CERC Directs Pilot Two-Shift Operation for Thermal Power Plants to Address Grid Frequency Challenges: Suo-Motu Order

CERC Orders Pilot Two-Shift Operation for Thermal Power Plants to Tackle Grid Over-Frequency Issues

New Delhi, March 29, 2025 – In a significant suo-motu order, the Central Electricity Regulatory Commission (CERC) has directed the National Load Despatch Centre (NLDC) to implement a pilot project for two-shift operation of selected thermal power plants. This move aims to mitigate persistent high-frequency operation in the Indian power grid, primarily caused by the increasing integration of renewable energy and fluctuating demand patterns.

The order, issued by a bench comprising Chairperson Shri Jishnu Barua and Members Shri Ramesh Babu V., Shri Harish Dudani, and Shri R.S. Dhillon , comes in response to a report submitted by Grid-India highlighting instances of prolonged high grid frequency in August 2024.

Background: Persistent High Grid Frequency

Grid-India's report pointed out that on August 4th, 11th, and 25th, 2024, the Indian power system experienced high-frequency operation, exceeding 50.05 Hz for a significant portion of the day. Factors contributing to this included suppressed demand due to widespread rains, over-injection by renewable energy sources (VRE), limited flexibility from hydropower, and under-drawal by states.

The CERC noted that these high-frequency events violate the Central Electricity Regulatory Commission (Indian Electricity Grid Code) Regulations, 2023, which mandate that the grid frequency should remain within the 49.900-50.050 Hz band.

Addressing the Root Causes: Over-injection and Under-drawal

The Commission's analysis of data from August 25th, 2024, revealed key issues:

Over-injection by Thermal Generators: Thermal power plants scheduled below their Minimum Turn Down Level (MTL) were consistently over-injecting to maintain operations near MTL, contributing to excess power in the grid.

Over-injection by Renewable Energy Sources: RE generators also contributed to over-injection, further exacerbating the high-frequency problem.

Under-drawal by States: Some states were drawing less power than scheduled, possibly due to high renewable energy generation within their own territories or suppressed demand.

NTPC, in a letter to CERC, highlighted the problem of "infeasible schedules" where thermal units receive schedules below MTL during off-peak hours and full schedules during peak hours. This forces plants to over-inject to maintain technical minimum loading, leading to grid violations and financial losses for generators.

Pilot Project: Two-Shift Operation for Thermal Plants

To address these challenges, particularly the need for grid flexibility with increasing renewable energy penetration, the CERC has directed a pilot project to operationalize two-shift operation for select thermal power plants.

> "Although the standard specifications provide for two shifts , the thermal units have not been operated in two-shift mode. Hence, there is a need to first operate some of the coal based thermal units on two shifts on a pilot basis to gain experience and address technical issues encountered during the course of such pilot operation." - CERC Order

Under this pilot, NLDC, in consultation with plant owners and the Central Electricity Authority (CEA), will identify regional entity thermal generating stations for two-shift operation. The Commission specified that rail-fed 500 MW units may be preferred initially.

To incentivize participation, the CERC has approved an incentive of 20 paise/kWh for the "down reserve" created by operating in two shifts, recognizing the importance of flexibility for grid stability and renewable energy integration.

Key Directives and Way Forward

The CERC order outlines several key directives:

NLDC to identify pilot thermal units and develop a detailed procedure for two-shift operation within two months. This procedure must cover operational aspects, scheduling, dispatch, accounting, settlement, compensation, and start-up costs.

Incentive of 20 paise/kWh for down reserve created by two-shift operation.

NLDC and plant owners to submit a feedback report after six months of pilot operation assessing operational experience, financial impact, plant viability, and potential plant damage.

NLDC to furnish a report on Primary Response Ancillary Services (PRAS) provided by RE generators during the high-frequency events.

NLDC to develop modalities for Automatic Generation Control (AGC) services from RE generators to enhance grid management.

CERC staff to explore the feasibility of Energy Storage Systems (ESS) at thermal generating stations to absorb excess energy during off-peak hours.

The Commission emphasized that these directions are issued under Regulation 60 of the Grid Code, specifically clauses (2) and (3) of Regulation 30, to ensure grid frequency control and reliability.

This suo-motu initiative by the CERC marks a proactive step towards adapting the Indian power grid to the evolving energy landscape, balancing thermal generation with the growing influx of renewable energy, and ensuring stable and secure grid operations.