Patent ID: 11933197
Assignee: MITSUBISHI ELECTRIC CORPORATION
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F  Y | IPC F

Claim 0:
1. A method for starting up a combined cycle plant including a gas turbine configured to be driven by fuel supply, a waste heat recovery boiler configured to generate steam by using heat from exhaust gas exhausted from the gas turbine, a steam turbine configured to be driven by the steam from the waste heat recovery boiler, a condenser configured to return the steam exhausted from the steam turbine to water, and a generator configured to generate electricity by drive of the steam turbine, the method comprising:
a gas turbine start-up step of increasing an output of the gas turbine to a rated output by supplying fuel to the gas turbine;
a steam admission step of, when a temperature of the steam from the waste heat recovery boiler reaches or exceeds a predetermined temperature, starting steam supply to the steam turbine;
a synchronization step of, after the steam admission step, when a rotational speed of the steam turbine reaches a rated rotational speed, synchronizing the generator to a power system;
an ST generator output control step of, after the generator is synchronized, controlling a flow rate of the steam flowing into the steam turbine so that an output of the generator increases according to a target output change pattern; and
a thermal stress estimation step of estimating a thermal stress generated in the steam turbine based on a temperature of the steam flowing into the steam turbine, wherein
in the ST generator output control step, when the thermal stress estimated in the thermal stress estimation step reaches or exceeds a predetermined first thermal stress, the flow rate of the steam flowing into the steam turbine is controlled so that a change in the output of the generator is smaller than a change indicated by the target output change pattern.