Karnataka Electricity Regulatory Commission Discussion note on Draft KERC (Forecasting, Scheduling, Deviation settlement and related matters for Wind and Solar Generation sources) Regulations, 2015. 1.0. Preamble: a) The installed capacity of Renewable Energy generation in Karnataka was 5068 MWs as on 31-03-2015, which accounts for 33.66% of the total installed capacity of 15052 MW including the State s share from CGS. The installed capacity of wind generation is about 2400 MW accounting to about 47.35 % of Renewable Energy generation and is about 15.94 % of total installed capacity in the State. b) A minimum load of 4125 MW was recorded in the State at about 3.0 AM on 31-08-2014 (with a peak load of 5878 MW on the same day and the peak demand of 9549 MW during FY-15). The wind generation was maximum from 30 th August, 2014 to 8 th September, 2014. There was a forced backing down of the wind generation ranging between 761 MW to about 1742 MW during the maximum wind generation period to maintain the frequency band within maximum permissible limit of 50.2 Hz, after taking all other possible measures like minimizing the thermal and hydel generation. In spite of backing down the wind generation, the RE generation was about 35 to 40 MU per day and wind generation was about 17.96 MU to 27.80 MU per day during these days. (The details are shown in annexure-a) c) The installed capacity of solar generation in the State is about 83 MW and about 800-1000 MW capacity is proposed to be added during FY16 and FY17. A big solar generation park of 2000 MW is proposed to be established in Pavagada Taluka of Tumukuru district. d) Renewable energy generation (wind and others) in the southern region as on 30-04-2015 was about 15117 MW which accounts for 23.20% of 1
total installed generation capacity of 65080 MW from all sources and about 80% of renewable energy sources in the region. e) Karnataka State is having substantial agricultural loads and these loads will be minimum (sometimes zero) during monsoon season when the wind generation will be maximum during this period. The system loads in the Karnataka will be minimum and also there will be substantial quantum of generation from the mini and major hydro plants from the water flows down stream of the pick-up dams and storage dams, under normal monsoon conditions. f) The Wind energy generation is found to be very consistent from year to year, but has significant variation over shorter time scales (high variability). Generally, the peak wind resource availability will not coincide with the system peak demand but coincides with light loads during night hours of monsoon period when the system demand is lowest during the year. The wind generation being infirm power, there will be frequent ramp up and ramp down in its generation due to varying wind speed. The thermal plants generation cannot be reduced below a certain capacity due to technical reasons. The load and generation balancing due to frequent ramp up and ramp down of wind generation is causing serious Grid operational problems. Grid operation becomes a big challenge for facilitating large scale integration of variable nature of Renewable Energy Sources (RES), like wind and solar without compromising on the stability and security of the Grid. Moreover, as the country is deploying strict grid disciplinary measures and moving towards a tighter operational frequency band, it becomes even more challenging to balance and operate with wide variability of wind generation. The wind and solar power penetration of more than 25 % to 30 % of system demand at any point of time will create operational and balancing issues. The variation in grid frequency and the ability of the conventional generators to respond in short 2
duration of time are the two main concerns arising out of the variable wind and solar generation. g) Generation of power from wind and solar is totally influenced by the nature, i.e. wind velocity and solar insolation, climatic changes and geographical condition, which are difficult to accurately predict /forecast. h) In the last two years, many of the wind generation plants are backed down in Karnataka during high wind and low load monsoon periods for the grid operational issues of high system frequency. The problem will become more acute during the subsequent years due to addition of more wind and large scale solar power generators in Karnataka. i) Adequate capacity of Hydro and Gas based generation capable of responding to quick ramp up and ramp downs of wind and solar generation will mitigate to some extent such problems caused by variable wind and solar generation. j) Access to transmission and proper evacuation to load centres another very important consideration in developing wind and solar energy. k) It is also important to note that uncertainty in wind and solar energy generation and the challenge to forecast. The complexity of weather related factors and geographical features make it difficult to predict wind velocity and potential for electricity generation at a location. Solar irradiance at a location is influenced by a number of factors, which include time of the day, temperature, cloud cover and particulate matter in the air. l) Most of the wind and solar energy generators are presently connected to intra-state network and in future are likely to be connected to the inter-state and inter-regional transmission system (ISTS & IRTS). As of now there is no power flow from wind and solar generations between interregions and inter-state since most of the wind and solar generators are tied up with respective State power distribution utilities and third party sales through Open access within the State boundaries. 3
m) Recently, the CERC has issued the amendment to the CERC DSM and related matter Regulations, 2014 for Forecasting, Scheduling and Imbalance handling of interstate transactions of Wind and Solar Generation. n) Hence it is found necessary to formulate Karnataka Electricity Regulatory Commission (Forecasting, Scheduling, Deviation settlement and related matters for Wind and Solar Generation sources) Regulations, 2015 for the optimal utilization of wind and solar generations. 2.0. Objective and Scope: a) The objective of this proposals is to formulate KERC (Forecasting, Scheduling, Deviation settlement and related matters for Wind and Solar Generation sources) Regulations, 2015 in order to facilitate large scale integration of Wind and Solar generating stations while maintaining the grid stability and security as envisaged under IEGC and KEGC, through forecasting, scheduling and commercial mechanism for deviation settlement of these generators. b) It is essential that the Grid operator has information in advance regarding the quantum of the wind and solar energy that is expected to be injected into the grid. This is especially critical for variable and infirm energy sources of such wind and solar. Forecasting and scheduling of these generators is critical to anticipate balancing requirements and establish requisite generation reserves to maintain load generation balance and grid reliability. At the same time, due to the intermittent nature of these sources, special provisions must be made so that the generators are not unduly penalized. 4
3.0. Forecasting Tools: a) Renewable Energy Management Centres (REMCs): REMS, equipped with advanced forecasting tools are being established in the country for forecasting wind and solar generation. b) M/s NIWE (National Institute of Wind Energy) have already taken up a pilot study for wind forecasting project by installing wind forecasting tools in all the wind mill locations in Tamil Nadu. The project envisages installing of wind forecasting tools and also collecting live energy data from wind energy pooling substations, installing equipments for real time measurement of wind generation with communicative ABT meters in all wind energy pooling substations and providing consolidated real time wind energy data on a dash board installed at Central Station in Chennai. In addition, the real time data will be fed into NIWE s forecasting system that can be used for scheduling and forecasting wind generation. The forecasting of 7480 MW wind installations is now operational and made available to Tamil Nadu SLDC and it is learnt that it is almost 85% near to actual. 4.0. Draft Frame work for Forecasting, Scheduling & Handling deviations from schedule for the infirm wind and solar generation. 4.1. Applicability : The proposed frame work is applicable to: a) All Wind Generators having a combined installed capacity of 10.0 MW and above at the pooling station whether they are supplying power to ESCOMs or to third party consumers through open access or for captive consumption through open access within or outside the State. b) All Solar Generators with installed capacity of 5.0 MW and above at the pooling station whether they are supplying power to ESCOMs or 5
to third party consumers through open access or for captive consumption through open access within or outside the State. 4.2. Fore casting: a) The forecasting is an estimation of probable generation of wind and solar power plants. Forecasting is an essential pre-requisite and shall be made mandatory for scheduling of the wind and solar generation. b) The existing wind and solar power plants shall either by themselves or through Qualified Coordinating Agency (QCA) or through an Aggregator shall establish forecasting tools within three months from the effective date of these Regulations and for new wind and solar generators they shall be established before commissioning of their plants. c) Alternately services of REMCs (Renewable Energy Management Centres) may be availed for installing forecasting tools and generation forecasting. d) The forecast by the wind and solar generators shall be wind-farm/solar facility centric and will form the basis of scheduling. 4.3. Scheduling ( Generation and Loads): a) Schedule details: i. The wind and solar power plants either by themselves or through Qualified Coordinating Agency (QCA) or through an Aggregator shall furnish weekly, day ahead and intraday generation schedules of 15 minutes interval block period to SLDC by using / establishing appropriate forecasting tools at their Wind-farm /Solar facility. ii. Forecasting and scheduling Point: The forecasting and scheduling of wind and solar generators shall be conducted at pooling station level which being a commercial metering point, though the forecasting tools are installed at wind-farm/solar facility. 6
b) Frequency of Revisions Considering the fact that wind and solar generation is intermittent and variable in nature and also taking into account the fact that accuracy of forecast improves as we move closer in time, the Wind and Solar energy generator shall be allowed more opportunities to revise the schedule. It is therefore proposed to provide an opportunity to the Wind and Solar generators to revise the day ahead schedules for a maximum of 16 revisions during the intraday, one each in one and half hour time slot starting from 00:00 hours during the day with prior notice of at least 60 minutes for each revision. c) The wind, solar power and other RES should be given first priority in generation scheduling and dispatching under normal power system operating conditions. d) Grid operator (SLDC) should consider forecasted generation schedule of wind and solar power in the midterm to long term, day-ahead and intraday operation planning processes of scheduling and fully make use of the flexibility from conventional power plants, as well as the capacity of inter grid tie-lines to accommodate the maximum wind and solar power while maintaining system security and reliability. e) The Principal generator/ QCA/ Aggregator involved for connectivity, long-term open access and medium-term open Access in intra-state transmission and related matters including long term agreements with ESCOMs shall undertake all operational and commercial responsibilities including forecasting and scheduling for the wind and solar generating station. 4.4. Computation of error quantity: % Error (deviation) = (Actual Generation - Scheduled Generation) X 100 (Scheduled Generation) 7
5.0. Metering, sharing of data and Telemetry. a) Metering: SEMs (Special Energy Meters 0.2s class of accuracy) shall be provided at the pooling station of wind and solar power plants, with a provision for recording and storing all the load survey and billing parameters for every 15 minutes interval block period. Monthly meter readings shall be forwarded to the SLDC in addition to data acquisition through SCADA, for energy accounting as per the existing practice b) Telemetry: Data telemetry shall be mandatorily adopted at the turbine/inverter level. Parameters such as turbine availability, power output and realtime weather measurements (wind speed, temperature, pressure etc) must be provided by each wind and solar Principal generator/ QCA /Aggregator. c) Communication: i. The wind and solar Principal generator/ QCA / Aggregator whose scheduling is done by the SLDCs, shall provide full data telemetry and communication facilities to the concerned SLDC. ii. A preparatory window shall be provided for the wind and solar Principal generator/ QCA /Aggregator to ensure installation of data measurement and telemetry equipment and for SLDCs to prepare their systems and teams for receipt of regular data and schedules. d) Procedure for data telemetry and communication requirements: The SLDC will evolve the detailed procedure for data telemetry and communication requirements solicit public comments and seek necessary approval of the Commission for such procedure within two month from the effective date of Regulation. 8
6.0. Implementation of Intra-State ABT and Imbalance Handling (Deviation Settlement Mechanism): 6.1. Methodology to account for and settle the deviations by wind and solar energy generators. a) The day ahead scheduling in the country is being done for all inter- State schedules as per the Indian Electricity Grid Code on the basis of 15 minutes interval time blocks except for RES. The deviation between schedule and actual power flow is called Unscheduled Interchange (UI) for which commercial settlement is done as per the Unscheduled Interchange (UI) rates specified by the Central Electricity Regulatory Commission (CERC). The UI rates are variable depending on the frequency and the quantum of drawal and they tend to discourage over drawal and under generation. The day ahead schedules can also be revised with prior notice of 60 minutes. b) KERC vide ORDER No.B/09/5 dated 20 th June 2006 have brought the following Users and Generators in the State under intra State ABT and deviation settlement mechanism: i. All ESCOMs and Hukeri Electricity Cooperative Society ii. All State owned generating stations 25 MW & above iii. IPPs of 25 MW & above iv. Bio-mass and Co-generation plants of 25 MW & above. v. CPPs supplying power to the grid - 25 MW & above c) The same is yet to be fully implemented. The Independent power projects (IPPs) like Ms UPCL, M/s Jindal, M/s Sathavahana Ispat etc which are interstate projects and CGS units in the State have been brought under ABT mechanism and deviation settlement mechanism and are being monitored by SLDC and SRLDC. But ABT mechanism and deviation settlement mechanism are yet to be adopted for M/s KPCL thermal and hydel units. 9
6.2. Tolerance limits and deviation bands: 6.2.1. At present the wind, solar and other RES generators (excluding Bio-mass and Co-generation plants of 25 MW & above) are exempted from the purview of Unscheduled Interchange (UI) and Deviation Settlement Mechanism (DSM) within the State. 6.2.2. The wind and solar generators are now proposed to be brought under purview of DSM as detailed below: a) The permissible deviation for all the wind and solar plants shall be ± 15 % ( with in the limits of >85% & <115%) of schedule ie the actual generation shall be with in the premissible limits of 85% to 115% of schedule. b) There will not be any DSM charges. if the deviation of generation is within the specified limits of ± 15 % ( ie between - 85% to +115% of schedule). c) The energy charges will be paid to the generators as per the actual energy supplied, irrespective of the schedule quantum of energy. 6.2.3. DSM charges to DSM pool account for any deviations beyond the permissible limits a) Wind and Solar generators having PPA with ESCOMs or directly supplying power to consumers availing open access for wheeling the power within or outside the State, shall pay to DSM pool account for any deviations of the schedules at the rates show in the following table. Sl No Particulars Deviation range Payment to DSM pool account by generators For wind and solar Rs 0.50 per kwh for the quantum of 1 generators having PPAs with > ± 15 % ± 25 % short fall or excess of energy beyond ± 15 % and up to ± 25 % ESCOMs of deviation from the schedule 10
and for ( ie., ± 10% above tolerable limits of supplying power ±15%) to consumers availing open Rs 0.50 per kwh for the quantum of access facilities short fall or excess of energy for wheeling the beyond ± 15 % and up to ± 25 2 power within or outside the State > ± 25 % ± 35 % % of deviation + (plus) Rs 1.0.per kwh for the remaining quantum of short fall or excess energy for deviation from schedule beyond ± 25 % & up to ± 35 %. Rs 0.50 per kwh for the quantum of short fall or excess of energy for deviation from schedule beyond ± 15 % and up to ± 25 % + (plus) Rs 1.0.per kwh for the 3 more > ± 35 % than remaining quantum of short fall or excess of energy for deviation beyond ± 25 % up to ± 35 % + (plus) Rs 1.50 per kwh for the quantum of short fall or excess of energy deviation from schedule beyond ± 35 % The illustaration shown in Annexure-B b) The SLDC shall maintain the pool account of collection of the DSM charges. 11
7.0. Effective monitoring and compliance: The SLDC will be assigned the task of tracking and monitoring compliance by the wind and solar generators by making necessary provisions in the proposed Karnataka Electricity Regulatory Commission (Forecasting, Scheduling, Deviation settlement and related matters for Wind and Solar Generation sources) Regulations, 2015. 8.0. Grid Strengthening for RES Evacuation: (Green Corridor). Provisions will be made in the Karnataka Electricity Grid Code 2005 for identifying the constraints in evacuation of wind & solar power locally as well as at grid level (upstream) during high wind and solar energy penetration and low local loads and take immediate measures for implementation of grid strengthening proposals by the Transmission utility. 9.0. A separate regulations called Karnataka Electricity Regulatory Commission (Forecasting, Scheduling, Deviation settlement and related matters for Wind and Solar Generation sources) Regulations, 2015 is proposed to be formulated. 12
Annexure: Annexure-A : Wind Generation Backing down due to operational problems Sl No Date Hrs of opening From To Maximum Backing Down of the wind generation in MW (installed capacity) Frequency HZ Minimum Load in MW during the day RE Generation during the day in MU Wind geeration during the day in MU 1 27-08-14 16.06 Hrs 19.06 Hrs 20 50.17 4636 34.98 17.96 2 30-08-14 23.24 Hrs 00.00 Hrs 760.96 50.12 4012 40.83 26.674 3 31-08-14 22.00 Hrs 00.00 Hrs 1063.2 50.3 4125 39.11 27.799 4 1/9/2014 00.30 Hrs 6.00 Hrs 855.03 50.23 4200 38.33 25.403 5 6/9/2014 23.10 Hrs 00.00 Hrs 845.58 50.13 5004 39.35 24.729 6 7/9/2014 00.00 Hrs 7.00 Hrs 1013.7 50.13 4713 34.25 18.686 7 8/9/2014 00.00 Hrs 6.00 Hrs 1741.99 50.12 4715 40.92 25.159 13
Annexure-B: Illustration for computation of deviation charges for wind and solar generators Particulars Unit Scenario-1 with in permissible deviation range Scenario-2 Scenario-3 Scenario-4 % of deviations Rs < than ± 15 % > ± 15 % - < ± 25 % > ± 25 % - < ± 35 % more than > ± 35 % Schedule energy kwh 1000 1000 1000 1000 Actual generation kwh 900 800 700 600 Deviation energy quantum of kwh 100 200 300 15 % of 1000 =150 % Deviation % 10% ie < 15% 20% ie > 15% & < 25% 30 % ie > 25% & <35% 40% ie > 35 % Quantum of deviation for which the charges to be levied kwh Nil up to 15 % ie 150 200-150=50 300-150-100=50 400-150-100-100=50 14
Rate of DSM Rs Nil Rs 0.50 per Rs 0.50 per kwhfor Rs 0.50 per kwhfor first charges kwh first 100 (250-150) 100 (250-150) kwh kwh + + Plus Rs 1.0. per kwh Plus Rs 1.0. per kwh (350-150-100) for 100 (300-150-100) for kwh energy + Plus Rs 50 kwh energy 1.50 ( 400-350)for deviation to remaining 50 kwh schedule deviation to schedule Permissible energy deviation kwh 15 % of 1000 =150 15 % of 1000 =150 15 % of 1000 =150 15 % of 1000 =150 Deviation energy above limits kwh Nil (200-150) = 50 kwh 300-150 = 150 kwh 400-150= 250 kwh DSM charges payable by Generator Rs Nil 50*0.5 = 25 [{(100*0.5}+ {50 *1.0}]= 100 [{(100*0.5}+ {100 *1.0} +50*1.5]= 225 15