An expert group reviewing the Indian Electricity Grid Code (IEGC) has asserted that renewable energy power plants shall be treated as “must run” and electricity from these plants shall not be curtailed for any commercial reasons. Part of the latest draft IEGC prepared by the group, the provision comes at a time when a number of states have repeatedly resorted to not scheduling power from renewable sources, citing high costs.
A ‘must run’ status means that the concerned power plant has to supply electricity to the grid under all conditions.
The group has added new codes in the latest IEGC draft — the Protection and Commissioning code, which entails a centralised database containing details of relay setting for grid elements, and the Cyber Security code, which provides for identification of critical information infrastructure.
The IEGC lays down regulations for various persons and participants in the country’s power ecosystem to plan, develop, maintain and operate power system in the country “in a secure, economic, reliable, resilient and efficient manner”, states the draft.
“Wind, solar, wind-solar hybrid and hydro plants (in case of excess water leading to spillage) shall be treated as MUST RUN power plants and shall not be subjected to curtailment on account of merit order despatch or any other commercial consideration,” stated the group, headed by former Central Electricity Authority (CEA) chairman Rakesh Nath and having former CEA chairman Ravinder and Director POSOCO, SR Narasimhan among its members, in its January 2020 report.
Renewable players have raised concerns in recent months about rising instances of state power distribution companies unplugging their generating capacity from the grid and delaying payments. The unplugging, also called backing-down, stems from the poor financial status of discoms, because of which a number of them have started going back on their PPA commitments with solar and wind power producers.
In the event of transmission or system security constraint, the renewable generation may be curtailed after harnessing “available flexible resources including energy storage systems”, as per the report. The group added that, in case of “extreme circumstances” that leads to the curtailment of a must run plant, details of the renewable energy generation plant being curtailed, the duration of curtailment and reasons for doing so must be given.
“In the event of constraints in the transmission system, the renewable generation may be curtailed if it is the only source which relieves the constraint,” stated the report. Curtailment could be required in case “all” flexible resources are harnessed by the appropriate load despatch centre (LDC) but frequency remains above 50.05 Hz and the Area Control Error (ACE) remains high. It could also be required if any further reduction in conventional generation would necessitate de-commitment of units leading to “shortage conditions and possible load shedding during the peak hours,” said the group.
“Accommodating a larger percentage share of renewable energy in the system can lead to a few hours of over-supply in a year necessitating curtailment of renewable energy as an economic option,” it added.
“Various measures proposed to be enforced for grid security, reliability and renewable integration are technically feasible, in compliance with CEA standards and established in renewable rich countries,” stated the group.
The renewable sector was previously accorded a ‘must run’ status in the 2010 IEGC, despite which states like Tamil Nadu and Andhra Pradesh have curtailed electricity from such sources. The Andhra Pradesh government, which has received flak over the last year for renegotiating and revising renewable power purchase agreements, had curtailed electricity supply from such sources, reportedly without citing any valid reasons.
In March 2019, the Tamil Nadu Electricity Regulatory Commission (TNERC), in a case against TANGEDCO, TNSLDC, TANTRANSCO and MNRE, had observed that Tamil Nadu had “failed” to provide data showing that its decision to back down or issue curtailment instructions to solar projects was due to grid security or safety of equipment or personnel.
“It is submitted that the backing down was carried out due to surplus generation and without following the merit order despatch and only by considering the commercial implication of backing down of low cost conventional generation as well as wind generation to avoid procurement of higher cost solar power generation,” TNERC had stated.
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