Cold-state preheating start control test method for steam turbine of gas-steam combined cycle unit

The invention provides a cold-state preheating start control test method for a steam turbine of a gas-steam combined cycle unit, the method is applied to a coaxial gas-steam combined cycle unit, and a high-pressure preheating steam pipeline and a medium-pressure preheating steam pipeline are additionally arranged on the steam turbine side of the coaxial gas-steam combined cycle unit, the high-pressure pre-heating steam pipeline is connected with a main steam pipeline of the high-pressure cylinder, and the medium-pressure pre-heating steam pipeline is directly communicated with the side of the medium-pressure cylinder; comprising the following steps: checking control of a pre-warming valve group; the starting control logic of the steam turbine is adjusted by combining the connection mode of the high-pressure pre-heating steam pipeline and the medium-pressure pre-heating steam pipeline; determining a starting mode of a gas turbine in the coaxial gas-steam combined cycle unit; testing the cold-state pre-heating