Report on Renewable Energy
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REPORT ON RENEWABLE ENERGY CURTAILMENT IN TAMIL NADU (For the period 01.03.2017 TO 30.06.2017) IN COMPLIANCE TO THE DIRECTIONS OF THE HON’BLE APTEL VIDE ORDER DATED 26.08.2020 IN APPEAL NO. 197/2019 Power System Operation Corporation Limited B-9 (1st Floor), Qutab Institutional Area, Katwaria Sarai, New Delhi-110016 Table of Contents List of Acronyms……………………………………………………………………………………………….……...04 Executive Summary……………………………………………………................................................05 1. Brief Background……………………………………………………………........................................09 2. Actions taken………………………………………………………….….............................................09 3. Regulatory Provisions ………………………….………………………………………………..................10 4.Approach of Analysis…………..………………………………………….………………………………..……13 4.1 Verification of the data ……………………………………………………….................................13 4.2 Intentional curtailment or on account of grid safety measure……………………………..30 4.3 Wether Fair & justifiable curtailment of power from all generators both renewable & non-renewable, actual generation and injection of energy.…………………………………..35 5.RE scheduling and Forecasting in Tamil Nadu…………..……………………………………….……43 6.Summary of Findings…………..………………………………………….………………………………..…….44 List of Annexures Annexure1: Hon’ble APTEL Order dated 26.08.2020……….………………………….……………..46 Annexure2: POSOCO Letter dt 03.09.2020 to NSEFI & TNSLDC…………….……………….…..48 Annexure3: Data submission status along with remarks of SRLDC & TN………….…………52 Annexure4: TNSLDC Letter dt 10.09.2020 to POSOCO……………………………….…..............55 Annexure5: TNSLDC Letter dt 14.09.2020 to POSOCO……………………………………………....57 Annexure6 Developer wise Block wise Estimated Curtailment in MW…..……..……………60 Annexure7 ISGS & State thermal units under outage……….………………………………………..81 Annexure8 Block wise curtailment analysis for curtailed blocks……….……………………….85 List of Tables Table1: Summary of analysis……………………………………………..………………………………..…07 Table2: Sources of Data……………………………………………………………………………………….…14 Table3: Data received status from developers/generators……………………………………..16 Table4: List of Irrigation Based Hydro Projects ………………..……………………………………..19 Table5: Sample observation on data submitted by one of the developers.................21 Table6: Curtailment blocks considered for Analysis……………………………………………..….21 Table7a: Estimated Curtailment in MU………………………….…………………………………….....25 Table7b: Estimated Curtailment in %…………………………….…………………………………….....26 Table8: ISGS Technical Minimum…..………………………………………………………………….…....27 Table9: Technical Minimum of State thermal Plants………………..………………………….....27 Table10: Blocks of over drawl by TN control area during non-solar hours on the days of curtailment.……………………………………………………………………………………………..…30 Table11: Classification of curtailment analysis………………………….…………….………………33 Table12: Analysis of curtailment.……………………….…………….…………………………………….34 Table13: Equitably from solar perspective…………………………………………………………………………40 Table14: Equitably from wind perspective…………………………………………………………………………40 Table15: Month wise average solar & wind curtailment in %..........…………………….....41 List of Figures Figure1: Comparison of Month wise Median of Irradiance Based and Actual Generation…………………………………………………………………………………………………..…………….…23 Figure2: Curtailment estimation based on irradiance-based generation vs developer curtailment data in MU……………………………………………………………………………..…………….…….26 Figure3: RSD, Total Units Outage & Curtailment in MW………………………………………………...29 Figure4: Curtailment analysis…………………………………………………………………………………………35 Figure5: No of Days curtailment Instruction received by the developer…………………………36 Figure6: Percentage of blocks out of total curtailment blocks received by the developer.37 Figure7: Developer wise Curtailment MU as a percentage of non-curtailed MU……….……37 Figure8: Actual wind curtailment vs equitable wind curtailment…………………………………..39 Figure9: Actual solar curtailment vs equitable solar curtailment……………………………………39 Figure10: Day wise Solar and wind Curtailment percentage……………………………………….…41 List Of Acronyms 1. ACE: Area Control Error 2. CERC: Central Electricity Regulatory Commission 3. CPP: Captive Power Plant 4. DSM: Deviation Settlement Mechanism 5. IEGC: Indian Electricity Grid Code 6. IPP: Independent Power Provider 7. ISGS: Inter State Generating Station 8. ISTS: Inter State Transmission System 9. POSOCO: Power System Operation Corporation Ltd. 10. LTA: Long Term Access 11. MU: Million Units 12. MW: Megawatt 13. MTOA: Medium Term Open Access 14. NLDC: National Load Despatch Centre 15. NSEFI: National Solar Energy Federation of India (Appellant) 16. RE: Renewable Energy 17. RLDC: Regional Load Despatch Centre 18. RSD: RESERVE SHUTDOWN 19. SCADA: Supervisory Control and Data Acquisition 20. SLDC: State Load Despatch Centre 21. SRLDC: Southern Regional Load Despatch Centre 22. SSGS: State Sector Generating Station 23. SPD: Solar Power Developer 24. S/S: Sub Station 25. TNSLDC: Tamilnadu State Load Despatch Centre (Respondent) 26. TNERC: Tamil Nadu Electricity Regulatory Commission 27. TNEGC: Tamil Nadu Electricity Grid Code Executive Summary The Hon'ble Appellate Tribunal For Electricity (APTEL), New Delhi in APL No. 197 of 2019 & IA No. 1706 of 2019 passed the Order dated 26th August 2020 wherein Power System Operation Corporation Limited (POSOCO) was directed to act as third party to make detailed verification of the data after considering the contentions raised by the parties and submit report to the Tribunal within four weeks. POSOCO was directed to indicate whether there was intentional curtailment of scheduling of power by the Respondents/SLDC or whether it was on account of grid safety measure taken by SLDC as contended by the Respondents. POSOCO was also directed to clearly state whether there was any fair and justifiable curtailment of power from all generators, both renewable and non-renewable, the actual generation and injection of energy. Both the parties were directed to cooperate and assist POSOCO to comply with the direction in conducting the enquiry. Accordingly, Power System Operation Corporation Limited (POSOCO), acting as third party, had conducted the enquiry, validated the data and concluded the findings based on the available material facts. The report is being submitted in pursuance to the above directions. The report covers the regulatory provisions, curtailment analysis aspects such as approach adapted, sources of data, screening of data for analysis, filtering of curtailment blocks for the purpose of analysis, validation of data, estimation of curtailment, computation of margins available for backing down in conventional generators, analysis & summary of findings to the specific questions raised by Hon’ble APTEL. The findings are summarised below for each of the directions of Hon’ble APTEL based on the detailed analysis covered in this report a) Detailed verification of the data after considering the contentions raised by the parties • Analysis was done for the period from 01.03.2017 to 30.06.2017 • Out of the 56 generators, 16 generators with total installed capacity of 1052 MW submitted the data. Data of 10 generators were complete and data of 6 generators was partial. • Some Inconsistencies were found in curtailment data provided by the generator. • Median of irradiance-based generation was validated with Median of actual generation on non-curtailed days and found to be in order. • The Block-wise Difference between irradiance-based Generation (MW) and actual generation (MW) during the common curtailment blocks was computed on Daily basis. This was taken as the Curtailment Quantum expressed as a formula: - Curtailment Quantum (MW) = Irradiance based Generation (MW) – Actual Generation (MW) Note: Negative values were made zero as curtailment quantum cannot be less than zero. b) Indicate whether there was intentional curtailment of scheduling of power by the Respondents/SLDC or whether it was on account of grid safety measure taken by SLDC as contended by the Respondents. Grid frequency is collectively controlled by all entities in the grid and not by any individual state or entity. The operating frequency band of 49.90-50.05 Hz indicated in the IEGC in no way implies that frequency cannot go outside this band. It can go below 49.90 Hz in case of any generator tripping but actions by entities should bring the frequency back to within the band. Adequate generation reserves for UP regulation is to be maintained at both the interstate and intra state level to minimize operation below 49.90 Hz. Similarly, adequate reduction or DOWN capability of generation would help avert operation above 50.05 Hz. There was no abnormal voltage condition at 400kV level of the grid and no network loading issue which required backing down / curtailment during the said period. Further no Specific constraint is expressed by TNSLDC at State level. Voltage and Transmission Constraints tend to be localised. The Curtailment instruction by TNSLDC was state-wide. There were no constraints/Violation which necessitated the state wide curtailment during the period under consideration. The area control error / Deviation from the grid is to be controlled by the State using proper load forecasting and renewable forecasting as well as adequate generation reserves in line with the clause 5.3 and 6.5.23 of Indian Electricity Grid Code 2010. As per the Grid Code, each day is divided into time blocks of 15 minutes each. Accordingly, each case of curtailment is expressed as a time block of 15 minutes. The analysis of curtailment data submitted