A gas turbine is an engine that burns natural gas to spin a generator and make electricity. Air is compressed, gas is burned in the compressed air, and the hot gas spins the turbine blades. The blades turn the generator. Gas turbines make a large share of the world's electricity.
In India, gas-fired plants supply only a small part of the electricity, because coal is cheaper and gas supply is limited. So Indian grid operators keep them mainly for the hours when demand is highest.
Their special strength is speed. A coal plant takes many hours to start. A large gas turbine can start and reach full power in 10 to 30 minutes. A smaller one can do it in under 10 minutes. So the grid operator uses gas turbines when demand jumps. Say it is 7 pm in a Delhi summer and every home in the city switches on its air conditioner at the same time. The grid operator's energy management system orders a gas turbine to start, and it adds power within minutes. This is a main tool of grid balancing.
Some plants use the hot exhaust a second time. The exhaust boils water, and the steam spins a second turbine. This is called a combined-cycle plant, and it makes more electricity from the same gas. A gas turbine can also be used on its own, which is simpler and starts faster, but wastes more heat.
A gas turbine runs at very high temperatures, so its parts wear out. The maker therefore keeps sensors on it and services it for decades. This is part of aftermarket service, and it is often more profitable than selling the turbine. The sensors send readings to remote monitoring by the maker, and the plant owner uses asset performance management software to plan repairs.
Engineers also build a digital twin of the plant, a copy of it in software. They use the copy to test settings before trying them on the real machine.