‘Flexible’ thermal plants to operate at 40% average minimum load

Insights Bureau

The power ministry has begun the process of making thermal power plants ‘flexible’ in operations to sync with growing but unstable renewable generation. To meet commitments of minimum Renewable Energy generation, thermal power plants will have to operate at an average minimum load of 40 percent by 2030 considering the 500 GW renewable energy integration by then. This will drastically impact their coal consumption and the schedule of most of the conventional generating plants.

“In near future thermal power plants fleet is expected to operate at an average minimum load of 40 percent. It shall drastically impact the schedule of most of the conventional generating plants and shall lead to operating thermal power plants at part load. Hence, thermal generating units shall have to be tuned such that they can meet the new load demands in a very effective and efficient manner. And if any gaps are found, the same needs to be fixed,” a report issued by Central Electricity Authority (CEA) titled ‘Flexiblisation of Coal-Fired Power Plants: Roadmap for achieving 40 percent Technical Minimum Load’, says.

“Flexible thermal units are one of the cheapest source of flexible power presently in the country. Hence, it will be crucial to ready the existing thermal units for the new operating regime enforced by the renewables. It shall help to optimise the operation of thermal units and reduce emission burden of power plants,” Ghanshyam Prasad, Chairman, Central Electricity Authority has said in the report.

Minimum thermal load categories

To give effect to the flexiblisation, a committee was formed by CEA with the following objectives:

♦ Explore the new technical minimum load of thermal generating units without oil support

♦ Assessment of thermal flexible power and ramp rate available for integration of renewable generation

♦ Identify increase of net heat rate, O&M cost etc

♦ Targeting grid security and stability, less impact on tariff

♦ Explore cost implication of flexible operation of thermal unit

♦ Preparation of Roadmap for achieving new technical minimum load.

The committee has now come out with the detailed report. Necessary changes also have been brought to the relevant regulations.

In pursuance of clause (e) of sub-section (2) of Section 177 of the Electricity Act, 2003 read with clause (b) of Section 73 of the Act, CEA has made the following regulations under Central Electricity Authority (Flexible Operation of Coal based Thermal Power Generating Units) Regulations, 2023.

• Applicability

These regulations shall apply to all coal based thermal power generating units owned or under control of the Central Government, State Governments or owned by any private company, connected with the grid and to the load despatch centers.

Onthe basis of net heat rate increase due to minimum thermal load (MTL) operation, thermal generating units are categorised under very flexible (40 percent MTL), flexible (45 percent) and low flexible (50 percent) group.

In a particular day (with 175 GW Renewable Energy) about 90 very flexible units (24 GW), 78 flexible units (42 GW) and 75 low flexible units (52 GW) from 243 grid synchronized thermal generating units (118 GW) are required for safe &secured grid operation.

• General requirements

(1) The coal based thermal power generating units shall be designed or suitably retrofitted, if required, to comply with these regulations for full range of ambient and environmental conditions prevailing at the site

(2) All equipment and systems installed shall comply with the provisions of statutes, regulations and safety codes, as applicable

• Flexible operation of coal-based thermal power generating units

(1) The coal based thermal power generating units shall be capable of providing the flexible operation as per these regulations

(2) The implementation of flexible operation of the coal based thermal power generating units shall be as per the phasing plan specified by the Authority from time to time