The judgment emphasizes the need for operational flexibility in power generation to maintain grid frequency within regulatory limits, highlighting the importance of two-shift operations for thermal units and incentivizing renewable energy sources.

Order

Background:

1. Grid-India, vide its letter dated 17.09.2024, submitted a Report to the Commission on high-frequency operation on 4^th, 11^th, and 25^th August 2024. Grid-India, in its report, submitted that persistent high-frequency operation was observed on the 4^th, 11^th, and 25^th of August 2024 in India’s power system, with frequency remaining above 50.05 Hz for around 26%, 33%, and 38% of the time during the day, respectively. The key highlights with regard to high frequency of the grid on 4^th, 11^th and 25^th August 2024 are as under:

2. As per Grid-India’s Report, the contributing factors for high-frequency operation in the Indian power system on 04, 11, and 25 August 2024 are listed below:

a) Suppressed demand due to widespread rains and weekend b) Over-injection by VRE sources c) Limited flexibility from hydropower stations and pumped storage plants due to high inflows and high reservoir levels d) Inadequate flexibility of intra-state thermal generating stations and under- drawl e) Lack of DOWN reserves at the interstate level f) Inadequate liquidity in DAM/RTM, resulting in the states committing more units.

Frequency Profile:

3. On 04th August 2024, the frequency of the Indian grid exceeded the upper limit of the IEGC band (50.05 Hz) for a significant portion of the day. Starting at around 11:00 hrs., the frequency rose above 50.05 Hz and remained elevated until approximately 15:30 hrs. The maximum frequency recorded during the day was 50.39 Hz at 12:02:30 hrs. The frequency profile for 04th August 2024 is as under:

4. On 11th August 2024, the All-India power system experienced notable deviations in its frequency profile, with the system frequency consistently remaining above the Indian Electricity Grid Code ( IEGC ) permissible upper band of 50.05 Hz for a considerable portion of the day. The frequency remained high between 09:30 hrs and 15:00 hrs, barring a few minutes during this period.

The maximum instantaneous frequency recorded was 50.329 Hz at 13:44:50 hrs. Over the course of the day, the average frequency was measured at 50.043 Hz, which, although close to the nominal value of 50 Hz, highlights some deviation from the ideal frequency range. The frequency profile for 11^th August 2024 is as under:

5. On 25th August 2024, the All-India power system experienced deviations in its frequency profile, with the system frequency staying above the Indian Electricity Grid Code ( IEGC ) permissible upper band of 50.05 Hz for an extended period. The frequency remained above the IEGC band from approximately 08:30 hrs to 16:00 hrs, except for a few short intervals. The maximum instantaneous frequency recorded during the day was 50.377 Hz at 13:07:50 hrs, and the average frequency for the entire day was 50.065 Hz, which, while close to the nominal 50 Hz, still reflected deviations from the ideal range. The frequency profile for 25^th August 2024 is as under:

6. Grid-India, in its report, has suggested the following measures for enhancing flexibility in grid operations:

a) Reduction in a minimum turn down level of intrastate thermal stations as per CEA regulations

b) Reduction in a minimum turn down level to 40% of MCR

c) Two shift operation of selected thermal units with high energy charge rate

d) Incentivise flexible operation by notification of compensation for part load operation and start/stops

e) Implementation of resource adequacy framework

f) Increase the capacity of long duration storage

g) Power market reforms - reduce fragmentation of the market, raise the market cap, negative pricing

h) Frequency response from renewable energy sources

i) Curtailment of renewable energy generation as a last resort during sustained high-frequency Analysis and Decision

7. CERC