accomplished using Siemens PTI MUST software. MUST calculates the First Contingency Incremental Transfer Capability by modeling transfers from a sending subsystem to a receiving subsystem while monitoring all buses and branches in a defined group and taking contingencies one by one from a defined contingency list. The calculation demonstrates an incremental transfer capability, where the transfer is placed on top of the base case condition. The transfers were implemented by increasing load in the CenterPoint Energy area, including Texas New Mexico Power (TNMP) load pockets supplied from CenterPoint Energy, and reducing it by the same amount across the rest of ERCOT. The methodology for the initial first screening of the interconnection options took the following approach: - Evaluate the increase in additional transfer over the 2018 Study Case for each of the interconnection options. This analysis includes selected circuit reinforcements that limit the power transfer. - Estimate project costs for each of the interconnection options based on ERCOT s 2012 average transmission costs. - Rank the 25 interconnection options on a MW/$MM basis and screen them based on the incremental MW transfer, the MW/$MM, and any other additional relevant criteria such as flexibility for future expansion. 13

4.1 Description of the Interconnection Options The following section offers a high-level summary of each of the 25 interconnection options. The new circuit lengths include an additional 20% increase on point-to-point distance to account for uncertainty in line routing. For study purposes, any new 345 kv transmission line construction proposed, where applicable, was modelled using 3-959 ACSS conductor, which has an emergency rating of approximately 3350 MVA. However, the highest substation equipment that CenterPoint Energy currently uses at 345 kv is 5000 Amps; therefore, the emergency rating (Rate B as defined in the SSW procedural manual) used for each new circuit was 2988 MVA. Figure 4-1 and Figure 4-2 show the general geographical location and the interconnection points for each option. Option 1: New Jordan Lufkin 345 kv double-circuit. This option includes building a new 126-mile 345 kv double-circuit from CenterPoint Energy s Jordan Substation to Oncor Electric Delivery Company s (Oncor s) Lufkin Substation. Option 2: New Zenith Salem 345 kv double-circuit. This option includes building a new 50-mile 345 kv double-circuit line from CenterPoint Energy s Zenith Substation to Lower Colorado River Authority (LCRA) TSC s Salem Substation. Also loop the Fayette Power Project-Salem 345 kv line into Fayetteville 345 kv substation and add a 19.5 mile second circuit on the existing towers from Fayetteville 345 kv to Salem. Option 3: New Zenith Fayetteville 345 kv double-circuit. This option includes building a new 66-mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to LCRA TSC s Fayetteville Substation and loop the Fayette Power Project-Salem 345 kv line into Fayetteville 345 kv substation. This option can be expanded by building a Salem to ibbons Creek 345 kv circuit to provide additional North to Houston transfer capability, if needed in future years as in Option 10. Option 4: New Zenith ibbons Creek 345 kv double-circuit. This option includes building a new 63- mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to Texas Municipal Power Agency s (TMPA s) ibbons Creek Substation. Option 5: New Obrien Fayetteville 345 kv double-circuit. This option includes building a new 74- mile double-circuit from CenterPoint Energy s Obrien Substation to LCRA TSC s Fayetteville Substation and loop the Fayette Power Project-Salem 345 kv line into Fayetteville 345 kv substation. Option 6: New Obrien Salem 345 kv double-circuit. This option includes building a new 63-mile 345 kv double-circuit from CenterPoint Energy s Obrien Substation to LCRA TSC s Salem Substation. Also loop the Fayette Power Project-Salem 345 kv line into Fayetteville 345 kv substation and add a 19.5 mile second circuit on the existing towers from Fayetteville 345 kv to Salem. Option 7: New Obrien Holman 345 kv double-circuit. This option includes building a new 84-mile 345 kv double-circuit from CenterPoint Energy s Obrien Substation to Austin Energy s Holman Substation. Option 8: New Zenith Salem and Salem ibbons Creek 345 kv double-circuits. This option includes building a new 50-mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to LCRA TSC s Salem Substation and a new 49-mile 345 kv double-circuit from LCRA TSC s Salem Substation to TMPA s ibbons Creek Substation.. 14

Option 9: New Zenith Salem and Salem TNP One 345 kv double-circuits. This option includes building a new 50-mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to LCRA TSC s Salem Substation and a new 89-mile 345 kv double-circuit from LCRA TSC s Salem Substation to Texas- New Mexico Power s (TNMP s or TNP s) TNP One Substation. Option 10: New Zenith Fayetteville and Salem ibbons Creek 345 kv double-circuits. This option includes building a new 66-mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to LCRA TSC s Fayetteville Substation and a new 49-mile 345 kv double-circuit from LCRA TSC s Salem Substation to TMPA s ibbons Creek Substation. This option would also loop the Fayette Power Project- Salem 345 kv line into the Fayetteville 345 kv substation and add a 19.5-mile second circuit on the existing towers from Fayetteville 345 kv to Salem. Option 11: New Sandow - Zenith 345 kv double-circuit. This option includes building a new 109-mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to Oncor s Sandow Substation. Option 12: New Marion - Holman - Obrien 345 kv double-circuits. This option includes building a new 84-mile 345 kv double-circuit from CenterPoint Energy s Obrien Substation to Austin Energy s Holman Substation and a new 93-mile 345 kv double-circuit LCRA TSC s Marion Substation to Holman Substation. Option 13: New Hillje - Obrien 345 kv double-circuit. This option includes building a new 65-mile 345 kv double-circuit from CenterPoint Energy s Obrien Substation to CenterPoint Energy s Hillje Substation. Option 14: New Twin Oak - Salem and Fayetteville - Zenith 345 kv double-circuits. This option includes building a new 66-mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to LCRA TSC s Fayetteville Substation and a new 89-mile 345 kv double-circuit from Oncor s Twin Oak Substation to LCRA TSC s Salem Substation. This option would also loop the Fayette Power Project- Salem 345 kv line into the Fayetteville 345 kv substation and add a 19.5-mile second circuit on the existing towers from Fayetteville 345 kv to Salem. Option 15: New Twin Oak - Zenith 345 kv double-circuit. This option includes building a new 117-mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to Oncor s Twin Oak Substation. Option 16: New Twin Oak Salem Zenith 345 kv double-circuits. This option includes building a new 138-mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to Oncor s Twin Oak Substation with one of the circuits looping through LCRA s Salem Substation and the second bypasses the Salem Substation and both circuits continue to terminate at the Zenith Substation. Option 17: New Limestone ibbons Creek Zenith 345 kv double-circuits. This option includes building a new 63-mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to TMPA s ibbons Creek Substation and a new 67-mile 345 kv double-circuit from TMPA s ibbons Creek Substation to CenterPoint Energy s Limestone Substation. Option 18: New Big Brown Jordan 500 kv double-circuit. This option includes building a new 182- mile 500 kv double-circuit from CenterPoint Energy s Jordan Substation, which would be a new 500 kv switchyard to a new 500 kv switchyard connected to Oncor s Big Brown 345 kv Substation. Option 19: New Big Brown Zenith 345 kv double-circuit. This option includes building a new 159- mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to Oncor s Big Brown Substation. 15

Option 20: New Navarro Zenith 345 kv double-circuit. This option includes building a new 178-mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to Lone Star Transmission Company s (Lone Star s) Navarro Substation. Option 21: Upgrade existing circuit 74, 98, 99, and 75 345 kv double-circuits. This options includes upgrading the existing CenterPoint Energy circuit 74 King - Rothwood Kuykendahl Tomball - Singleton, circuit 98 Zenith Singleton, circuit 99 Zenith Singleton and circuit 75 King Kuykendahl - Roans Prairie - Singleton using 3-959 ACSS conductor. The estimated length of re-conductoring is 263 miles. Option 22: New Limestone Zenith 345 kv double-circuit. This option includes building a new 130- mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to Limestone Substation. Option 23: New Limestone Singleton Zenith 345 kv double-circuits. This option includes building a new 66-mile 345 kv double-circuit from CenterPoint Energy s Limestone Substation to Singleton Substation and a 64-mile 345 kv double-circuit from Singleton Substation to Zenith Substation on a different corridor than the existing Zenith Substation to Singleton Substation circuits. Option 24: New Ragan Creek Zenith 345 kv double-circuit. This option includes building a new 69- mile 345 kv double-circuit from CenterPoint Energy s Zenith Substation to a proposed new CenterPoint Energy 345 kv substation identified as Ragan Creek located at a to-be-determined position between TMPA s Jack Creek Substation and ibbons Creek Substation. The circuits connecting ibbons Creek Substation Jack Creek Substation and ibbons Creek Substation Twin Oak Substation would be looped into the new Ragan Creek Substation. This option can be expanded by building a Ragan Creek Limestone 345 kv double-circuit to provide additional North to Houston transfer capability (see Option 25). Option 25: New Limestone Ragan Creek - Zenith 345 kv double-circuits. This Option expands on Option 24 by also building a new 61-mile 345 kv double-circuit from CenterPoint Energy s new Ragan Creek Substation to CenterPoint Energy s Limestone Substation.. 16

Figure 4-1: Interconnection Options 1 to 16 17

Figure 4-2: Interconnection Options 17 to 25 18

4.2 Transfer Capability Analysis An initial transfer capability analysis was performed on the 2018 Study Case for each of the 25 identified interconnection options using linear transfer capability evaluation (Siemens MUST). The detailed output is located in Appendix A. Table 4-1 shows the initial transfer through the existing ties and the new tie prior to increasing transfer, and the potential maximum total transfer power into the Houston Region after increasing transfer to the thermally constrained contingency limit. In defining the maximum transfer, selected system reinforcements were simulated with the objective of further increasing the total transfer until major system reinforcements, defined as Limiting Element on the table, were necessary. The transfers were modelled by increasing load in the Houston Region, including TNMP load pockets supplied from CenterPoint Energy, and reducing load by the same amount across the rest of ERCOT. All the 345 and 138 kv transmission lines connecting the Houston Region with the rest of ERCOT were monitored using Rate B, and the contingencies were evaluated utilizing ERCOT s NERC Category B and C contingency files. Table 4-1: Transfer Capability Analysis Alternative Tie Flows No Transfer (MW) Maximum Transfer with Selected Reinforcements (MW) Option North to Houston Flow South to Houston Flow 138 kv Circuits New Tie Increase from 2018 Study Case Total Transfer Limiting Element 2018 Study Case 3351 2937 162 N/A N/A 6450 Singleton-Zenith 345 kv Option 1 : Lufkin-Jordan 2910 2759 117 654 1464 7914 Singleton-Zenith 345 kv Option 2 : Salem - Zenith 3085 2643 48 658 824 7273 Singleton-Zenith 345 kv Option 3 : Zenith - Fayetteville 3041 2596 38 758 964 7414 Singleton-Zenith 345 kv Option 4 : Zenith- ibbons Creek 2446 2776 124 1080 1914 8364 Jewett - Singleton 345 kv Option 5 : Obrien - Fayetteville 3061 2565 31 773 884 7334 Singleton-Zenith 345 kv Option 6 : Obrien -Salem 3109 2626 31 652 720 7169 Singleton-Zenith 345 kv Option 7 : Holman -Obrien 3087 2550 58 735 793 7242 Singleton-Zenith 345 kv Option 8 : Zenith- Salem -ibbons Creek 2800 2720 82 827 2587 9037 Zenith - T.H. Wharton 345 kv Option 9 : Zenith-Salem-TNPONE 2808 2678 79 864 1989 8439 Singleton-Zenith 345 kv Option 10 : Zenith - Fayetteville & Salem-ibbons Creek 2825 2637 74 894 2132 8582 Singleton-Zenith 345 kv Option 11 : Sandow to Zenith 2987 2695 95 657 1296 7746 Singleton-Zenith 345 kv Option 12 : Marion-Holman-Obrien 3073 2557 49 751 884 7334 Singleton-Zenith 345 kv Option 13 : Hillje-Obrien 3249 2333 119 731 262 6711 Singleton-Zenith 345 kv Option 14 : Twin Oak-Salem -Fayetteville-Zenith 2778 2630 86 935 2032 8482 Singleton-Zenith 345 kv Option 15 : Twin Oak-Zenith 2625 2712 100 974 2701 9151 Zenith - T.H. Wharton 345 kv Option 16 : Twin Oak-Salem-Zenith 2749 2696 87 899 2227 8677 Singleton-Zenith 345 kv Option 17 : Limestone-ibbons Creek-Zenith 2473 2710 105 1137 2542 8991 Zenith - T.H. Wharton 345 kv Option 18 : Big Brown - Jordan 500 kv 2801 2734 110 793 2179 8629 Singleton-Zenith 345 kv Option 19 : Big Brown-Zenith 2785 2738 111 802 2067 8517 Singleton-Zenith 345 kv Option 20 : Navarro-Zenith 2945 2785 123 584 1536 7986 Singleton-Zenith 345 kv Option 21 : Upgrade 345 kv conductors 3376 2905 154 0 1541 7991 Jewett - Singleton 345 kv Option 22 : Limestone-Zenith 2678 2724 108 925 2603 9053 Singleton-Zenith 345 kv Option 23 : Limestone-Singleton-Zenith 2544 2718 107 1056 2685 9135 Zenith - T.H. Wharton 345 kv Option 24 : Ragan Cr-Zenith 2485 2761 115 1061 1960 8409 Jewett - Singleton 345 kv Option 25 : Limestone-Ragan Cr-Zenith 2486 2706 104 1130 2532 8982 Zenith - T.H. Wharton 345 kv 19

4.3 Preliminary Cost Estimates A preliminary project cost estimate for each of the 25 interconnection options was developed using ERCOT s average generic dollar per transmission mile cost as shown in Table 4-2. The preliminary estimates were used to provide a relative cost comparison of the interconnection options and to calculate a ratio of MW per million dollars spend for comparing transfer improvement performance. The preliminary project cost estimates for the interconnection options, including their selected reinforcements, are listed in Appendix B. Table 4-2: Average Cost Estimates - ERCOT Rural Urban ($ MM/mi) ($ MM/mi) 345 kv New Single circuit (on double circuit capable towers) 1.95 3.25 New double circuit 2.44 4.1 Re-conductoring of existing single circuit line 0.72 1.43 Re-conductoring of existing double circuit line 1.14 1.99 Rebuilt existing single (complete tear down of towers and conductors) 1.46 2.3 Rebuilt existing double (complete tear down of towers and conductors) 2.07 3.53 add second circuit to an existing double circuit capable line 0.56 0.64 138 kv New Single circuit (on double circuit cpable towers) 1.14 1.96 New double circuit 1.37 2.46 Re-conductoring of existing single circuit line 0.59 0.87 Re-conductoring of existing double circuit libe 0.64 1.22 Rebuilt existing single (complete tear down of towers and conductors) 0.75 1.1 Rebuilt existing double (complete tear down of towers and conductors) 1.17 1.66 add second circuit to an existing double circuit capable line 0.27 0.4 500 kv New Single circuit (on double circuit capable towers) 2.7 New double circuit 2.98 HVDC 3000 MW capacity 3.01 Transformer ($ MM) 138/345 lesser than or equal to 600 MVA 7.98 138/345 lesser than or equal to 800 MVA 9.75 345/500 transformer 1200 MVA 16.73 eneral Substation ($ MM) 138 kv Substation 9.05 345 kv -ring bus 6-line terminals 15.94 345 kv substation breaker&1/2 > 6 - line terminal 23.22 6-breaker 500 kv ring substation 25.72 Two - HVDC 3000 MW Converter Station 510 Expand substation with one additional line terminations 2 500kV substation breaker&1/2 > 6 - line terminal 35 Series Compensation (50%) 39 Series Comp > 100 mi 25 20

4.4 Initial Screening of Options Once the preliminary project cost estimates were calculated, the interconnection options were ranked according to the ratio of MW of increased transfer per million dollars cost (i.e. MW/$MM) as listed in Table 4-3. From the initial 25 interconnection options, CenterPoint Energy selected Options 8, 15, 21, 24, and 25 as the five leading options to consider further due to their relatively high transfer performance results compared to their preliminary project cost. These options are similar in that they include building a new 345 kv double-circuit transmission line from Zenith to the north to Twin Oak, ibbons Creek, Limestone or the proposed Ragan Creek Substations. A discussion of the selection process for the leading options follows. Options 17, 22, 23, and 25 are very similar projects as they begin at Zenith Substation and end at Limestone Substation. Three of the options (17, 23, and 25) connect into a switching station (ibbons Creek, Singleton, or the proposed Ragan Creek) before continuing to the Limestone Substation. Option 23 performs the best of these four options; however, this would terminate all six North to Houston tie lines at a single substation (i.e. Singleton Substation), which would be a significant reliability concern. Therefore, despite its performance advantages, CenterPoint Energy eliminated Option 23 from further consideration. Options 15 and 22 are similar and both perform very well; however, Option 15 was chosen based on slightly better performance and cost. Option 17 has one of the shortest assumed mileages, because ibbons Creek Substation is located very near a straight line distance between Zenith and Limestone Substations. However, because ibbons Creek Substation is a fixed tie point, if the final route alignment deviates several miles to the west of ibbons Creek, the cost of Option 17 would increase and approach the cost of Option 25. Option 25 has the advantage of being able to adjust to route alignment uncertainty by locating the new Ragan Creek Substation anywhere along the ibbons Creek to Jack Creek path; thus, minimizing the length of the transmission line. If the actual route is located very close to either Jack Creek or ibbons Creek, it may be appropriate to consider terminating into one of those substations rather than building a new Ragan Creek Substation. If either of these options are considered, additional short circuit analysis will be required. For this reason, CenterPoint Energy will proceed with analysis on Option 25; however, CenterPoint Energy recognizes that Option 17 and 25 are almost identical in performance. Options 4 and 24 are very similar with Option 4 terminating into ibbons Creek, and Option 24 terminating into a new Ragan Creek Substation. Both options yield similar Transfer Capability, with Option 24 slightly higher, but Option 4 has a better transfer increase to cost ratio. Because Option 4 expands an existing substation (i.e. ibbons Creek Substation, which is a fixed point), while Option 24 builds a new substation at a flexible location, the cost difference between the two diminishes greatly if the final route alignment falls approximately six miles west of the existing ibbons Creek Substation. Due to the routing flexibility offered by Option 24, CenterPoint Energy proceeded with analysis of Option 24 rather than Option 4. However, CenterPoint Energy recognizes that Option 4 and Option 24 are almost identical in performance. Option 8 provided the largest transfer increase of the options connecting CenterPoint Energy s service area with the 345 kv grid to the west and was included as one of the five leading options based on performance. Options 16, 10, and 9 are similar to the options discussed above, but were not as cost effective, so they were eliminated from further consideration. Option 21, the upgrade of the existing 345 kv conductors, 21

was selected as a leading option based on its Transfer Capability and preliminary project cost. However, the preliminary project cost may be artificially low because its cost basis only considers the reconductoring cost and does not take into account any tower reinforcements nor the cost of temporary solutions for the time period in which the work would be performed on the existing circuits. Option 21 would minimize landowner impact, because it is confined in scope to upgrading existing 345 kv lines. The other options presented in Table 4-3 were not selected, because they either have a relatively low increase in Transfer Capability (i.e. Options 2, 3, 5, 6, 7, 12, and 13) or have a lower MW/$MM value (i.e. Options 1, 11, 14, 18, 19, and 20). The five selected interconnection options are shown in Figure 4-4 through Figure 4-8 and were further evaluated in Phase III using a more detailed cost analysis, a voltage stability analysis, an AC contingency analysis, and a Short Circuit analysis. Figure 4-3 depicts the system configuration in the 2018 Study Case. 22

Table 4-3: Initial Comparison of Interconnection Options Based on Preliminary MW per $ MM Option Transfer Increase (MW) Preliminary Project Cost ($ MM) MW per $ MM (Thermal limit) Continue to Evaluate Option 4 : Zenith- ibbons Creek 1914 164 11.68 N Option 24 : Ragan Creek-Zenith 1960 198 9.90 Y Option 8 : Zenith- Salem -ibbons Creek 2587 280 9.25 Y Option 15 : Twin Oak-Zenith 2701 303 8.92 Y Option 23 : Limestone-Singleton-Zenith 2685 349 7.69 N Option 22 : Limestone-Zenith 2603 341 7.63 N Option 17 : Limestone-ibbons Creek-Zenith 2542 342 7.43 N Option 25 : Limestone-Ragan Creek-Zenith 2532 364 6.95 Y Option 16 : Twin Oak-Salem-Zenith 2227 355 6.28 N Option 10 : Zenith - Fayetteville & Salem-ibbons Creek 2132 351 6.08 N Option 9 : Zenith-Salem-TNPONE 1989 356 5.58 N Option 21 : Upgrade 345 kv conductors 1541 281 5.48 Y Option 3 : Zenith - Fayetteville 964 184 5.23 N Option 19 : Big Brown-Zenith 2067 411 5.02 N Option 11 : Sandow to Zenith 1296 274 4.73 N Option 14 : Twin Oak-Salem -Fayetteville-Zenith 2032 448 4.53 N Option 1 : Lufkin-Jordan 1464 334 4.38 N Option 5 : Obrien - Fayetteville 884 204 4.34 N Option 2 : Salem - Zenith 824 197 4.19 N Option 7 : Holman -Obrien 793 227 3.50 N Option 20 : Navarro-Zenith 1536 442 3.47 N Option 18 : Big Brown - Jordan 500 kv 2179 661 3.30 N Option 6 : Obrien -Salem 720 224 3.21 N Option 12 : Marion-Holman-Obrien 884 454 1.95 N Option 13 : Hillje-Obrien 262 167 1.57 N 23

Figure 4-3: 2018 Study Case Configuration Limestone Twin Oak Jewett Jack Creek Sandow ibbons Creek Singleton ROANS PR 2018 Bobvle Tomball Salem Zenith T.H. W North Belt Addicks Fayetteville Fayette Plant O Brien Brazos Valley Holman WAP Oasis DOW Hillje STP 24

Figure 4-4: Option 8 Zenith Salem ibbons Creek 345 kv Twin Oak Jewett Jack Creek ibbons Creek Singleton ROANS PR 2018 Bobvle New 345 kv Tomball Salem Zenith T.H.W North Belt Addicks Fayette Plant Fayetteville O Brien Figure 4-5: Option 15 Twin Oak - Zenith 345 kv Limestone Twin Oak Jewett TNPONE Jack Creek ibbons Creek Singleton ROANS PR 2018 Bobvle Tomball New 345 kv Zenith T.H.W North Belt 25

Figure 4-6: Option 21 345 kv Upgrade Jewett ibbons Creek Singleton ROANS PR 2018 Conductor upgrades in green Conductor upgrades in green Bobvle Kuykendahl Conductor upgrades in green Tomball Rothwood Kuykendahl Zenith T.H.W North Belt King Figure 4-7: Option 24 Zenith Ragan Creek 345 kv Limestone Twin Oak Nucor Jewett Jack Creek Ragan Creek ibbons Creek Singleton ROANS PR 2018 Bobvle Tomball New 345 kv Zenith T.H.W North Belt 26

Figure 4-8: Option 25 Limestone Ragan Creek Zenith 345 kv Limestone Twin Oak Nucor Jewett Jack Creek New 345 kv Ragan Creek ibbons Creek Singleton ROANS PR 2018 Bobvle Tomball Zenith T.H. W North Belt 27

5. Phase III Selected Interconnection Options Studies 5.1 Steady State Voltage Stability Analysis PV Analysis was performed on the 2018 Study Case load flow for each of the five selected interconnection options to determine the impact on the voltage stability when transferring power into the Houston Region. This methodology was chosen in order to illustrate the transfer effect of new lines in conjunction with the already existing tie lines into the Houston Region. The analysis was performed using PowerTech Labs VSAT software by increasing the load in the Houston Region and reducing the load in the remaining ERCOT system. Figure 5-1 below compares the voltage stability of various known limiting contingencies for load-to-load transfer into the Houston Region in the 2018 Study Case. The contingency with the lowest collapse point for this case is the loss of the Roans Prairie to Tomball corridor; similar results were obtained for the PV analysis on the five selected interconnection options as described in Appendix D. For evaluating the voltage stability performance, this worst contingency was used. Figure 5-2 includes the PV curves for the five selected interconnection options for the Roans Prairie to Tomball 345 kv corridor outage. These curves plot the total ERCOT to Houston pre-contingency interface flow versus the bus voltage at the Bellaire 345 kv, which is central to CenterPoint Energy s transmission system. The ERCOT to Houston interface for each option includes the flow on the new line. The maximum total transfer for each of the options is defined by the interface transfer at the point of voltage collapse. Figure 5-3 includes the PV curves for the five selected interconnection options for the Roans Prairie to Tomball 345 kv corridor outage. These curves plot the total Houston Region load versus the bus voltage at the Bellaire 345 kv bus. ERCOT Transmission Planning Criteria requires a voltage stability margin of 2.5% increase in load above expected peak supplied from resources external to the transmission service provider-defined areas and NERC Category C operating conditions. It is observed that all the alternatives have a higher margin, with the most limited being Option 21. Table 5-1 includes a comparison of the total power transfer between thermal and voltage limits for the five selected interconnection options. It is observed that Options 8 and 15 have their total transfer limited by voltage stability considerations. CenterPoint Energy correspondingly added a 200 MVAR capacitor bank at the Zenith 345 kv Substation with the objective of increasing its power transfer, because it has slightly lower voltage stability limits than thermal transfer limits into the Houston Region. The additional cost of $3 MM for this reinforcement is included in the detailed project costs. 28

Table 5-1: Thermal and Voltage Stability Total Transfer into Houston Selected Interconnection Options Option Total Transfer Thermal Total Transfer PV Margin Option 8 : Zenith- Salem -ibbons Creek 9037 8945-92 Option 15 : Twin Oak-Zenith 9151 9088-63 Option 21 : Upgrade 345 kv conductors 7991 8291 300 Option 24 : Ragan Creek-Zenith 8409 9037 628 Option 25 : Limestone-Ragan Creek-Zenith 8982 9198 216 29

Figure 5-1: Study Case Interface Transfers (MW) vs. Bellaire 345 kv Bus Voltage (p.u.) 2018 Base Case - ERCOT to Houston Transfer PV curves for Various Contingencies Base Case 1.04 1.02 Roans - Tomball corridor Jewett - Singleton corridor 1 Singleton - Roans corridor Bellaire 345 kv Voltage (p.u.) 0.98 0.96 0.94 0.92 Singleton - Zenith corridor Pre-contingency Singleton - ibbons Creek corridor STP - Dow corridor 0.9 0.88 0.86 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000 9200 9400 ERCOT to Houston Pre-Contingency Interface Flow (MW) Figure 5-2: ERCOT to Houston Flow (MW) vs. Bellaire 345 kv Bus Voltage (p.u.) 1.04 1.02 Roans to Tomball 345 kv Outage PV - Selected Options 1 0.98 Bellaire 345 kv (p.u.) 0.96 0.94 0.92 Base Case Option 8 Option 15 Option 21 Option 24 Option 25 0.9 0.88 0.86 6400 6900 7400 7900 8400 8900 9400 ERCOT to-houston Pre-Contingency Interface Flow (MW) 30

Figure 5-3: Houston Region (MW) vs. Bellaire 345 kv Bus Voltage (p.u.) 1.04 1.02 Roans to Tomball 345 kv Outage PV - Selected Options 1 0.98 Bellaire 345 kv (p.u.) 0.96 0.94 0.92 Option 15 Option 21 Option 25 Base Case Option 8 Option 24 0.9 0.88 0.86 21650 22150 22650 23150 23650 24150 24650 Houston Region load (MW) 5.2 Detailed Cost Analysis New, more detailed, transmission and substation cost estimates are used in this phase of analysis and are based on CenterPoint Energy s internal cost assessments. The detailed project cost estimates utilized in Phase III are higher than the Phase II preliminary project cost estimates that were based on ERCOT s average generic estimates, but they reflect CenterPoint Energy s recent historical costs for building new transmission lines. The estimated cost for each of the five selected interconnection options includes the cost to build the new transmission lines, to expand each substation for the new line terminations, and to make other necessary upgrades to existing facilities to achieve the full benefits of the project. ERCOT s average generic costs provided in Table 4-2 are only utilized in Phase III for non- CenterPoint Energy proposed reinforcements. The new detailed project cost estimates are provided in Appendix C and summarized below in Table 5-2. Figure 5-4 shows the geographical location for the final set of the five selected interconnection options. 31

Figure 5-4: Selected Interconnection Options Limestone Twin Oak 15 25 Ragan Cr 24 ibbons Cr Singleton 8 Salem Zenith 32

Table 5-2: Detailed Cost Analysis Selected Interconnection Options Option Transfer Increase (MW) Detailed Project Cost ($MM) MW/$MM (Thermal limit) Option 8 : Zenith- Salem -ibbons Creek 2587 421 6.15 Option 15 : Twin Oak-Zenith 2701 462 5.85 Option 21 : Rebuild existing 345 kv circuits 1541 400 3.85 Option 24 : Ragan Creek-Zenith 1960 297 6.60 Option 25 : Limestone-Ragan Creek-Zenith 2532 532 4.76 Based on Table 5-1 and Table 5-2, CenterPoint Energy selected Options 15, 24, and 25 as its three primary interconnection options for additional analysis. Option 8 was eliminated, although it had a similar incremental transfer to Options 15 and 25, because it provides a less robust voltage stability improvement. Also, Option 8 ties to the west and then to the north, while Options 15, 24, and 25 provide a more direct path to the North. The best performing options all feature a tie to the North. Option 24 is advantageous, because it can be expanded in future years by adding a double-circuit transmission line into the Limestone Substation to provide a higher transfer increase, thus transforming it into Option 25. Option 21 was eliminated due to its lower thermal and PV limits coupled with its relatively high cost. The selected three primary interconnection options shown in Figure 5-5 would supply the Houston Region with power to serve the load for a period of approximately 10 years for Option 25 and Option 15, and 8 years for Option 24 considering an average annual load increase of 1.3% and no changes in the total installed generation. 33

Figure 5-5: Primary Interconnection Options Limestone Twin Oak 15 25 Ragan Cr 24 ibbons Cr Singleton Zenith 34

5.3 AC Contingency Analysis Primary Interconnection Options In addition to transfer capability analysis, CenterPoint Energy performed normal steady-state power flow contingency analysis on the 2018 Study Case and the three selected primary interconnection options, Options 15, 24, and 25. CenterPoint Energy also evaluated the sensitivity analysis scenario corresponding to the Study Cases without previously or currently mothballed units. The contingency analysis should identify any underlying overloads that may exist for the different options not captured by the transfer analysis. Table 5-3 to 5-5 provide the results for the contingency analysis for the following load flow cases: the ERCOT 2018 Base Case (with CBY2); the 2018 Study Case; and the three primary interconnection options. All elements that are 69 kv and above are monitored inside CenterPoint Energy s system, while elements 138 kv and above are monitored in the other ERCOT areas. For the tables, loading is calculated using the emergency Rate B line rating. For the contingency studies, the overloaded branches listed are only those branches where any option had a non-trivial effect on the loading. None of the proposed circuit reinforcements as previously described in Appendix B have been implemented in this analysis. As shown in Table 5-3, the different configurations of the interconnection options do not create significant increases in circuit loading when compared to the 2018 Study Case. For the contingency loss of a common tower, 345 kv the existing overload in the 2018 Study Case is not observed for any of the three primary interconnection options. As shown in Table 5-4 and Table 5-5, for the scenarios where the mothballed generating units are out of service, the different interconnection options eliminate the existing overloads in the 2018 Study Case. Table 5-3: Common Mode and Category C Contingencies- Maximum Overload Overloaded Branch 44645-44900 CKT 99 SNLTN_345 to ZENITH 345A 46110-3WNDTR CKT A2 N_BELT 138A to M102322 46100-3WNDTR CKT A2 N_BELT 345A to M102322 Rating (MVA) 1450 672 672 Contingency DB_ID_7651: 40600-40630 CKT 75 ROANS 345C TO BOBVLE 345X & 46500-44645 CKT 74 TOMBAL 345B TO SNLTN_345 DB_ID_6089: 46100-46110 CKT A1 N_BELT 345A TO N_BELT 138A & 46100-46110 CKT A3 N_BELT 345A TO N_BELT 138A DB_ID_6089: 46100-46110 CKT A1 N_BELT 345A TO N_BELT 138A & 46100-46110 CKT A3 N_BELT 345A TO N_BELT 138A ERCOT 2018 Base Case 100.6% (1x) 102.1% (1x) 2018 Study Case 100.8% (2x) 98.3% (0x) 99.4% (0x) Option 15 Option 24 Option 25 98.8% (0x) 99.9% (0x) 98.7% (0x) 99.8% (0x) 98.7% (0x) 99.9% (0x) 35

Table 5-4: Single (N-1) Contingencies with Mothballed Units Out-of-Service Maximum Overload Overloaded Branch 44645-44900 CKT 98 SNLTN_345 to ZENITH 345A 44645-44900 CKT 99 SNLTN_345 to ZENITH 345A 44645-967 CKT 99 SNLTN_345 to IBN_CREK_5 Rating (MVA) 1450 1450 1631 Contingency 44645-44900 CKT 99 SNLTN_345 TO ZENITH 345A 44645-44900 CKT 98 SNLTN_345 TO ZENITH 345A 44645-967 T 75 SNLTN_345 TO BN_CREK_5 3 ERCOT 2018 Base Case 2018 Study Case 98.9% (0x) 98.9% (0x) 95.7% (0x) Option 15 Option 24 Option 25 36

Table 5-5: Common Mode and Category C Contingencies with Mothballed Units Out-of-Service Maximum Overload Overloaded Branch 7294-7570 CKT 1 L_BRENNO8_1Y to L_SANDHI8_1Y 7289-7291 CKT 1 L_SALEM_8_1Y to L_HIH368_1Y 46220-7270 CKT 1 PETERS 138B to L_BELLSO8_1Y 3133-3380 CKT 1 RICHLND2_5 to BIBRN 5 44645-3391 CKT 1 SNLTN_345 to JEWETT_N5 44645-3390 CKT 1 SNLTN_345 to JEWETT_S5 46261-46295 CKT 66 RAYFRD668020 to RTHWOD 138A 44645-46500 CKT 74 SNLTN_345 to TOMBAL 345B Rating (MVA) 128 392 382 1052 1450 1450 526 1924 Contingency DB_ID_10984: 7291-7289 CKT 1 L_HIH368_1Y TO L_SALEM_8_1Y & 7291-7292 CKT 1 L_HIH368_1Y TO L_BRENHA8_1Y DB_ID_10505: 7289-7292 CKT 1 L_SALEM_8_1Y TO L_BRENHA8_1Y & 7289-7564 CKT 1 L_SALEM_8_1Y TO L_UYBUR8_1Y DB_ID_8263: 40630-40900 CKT &1 BOBVLE 345X TO KIN 345A & 44645-46500 CKT 74 SNLTN_345 TO TOMBAL 345B DB_ID_16115: 2427-3123 CKT 1 WATMLL_W5 TO TRINDAD1_5 & 2428-2432 CKT 1 WATMLL_E5 TO TRICRN1_5 DB_ID_8281: 967-44645 CKT 75 IBN_CREK_5 TO SNLTN_345 & 967-44645 CKT 99 IBN_CREK_5 TO SNLTN_345 DB_ID_8281: 967-44645 CKT 75 IBN_CREK_5 TO SNLTN_345 & 967-44645 CKT 99 IBN_CREK_5 TO SNLTN_345 DB_ID_8624: 46510-46240 CKT &1 TOMBAL 138A TO PINHUR 138A & 46510-46570 CKT &1 TOMBAL 138A TO WESFLD 138B DB_ID_8611: 44645-44900 CKT 98 SNLTN_345 TO ZENITH 345A & 44645-44900 CKT 99 SNLTN_345 TO ZENITH 345A ERCOT 2018 Base Case 95.6% (0x) 95.2% (0x) 100.8% (1x) 96.4% (0x) 96.0% (0x) 2018 Study Case 106.2% (1x) 101.5% (1x) 99.6% (0x) 98.9% (0x) 99.6% (0x) 97.2% (0x) 99.5% (0x) 108.5% (1x) Option 15 Option 24 Option 25 100.8% (1x) 95.2% (0x) 97.7% (0x) 96.1% (0x) 100.9% (1x) 95.2% (0x) 100.9% (1x) 37

Overloaded Branch 44645-44900 CKT 98 SNLTN_345 to ZENITH 345A 44645-44900 CKT 99 SNLTN_345 to ZENITH 345A 44645-967 CKT 99 SNLTN_345 to IBN_CREK_5 46100-3WNDTR CKT A2 N_BELT 345A to M102322 Rating (MVA) 1450 1450 1631 672 Contingency DB_ID_8263: 40630-40900 CKT &1 BOBVLE 345X TO KIN 345A & 44645-46500 CKT 74 SNLTN_345 TO TOMBAL 345B DB_ID_7651: 40600-40630 CKT 75 ROANS 345C TO BOBVLE 345X & 46500-44645 CKT 74 TOMBAL 345B TO SNLTN_345 DB_ID_8263: 40630-40900 CKT &1 BOBVLE 345X TO KIN 345A & 44645-46500 CKT 74 SNLTN_345 TO TOMBAL 345B DB_ID_7651: 40600-40630 CKT 75 ROANS 345C TO BOBVLE 345X & 46500-44645 CKT 74 TOMBAL 345B TO SNLTN_345 DB_ID_16569: 967-964 T 2 IBN_CREK_5 TO IBN_CREK_8 & 967-44645 CKT 75 IBN_CREK_5 TO SNLTN_345 DB_ID_6089: 46100-46110 CKT A1 N_BELT 345A TO N_BELT 138A & 46100-46110 CKT A3 N_BELT 345A TO N_BELT 138A ERCOT 2018 Base Case 113.2% (2x) 113.3% (2x) 101.2% (1x) 2018 Study Case 134.3% (3x) 134.4% (3x) 95.9% (0x) 98.0% (0x) Option 15 Option 24 Option 25 99.8% (0x) 98.9% (0x) 99.6% (0x) 38

5.4 Short Circuit Analysis Primary Interconnection Options Three phase and single line to ground (SL) fault analyses were performed on the three primary interconnection options (Options 15, 24, and 25) to determine the required fault duty rating of any new or existing substations and to identify potential circuit breaker upgrades that may be required. Table 5-6 and Table 5-7 include the results of the analyses. CenterPoint Energy s short circuit rating criteria require that three-phase and single-phase fault currents not exceed 99% of any facility s short circuit rating. All CenterPoint Energy substations were found to be within this criteria. Ratings for Oncor s Twin Oak 345 kv and TMPA s Jack Creek 345 kv buses were not available for this study. The new short circuit levels indicate some significant deviation with respect to their base case values. The Twin Oak 345 kv three-phase fault values exceeded 50 ka for Options 15, 24, and 25 with Option 15 having the worst case with a 8.2% increase over the 2018 Study Case. The Jack Creek 345 kv three-phase fault value for Option 24 was the worst case with a 41.9% increase over the 2018 Study Case. Because the short circuit ratings for Twin Oak 345 kv and Jack Creek 345 kv were not available for this study, no reinforcement costs were assumed or added for the fault duty upgrades at these substations. Table 5-6: Three-Phase Short Circuit Results Bus Rating (ka) 2018 Study Case OPT_15 OPT_24 OPT_25 ka Loading ka Loading ka Loading ka Loading Addicks 345 63 37.2 59.0% 38.3 60.8% 38.3 60.7% 38.4 61.0% Clodine 138 63 43.5 69.1% 44.1 69.9% 44.0 69.9% 44.1 70.0% Fayetteville 345 63 19.2 30.5% 19.3 30.6% 19.2 30.5% 19.3 30.6% Fayetteville 138 40 28.8 72.1% 29.0 72.4% 28.8 72.1% 29.0 72.4% ib Creek 345 63 36.1 57.3% 36.1 57.3% 39.1 62.0% 41.3 65.6% ib Creek 138 40 36.8 92.0% 36.8 92.1% 37.8 94.5% 38.4 96.1% Jack Creek 345 -- 21.5 -- 21.7 -- 30.5 -- 22.3 -- Kluge 138 63 27.8 44.1% 28.0 44.4% 28.0 44.4% 28.0 44.4% Limestone 345 63 53.6 85.1% 54.6 86.7% 54.3 86.2% 58.0 92.0% Obrien 345 50 42.0 84.0% 44.0 88.0% 44.0 88.1% 44.3 88.6% Obrien 138 63 59.9 95.1% 61.2 97.1% 61.1 97.0% 61.3 97.3% Peters 138 26.8 13.9 52.0% 14.8 55.2% 14.0 52.2% 14.8 55.1% Rag Creek 345 50 N/A N/A N/A N/A 35.0 69.9% 36.9 73.8% Roans Pr 345 50 30.9 61.9% 30.9 61.8% 31.4 62.8% 31.9 63.7% Salem 345 40 11.3 28.2% 11.3 28.3% 11.3 28.2% 11.3 28.3% Salem 138 40 23.1 57.7% 23.3 58.3% 23.2 57.9% 23.3 58.3% Singleton 345 63 41.6 66.1% 41.6 66.0% 42.9 68.1% 44.1 70.0% THW 345 50 43.7 87.5% 45.8 91.6% 45.8 91.5% 46.1 92.2% THW 138 52.3 40.6 77.7% 41.1 78.5% 41.0 78.4% 41.1 78.6% Tw in Oak 345 -- 49.9 -- 54.0 -- 51.9 -- 51.2 -- Zenith 345 50 40.4 80.7% 44.9 89.8% 45.1 90.2% 45.7 91.3% Zenith 138 63 31.6 50.2% 32.2 51.1% 32.3 51.3% 32.3 51.2% 39

Table 5-7: Single-line-to-ground Short Circuit Results Bus Rating (ka) 2018 Study Case OPT_15 OPT_24 OPT_25 ka Loading ka Loading ka Loading ka Loading Addicks 345 63 30.1 47.8% 30.6 48.6% 30.6 48.6% 30.7 48.7% Clodine 138 63 26.0 41.3% 26.2 41.5% 26.2 41.5% 26.2 41.6% Fayetteville 345 63 12.9 20.4% 12.9 20.4% 12.9 20.4% 12.9 20.4% Fayetteville 138 40 7.8 19.5% 7.9 19.7% 7.8 19.5% 7.9 19.7% ib Creek 345 63 31.4 49.8% 31.4 49.8% 33.5 53.2% 34.4 54.5% ib Creek 138 40 37.3 93.4% 37.4 93.4% 38.2 95.6% 38.6 96.4% Jack Creek 345 -- 12.3 -- 12.5 -- 18.2 -- 13.1 -- Kluge 138 63 16.4 26.0% 16.4 26.0% 16.4 26.0% 16.4 26.1% Limestone 345 63 51.2 81.3% 52.0 82.5% 51.8 82.1% 53.4 84.8% Obrien 345 50 34.1 68.2% 35.1 70.1% 35.2 70.3% 35.2 70.4% Obrien 138 63 56.4 89.6% 57.2 90.7% 57.2 90.8% 57.3 90.9% Peters 138 26.8 7.9 29.5% 8.2 30.5% 7.9 29.5% 8.2 30.4% Rag Creek 345 50 N/A N/A N/A N/A 22.0 44.0% 21.9 43.8% Roans Pr 345 50 26.0 51.9% 25.9 51.9% 26.2 52.4% 26.3 52.7% Salem 345 40 6.7 16.8% 6.7 16.8% 6.7 16.8% 6.7 16.8% Salem 138 40 7.1 17.7% 7.2 18.1% 7.1 17.8% 7.2 18.1% Singleton 345 63 31.4 49.9% 31.4 49.9% 32.0 50.8% 32.3 51.3% THW 345 50 37.5 74.9% 38.5 77.1% 38.6 77.2% 38.7 77.4% THW 138 52.3 37.0 70.7% 37.2 71.2% 37.2 71.2% 37.3 71.3% Twin Oak 345 -- 26.3 -- 28.9 -- 27.8 -- 26.8 -- Zenith 345 50 27.3 54.6% 29.9 59.7% 30.5 61.0% 30.6 61.2% Zenith 138 63 26.6 42.3% 27.3 43.3% 27.4 43.5% 27.4 43.5% 40

6. Conclusions The primary objective of the study was to determine solutions for reliability concerns related to import capacity limitations into the Houston Region under the current projected generation and demand scenarios for years 2015 to 2018. CenterPoint Energy created Study Cases for years 2015 to 2018 from ERCOT s SSW base cases and analysed them according to ERCOT s Planning Criteria: Planning uide 4.1.1.2 (1)(b) Consistent with previous ERCOT assessments, the results shown in this report for the different scenarios under consideration indicate that ERCOT s generating unit unavailability criterion is not satisfied in the Study Case for anticipated system conditions beginning in 2018 unless new import transmission paths are constructed. In the initial screening studies, CenterPoint Energy evaluated 25 interconnection options to improve the import capacity into the Houston Region and selected the following three preferred interconnection options: Option 15: New Twin Oak - Zenith 345 kv double-circuit. The transfer capability is improved by approximately 2,701 MW with an estimated project cost of $462 million and a transfer improvement value of 5.85 MW/$MM invested. This option affects Oncor s and CenterPoint Energy s substations and possibly positions at Twin Oak owned by TNMP. The proposed reinforcements to achieve this transfer affect LCRA s and CenterPoint Energy s transmission networks. New and additional system improvements included: o o o Build new 117 mile 345 kv double-circuit from Zenith Substation to Oncor's Twin Oak Substation Add two 345 kv line terminations at Zenith Substation Add two additional 345 kv line terminations at Oncor s Twin Oak substation o Upgrade Bellaire Substation to Smithers Substation 345 kv circuit 98 o o o o Upgrade 138 kv substation equipment at Rayford Substation Upgrade 138 kv tie-line and substation equipment from Peters Substation to LCRA's Bell South Substation Re-conductor single 138 kv circuit between LCRA's Salem and Hwy3613 Substations Build new 200 MVAR capacitor bank at Zenith Substation. Option 24: New Ragan Creek - Zenith 345 kv double-circuit. The transfer capability is improved by approximately 1,960 MW with an estimated project cost of $297 million and a transfer improvement value of 6.60 MW/$MM invested. This option affects only CenterPoint Energy s substations. The proposed reinforcements to achieve this transfer affect Oncor s, TMPA s, LCRA s, and CenterPoint Energy s transmission networks. This option can be expanded in the 41

future to interconnect the Limestone Substation, the same as considered in Option 25. New and additional system improvements included: o Build new 69 mile 345 kv double-circuit from Zenith Substation to new Ragan Creek 345 kv Substation o o Add two 345 kv line terminations at Zenith Substation Build new 345 kv Ragan Creek Substation with eight positions located along and looping in the double-circuit line from TMPA's ibbons Creek Substation to Oncor's Twin Oak Substation o Upgrade Bellaire Substation to Smithers Substation 345 kv circuit 98 o o Upgrade 138 kv substation equipment at Rayford Substation Re-conductor single 138 kv circuit between LCRA's Salem and Hwy3613 Substations. Option 25: New Limestone - Ragan Creek - Zenith 345 kv double-circuits: The transfer capability is improved by approximately 2,532 MW with an estimated project cost of $532 million and a transfer improvement value of 4.76 MW/$MM invested. This option affects only CenterPoint Energy s substations. The proposed reinforcements to achieve this transfer affect LCRA s and CenterPoint Energy s transmission networks. New and additional system improvements included: o Build new 69 mile 345 kv double-circuit from Zenith Substation to new Ragan Creek 345 kv Substation o o o o Add two 345 kv line terminations at Zenith Substation Build new 345 kv Ragan Creek Substation with 8 positions located along and looping in the double-circuit line from TMPA's ibbons Creek Substation to Oncor's Twin Oak Substation Build new 61 mile 345 kv double-circuit from new 345 kv Ragan Creek Substation to Limestone Substation Add two 345 kv line terminations at Limestone Substation o Upgrade Bellaire Substation to Smithers Substation 345 kv circuit 98 o o o Upgrade 138 kv substation equipment at Rayford Substation Upgrade 138 kv tie-line and substation equipment from Peters Substation to LCRA's Bell South Substation Re-conductor single 138 kv circuit between LCRA'S Salem and Hwy3613 Substations. CenterPoint Energy is willing to pursue any reasonable alternative to relieve the reliability concerns. Due to the critical need for these facilities, CenterPoint Energy is seeking an ERCOT determination that the ERCOT selected project to relieve the Houston Import Constraint is critical to reliability. If the ERCOT Board of Directors approves a project by November of 2013 and ERCOT designates the project as critical to reliability, CenterPoint Energy may be able to complete the ERCOT selected project by May 2018. 42

. 7. References [1] North to Houston Constraint Mitigation Project, CenterPoint Energy, July 2009 [2] Houston Import Project, Version 1, ERCOT, July 2010 [3] LTSA 2012 Transmission Needs Analysis, ERCOT December 2012 [4] ERCOT Report on Existing and Potential Electric System Constraints and Needs, ERCOT, December 2012 43

Appendix A. Transfer Capability of Identified Options 44

Rating B (MW) 2018 Study Case Init Init OPTION FCITC Limiting Constraint Contingency Description OPTION 1 Lufkin-Jordan -1582.2 L: 3118 LUFKNSS_8 138 3340 LUFKIN_8 138 1-251.0-157.4-111.7 Open 3109 STRYKER_5 345 3117 LUFKNSS_5 34 5 1 575.6 427.1-716 L: 46100 N_BELT 345A 345 B$0097 M102322 1.00 A 672.0 368.3 356.3 Open 46100 N_BELT 345A 345 B$0035 ALM21531 1.0 0 A1 384.7 372.7 Open 46110 N_BELT 138A 138 B$0035 ALM21531 1.0 0 A1 Open 49050 N_BELT_A1TER23.0 B$0035 ALM21531 1.0 0 A1 Open 46100 N_BELT 345A 345 B$0017 408589 1.0 0 A3 343 331.6 Open 46110 N_BELT 138A 138 B$0017 408589 1.0 0 A3 Open 49075 N_BELT_A3TER23.0 B$0017 408589 1.0 0 A3 1472.9 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 739 896.9 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 538.6 667 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 894.2 1058 OPTION 2 Salem - Zenith -649.7 L: 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 2 1086.0 629.6 579 Open 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 34 5 1 629.6 579 290.8 L: 7057 L_FAYETT5_1Y 345 7286 L_FAYETT8_1Y 138 1 685.0 338.4 339.3 Open 7057 L_FAYETT5_1Y 345 7058 L_SALEM_5_1Y 34 5 1 456.2 478.4 Open 7057 L_FAYETT5_1Y 345 7058 L_SALEM_5_1Y 34 5 2 456.2 478.4 840.2 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 744.4 831.8 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 618.9 705 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 977.6 1085.1 OPTION 3 Zenith - Fayetteville -1074.7 L: 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 2 1086.0 673.5 581.6 Open 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 34 5 1 673.5 581.6 981.2 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 728.5 828.4 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 613.1 712.9 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 971.6 1096.2 OPTION 4 Zenith- ibbons Creek 1437 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137.0 563 603.9 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 560.7 602.3 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-361.9-417.2 1660.8 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478.0-248.1-285.7 C:DB_ID_6139 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-246.5-284 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-300.6-316.8 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 44512 OBRIEN73138D138 1719.8 L: 7289 L_SALEM_8_1Y 138 7291 L_HIH368_1Y 138 1 392.0 178.2 213 Open 7289 L_SALEM_8_1Y 138 7292 L_BRENHA8_1Y 13 8 1 124.9 145.6 Open 7289 L_SALEM_8_1Y 138 7564 L_UYBUR8_1Y 13 8 1 83.9 85.8 1938.4 L: 3391 JEWETT_N5 345 44645 SNLTN_345 345 1 1450.0 578.2 826.9 C:DB_ID_15655 Open 967 IBN_CREK_5 345 3400 TWIN_OAK 5 34 5 1-648.1-865.8 Open 975 JKCREEK1 345 3400 TWIN_OAK 5 34 5 1-714.3-934.8 OPTION 5 Obrien - Fayetteville -1130.8 L: 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 2 1086.0 678.4 580.8 Open 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 34 5 1 678.4 580.8-1025.4 L: 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 1 1103.0 678.4 589.9 Open 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 34 5 2 678.4 589.9 903.8 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 747.8 844 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 604.6 694.9 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 961.3 1074 OPTION 6 Obrien -Salem -637.9 L: 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 2 1086.0 626.7 577.9 Open 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 34 5 1 626.7 577.9 174 L: 7057 L_FAYETT5_1Y 345 7286 L_FAYETT8_1Y 138 1 685.0 338.1 338.6 Open 7057 L_FAYETT5_1Y 345 7058 L_SALEM_5_1Y 34 5 1 453.5 466.6 Open 7057 L_FAYETT5_1Y 345 7058 L_SALEM_5_1Y 34 5 2 453.5 466.6 752.1 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 763.6 845.5 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 612.6 688.6 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 969.6 1064.5 OPTION 7 Holman -Obrien 222 L: 7055 L_FPPYD25_1Y 345 9073 HOLMAN 345 1 1150.0 777.3 807.6 Remove unit U1 from bus 110351 STP_STP_1 25.0 1375.0 MWdispatch Remove unit U2 from bus 110352 STP_STP_2 25.0 1375.0 MWdispatch 811.7 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 756.8 845 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 609.4 691.4 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 964.6 1066.5 Base Case Final 45

OPTION FCITC Limiting Constraint Contingency Description OPTION 8 Zenith- Salem - ibbons Creek 1685.6 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137.0 556.8 600.0 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 554.3 598.3 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-365.2-433.8 1725.8 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478.0-246.6-285.3 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-245.1-283.5 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-306.0-327.8 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 44512 OBRIEN73138D138 Rating B (MW) 2018 Study Case Init Init Base Case Final 1852.7 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526.0-353.3-393.9 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-250.7-282.2 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 326.3 381.7 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 2391.2 L: 7056 L_FPPYD15_1Y 345 7058 L_SALEM_5_1Y 345 1 1086.0 602 834.1 Open 967 IBN_CREK_5 345 3400 TWIN_OAK 5 34 5 1-585.1-777.2 Open 975 JKCREEK1 345 3400 TWIN_OAK 5 34 5 1-649.6-843.8 2608.5 L: 44900 ZENITH 345A 345 45500 T_H_W 345B 345 9 1450.0 498.4 757.3 Open 44900 ZENITH 345A 345 B$0244 ZENITH 1.0 0 A1 617 739 Open 44910 ZENITH 138A 138 B$0244 ZENITH 1.0 0 A1 Open 49085 49085_STAR 23.0 B$0244 ZENITH 1.0 0 A1 Open 44900 ZENITH 345A 345 45500 T_H_W 345B 34 5 71 498.4 757.3 OPTION 9 Zenith-Salem- TNPONE 1707.2 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137 556 600.1 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 553.5 598.4 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-364.2-433.2 OPTION 10 1729.1 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478 -246.5-285.4 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-245 -283.6 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-304.4-325.3 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 44512 OBRIEN73138D138 1733.4 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526 -354.9-392.9 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-255 -284.8 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 330 382.1 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 2010.2 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450 658.2 844.1 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 571.2 764.7 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 921 1162.4 Zenith - Fayetteville & Salem-ibbons Creek -78.9 L: 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 2 1086 594.4 587.9 Open 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 34 5 1 594.4 587.9 1690.5 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526 -355.2-392.8 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-255.3-285.4 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 330.5 382.4 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 1707.8 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478 -247-285.4 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-245.4-283.6 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-304.8-326.1 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 44512 OBRIEN73138D138 1828.1 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137 552.8 598.1 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 550.2 596.4 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-366.5-441.5 2153.2 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450 661.9 876.8 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 575.4 792.1 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 925.7 1196.1 46

OPTION FCITC Limiting Constraint Contingency Description OPTION 11 Sandow to Zenith 1310.4 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 718.1 843.4 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 599.6 727.1 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 952.1 1110.4 OPTION 12 Rating B (MW) 2018 Study Case Init Init Base Case Final Marion-Holman- Obrien 903.4 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 752.3 846.6 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 606.8 696 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 962.4 1073.3 OPTION 13 Hillje-Obrien 279.2 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 806.4 841 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 641.4 671.8 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 995.7 1033 OPTION 14 Twin Oak-Salem - Fayetteville-Zenith 722.8 L: 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 2 1086.0 535.8 588 Open 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 34 5 1 535.8 588 1665.1 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478.0-247.7-285.5 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-246.2-283.7 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-303.5-323.6 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 1725 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526.0-354.8-392.8 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-254.4-284.4 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 330.1 382.4 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 1823.3 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137.0 552.5 598.1 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 550 596.3 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-366.8-441.5 2053.7 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 647.4 840.3 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 567.6 767.7 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 915.9 1165.2 OPTION 15 Twin Oak-Zenith 1570.1 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137 558.6 602.1 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 556.2 600.4 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-363.5-424.6 1675.5 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478 -247.7-285.6 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-246.2-283.9 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-302.1-319 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 1856 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526 -352.8-393.3 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-253.5-284.1 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 328.7 382.1 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 2545.1 L: 7270 L_BELLSO8_1Y 138 46220 PETERS 138B 138 1 382 161.2 271 Open 44230 FLEWLN 138A 138 44510 OBRIEN 138A 13 8 73-320.8-333.9 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-302.1-327.8 2739 L: 44900 ZENITH 345A 345 45500 T_H_W 345B 345 9 1450 495.3 750.2 Open 44900 ZENITH 345A 345 B$0244 ZENITH 1.0 0 A1 616.1 738.8 Open 44910 ZENITH 138A 138 B$0244 ZENITH 1.0 0 A1 Open 49085 49085_STAR 23.0 B$0244 ZENITH 1.0 0 A1 Open 44900 ZENITH 345A 345 45500 T_H_W 345B 34 5 71 495.3 750.2 47

OPTION FCITC Limiting Constraint Contingency Description OPTION 16 Twin Oak-Salem-Zenith 1657 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137 558.6 602.1 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 556.2 600.4 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-363.5-424.6 1720.8 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478 -247.7-285.6 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-246.2-283.9 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-302.1-319 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 44512 OBRIEN73138D138 1771 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526 -354.2-393.1 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-253.5-284.1 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 328.7 382.1 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 2245 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450 640.2 848.1 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 560.7 775.9 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 908.4 1176.5 OPTION 17 Limestone-ibbons Creek-Zenith 1560.3 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137.0 558.7 601.7 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 556.2 600 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-365.1-426.2 1630.8 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478 -248.5-285.6 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-246.1-283.9 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-301 -317.7 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 44512 OBRIEN73138D138 2011.8 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526 -351-394.4 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-245.6-279.4 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 322.5 382.2 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 2537.3 L: 7270 L_BELLSO8_1Y 138 46220 PETERS 138B 138 1 382 161.3 270.4 Open 44230 FLEWLN 138A 138 44510 OBRIEN 138A 13 8 73-322.7-336.7 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-302.8-328.8 2567 L: 44900 ZENITH 345A 345 45500 T_H_W 345B 345 9 1450 511 755.2 Open 44900 ZENITH 345A 345 B$0244 ZENITH 1.0 0 A1 620.7 737.3 Open 44910 ZENITH 138A 138 B$0244 ZENITH 1.0 0 A1 Open 49085 49085_STAR 23.0 B$0244 ZENITH 1.0 0 A1 Open 44900 ZENITH 345A 345 45500 T_H_W 345B 34 5 71 511 755.2 Rating B (MW) 2018 Study Case Init Init Base Case Final 48

OPTION FCITC Limiting Constraint Contingency Description OPTION 18 Big Brown - Jordan 500 kv -836.4 L: 46100 N_BELT 345A 345 B$0097 M102322 1.00 A 672.0 371.6 356.3 Open 46100 N_BELT 345A 345 B$0035 ALM21531 1.0 0 A1 388 372.9 Rating B (MW) 2018 Study Case Init Init Open 46110 N_BELT 138A 138 B$0035 ALM21531 1.0 0 A1 Open 49050 N_BELT_A1TER23.0 B$0035 ALM21531 1.0 0 A1 Open 46100 N_BELT 345A 345 B$0017 408589 1.0 0 A3 346 331.6 Open 46110 N_BELT 138A 138 B$0017 408589 1.0 0 A3 Open 49075 N_BELT_A3TER23.0 B$0017 408589 1.0 0 A3-506.6 L: 3133 RICHLND2_5 345 3380 BIBRN 5 345 1 1052.0 486 453.9 C:DB_ID_16038 Open 2427 WATMLL_W5 345 3123 TRINDAD1_5 34 5 1-672.3-693.5 Open 2428 WATMLL_E5 345 2432 TRICRN1_5 34 5 1-1122.6-1118.1 Base Case Final 1828 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137.0 558.4 607.1 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 556 605.5 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-340.8-404.6 1938.7 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526.0-352.5-393.3 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-269.4-307.9 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 320.7 373.7 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 2133.5 42000 P_H_R 345E 345 B$0032 ALM21311 1.00 A 717 276.7 332.3 Open 42000 P_H_R 345E 345 B$0006 12053-01 1.0 0 A4 415.7 507.8 Open 42010 P_H_R 138A 138 B$0006 12053-01 1.0 0 A4 Open 49047 P_H_R A4TER23.0 B$0006 12053-01 1.0 0 A4 Open 42000 P_H_R 345E 345 B$0105 PHR A1 NEW 1.0 0 A1 351.3 424.3 Open 42015 P_H_R 138C 138 B$0105 PHR A1 NEW 1.0 0 A1 Open 49026 P_H_R A1TER23.0 B$0105 PHR A1 NEW 1.0 0 A1 2190.5 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 711.7 924.2 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 511.8 682.3 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 866.4 1087.4 OPTION 19 Big Brown-Zenith -523.2 L: 3133 RICHLND2_5 345 3380 BIBRN 5 345 1 1052.0 486.1 454.3 Open 2427 WATMLL_W5 345 3123 TRINDAD1_5 34 5 1-672.1-693.1 Open 2428 WATMLL_E5 345 2432 TRICRN1_5 34 5 1-1122.2-1117 1554.6 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137.0 560.1 603 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 557.7 601.3 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-360.7-421.1 1719.8 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526.0-354.7-392.4 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-255.8-286.2 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 330.5 382.8 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 1723.9 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478.0-246.7-285.7 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-245.2-283.9 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-300.4-317.8 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 44512 OBRIEN73138D138 2079.6 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 655.1 845.9 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 564.6 760.0 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 911.2 1153.0 OPTION 20 Navarro-Zenith 1505.8 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137.0 562.9 604.4 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 560.5 602.8 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-356.7-415.1 1547.9 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450.0 709.2 854.4 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 589.0 736.0 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 938.4 1120.2 49

OPTION FCITC Limiting Constraint Contingency Description OPTION 21 Upgrade 345 kv conductors 1239.2 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526 -362.6-391.2 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-276.4-302.6 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 346 386.5 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 1297.5 L: 7289 L_SALEM_8_1Y 138 7291 L_HIH368_1Y 138 1 392 185.2 212.8 Open 7289 L_SALEM_8_1Y 138 7292 L_BRENHA8_1Y 13 8 1 129.1 145.6 Open 7289 L_SALEM_8_1Y 138 7564 L_UYBUR8_1Y 13 8 1 84.5 86.1 1322 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137 570.5 609.5 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 568.3 608 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-346.7-394.4 1556.6 L: 3391 JEWETT_N5 345 44645 SNLTN_345 345 1 1450 585 786.2 Open 967 IBN_CREK_5 345 44645 SNLTN_345 34 5 75 679.1 865.2 Open 967 IBN_CREK_5 345 44645 SNLTN_345 34 5 99 679.1 865.2 Open 967 IBN_CREK_5 345 44645 SNLTN_345 34 5 99 679.1 885.1 OPTION 22 Limestone-Zenith 1561.4 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137 559.3 602.4 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 556.9 600.8 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-362.4-423.2 1691.2 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478 -247.3-285.7 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-245.8-283.9 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-301.4-318.5 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 44512 OBRIEN73138D138 Rating B (MW) 2018 Study Case Init Init 1814.6 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526 -353.5-393 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-252.2-283.8 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 327.7 382.4 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 2520.6 L: 7270 L_BELLSO8_1Y 138 46220 PETERS 138B 138 1 382 162.9 271.5 Open 44230 FLEWLN 138A 138 44510 OBRIEN 138A 13 8 73-319.1-332.2 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-301.4-326.9 2618.6 L: 44645 SNLTN_345 345 44900 ZENITH 345A 345 9 1450 619.6 851.8 Open 40600 ROANS 345C 345 40630 BOBVLE 345X 34 5 75 547.6 789.6 Open 44645 SNLTN_345 345 46500 TOMBAL 345B 34 5 74 891.9 1191.4 Base Case Final 50

OPTION FCITC Limiting Constraint Contingency Description OPTION 23 Limestone-Singleton- Zenith 1556.1 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137 559.1 602.1 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 556.7 600.4 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-364 -424.6 1658.5 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478 -248.1-285.7 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-246.5-283.9 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-302.2-319 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 44512 OBRIEN73138D138 1939.6 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526 -351.8-394.1 Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-248 -281.6 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 324.3 382.8 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 2523.2 L: 7270 L_BELLSO8_1Y 138 46220 PETERS 138B 138 1 382 162.4 271.1 Open 44230 FLEWLN 138A 138 44510 OBRIEN 138A 13 8 73-314.3-323.7 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-299.5-322.3 2709.8 L: 44900 ZENITH 345A 345 45500 T_H_W 345B 345 9 1450 474.8 750.7 Open 44900 ZENITH 345A 345 B$0244 ZENITH 1.0 0 A1 618.1 739.7 Open 44910 ZENITH 138A 138 B$0244 ZENITH 1.0 0 A1 Open 49085 49085_STAR 23.0 B$0244 ZENITH 1.0 0 A1 Open 44900 ZENITH 345A 345 45500 T_H_W 345B 34 5 71 502.1 755.1 OPTION 24 Ragan Creek-Zenith 1467.4 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137 562 603.5 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 559.6 601.8 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-362.3-419 1662.4 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478 -248-285.7 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-246.5-283.9 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-300.9-317.3 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 44512 OBRIEN73138D138 1798.9 L: 7289 L_SALEM_8_1Y 138 7291 L_HIH368_1Y 138 1 392 177.1 213 Open 7289 L_SALEM_8_1Y 138 7292 L_BRENHA8_1Y 13 8 1 124.2 145.6 Open 7289 L_SALEM_8_1Y 138 7564 L_UYBUR8_1Y 13 8 1 83.8 85.7 1988 L: 3391 JEWETT_N5 345 44645 SNLTN_345 345 1 1450 543.5 787.9 Open 3400 TWIN_OAK 5 345 49088 RA_CR 34 5 1 696.5 932.1 Open 975 JKCREEK1 345 3400 TWIN_OAK 5 34 5 1-754.8-997.5 OPTION 25 Limestone-Ragan Creek- Zenith 1567 L: 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 1137 558.4 601.6 Open 44005 W_A_P 345B 345 47000 BELAIR 345A 34 5 50 556 599.9 Open 47000 BELAIR 345A 345 47300 JENETA 345B 34 5 64-365.2-426.6 1631.6 L: 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7-478 -248.5-285.6 Open 44140 CLODIN 138B 138 44150 CCLODIN_138C 13 8 25-246.9-283.9 Open 44510 OBRIEN 138A 138 44511 OBRIEN25138C 13 8 25 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-302.9-319.6 Move 100.0 percent load from bus 44511 OBRIEN25138C138 tobus 44512 OBRIEN73138D138 1999.7 L: 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6-526 -351.1-394.2 Rating B (MW) 2018 Study Case Init Init Base Case Final Open 46240 PINHUR 138A 138 46520 CTOMBAL_8110 13 8 81-246 -279.4 Open 46510 TOMBAL 138A 138 46520 CTOMBAL_8110 13 8 81 Open 46510 TOMBAL 138A 138 46512 TOMBAL818045 13 8 81 322.8 382.1 Open 46052 LOUETA818005 138 46570 WESFLD 138B 13 8 81 Move 100.0 percent load from bus 46512 TOMBAL818045138 tobus 46511 TOMBAL668070138 Move 100.0 percent load from bus 46052 LOUETA818005138 tobus 46051 LOUETA668000138 2550.2 L: 7270 L_BELLSO8_1Y 138 46220 PETERS 138B 138 1 382 160.8 270.3 Open 44230 FLEWLN 138A 138 44510 OBRIEN 138A 13 8 73-322.9-337.1 Open 44450 MASON 138A 138 44510 OBRIEN 138A 13 8 25-302.9-329.1 2555.7 L: 44900 ZENITH 345A 345 45500 T_H_W 345B 345 7 1450 510.3 754.3 Open 44900 ZENITH 345A 345 B$0244 ZENITH 1.0 0 A1 620.5 736.8 Open 44910 ZENITH 138A 138 B$0244 ZENITH 1.0 0 A1 Open 49085 49085_STAR 23.0 B$0244 ZENITH 1.0 0 A1 Open 44900 ZENITH 345A 345 45500 T_H_W 345B 34 5 71 510.3 754.3 51

Appendix B. Preliminary Cost Estimates of Identified Options 52

ERCOT ESTIMATES Rural Urban Option 1 Option 2 Option 3 Option 4 Option 5 Lufkin-Jordan Salem - Zenith Zenith - Fayette Zenith- ibbons Creek Obrien - Fayetteville ($ MM/mi) ($ MM/mi) mi/units $ MM mi/units $ MM mi/units $ MM mi/units $ MM mi/units $ MM 345 kv New Single circuit (on double circuit capable towers) 1.95 3.25 19.25 37.54 New double circuit 2.44 4.10 127.40 310.86 50.00 122.00 66.00 161.04 63.00 153.72 74.00 180.56 Re-conductoring of existing single circuit line 0.72 1.43 0.00 0.00 0.00 0.00 Re-conductoring of existing double circuit line 1.14 1.99 Rebuilt existing double (complete tear down of towers and conductors) 2.07 3.53 add second circuit to an existing double circuit capable line 0.56 0.64 138 kv New Single circuit (on double circuit capable towers) 1.14 1.96 New double circuit 1.37 2.46 Re-conductoring of existing single circuit line 0.59 0.87 Re-conductoring of existing double circuit libe 0.64 1.22 500 kv New Single circuit (on double circuit capable towers) 2.70 Transformer 138/345 lesser than or qual to 600 MVA 7.98 138/345 lesser than or qual to 800 MVA 9.75 345/500 transformer 1200 MVA 16.73 eneral Susbstation 345 kv -ring bus 6-line terminals 15.94 0 0 345 kv substation breaker&1/2 > 6 - line terminal 23.22 6-breaker 500 kv ring substation 25.72 Expand substation with one additional line terminations 2 6 12 9 18 7 14 4 8 7 14 500kV substation breaker&1/2 > 6 - line terminal 35 TOTAL - TIE ONLY 323 178 175 162 195 REINFORCEMENTS $ MM/mi mi 7055 L_FPPYD25_1Y 345 9073 HOLMAN 345 1 0.72 10.89 7057 L_FAYETT5_1Y 345 7286 L_FAYETT8_1Y 138 1 9.75 1 1.00 9.75 7289 L_SALEM_8_1Y 138 7291 L_HIH368_1Y 138 1 0.59 3.36 3.36 1.98 3118 LUFKNSS_8 138 3340 LUFKIN_8 138 1 0.59 2.8 2.80 1.65 45500 T_H_W 345B 345 B$0011 4007037 1.00 A 10.7 1 7056 L_FPPYD15_1Y 345 7058 L_SALEM_5_1Y 345 1 0.72 27 46100 N_BELT 345A 345 B$0097 M102322 1.00 A 9.75 1 1.00 9.75 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 2 1.14 8.16 8.16 9.30 8.16 9.30 8.16 9.30 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 0.1 1 1.00 0.10 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6 1 1 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7 0.01 1 1.00 0.01 7270 L_BELLSO8_1Y 138 46220 PETERS 138B 138 1 0.59 8.72 44900 ZENITH 345A 345 B$0244 ZENITH 1.00 A 10.7 1 44900 ZENITH 345A 345 45500 T_H_W 345B 345 9 1.14 15.11 3391 JEWETT_N5 345 44645 SNLTN_345 345 1 0.72 49 3133 RICHLND2_5 345 3380 BIBRN 5 345 1 0.72 20 45500 T_H_W 345B 345 45600 ADICKS 345A 345 7 0.72 10.7 7273 L_WILLSP8_1Y 138 7286 L_FAYETT8_1Y 138 1 0.59 4.51 967 IBN_CREK_5 345 44645 SNLTN_345 345 7 1.12 9.41 42015 P_H_R 138C 138 B$0032 ALM21311 1.00 A2 9.75 1 COST of REINFORCEMENTS 11 19 9 2 9 Capacitor banks 3 1 TOTAL ESTIMATE 334 197 184 164 204 53

ERCOT ESTIMATES Rural Urban Obrien -Salem Holman -Obrien Creek Creek ($ MM/mi) ($ MM/mi) mi/units $ MM mi/units $ MM mi/units $ MM mi/units $ MM mi/units $ MM 345 kv New Single circuit (on double circuit capable towers) 1.95 3.25 19.25 37.54 19.25 37.54 New double circuit 2.44 4.10 63.00 153.72 84.00 204.96 98.4 240.096 139 339.16 115 280.6 Re-conductoring of existing single circuit line 0.72 1.43 Re-conductoring of existing double circuit line 1.14 1.99 Rebuilt existing double (complete tear down of towers and conductors) 2.07 3.53 add second circuit to an existing double circuit capable line 0.56 0.64 Option 6 Option 7 Option 8 Option 9 Option 10 Zenith- Salem Salem-ibbons Zenith-Salem- TNPONE Fayeteville -Zenith Salem-ibson 138 kv New Single circuit (on double circuit capable towers) 1.14 1.96 New double circuit 1.37 2.46 Re-conductoring of existing single circuit line 0.59 0.87 Re-conductoring of existing double circuit libe 0.64 1.22 500 kv New Single circuit (on double circuit capable towers) 2.70 Transformer 138/345 lesser than or qual to 600 MVA 7.98 138/345 lesser than or qual to 800 MVA 9.75 345/500 transformer 1200 MVA 16.73 eneral Susbstation 345 kv -ring bus 6-line terminals 15.94 345 kv substation breaker&1/2 > 6 - line terminal 23.22 6-breaker 500 kv ring substation 25.72 Expand substation with one additional line terminations 2 7 14 7 14 8 16 8 16 11 22 500kV substation breaker&1/2 > 6 - line terminal 35 TOTAL - TIE ONLY 205 219 256 355 340 REINFORCEMENTS $ MM/mi mi 7055 L_FPPYD25_1Y 345 9073 HOLMAN 345 1 0.72 10.89 10.89 7.84 7057 L_FAYETT5_1Y 345 7286 L_FAYETT8_1Y 138 1 9.75 1 1.00 9.75 7289 L_SALEM_8_1Y 138 7291 L_HIH368_1Y 138 1 0.59 3.36 3118 LUFKNSS_8 138 3340 LUFKIN_8 138 1 0.59 2.8 45500 T_H_W 345B 345 B$0011 4007037 1.00 A 10.7 1 7056 L_FPPYD15_1Y 345 7058 L_SALEM_5_1Y 345 1 0.72 27 27.00 19.44 46100 N_BELT 345A 345 B$0097 M102322 1.00 A 9.75 1 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 2 1.14 8.16 8.16 9.30 8.16 9.30 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 0.1 1 1.00 0.10 1.00 0.10 1.00 0.10 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6 1 1 1.00 1.00 1.00 1.00 1.00 1.00 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7 0.01 1 1.00 0.01 1.00 0.01 1.00 0.01 7270 L_BELLSO8_1Y 138 46220 PETERS 138B 138 1 0.59 8.72 44900 ZENITH 345A 345 B$0244 ZENITH 1.00 A 10.7 1 44900 ZENITH 345A 345 45500 T_H_W 345B 345 9 1.14 15.11 3391 JEWETT_N5 345 44645 SNLTN_345 345 1 0.72 49 3133 RICHLND2_5 345 3380 BIBRN 5 345 1 0.72 20 45500 T_H_W 345B 345 45600 ADICKS 345A 345 7 0.72 10.7 7273 L_WILLSP8_1Y 138 7286 L_FAYETT8_1Y 138 1 0.59 4.51 967 IBN_CREK_5 345 44645 SNLTN_345 345 7 1.12 9.41 42015 P_H_R 138C 138 B$0032 ALM21311 1.00 A2 9.75 1 1.00 9.75 COST of REINFORCEMENTS 19 8 21 1 10 Capacitor banks 3 1 1 3 TOTAL ESTIMATE 224 227 280 356 351 54

345 kv ERCOT ESTIMATES Rural Urban ($ MM/mi) ($ MM/mi) mi/units $ MM mi/units $ MM mi/units $ MM mi/units $ MM mi/units $ MM New Single circuit (on double circuit capable towers) 1.95 3.25 19.250 37.538 New double circuit 2.44 4.10 109 265.96 177 431.88 65 158.6 155 378.2 117 285.48 Re-conductoring of existing single circuit line 0.72 1.43 Re-conductoring of existing double circuit line 1.14 1.99 Rebuilt existing double (complete tear down of towers and conductors) 2.07 3.53 add second circuit to an existing double circuit capable line 0.56 0.64 Option 11 Option 12 Option 13 Option 14 Sandow to Zenith Marion-Holman- Obrien Hillje-Obrien Twin Oak-Salem- Fayeteville -Zenith Option 15 Twin Oak-Zenith 138 kv New Single circuit (on double circuit capable towers) 1.14 1.96 New double circuit 1.37 2.46 Re-conductoring of existing single circuit line 0.59 0.87 Re-conductoring of existing double circuit libe 0.64 1.22 500 kv New Single circuit (on double circuit capable towers) 2.70 Transformer 138/345 lesser than or qual to 600 MVA 7.98 138/345 lesser than or qual to 800 MVA 9.75 345/500 transformer 1200 MVA 16.73 eneral Susbstation 345 kv -ring bus 6-line terminals 15.94 345 kv substation breaker&1/2 > 6 - line terminal 23.22 6-breaker 500 kv ring substation 25.72 Expand substation with one additional line terminations 2 4 8 11 22 4 8 11 22 4 8 500kV substation breaker&1/2 > 6 - line terminal 35 TOTAL - TIE ONLY 274 454 167 438 293 REINFORCEMENTS $ MM/mi mi 7055 L_FPPYD25_1Y 345 9073 HOLMAN 345 1 0.72 10.89 7057 L_FAYETT5_1Y 345 7286 L_FAYETT8_1Y 138 1 9.75 1 7289 L_SALEM_8_1Y 138 7291 L_HIH368_1Y 138 1 0.59 3.36 3118 LUFKNSS_8 138 3340 LUFKIN_8 138 1 0.59 2.8 45500 T_H_W 345B 345 B$0011 4007037 1.00 A 10.7 1 7056 L_FPPYD15_1Y 345 7058 L_SALEM_5_1Y 345 1 0.72 27 46100 N_BELT 345A 345 B$0097 M102322 1.00 A 9.75 1 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 2 1.14 8.16 8.16 9.30 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 0.1 1 1.00 0.10 1.00 0.10 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6 1 1 1.00 1.00 1.00 1.00 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7 0.01 1 1.00 0.01 1.00 0.01 7270 L_BELLSO8_1Y 138 46220 PETERS 138B 138 1 0.59 8.72 8.72 5.14 44900 ZENITH 345A 345 B$0244 ZENITH 1.00 A 10.7 1 44900 ZENITH 345A 345 45500 T_H_W 345B 345 9 1.14 15.11 3391 JEWETT_N5 345 44645 SNLTN_345 345 1 0.72 49 3133 RICHLND2_5 345 3380 BIBRN 5 345 1 0.72 20 45500 T_H_W 345B 345 45600 ADICKS 345A 345 7 0.72 10.7 7273 L_WILLSP8_1Y 138 7286 L_FAYETT8_1Y 138 1 0.59 4.51 967 IBN_CREK_5 345 44645 SNLTN_345 345 7 1.12 9.41 42015 P_H_R 138C 138 B$0032 ALM21311 1.00 A2 9.75 1 COST of REINFORCEMENTS 0 0 0 10 6 Capacitor banks 3 1 1 3 TOTAL ESTIMATE 274 454 167 448 303 55

ERCOT ESTIMATES Rural Urban Big Brown-Zenith Navarro-Zenith Zenith ($ MM/mi) ($ MM/mi) mi/units $ MM mi/units $ MM mi/units $ MM mi/units $ MM mi/units $ MM 345 kv New Single circuit (on double circuit capable towers) 1.95 3.25 New double circuit 2.44 4.10 140 341.6 130.32 317.98 159 387.96 178 434.32 Re-conductoring of existing single circuit line 0.72 1.43 Re-conductoring of existing double circuit line 1.14 1.99 Rebuilt existing double (complete tear down of towers and conductors) 2.07 3.53 add second circuit to an existing double circuit capable line 0.56 0.64 Option 16 Twin Oak-Zenith - Salem Option 17 Option 18 Option 19 Option 20 Limestone- ibbons Creek- Big Brown - Jordan 500 kv 138 kv New Single circuit (on double circuit capable towers) 1.14 1.96 New double circuit 1.37 2.46 Re-conductoring of existing single circuit line 0.59 0.87 Re-conductoring of existing double circuit libe 0.64 1.22 500 kv New Single circuit (on double circuit capable towers) 2.70 182 491.4 Transformer 138/345 lesser than or qual to 600 MVA 7.98 138/345 lesser than or qual to 800 MVA 9.75 345/500 transformer 1200 MVA 16.73 4 66.92 eneral Susbstation 345 kv -ring bus 6-line terminals 15.94 345 kv substation breaker&1/2 > 6 - line terminal 23.22 6-breaker 500 kv ring substation 25.72 Expand substation with one additional line terminations 2 6 12 8 16 4 8 4 8 4 8 500kV substation breaker&1/2 > 6 - line terminal 35 2 70 TOTAL - TIE ONLY 354 334 636 396 442 REINFORCEMENTS $ MM/mi mi 7055 L_FPPYD25_1Y 345 9073 HOLMAN 345 1 0.72 10.89 7057 L_FAYETT5_1Y 345 7286 L_FAYETT8_1Y 138 1 9.75 1 7289 L_SALEM_8_1Y 138 7291 L_HIH368_1Y 138 1 0.59 3.36 3.36 1.98 3118 LUFKNSS_8 138 3340 LUFKIN_8 138 1 0.59 2.8 45500 T_H_W 345B 345 B$0011 4007037 1.00 A 10.7 1 7056 L_FPPYD15_1Y 345 7058 L_SALEM_5_1Y 345 1 0.72 27 46100 N_BELT 345A 345 B$0097 M102322 1.00 A 9.75 1 1.00 9.75 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 2 1.14 8.16 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 0.1 1 1.00 0.10 1.00 0.10 1.00 0.10 1.00 0.10 1.00 0.10 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6 1 1 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7 0.01 1 1.00 0.01 1.00 0.01 1.00 0.01 7270 L_BELLSO8_1Y 138 46220 PETERS 138B 138 1 0.59 8.72 8.72 5.14 44900 ZENITH 345A 345 B$0244 ZENITH 1.00 A 10.7 1 44900 ZENITH 345A 345 45500 T_H_W 345B 345 9 1.14 15.11 3391 JEWETT_N5 345 44645 SNLTN_345 345 1 0.72 49 3133 RICHLND2_5 345 3380 BIBRN 5 345 1 0.72 20 20.00 14.40 20.00 14.40 45500 T_H_W 345B 345 45600 ADICKS 345A 345 7 0.72 10.7 7273 L_WILLSP8_1Y 138 7286 L_FAYETT8_1Y 138 1 0.59 4.51 967 IBN_CREK_5 345 44645 SNLTN_345 345 7 1.12 9.41 42015 P_H_R 138C 138 B$0032 ALM21311 1.00 A2 9.75 1 1.00 9.75 1.00 9.75 COST of REINFORCEMENTS 1 8 25 16 0 Capacitor banks 3 1 TOTAL ESTIMATE 355 342 661 411 442 56

\ 345 kv ERCOT ESTIMATES Rural Urban New Single circuit (on double circuit capable towers) 1.95 3.25 ($ MM/mi) ($ MM/mi) mi/units $ MM mi/units $ MM mi/units $ MM mi/units $ MM mi/units $ MM New double circuit 2.44 4.10 130 317.2 130 317.2 69 168.36 130 317.2 Re-conductoring of existing single circuit line 0.72 1.43 Re-conductoring of existing double circuit line 1.14 1.99 33.60 66.86 0 0 0 Rebuilt existing double (complete tear down of towers and conductors) 2.07 3.53 102.1 211.35 add second circuit to an existing double circuit capable line 0.56 0.64 Option 21 Option 22 Option 23 Option 24 Option 25 Upgrade 345 kv conductors Limestone-Zenith Limestone- Singleton-Zenith Ragan Creek- Zenith Limestone-Ragan Creek-Zenith 138 kv New Single circuit (on double circuit capable towers) 1.14 1.96 New double circuit 1.37 2.46 Re-conductoring of existing single circuit line 0.59 0.87 Re-conductoring of existing double circuit libe 0.64 1.22 500 kv New Single circuit (on double circuit capable towers) 2.70 Transformer 138/345 lesser than or qual to 600 MVA 7.98 138/345 lesser than or qual to 800 MVA 9.75 345/500 transformer 1200 MVA 16.73 eneral Susbstation 345 kv -ring bus 6-line terminals 15.94 345 kv substation breaker&1/2 > 6 - line terminal 23.22 1 23.22 1 23.22 6-breaker 500 kv ring substation 25.72 Expand substation with one additional line terminations 2 4 8 8 16 2 4 4 8 500kV substation breaker&1/2 > 6 - line terminal 35 TOTAL - TIE ONLY 278 325.2 333 196 348 REINFORCEMENTS $ MM/mi mi 7055 L_FPPYD25_1Y 345 9073 HOLMAN 345 1 0.72 10.89 7057 L_FAYETT5_1Y 345 7286 L_FAYETT8_1Y 138 1 9.75 1 7289 L_SALEM_8_1Y 138 7291 L_HIH368_1Y 138 1 0.59 3.36 3.36 1.98 3.36 1.98 3118 LUFKNSS_8 138 3340 LUFKIN_8 138 1 0.59 2.8 45500 T_H_W 345B 345 B$0011 4007037 1.00 A 10.7 1 7056 L_FPPYD15_1Y 345 7058 L_SALEM_5_1Y 345 1 0.72 27 46100 N_BELT 345A 345 B$0097 M102322 1.00 A 9.75 1 7056 L_FPPYD15_1Y 345 7057 L_FAYETT5_1Y 345 2 1.14 8.16 44650 SMTHRS 345A 345 47000 BELAIR 345A 345 9 0.1 1 1.00 0.10 1.00 0.10 1.00 0.10 1.00 0.10 1.00 0.10 46261 RAYFRD668020 138 46295 RTHWOD 138A 138 6 1 1 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 44140 CLODIN 138B 138 44512 OBRIEN73138D 138 7 0.01 1 1.00 0.01 1.00 0.01 1.00 0.01 1.00 0.01 7270 L_BELLSO8_1Y 138 46220 PETERS 138B 138 1 0.59 8.72 8.72 5.14 8.72 5.14 8.72 5.14 44900 ZENITH 345A 345 B$0244 ZENITH 1.00 A 10.7 1 44900 ZENITH 345A 345 45500 T_H_W 345B 345 9 1.14 15.11 3391 JEWETT_N5 345 44645 SNLTN_345 345 1 0.72 49 3133 RICHLND2_5 345 3380 BIBRN 5 345 1 0.72 20 0.00 0.00 0.00 45500 T_H_W 345B 345 45600 ADICKS 345A 345 7 0.72 10.7 7273 L_WILLSP8_1Y 138 7286 L_FAYETT8_1Y 138 1 0.59 4.51 967 IBN_CREK_5 345 44645 SNLTN_345 345 7 1.12 9.41 42015 P_H_R 138C 138 B$0032 ALM21311 1.00 A2 9.75 1 1.00 9.75 1.00 9.75 1.00 9.75 COST of REINFORCEMENTS 3 16 16 2 16 Capacitor banks 3 1 0 TOTAL ESTIMATE 281 341 349 198 364 57

Appendix C. Detailed Cost Estimates of Selected Options 58

Option 8 - Zenith Substation to Salem Substation to ibbons Creek Substation Description Transmission Cost ($) Substation Cost ($) Build new 50 mile 345 kv double circuit from Zenith Substation to TSC's Salem Substation using 3-959 ACSS. Add two 345 kv line terminations at Zenith Substation rated at least 5000 Amps. Add two 345 kv terminations at Salem Substation Build new 49 mile 345 kv double circuit from TSC's Salem Substation to TMPA's ibbons Creek Substation using 3-959 ACSS. Add two 345 kv terminations at Salem Substation Expand TMPA's ibbons Creek Substation with two additional 345 kv line terminations with 5000 amp equipment. Upgrade 27 mile 345 kv circuit from TSC's Salem Substation to Fayeteville Substation using 3-959 ACSS. Upgrade Bellaire Substation to Smithers Substation circuit 98 to at least 1900 Amps continuous rating and at least 2010 Amps emergency rating. 190,909,000 8,000,000 186,364,000 4,000,000 0 4,000,000 19,440,000 10,000 0 Upgrade Substation equipment at Rayford Substation to increase rating of Rothwood Substation to Rayford Substation Circuit 66 to at least 3000 Amps. Upgrades circuit between Oncor's Twin Oak and and TMPA's ibbons Creek substations (one circuit loops into Jack Creek) 0 200,000 5,000,000 200 MVAr Capacitor banks at Zenith 3,000,000 TOTAL COST ALTERNATIVE ($ MM) 421 59

Option 15 - Zenith Substation to Twin Oak Substation Description Build new 117 mile 345 kv double circuit from Zenith Substation to Oncor's Twin Oak Substation using 3-959 ACSS. Add two 345 kv line terminations at Zenith Substation rated at least 5000 Amps. Expand Oncor's Twin Oak Substation with two additional 345 kv line terminations with 5000 amp equipment. Upgrade Bellaire Substation to Smithers Substation circuit 98 to at least 1900 Amps continuous rating and at least 2010 Amps emergency rating. Upgrade Substation equipment at Rayford Substation to increase rating of Rothwood Substation to Rayford Substation Circuit 66 to at least 3000 Amps. Upgrade tie-line Peters Substation to LCRA's Bell South Substation to at least 2000 Amps. Re-conductorin single 138 kv circuit between LCRA'S Salem and Hwy3613 substations Transmission Cost ($) Substation Cost ($) 443,182,000 4,000,000 0 4,000,000 10,000 0 0 200,000 5,145,000 400,000 1,983,000 0 200 MVAr Capacitor banks at Zenith 3,000,000 TOTAL COST ALTERNATIVE ($ MM) 462 60

Option 21 - Reconductor Existing N-H Tielines Description Upgrade 345 kv circuit 74 King Substation to Rothwood Substation with 25.67 miles of 3-959 ACSS and 5000 amp equipment. Upgrade 345 kv circuit 74 Rothwood Substation to Kuykendahl Substation with 2.62 miles of 3-959 ACSS and 5000 amp equipment. Upgrade 345 kv circuit 74 Kuykendahl Substation to Tomball Substation with 7.49 miles of 3-959 ACSS and 5000 amp equipment. Upgrade 345 kv circuit 75 King Substation to Kuykendahl Substation with 28.08 miles of 3-959 ACSS and 5000 amp equipment. Rebuild 345 kv circuit 74 and circuit 75 common tower double circuit from Tomball Substation corner to Singleton Substation with 46.47 double circuit miles of 3-959 ACSS and install 5000 amp equipment at terminal substations. Rebuild 345 kv circuit 98 and circuit 99 common tower double circuit from Zenith Substation to Singleton Substation with 53.17 double circuit miles of 3-959 ACSS and 5000 amp equipment at terminal substations. Upgrade Bellaire Substation to Smithers Substation circuit 98 to at least 1900 Amps continuous rating and at least 2010 Amps emergency rating. Upgrade Substation equipment at Rayford Substation to increase rating of Rothwood Substation to Rayford Substation Circuit 66 to at least 3000 Amps. Re-conductoring single 138 kv circuit between LCRA'S Salem and Hwy3613 substations Transmission Cost ($) Substation Cost ($) 16,500,000 1,500,000 1,700,000 0 4,800,000 1,500,000 17,900,000 1,500,000 157,000,000 4,700,000 190,000,000 400,000 10,000 0 0 200,000 1,983,000 0 TOTAL COST ALTERNATIVE ($ MM) 400 61

Option 24 - Zenith Substation to Ragan Creek 345 kv Substation Description Build new Ragan Creek 345 kv Substation with 8 positions located along and looping in the line TMPA's ibbons Creek Substation to Oncor's Twin Oak Substation. Loop in adjacent circuit TMPA's ibbons Creek Substation to TMPA's Jack Creek Substation. Substation equipment rated 5000 Amps. Build new 69 mile 345 kv double circuit from Zenith Substation to new 345 kv Substation using 3-959 ACSS. Add two 345 kv line terminations at Zenith Substation rated at least 5000 Amps. Upgrade Bellaire Substation to Smithers Substation circuit 98 to at least 1900 Amps continuous rating and at least 2010 Amps emergency rating. Re-conductoring single 138 kv circuit between LCRA'S Salem and Hwy3613 substations Upgrades circuit between Oncor's Twin Oak and and TMPA's ibbons Creek substations (one circuit loops into Jack Creek) TOTAL COST ALTERNATIVE ($ MM) Transmission Cost ($) Substation Cost ($) 5,000,000 20,000,000 261,364,000 4,000,000 10,000 0 1,983,000 0 5,000,000 297 62

Option 25 - Zenith Substation to Ragan Creek to Limestone Substation Description Transmission Cost ($) Substation Cost ($) Build new Ragan Creek 345 kv Substation with 8 positions located along and looping in the line TMPA's ibbons Creek Substation to Oncor's Twin Oak Substation. Loop in adjacent circuit TMPA's ibbons Creek Substation to TMPA's Jack Creek Substation. Substation equipment rated 5000 Amps. Build new 69 mile 345 kv double circuit from Zenith Substation to new 345 kv Substation using 3-959 ACSS. Add two 345 kv line terminations at Zenith Substation rated at least 5000 Amps. 5,000,000 20,000,000 261,364,000 4,000,000 Build new 61 mile 345 kv double circuit from new 345 kv Substation to Limestone Substation using 3-959 ACSS. Add two 345 kv line terminations at Limestone Substation rated at least 5000 Amps. 231,818,000 4,000,000 Upgrade Bellaire Substation to Smithers Substation circuit 98 to at least 1900 Amps continuous rating and at least 2010 Amps emergency rating. 10,000 0 Upgrade Substation equipment at Rayford Substation to increase rating of Rothwood Substation to Rayford Substation Circuit 66 to at least 3000 Amps. 0 200,000 Upgrade tie-line Peters Substation to LCRA's Bell South Substation to at least 2000 Amps. 5,145,000 400,000 TOTAL COST ALTERNATIVE ($ MM) 532 63

Appendix D. PV Analysis of Selected Options 64

2018 Base Case - ERCOT to Houston Transfer PV curves for Various Contingencies Option 8 1.04 Roans to Tomball Corridor' 1.02 Singleton to Roans Corridor' 1 Singleton to Zenith Corridor' Bellaire 345 kv Voltage (p.u.) 0.98 0.96 0.94 0.92 Pre-contingency' ibbons Creek to Singleton' STP to Dow Corridor' 0.9 0.88 0.86 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000 9200 9400 Ercot to Houston Pre-Contingency Interface Flow (MW) 2018 Base Case - ERCOT to Houston Transfer PV curves for Various Contingencies Option 15 1.04 1.02 Roans to Tomball Corridor' Jewett to Singleton Corridor' 1 Singleton to Roans Corridor' Bellaire 345 kv Voltage (p.u.) 0.98 0.96 0.94 0.92 Singleton to Zenith Corridor' Pre-contingency' ibbons Creek to Singleton' STP to Dow Corridor' 0.9 0.88 0.86 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000 9200 9400 ERCOT to Houston Pre-Contingency Interface Flow (MW) 65

2018 Base Case - ERCOT to Houston Transfer PV curves for Various Contingencies Option 21 1.04 1.02 Roans to Tomball Corridor' Jewett to Singleton Corridor' 1 Singleton to Roans Corridor' Bellaire 345 kv Voltage (p.u.) 0.98 0.96 0.94 0.92 Singleton to Zenith Corridor' Pre-contingency' ibbons Creek to Singleton' STP to Dow Corridor' 0.9 0.88 0.86 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000 9200 9400 ERCOT to Houston Pre-Contingency Interface Flow (MW) 2018 Base Case - ERCOT to Houston Transfer PV curves for Various Contingencies Option 24 1.04 1.02 Roans to Tomball Corridor' Jewett to Singleton Corridor' 1 Singleton to Roans Corridor' Bellaire 345 kv Voltage (p.u.) 0.98 0.96 0.94 0.92 Singleton to Zenith Corridor' Pre-contingency' ibbons Creek to Singleton' STP to Dow Corridor' 0.9 0.88 0.86 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000 9200 9400 ERCOT to Houston Pre-Contingency Interface Flow (MW) 66

2018 Study Case - ERCOT to Houston Transfer PV curves for Various Contingencies Option 25 1.04 1.02 Roans to Tomball Corridor' Jewett to Singleton Corridor' 1 Singleton to Roans Corridor' Bellaire 345 kv Voltage (p.u.) 0.98 0.96 0.94 0.92 Singleton to Zenith Corridor' Pre-contingency' ibbons Creek to Singleton' STP to Dow Corridor' 0.9 0.88 0.86 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000 9200 9400 ERCOT to Houston Pre-Contingency Interface Flow (MW) 67