Combined cycle plant, control device thereof, and operation method thereof

1. An operation method of a combined cycle plant comprising:

a first gas turbine unit including a first gas turbine and a first heat recovery steam generator which is configured to generate steam using heat of an exhaust gas of the first gas turbine;

a steam turbine which is configured to be driven by steam generated from the first heat recovery steam generator;

an auxiliary combustion device which is configured to burn fuel in a steam generator frame of the first heat recovery steam generator to increase an amount of generated steam so that an output of the steam turbine is increased; and

a second gas turbine unit including a second gas turbine and a second heat recovery steam generator which is configured to generate steam using heat of an exhaust gas of the second gas turbine,

the operation method of the combined cycle plant executing:

a first operation section in which the first gas turbine unit is driven without driving the auxiliary combustion device, or the first gas turbine unit and the steam turbine are driven without driving the auxiliary combustion device;

a second operation section in which the first gas turbine unit, the auxiliary combustion device, and the steam turbine are driven when a required output that is equal to or greater than a maximum output in the first operation section is received; and

a third operation section in which the first gas turbine unit, the second gas turbine unit, and the steam turbine are driven without driving the auxiliary combustion device when a required output that is equal to or greater than a maximum output in the second operation section is received.

2. The operation method of the combined cycle plant according to claim 1 , wherein any one of performance of an alternative second operation section in which the first gas turbine unit, the second gas turbine unit, and the steam turbine are driven without driving the auxiliary combustion device, and performance of the second operation section is selectable when a required output that is equal to or greater than a maximum output in the first operation section is received.

3. The operation method of the combined cycle plant according to claim 2 , wherein an indication that any one of the alternative second operation section and the second operation section is executable is displayed when a required output that is equal to or greater than a maximum output in the first operation section is received.

4. The operation method of the combined cycle plant according to claim 3 , wherein a plant efficiency when the alternative second operation section is performed and a plant efficiency when the second operation section is performed are displayed.

5. A control device of a combined cycle plant including:

a first gas turbine unit including a first gas turbine and a first heat recovery steam generator which is configured to generate steam using heat of an exhaust gas of the first gas turbine;

a steam turbine which is configured to be driven by steam generated from the first heat recovery steam generator;

an auxiliary combustion device which is configured to burn fuel in a steam generator frame of the first heat recovery steam generator to increase an amount of generated steam so that an output of the steam turbine is increased; and

a second gas turbine unit including a second gas turbine and a second heat recovery steam generator which is configured to generate steam using heat of an exhaust gas of the second gas turbine,

the control device of the combined cycle plant comprising a control unit which controls the first gas turbine unit, the steam turbine, the auxiliary combustion device, and the second gas turbine unit such that they are able to perform:

a first operation section in which the first gas turbine unit is driven without driving the auxiliary combustion device, or the first gas turbine unit and the steam turbine are driven without driving the auxiliary combustion device;

a second operation section in which the first gas turbine unit, the auxiliary combustion device, and the steam turbine are driven when a required output that is equal to or greater than a maximum output in the first operation section is received; and

a third operation section in which the first gas turbine unit, the second gas turbine unit, and the steam turbine are driven without driving the auxiliary combustion device when a required output that is equal to or greater than a maximum output in the second operation section is received.

6. The control device of the combined cycle plant according to claim 5 , further comprising a receiving unit which receives any one selection between an alternative second operation section in which the first gas turbine unit, the second gas turbine unit, and the steam turbine are driven without driving the auxiliary combustion device, and the second operation section, and causes the control unit to perform the received operation section when a required output that is equal to or greater than a maximum output in the first operation section is received.

7. The control device of the combined cycle plant according to claim 6 , further comprising a display unit which displays an indication that any one of the alternative second operation section and the second operation section is executable when a required output that is equal to or greater than a maximum output in the first operation section is received.

8. The control device of the combined cycle plant according to claim 7 , wherein the display unit displays a plant efficiency when the alternative second operation section is performed and a plant efficiency when the second operation section is performed.

9. A combined cycle plant comprising:

the control device of the combined cycle plant according to claim 5 ;

the first gas turbine unit;

the steam turbine;

the auxiliary combustion device; and

the second gas turbine unit.