Flexible Power Generation

Flex power
India’s large coal-based installed capacity of approximately 193 GW accounts for 58% of the country’s total installed capacity. There is a growing need for flexible operations in the coal fleet to meet the variations and intermittence of VRE capacity, primarily wind and solar, into the grid. The NREL grid integration study under GTG establishes that the Indian power grid shall be able to integrate large-scale VRE with minimal curtailment provided the balancing sources like coal are available to support grid stability. A 2016 POSOCO study also identified the need for flexible operations in India.

During high VRE penetration, the coal-based plants shall be required to run at minimal loads (technical minimum) and should be able to quickly ramp up/down as per the variations in VRE resources to address grid stability. Presently, this flexible generation of coal-based plants in India is mandated at a minimum of 55% for interstate generating plants. In the near future, with increased VRE penetration, operators shall be required to run their plants at further reduced loads. Existing plant configurations, firing systems, controls and instrumentation impose legitimate constraints on ramp rates and technical minimums. The GTG-RISE pilot will examine to what extent retrofits/upgrades and
operating practice changes are required in the Indian coal-based plants to improve ramp rates and achieve lower technical minimums.

The pilot will examine the possibility of faster ramp rates and lower technical minimums in two coal-based power generating units one each at NTPC Ltd and Gujarat State Electricity Corporation Limited (GSECL). It will also support implementation of the recommended measures by NTPC and GSECL for achieving the flexible operations of the units. The pilot will suggest potential modifications to the generating units, identify operating practice changes, and build the business case for policy and regulatory changes to implement coal flexing at a larger scale. NTPC and GSECL stations shall benefit by adapting recommendations that would be replicable for their similar range of coal fleet units.

GTG-RISE has already completed feasibility studies, with technical assistance from Intertek AIM, USA, at NTPC’s Jhajjar and Ramagundam plants, while data from 210 and 500 MW unit of GSECL’s Ukai plant is also being reviewed. During the process, a two- day Knowledge Dissemination Workshop was organized at NTPC to share the learnings from the studies. The feasibility report for the GSECL plant is under preparation and the findings will be shared at a state level Knowledge Dissemination workshop. The next stage of the pilot aims at providing strategic support to NTPC and GSECL, including investment case and regulatory business scenario followed by implementation phase.