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In India, renewable energies, especially wind and solar There is a diverse range of strategies that can make
technology, efficiency improvement measures, and existing conventional power plants more flexible. CEA
how the existing power plant operates, are playing a has developed a road map for flexibilisation of thermal
fundamental role in reaching this goal. To achieve these power plants, which underlines the importance of ramp
carbon-free energy targets, Government of India plans rate (not a challenging factor, however, need to improve
to install 175 GW renewable energy with a daily net at least 1%/minute), financial framework (compensation
load swing of up to 80 GW by March 2022. for the increase in Capex and Opex due to change in
the operating scenario) and revision of Grid Codes in
As per NITI Aayog, the total primary energy will terms of tariff structure. Considering this, there will be
increase almost three times between 2017 and 2042, a considerable investment to develop thermal power
equivalent to an annual growth rate of approximately plants to operate up to 30 to 40% load flexibly.
4%. However, coal will continue to remain predominant
among all other commercial sources of energy in India. The other major factor for flexible operation of the
Considering the scale of demand in the country and grid is the operational philosophy (start-up and ramp-
abundant availability coal, it will remain the primary up characteristics) of the power plant. Gas-based
source for generating electricity, followed by hydro, gas, combined cycle power plant with its high operationally
nuclear, and renewable energy. flexible (high ramp rates & low start-up time) can suffice
this requirement. The latest Indian grid code for RGMO
However, coal usage will gradually transition towards (Restricted Governor mode of operation) mandates a
clean coal technologies like supercritical (SC), and speedy and sustainable response to the grid frequency
ultra-supercritical (USC) power plants, which will reflect fluctuations. Providing the primary frequency response
in higher efficiency, more considerable power from coal will improve the grid stability, during daily load swing
with lesser coal consumption. Moreover, as compared when renewables enter the grid. As per CEA, the
to other fuels like oil and natural gas, which are mainly required ramp rate in 2022 is 217 MW/min. (down) &
imported due to limited domestic resource availability, 220MW/min (up).
coal is available domestically in abundance. The older
and smaller thermal power plants will retire and get The typical ramp rates of various type of units in India
replaced by larger SC / USC thermal power plants. are depicted below.

Further with the renewable penetration in the grid,
five states of India (Karnataka, Tamil Nadu, Rajasthan, Ramp Rate (Load per minute)
Andhra Pradesh and Gujarat) face significant system 25%
integration challenges, as solar and wind shares rise 20%
above 15%. 15%

More states will experience higher shares of variable 10%
renewables, as solar power will be available during 5%
daytime and only when the sun is shining; and wind
power is also dependent only when the wind blows. 0%
Coal based
Coal based
All these conditions create newer challenges and Nuclear Combined Power Plant Power Plant Simple Cycle
Power
Cycle
Power Plant
require significant change to the operation of the Plant Power Plant Super Sub Critical
thermal power plants. This will create an opportunity Critical
for flexibility in the thermal power plant’s operation and Source: Gathered from various operating plant information
cleaner energy mix.

Considering the thermal power plant’s percentage in It may be noted that a simple cycle power plant has
the Indian power system, thermal power plants are the the highest ramp rate followed by a combined cycle
predominant source for the system flexibility. With its power plant (CCPP) and coal-based power plant. The
operating flexibility and lower loads and ramping rate, gas power plant in priority can support the daily swings
these plants can accommodate supply and demand as they possess higher ramping characteristics than the
variability and uncertainty. coal-based power plant.

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