Natural gas shortage in winter will cause insufficient heating output of gas-steam combined cycle thermal power generation units

which seriously affects the heating quality. For this reason

this article researches the flexible heating technology of a gas-steam combined cycle unit. Six heating modes are designed for conditions with different natural gas volumes and heating loads

namely high back pressure heating mode

high back pressure heating mode with extraction steam

low-pressure cylinder no-load operation mode for heating

single waste heat boiler coupling with high back pressure heating mode

single waste heat boiler coupling with no-load operation heating mode

and double waste heat boiler heating mode. Moreover

a control strategy is developed for all heating conditions

which mainly includes heating mode switching strategies and heating online optimization strategies. Furthermore

engineering test of the control strategy under six heating modes was carried out on a gas-steam combined cycle unit in Shanxi

and the results show that

the flexible heating control strategy can automatically select mode switching or operation parameter optimization according to the system state in real time and accurately

so that the error between heating load and heating demand can be controlled below 1%. The unit can provide 52 000 GJ heat per day at a fixed natural gas volume of 3 million m3/d

namely the thermal peak regulation capacity of the unit increased by about 45%

indicating the capacity of the unit in flexible heat supply and peak load regulation is dramatically improued.