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

Claim 15:
16. A start-up control program for a combined cycle plant, the 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,
a generator configured to generate electricity by drive of the steam turbine,
a circuit breaker configured to electrically connect the generator to a power system in response to an external command and to electrically disconnect the generator from the power system in response to an external command,
a fuel control valve configured to adjust a flow rate of fuel to be supplied to the gas turbine,
a main steam line configured to guide the steam from the waste heat recovery boiler to the steam turbine,
a steam control valve provided in the main steam line and configured to adjust a flow rate of the steam flowing into the steam turbine,
a thermometer provided in the main steam line closer to the waste heat recovery boiler than the steam control valve and configured to detect a temperature of the steam flowing through the main steam line,
a rotational speed meter configured to detect a rotational speed of the steam turbine, and
an output gauge configured to detect an output that is an amount of power generated by the generator,
the start-up control program for the combined cycle plant causing a computer to execute:
a gas turbine start-up step of commanding the fuel control valve to start fuel supply to the gas turbine and commanding the fuel control valve on a flow rate of fuel to be supplied to the gas turbine so that the output of the gas turbine increases to a rated output;
a steam admission step of, when the temperature of the steam detected by the thermometer reaches or exceeds a predetermined temperature, commanding the steam control valve to open so as to start steam supply to the steam turbine;
a synchronization step of, when the rotational speed detected by the rotational speed meter reaches a rated rotational speed of the steam turbine, commanding the circuit breaker to electrically connect the generator to the power system;
an ST generator output control step of, after the generator is electrically connected to the power system, commanding the steam control valve on a flow rate of the steam to flow into the steam turbine so that the output detected by the output gauge increases according to a target output change pattern; and
a thermal stress estimation step of estimating thermal stress generated in the steam turbine based on the temperature of the steam detected by the thermometer, wherein
in the ST generator output control step, when the thermal stress estimated in the thermal stress estimation step reaches or exceeds a predetermined value, the flow rate of the steam to flow into the steam turbine is commanded to the steam control valve so that the change in the output detected by the output gauge is smaller than a change indicated by the target output change pattern.