How To Operate The Williston Uvls

Transcription

1 WND Winter Operating Guide 2012/2013 1

2 WND Operating Study Using EQ WIN- FINAL.sav developed through the 890 process Got load updates from MDU, Central Power, UM G&T Made several topology updates to the case MDU Ray sub Dickinson-Green River Caps Swapped some NESET load over to Blaisdell Blaisdell is now serving Palermo, Stanley- MW7, Belden, Robinson lake, Finstad, East Newtwon, Parshall Adjusted some power factors based upon what was seen in the summer Set Kenaston, SWMINOT, HESS GASS, GARDENCREEK, Stateline to non-scaleable. These are large industrial loads and should be fairly constant. 2

3 Base Case The base case has a Williston Load Pocket Value of 583 MW The loads were distributed as follows WILLD=583.6 CCWAT=245.0 WATFORD_LOAD=90.5 KENMARE_LOAD=29.1 STANLEY_LOAD=18.7 WILLISTON_LOAD=78.7 WN_JUDSON_FLOW=112.6 TIOGA_LOAD=18.7 NESET_LOAD=65.7 KILLDEER_LOAD=45.2 CHARLIE_CRK_LOAD=16.6 DICKINSON_LOAD=84.6 MINOT_AREA=189.5 SWMINOT=8.4 BTHOLD=7.5 KENASTON=7.6 BLAISDELL= 71.4 MW 3

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5 Williston Area Load Pocket Defined interface that we use to track load levels. Have been tracking for a little over a year now. Last Winter peaked at 400 MW s How high will it get this Winter? How high can it reliably get this Winter? WOLF POINT 115 TO POPLAR 115 RICHLAND 115 TO WILLISTON 115 CHARLIE CREEK 230 TO WATFORD CITY 230 LOGAN 230 TO BLAISDELL 230 LOGAN 115 TO KENMARE 115 BDV 230 TO TIOGA 230 CULBERTSON GEN 5

6 Williston Area Load Pocket Cont. 400 WTN.SCADA.WN (WN ALGI WILLISTON LOAD POCKET MW) /07/11 10/27/11 12/16/11 02/04/12 03/25/12 05/14/12 07/03/12 08/22/12 10/11/12 6

7 Western North Dakota System Oneline Williston 230 Tioga 230 Logan 230 Watford 230 Charlie Creek 345 7

8 B10T Reduced to 65 MW s (S N) and Culbertson Generation offline

9 B10T Reduced to 15 MW S N and Culbertson Generation offline

10 B10T Reduced to 15 MW S N and Culbertson Generation online at 95 MW s

11 System Intact Main Concerns System Intact Voltage at Kenmare/ Kenaston Kenaston Caps were delayed to Spring of 2013 Looking at boosting the tap ratio at Tioga/NESET to provide a slight boost. Studies show this can provide a 1-1.5% p.u. voltage boost at Kenmare. Loss of WN 230/115 Tx Moving the WC WN 115 to 230 kv the Transformer becomes critical. B10T has very little effect on this contingency. Solution set up UVLS at either Williston May need MW depending upon the load level and scenario Loss of WC CCR 230 Next most critical contingency Low voltages in the region 11

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13 System Intact without Culbertson available Main Concerns Loss of WN 230/115 Tx Moving the WC WN 115 to 230 kv the Transformer becomes critical. B10T has very little effect on this contingency. UVLS at Williston will mitigate for this contingency Loss of WC CCR 230 Next most critical contingency Low voltages in the region At 475 MW s without Culbertson breaker the 230 kv ring will need to be opened to mitigate for this contingency. 13

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15 Kenmare Voltage Had trouble in Winter 2011/2012 staying above 109 kv (.95 p.u.) during peaks 115/57 kv Tx has a 30 MVA capacity This winter modeling an additional 7.5 MW s at Kenaston which is adjacent to Kenmare. Kenaston Caps were delayed until March 2013 Models show re-tapping the Tioga and Neset 230/115 Tx may provide an additional 1 1.5% boost in Kenmare 115 kv voltage 15

16 Kenmare Voltage Cont 16

17 Worst System Outages Williston 230/115 Tx Projected 200 MW hanging from Williston 115 kv system can not support this load Charlie Creek Watford City 230 kv Eliminates key 230 path north of the lake Hangs additional load off of Williston Logan Blaisdell 230 kv Eliminates key 230 path north of the lake Hangs additional load off of Tioga Antelope Valley Charlie Creek 345 kv line Eliminates key transmission path to the Western North Dakota Area Next contingency (N-2) may overload underlying 115kV system 17

18 Williston 230/115 Tx Concern Williston Winter Peak 2011/ 2012 Configuration and Loads Williston Winter Peak 2012/ 2013 Configuration and Peak Load assumptions TGA TGA CQE Grenora 38MW WN /115 CQE Judson 112 MW WN /115 WC FVW 81 MW WN 115 WC TGJ FVW 80 MW WN 115 TGJ Winter 2011/2012 load served from Williston peaked at 120 MW Winter 2012/2013 load served from Williston is expected to peak at 192 MW That s a 60% increase from last winter. Removed WC 115 kv source and added WC 230 kv source Puts higher reliance on the 230/115 kv Transformer at Williston Transformer is highly reliable and another one is expected to be placed in service by end of year 2013 along with additional generation and synchronous condenser at Pioneer 18

19 Williston 230/115 Tx Concern cont As Planners we plan for the worst So how bad could it be? Case 1: Worst Case Williston load pocket scaled to 583 MW and 192 MW served out of Williston Without Culbertson providing support At peak load without Culbertson providing support 50 MW would need to be shed to maintain kv or.9 p.u. And an additional 20 MW would need to be shed to maintain kv or.95 p.u. With Culbertson providing support At peak load with Culbertson providing support 30 MW would need to be shed to maintain kv or.9 p.u. And an additional 20 MW would need to be shed to maintain kv or.95 p.u. Case 2: Williston load pocket scaled to 495 MW and 160 MW served out of Williston Without Culbertson providing support This load level without Culbertson providing support 5 MW would need to be shed to maintain kv or.9 p.u. And an additional 15 MW would need to be shed to maintain kv or.95 p.u. With Culbertson providing support At peak load with Culbertson providing support 0 MW would need to be shed to maintain kv or.9 p.u. And an additional 0 MW would need to be shed to maintain kv or.95 p.u. Low probability of this contingency Implement UVLS to prevent the need for pre-contingent load limitations for such a low probability event. 19

20 Williston UVLS Initial Proposal for UVLS on Williston 57 kv bus and/or somewhere on Williston-Judson-Stateline-Mont-Strandahl-Barr Butte-Grenora-Plentywood 115 kv line UVLS required when the combined load on the Williston 57 kv bus and on the Judson 115 kv line is greater than 160 MW Stage Breaker Description Delay Load 1 WN 3152 Stony Creek, MDU, LYC Trenton 57 kv 2 sec 28 MW 2 WN 3656 MWEC 12.47, WAPA Station Service* 2.5 sec 10 MW 3 WN 3552 MDU Williston 57 kv 3 sec 30 MW *WAPA would request MWEC switch load off this circuit after a UVLS operation so station service could be restored Automatic UVLS provides a controlled way to reduce loading and prevent a voltage collapse from occurring The system could be reconfigured after automatic UVLS operates to allow remaining industrial loads to perform an emergency shut down and restore service to residential and high priority loads 20

21 Williston UVLS The WND Operating Guide contains steps such as starting Culbertson Generation above certain load levels to minimize the chance of UVLS operating by keeping post-contingent voltages as high as possible Worst Case UVLS Operation for Various Single Contingencies Culbertson Unavailable, Williston + Judson Load = 182 MW, Williston Load Pocket = 575 MW Outage Stages of Load Drop MW of Load Drop Williston 230/115 Transformer 2 38 Watford City Charlie Creek 230* 3 68 Watford City Charlie Creek 230 Open Tioga Boundary Dam 230 (B10T) 0 0 Leland Olds Logan Logan Blaisdell Antelope Valley Charlie Creek *The WND Operating Guide contains steps to open the 230 kv ring at Watford City for high load levels with Culbertson unavailable, this would prevent the Williston UVLS from operating 21

22 LGN-BLS 230 Table Williston Load Pocket Limitation - Blaisdell - Logan 230 kv Prior outage** B10T* MCCS Williston / Tioga Load (S to N) Cul CT (E tow) Limiting Elements Limiting Contingency Load < Richland - FVW, Logan - Berthold WAT - CCR < Load < Richland - FVW, Logan - Berthold WAT - CCR < Load < Kenmare, Kenaston, Berthold,Voltage System Intact Load >= Kenmare, Kenaston, Berthold,Voltage System Intact Main Concerns Hanging additional load off of Tioga and cutting 230 path to Tioga 110 MW short of system Intact limits Loss of Watford City Charlie Creek 230 is the most critical next contingency Opens both ends of the 230 kv loop Richland Fairview 115 kv overload Kenmare Stanley 115 kv overload, Logan Berthold Kenmare overload Low voltages at Kenmare, Stanley, Berthold Implement load curtailments somehow Reducing load at Kenmare will help with System Intact voltage Opening Breaker 782 on the Watford City 230 kv ring bus pre-contingent. 22

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24 LGN BLS 230 cont.. Table Williston Load Pocket Limitation - Blaisdell - Logan 230 kv Prior outage** Culbertson unavailable B10T* MCCS Williston / Tioga Load (S to N) Cul CT (E tow) Limiting Elements Limiting Contingency Load < Richland - FVW, Logan - Berthold WAT - CCR < Load < Richland - FVW, Logan - Berthold WAT - CCR 230 Load >= Kenmare, Kenaston, Berthold,Voltage System Intact Worst Case Culbertson unavailable how do limits look? Limit 450 MW s almost 150 MW s short of system Intact limit. Will likely see low voltages at Kenmare 24

25 LGN-BLS 230 Cont.. How does Opening Watford City Breaker 782 pre-contingent help? Allows us to overlook the worst contingency Done during Worst Case System Intact and Certain prior outages where it s advantageous Only done at certain load levels The next limiting contingency becomes Watford City Williston. Load reductions at Watford will not help this limit Watford City 230 kv Watford City 230 kv Williston Charlie Creek 230 Williston Charlie Creek Watford City 230/115 Tx Watford City 230/115 Tx Pre-contingent System Preposition Post-contingent fault operation 25

26 LGN BLS 230 cont

27 LGN BLS 230 and WC-CCR cont

28 Watford City CCR 230 kv Outage Virtually Identical to the Blaisdell Logan Prior Outage limits. Difference being the amount of load served at Blaisdell Main Concerns Cuts 230 kv path to Williston area. Hangs additional load off of Williston Almost 110 MW short of system intact limits and projected Winter Peak Loss of LGN BLS 230 is the most critical next contingency Opens both ends of the 230 kv loop Richland Fairview 115 kv overload Kenmare Stanley 115 kv overload, Logan Berthold Kenmare overload Low voltages at Kenmare, Stanley, Berthold Implement load curtailments somehow Reducing load at Kenmare will help with System Intact voltage Opening Breaker 1486 on the Blaisdell 230 kv ring Bus pre-contingent. 28

29 Watford City Watford City Winter Peak 2011/ 2012 Configuration and Peak Loads Watford City Winter Peak 2012/ 2013 Configuration and Peak Load assumptions 8.1 MVAR Williston 115 kv 68 MW WC 115 Charlie Creek MVAR 95 MW WC 115 WN /115 Charlie Creek 230 Williston 230 Winter 2011/2012 load served from Watford City peaked at 68 MW Concerns were system Intact voltage at Watford City Moved 8.1 MVAR mobile capacitor to Cherry Creek to help make it through Winter 2012/2013 Winter 2012/2013 load served from Watford City is expected to peak at 95 MW That s a 40% increase from last winter. 230 kv source is stronger and additional 30 MVARs at Watford City 115 kv bus eliminate System Intact voltage concerns. However in System Intact Conditions it is preferable to utilize the Killdeer delivery to it s full capability and offload the Watford City delivery to any extent possible. Offline studies estimate the Killdeer delivery can support up to 60 MW s Concern is post contingent CCR-Watford City operation. Offline studies show this configuration can only support 75 MW s at 109 kv or.95 p.u. post contingent Pre-contingent limits can be avoided by opening Breaker 782 in the ring bus to mitigate the effects of the Charlie Creek Watford City 230 kv fault. 29

30 AVS CCR 345 Table Williston Load Pocket Limitation - AVS - Charlie Creek 345 kv Prior outage Williston / Tioga B10T MCDC Limiting Limiting Elements Load (S to N) Cul CT (E to W) Contingency Note Load < 335 Haliday - Beulah Leland Olds - Logan 230 Dickinson - Mandan 1,2 335< Load 385 Haliday - Beulah online 20 Leland Olds - Logan 230 Dickinson - Mandan 3 385< Load Haliday - Beulah Dickinson - Mandan 4 Load => Haliday - Beulah Dickinson - Mandan 4, 5 Main Concerns Cuts major East-West path from the coal fields into the load pocket 160 MW short of system Intact limits Requires Miles City DC tie to stay at 20 MW East to West Loss of Dickinson - Mandan 230 is the most critical next contingency Leland Olds Logan 230 Overload Beulah Haliday Killdeer Charlie Creek 115 kv overload Low voltages at Haliday, Killdeer, Charlie Creek Possible solutions include Reverse Miles City DC Tie Run Miles City and/or Glendive CTs Shift load from Killdeer to Watford City (can t be done quickly) Implement load curtailments somehow 30

31 Load Limits how to implement? Worst Case with Culbertson unavailable may need up to 150 MW s Limits are set by operating guides for each prior outage if the load pocket is expected to exceed the limit then load reductions will be called for. Propose to break up into smaller area s and prioritize within each area Will be looking for larger industrial loads. Williston/ Judson-Stateline-Mont load Projected peak 60 MW s needed Tioga/Wheelock/Blaisdell load Projected peak 50 MW s needed Stanley/Kenmare/Kenaston/Berthold load 62.9 Projected peak 15 MW s needed Watford City load 90.5 Projected peak 25 MW s needed 31

32 Load Reductions Discussion Large loads would not necessarily need to be shut off. They could be reduced to a minimum output/ hibernation state. We would need to know what kind of a reduction this minimum state would provide Example load X is 15 MW s and their hibernation state is 3 MW s. Calling for load X to go into hibernation provides a 12 MW benefit and prevents their plant from sustaining irreparable damage. 32

33 Load Reductions discussion cont.. Williston/ Judson-Stateline-Mont load Reduction Stage Load Information Amount Estimated Entity Contact information 1 MDU Furnace 15 MW s MDU John Doe 2 Stateline 25 MW s MWE John Doe 3 xxxx 20 MW s xxx xxxxx Stage Tioga/Wheelock/Blaisdell load Reduction Load Information Amount Estimated Entity Contact information 1 xxxx 10 MW s xxxx John Doe 1 xxxx 10 MW s xxxx John Doe 2 xxxx 20 MW s xxxx John Doe 3 xxxx 10MW s xxx xxxxx 33

34 Conclusion System Intact limit for Winter 2012 /2013 is 600 MW s for the Williston Load Pocket Limitation is low system intact voltage at Kenmare/Kenaston WC-CCR 230 kv contingency Williston 230/115 kv Tx contingency will be mitigated with UVLS at Williston 115 kv substation Worst Case prior outages were studied and limits were derived Potentially 150 MW s could be called upon for pre-contingent reductions. These are Worst Case scenario s and the probability of them happening is quite low. However we need a plan of action in case they do. Otherwise we ll have to just start opening breakers or risk total system collapse. 34