1-axis type combined cycle plant
View Patent ↗A combined cycle plant includes a gas turbine fuel control valve which controls supply of first fuel; a duct burner fuel control valve which controls supply of second fuel; a generator; a gas turbine, a boiler and a steam turbine. The gas turbine drives the generator by burning the first fuel supplied through the gas turbine fuel control valve. The boiler has a duct burner, heats gas exhausted from the gas turbine by burning the second fuel supplied through the duct burner fuel control valve by the duct burner, and heats water with the heated exhausted gas to generate steam. The steam turbine is driven with the steam to drive the generator. The combined cycle plant is further comprised of a controller which controls the gas turbine fuel control valve and the duct burner fuel control valve. The controller controls an open degree of the gas turbine fuel control valve such that rapid increase of the supply of the first fuel is restrained when the supply of the second fuel to the duct burner is stopped.
1. A combined cycle plant comprising:
a gas turbine fuel control valve which controls supply of first fuel;
a duct burner fuel control valve which controls supply of second fuel;
a generator;
a gas turbine which drives said generator by burning said first fuel supplied through said gas turbine fuel control valve;
a boiler which has a duct burner, heats gas exhausted from said gas turbine by burning said second fuel supplied through said duct burner fuel control valve by said duct burner, and heats water with said heated exhausted gas to generate steam;
a steam turbine which is driven with said steam to drive said generator; and
a controller which controls said gas turbine fuel control valve and said duct burner fuel control valve, wherein said controller controls an open degree of said gas turbine fuel control valve such that rapid increase of the supply of said first fuel is restrained when the supply of said second fuel to said duct burner is stopped.
2. The combined cycle plant according to claim 1 , wherein said controller comprises:
a gas turbine controller which controls the open degree of said gas turbine fuel control valve in response to power generated by said generator; and
a duct burner controller which controls an open degree of said duct burner fuel control valve such that a flow rate of said second fuel supplied to said duct burner is coincident with a duct burner fuel flow rate instruction.
3. The combined cycle plant according to claim 2 , wherein said duct burner controller controls the open degree of said duct burner fuel control valve such that a change rate of the open degree of said duct burner fuel control valve falls within a predetermined range.
4. The combined cycle plant according to claim 3 , wherein said duct burner controller comprises:
a fuel flow instruction generating unit which generates said duct burner fuel flow rate instruction as an instruction value of the flow rate of said second fuel supplied to said duct burner,
said fuel flow instruction generating unit comprises:
a change rate limitation unit which limits said change rate of said duct burner fuel flow rate instruction within said predetermined range.
5. The combined cycle plant according to claim 2 , wherein said gas turbine controller controls the open degree of said gas turbine fuel control valve such that a permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a first period containing a combustion period of said duct burner is smaller than said permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a second period containing a non-combustion period of said duct burner.
6. The combined cycle plant according to claim 2 , wherein said gas turbine controller controls the open degree of said gas turbine fuel control valve such that a permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a first period containing a combustion period of said duct burner and a predetermined period subsequent to said combustion period is smaller than said permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a second period containing a non-combustion period of said duct burner.
7. The combined cycle plant according to claim 2 , wherein said gas turbine controller comprises:
a rotation speed set point generating unit which generates a gas turbine rotation speed set point;
a governor control unit which determines a governor control open degree instruction such that a rotation speed of said gas turbine is controlled to be coincident with said gas turbine rotation speed set point;
an output set point generating unit which generates a generator output set point;
a load limit control unit which determines a load limit control open degree instruction value such that an output of said generator is controlled to be coincident with said generator output set point; and
a gas turbine fuel control valve open degree determining unit which determines an instruction value of the open degree of said gas turbine fuel control valve in response to said governor control open degree instruction and said load limit control open degree instruction,
wherein said rotation speed set point generating unit sets said gas turbine rotation speed set point to a first predetermined value when the supply of said second fuel to said duct burner is stopped due to an abnormal event, and
said output set point generating unit sets said generator output set point to a second predetermined value when the supply of said second fuel to said duct burner is stopped due to said abnormal event.
8. The combined cycle plant according to claim 7 , wherein said rotation speed set point generating unit sets said gas turbine rotation speed set point to said first predetermined value by gradually decreasing said gas turbine rotation speed set point to said first predetermined point when the supply of said second fuel to said duct burner is stopped due to said abnormal event.
9. The 1-axis type combined cycle plant according to claim 7 , wherein said output set point generating unit sets said generator output set point to said second predetermined value by gradually decreasing said generator output set point to said second predetermined value when the supply of said second fuel to said duct burner is stopped due to said abnormal event.
10. The combined cycle plant according to claim 1 , wherein a turbine axis of said gas turbine, a turbine axis of said steam turbine and a rotor of said generator are coaxially connected and rotate together.
11. A 1-axis type combined cycle plant comprising:
a gas turbine;
a boiler which heats exhausted gas discharged from said gas turbine by a duct burner and heats water with said heated exhausted gas to generate steam;
a steam turbine which is driven with said steam;
a generator;
a gas turbine fuel control valve which supplies fuel to said gas turbine;
a duct burner fuel control valve which supplies fuel to said duct burner;
a gas turbine controller which controls an open degree of said gas turbine fuel control valve in response to power generated by said generator; and
a duct burner controller which controls an open degree of said duct burner fuel control valve,
wherein a turbine axis of said gas turbine, a turbine axis of said steam turbine and a rotor of said generator are coaxially connected and rotate together, and
said duct burner controller includes a duct burner fuel control valve open degree control unit which controls the open degree of said duct burner fuel control valve such that a decrease rate of the open degree of said duct burner fuel control valve falls within a predetermined range.
12. The 1-axis type combined cycle plant according to claim 11 , wherein said duct burner controller comprises:
a fuel flow instruction generating unit which generates a fuel flow instruction as an instruction value of the flow rate of fuel supplied to said duct burner,
said fuel flow instruction generating unit comprises:
a change rate limitation unit which limits a change rate of said fuel flow instruction within said predetermined range, and
said duct burner fuel control valve open degree control unit controls the open degree of said duct burner fuel control valve such that the flow rate of fuel supplied to said duct burner is coincident with said fuel flow instruction.
13. The 1-axis type combined cycle plant according to claim 11 , wherein said gas turbine controller controls the open degree of said gas turbine fuel control valve such that a permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a combustion period of said duct burner is smaller than said permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a non-combustion period of said duct burner.
14. The 1-axis type combined cycle plant according to claim 11 , wherein said gas turbine controller controls the open degree of said gas turbine fuel control valve such that a permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a combustion period of said duct burner and for a predetermined period subsequent to said combustion period is smaller than said permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a period other than said combustion period and said predetermined period.
15. The 1-axis type combined cycle plant according to claim 11 , wherein said gas turbine controller comprises:
a rotation speed set point generating unit which generates a gas turbine rotation speed set point;
a governor control unit which determines a governor control open degree instruction such that rotation speed of said gas turbine is controlled to be coincident with said gas turbine rotation speed set point;
an output set point generating unit which generates a generator output set point;
a load limit control unit which determines a load limit control open degree instruction value such that an output of said generator is controlled to be coincident with said generator output set point; and
a gas turbine fuel control valve open degree determining unit which determines an instruction value of the open degree of said gas turbine fuel control valve in response to said governor control open degree instruction and said load limit control open degree instruction,
wherein said rotation speed set point generating unit sets said gas turbine rotation speed set point to a first predetermined value when supply of fuel to said duct burner is stopped in an abnormal event, and
said output set point generating unit sets said generator output set point to a second predetermined value when the supply of fuel to said duct burner is stopped due to said abnormal event.
16. The 1-axis type combined cycle plant according to claim 15 , wherein said rotation speed set point generating unit sets said gas turbine rotation speed set point to said first predetermined value by gradually decreasing said gas turbine rotation speed set point to said first predetermined point when the fuel supply to said duct burner is stopped due to said abnormal event.
17. The 1-axis type combined cycle plant according to claim 15 , wherein said output set point generating unit sets said generator output set point to said second predetermined value by gradually decreasing said generator output set point to said second predetermined value when the fuel supply to said duct burner is stopped due to said abnormal event.
18. A 1-axis type combined cycle plant comprising:
a gas turbine;
a boiler which heats exhausted gas discharged from said gas turbine by a duct burner, and heats water with said heated exhausted gas and generates steam;
a steam turbine which is driven by said steam;
a generator;
a gas turbine fuel control valve which supplies said gas turbine with fuel;
a duct burner fuel control valve which supplies said duct burner with fuel;
a gas turbine controller which controls an open degree of said gas turbine fuel control valve in response to an output of said generator; and
a duct burner controller which controls an open degree of said duct burner fuel control valve,
wherein a turbine axis of said gas turbine, a turbine axis of said steam turbine and a rotor of said generator are coaxially connected and rotate together, and
said gas turbine controller controls the open degree of said gas turbine fuel control valve such that a permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a combustion period of said duct burner is smaller than said permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a non-combustion period of said duct burner.
19. A 1-axis type combined cycle plant comprising:
a gas turbine;
a boiler which heats exhausted gas discharged from said gas turbine by a duct burner, and heats water with said heated exhausted gas and generates steam;
a steam turbine which is driven by said steam;
a generator
a gas turbine fuel control valve which supplies fuel to said gas turbine;
a duct burner fuel control valve which supplies fuel to said duct burner;
a gas turbine control system which controls an open degree of said gas turbine fuel control valve in response to said generator output; and
a duct burner controller which controls the open degree of said duct burner fuel control valve,
wherein a turbine axis of said gas turbine, a turbine axis of said steam turbine and a rotor of said generator are coaxially connected and rotate together, and
said gas turbine controller controls the open degree of said gas turbine fuel control valve such that a permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a combustion period of said duct burner and for a predetermined period subsequent to said combustion period is smaller than said permitted maximum increase rate of the open degree of said gas turbine fuel control valve for a period other than said combustion period and said predetermined period.
20. A 1-axis type combined cycle plant comprising:
a gas turbine;
a boiler which heats exhausted gas discharged from said gas turbine by a duct burner, and heats water with said heated exhausted gas and generates steam;
a steam turbine which is driven by said steam;
a generator;
a gas turbine fuel control valve which supplies fuel to said gas turbine;
a duct burner fuel control valve which supplies fuel to said duct burner;
a gas turbine controller which controls an open degree of said gas turbine fuel control valve in response to an output of said generator; and
a duct burner controller which controls the open degree of said duct burner fuel control valve,
wherein a turbine axis of said gas turbine, a turbine axis of said steam turbine and a rotor of said generator are coaxially connected and rotate together, and
said gas turbine controller comprises:
a rotation speed set point generating unit which generates a gas turbine rotation speed set point;
a governor control unit which determines a governor control open degree instruction such that a rotation speed of said gas turbine is controlled to be coincident with said gas turbine rotation speed set point;
an output set point generating unit which generates a generator output set point;
a load limit control unit which determines a load limit control open degree instruction value such that the output of said generator is controlled to be coincident with said generator output set point; and
a gas turbine fuel control valve open degree determining unit which determines an instruction value of the open degree of said gas turbine fuel control valve in response to said governor control open degree instruction and said load limit control open degree instruction, and
said rotation speed set point generating unit sets said gas turbine rotation speed set point to a first predetermined value when the fuel supply of said duct burner is stopped in an abnormal event, and
said output set point generating unit sets said generator output set point to a second predetermined value when the fuel supply of said duct burner is stopped by said abnormal event.