Combined cycle unit, method for starting combined cycle unit, storage medium containing program for starting control of combined cycle unit, and computer program product

Abstract

In a start-up method of a combined cycle unit, the following procedures are executed: a gas turbine start-up procedure to increase an output of a gas turbine to a rated output; a bleeder procedure to start supplying steam to a steam turbine when a temperature of steam from a waste heat recovery boiler reaches a temperature set in advance or more; and an ST output control procedure to control a flow rate of the steam flowing into the steam turbine after incorporation of a generator to increase an output of the generator in accordance with a target output change pattern. In the ST output control procedure, when a thermal stress reaches a first thermal stress set in advance or more, the flow rate of the steam flowing into the steam turbine is controlled to make a change in the output of the generator smaller than that indicated by the target output change pattern.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a combined cycle unit having a gas turbine, a waste heat recovery boiler, and a steam turbine, a method for starting up the combined cycle unit, and a start-up control program for executing the method.

[0002] This application claims priority from Japanese Patent Application No. 2020-164685 filed on September 30, 2020, and the contents thereof are incorporated herein by reference. BACKGROUND

[0003] The combined cycle unit has a gas turbine that is driven by supplying fuel, a GT generator that generates electric power by the driving of the gas turbine, a waste heat recovery boiler that generates steam using heat of exhaust gas discharged from the gas turbine, a steam turbine that is driven by the steam from the waste heat recovery boiler, a condenser that restores the steam discharged from the steam turbine to water, and an ST generator that generates electric power by the driving of the steam turbine.

[0004] As the method for starting up the combined cycle unit, for example, there is the method disclosed in Patent Literature 1 below. In this start-up method, first, the gas turbine is started up, and after the rotational speed of the gas turbine reaches the rated rotational speed, the GT generator connected to the gas turbine is incorporated into the electric power system. Next, at the time point when the output of the gas turbine (the output of the GT generator) reaches an initial output, the amount of fuel supplied to the gas turbine is adjusted so that the initial output is maintained for a certain period of time. Next, when the temperature of the steam from the waste heat recovery boiler reaches a temperature set in advance or more, the steam from the waste heat recovery boiler is gradually supplied to the steam turbine. Note that the temperature set in advance here refers to a temperature set so as to be suitable for the start-up of the steam turbine. Then, after the rotational speed of the steam turbine reaches the rated rotational speed, the ST generator connected to the steam turbine is incorporated into the electric power system. Next, the amount of fuel supplied to the gas turbine is gradually increased so that the output of the gas turbine becomes the rated output. In this process, the flow rate of the steam from the waste heat recovery boiler increases, and the temperature of the steam also rises, so the output of the steam turbine also becomes the rated output.

[0005] When the output of the gas turbine is increased to the rated output, high-temperature steam flows into the cold steam turbine, and a high thermal stress is generated in the steam turbine. Therefore, in this start-up method, from the viewpoint of protecting the steam turbine, the output of the gas turbine is temporarily maintained at the initial output that is lower than the rated output, and then increased to the rated output.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: Japanese Patent Application Laid-Open No. 58-197408 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] In the power generation industry, there is a demand to shorten the time from the start of a gas turbine to the output of the gas turbine reaching the rated output as much as possible.

[0011] Therefore, an object of the present disclosure is to provide a technology that can suppress thermal stress generated in a steam turbine and can bring the output of a gas turbine to the rated output in a short time.

[0012] TECHNICAL SOLUTION

[0013] A start-up method of a combined cycle unit according to one aspect of the present disclosure is a start-up method of a combined cycle unit according to one aspect of the present disclosure.

[0014] The combined cycle unit includes a gas turbine that can be driven by supplying fuel; a waste heat recovery boiler that can generate steam using the heat of exhaust gas discharged from the gas turbine; a steam turbine that can be driven by steam from the waste heat recovery boiler; a condenser that restores steam discharged from the steam turbine to water; and a generator that generates power by the driving of the steam turbine.

[0015] In the start-up method of the combined cycle unit, the following procedures are performed: a gas turbine start-up procedure of supplying fuel to the gas turbine to increase the output of the gas turbine to the rated output; a bleeder procedure of starting to supply steam to the steam turbine when the temperature of the steam from the waste heat recovery boiler reaches a temperature set in advance or more; a merging procedure of merging the generator to a power system when the rotational speed of the steam turbine reaches a rated rotational speed after the bleeder procedure; an ST output control procedure of controlling the flow rate of steam flowing into the steam turbine to increase the output of the generator in accordance with a target output change pattern after the merging of the generator; and a thermal stress estimation procedure of estimating thermal stress generated in the steam turbine based on the temperature of steam flowing into the steam turbine. In the ST output control procedure, when the thermal stress estimated in the thermal stress estimation procedure reaches a first thermal stress set in advance or more, the flow rate of steam flowing into the steam turbine is controlled to make the change in the output of the generator smaller than that indicated by the target output change pattern.

[0016] The steam supply amount per unit time to the steam turbine has a positive correlation with respect to the steam turbine output as the output of the generator. Further, the thermal stress of the steam turbine has a positive correlation with respect to the steam turbine output during a prescribed time from when the generator connected to the steam turbine is incorporated into the power system. Therefore, in the present aspect, based on the steam turbine output, the flow rate of the steam flowing into the steam turbine is controlled so that the thermal stress generated in the steam turbine does not reach above a preset thermal stress. Therefore, in the present aspect, it is not necessary to maintain the gas turbine output at a low output lower than the rated output for a prescribed time in order to not increase the thermal stress generated in the steam turbine.

[0017] Therefore, in the present aspect, the thermal stress generated in the steam turbine can be suppressed, and the time for which the gas turbine output is made the rated output can be shortened compared to the case in which the gas turbine output is maintained at a low output for a prescribed time.

[0018] A combined cycle unit, as one embodiment of the aforementioned objective, comprises: a gas turbine driven by a fuel supply; a waste heat recovery boiler capable of generating steam using the heat from exhaust gases from the gas turbine; a steam turbine driven by steam from the waste heat recovery boiler; a condenser that restores steam from the steam turbine to water; a generator capable of generating electricity by the steam turbine; and a circuit breaker capable of externally connecting the generator to the power system according to an instruction, and externally disconnecting the generator from the power system according to an instruction. The system includes: a fuel regulating valve for regulating the flow rate of fuel supplied to the gas turbine; a main steam line for transmitting steam from the waste heat recovery boiler to the steam turbine; a steam regulating valve located on the main steam line for regulating the flow rate of steam flowing into the steam turbine; a thermometer located on the side of the main steam line closer to the waste heat recovery boiler than the steam regulating valve, for sensing the temperature of the steam flowing in the main steam line; a tachometer for sensing the rotational speed of the steam turbine; an output meter for sensing the output as the power generated by the generator; and a control device. The control device includes: a startup fuel control unit that instructs the fuel regulating valve to begin supplying fuel to the gas turbine and indicates the flow rate of the fuel supplied to the gas turbine so that the output of the gas turbine increases to the rated output; a ventilation indicator that instructs the steam regulating valve to open when the temperature sensed by the thermometer reaches or exceeds a preset temperature so that steam is supplied to the steam turbine; an input indicator that instructs the circuit breaker to electrically connect the generator to the power system when the rotational speed sensed by the tachometer reaches the rated rotational speed of the steam turbine; an ST output control unit that, after the generator is electrically connected to the power system, instructs the steam regulating valve to indicate the flow rate of steam flowing into the steam turbine so that the output sensed by the output meter increases according to a target output change pattern; and a thermal stress estimation unit that estimates the thermal stress generated in the steam turbine based on the temperature of the steam sensed by the thermometer. When the thermal stress estimated in the thermal stress estimation unit reaches or exceeds a preset value, the ST output control unit instructs the steam regulating valve to control the flow rate of steam flowing into the steam turbine, so that the change in output sensed by the output meter is less than the change shown in the target output change pattern.

[0019] The start-up control procedure for combined cycle units, as one method for achieving the stated purpose, is applied to the following combined cycle units.

[0020] The combined cycle unit has a gas turbine that can be driven by supplying fuel; a waste heat recovery boiler that can generate steam using heat of exhaust gas discharged from the gas turbine; a steam turbine that can be driven by steam from the waste heat recovery boiler; a condenser that restores steam discharged from the steam turbine to water; a generator that can generate electric power by driving of the steam turbine; a circuit breaker that electrically connects and disconnects the generator to and from an electric power system according to an instruction from the outside; a fuel regulating valve that can regulate a flow rate of fuel supplied to the gas turbine; a main steam line that conducts steam from the waste heat recovery boiler to the steam turbine; a steam regulating valve that is provided in the main steam line and can regulate a flow rate of steam flowing into the steam turbine; a thermometer that is provided in the main steam line on a side closer to the waste heat recovery boiler than the steam regulating valve and can sense a temperature of steam flowing in the main steam line; a rotation speed meter that can sense a rotation speed of the steam turbine; and an output meter that can sense an output as an amount of generated electric power by the generator.

[0021] The startup control program of the combined cycle unit causes a computer to execute the following procedures: a gas turbine startup procedure of instructing the fuel regulating valve to start supplying fuel to the gas turbine and instructing a flow rate of fuel supplied to the gas turbine so as to increase an output of the gas turbine to a rated output; an air passage instruction procedure of instructing the steam regulating valve to open the valve so as to start supplying steam to the steam turbine when a temperature sensed by the thermometer reaches a temperature set in advance or more; a merging procedure of instructing the circuit breaker to electrically connect the generator to an electric power system when a rotation speed sensed by the rotation speed meter reaches a rated rotation speed of the steam turbine; an ST output control procedure of instructing the steam regulating valve to a flow rate of steam flowing into the steam turbine so as to increase an output sensed by the output meter according to a target output change pattern after the generator is electrically connected to the electric power system; and a thermal stress estimation procedure of estimating a thermal stress generated in the steam turbine based on a temperature of steam sensed by the thermometer. In the ST output control procedure, the steam regulating valve is instructed to a flow rate of steam flowing into the steam turbine so as to change the output sensed by the output meter less than a change indicated by the target output change pattern when the thermal stress estimated in the thermal stress estimation procedure reaches a value set in advance or more.

[0022] Effect of the Invention

[0023] In one aspect of the present disclosure, a thermal stress generated in a steam turbine can be suppressed, and a gas turbine output can be increased to a rated output in a short time. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a system diagram of a combined cycle unit of the first embodiment of the present disclosure.

[0025] Figure 2 is an explanatory diagram showing a functional configuration of a control device of the first embodiment of the present disclosure.

[0026] Figure 3 is a flowchart showing an action of the control device at the time of acceptance of the GT normal start mode of the first embodiment of the present disclosure.

[0027] Figure 4 is a flowchart showing an action of the control device at the time of acceptance of the GT quick start mode of the first embodiment of the present disclosure.

[0028] Figure 5 is a graph showing changes in the gas turbine rotation speed, the gas turbine output, the steam turbine rotation speed, and the steam turbine output over time of the first embodiment of the present disclosure.

[0029] Figure 6 is a system diagram of a combined cycle unit of the second embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments related to a combined cycle unit of the present disclosure, and a start-up method of the combined cycle unit will be described.

[0031] "First Embodiment"

[0032] Reference Figures 1 to 5 , the present embodiment will be described.

[0033] As shown in Figure 1 , the combined cycle unit of the present embodiment is provided with: a gas turbine device G; a steam turbine device S; and a control device 50.

[0034] The gas turbine device G is provided with: a gas turbine 10; a GT generator 17 that generates electric power by driving of the gas turbine 10; a GT circuit breaker 18 that performs electrical connection and disconnection of the GT generator 17 to and from the power system 1; a waste heat recovery boiler 20 that generates steam by heat of exhaust gas EG discharged from the gas turbine 10; and a stack 29 that discharges the exhaust gas EG that has passed through the waste heat recovery boiler 20 to the atmosphere.

[0035] The gas turbine 10 is provided with: a compressor 11 that compresses air A; a combustor 14 that causes a fuel F to burn in the air A compressed by the compressor 11 to generate combustion gas; and a turbine 12 that is driven by the high-temperature and high-pressure combustion gas. A turbine rotor of the turbine 12 and a compressor rotor of the compressor 11 are connected to each other to constitute a gas turbine rotor 13. A rotor of the GT generator 17 is connected to the gas turbine rotor 13.

[0036] A fuel pipeline 15 that supplies fuel F from an external fuel supply source to the combustor 14 is connected to the combustor 14. A fuel regulating valve 16 that regulates the flow rate of the fuel F supplied to the combustor 14 is provided in the fuel pipeline 15.

[0037] A waste heat recovery boiler 20 is connected via a flue 25 to the exhaust port of the turbine 12. A stack 29 is provided at the exhaust port of the waste heat recovery boiler 20.

[0038] The GT generator 17 is electrically connected to the power system 1 via a power line 19. A GT circuit breaker 18 is provided in the power line 19. The GT circuit breaker 18 electrically connects and disconnects the GT generator 17 to and from the power system 1 according to an instruction from the outside.

[0039] The gas turbine plant G further includes a GT output meter 41 that can sense a gas turbine output that is electric power generated by the GT generator 17, and a GT rotation speed meter 42 that can sense the rotation speed of the gas turbine rotor 13.

[0040] The steam turbine plant S includes the waste heat recovery boiler 20, the stack 29, a steam turbine 30 that is driven by steam generated in the waste heat recovery boiler 20, an ST generator 37 that generates electric power by the driving of the steam turbine 30, an ST circuit breaker 38 that electrically connects and disconnects the ST generator 37 to and from the power system 1, a condenser 34 that restores steam discharged from the steam turbine 30 to water, and a water supply pump 35 that returns water in the condenser 34 to the waste heat recovery boiler 20. Thus, the waste heat recovery boiler 20 and the stack 29 are shared devices of the gas turbine plant G and the steam turbine plant S.

[0041] The steam turbine rotor 33 is connected to the rotor of the ST generator 37. Note that the steam turbine rotor 33 is not mechanically connected to the gas turbine rotor 13. Thus, the rotation of the gas turbine rotor 13 is not synchronized with the rotation of the steam turbine rotor 33, and even if the gas turbine rotor 13 rotates, the steam turbine rotor 33 does not necessarily rotate.

[0042] The ST generator 37 is electrically connected to the power system 1 via a power line 39. The ST circuit breaker 38 is provided in the power line 39. The ST circuit breaker 38 electrically connects and disconnects the ST generator 37 to and from the power system 1 according to an instruction from the outside.

[0043] The steam inlet of the steam turbine 30 is connected to the steam outlet of the waste heat recovery boiler 20 through a main steam line 21. In the main steam line 21, a steam regulating valve 22 is provided, which regulates the flow rate of the steam flowing into the steam turbine 30. The steam regulating valve 22 has a shut-off valve 22a, which can shut off the steam flowing into the steam turbine 30, and a control valve 22b, which can regulate the flow rate of the steam flowing into the steam turbine 30. The control valve 22b is disposed in the main steam line 21 on the side of the steam turbine 30 than the shut-off valve 22a.

[0044] The steam outlet of the steam turbine 30 is connected to the steam inlet of the condenser 34. In the main steam line 21, a bypass line 23 is branched from a position on the side of the waste heat recovery boiler 20 than the steam regulating valve 22. The bypass line 23 is connected to the steam inlet of the condenser 34. In the bypass line 23, a bypass valve 24 is provided, which regulates the flow rate of the steam passing through the bypass line 23. The condensate outlet of the condenser 34 is connected to the water inlet of the waste heat recovery boiler 20 through a feed water line 36. In the feed water line 36, a feed water pump 35 is provided.

[0045] In the main steam line 21, on the side of the waste heat recovery boiler 20 than the branching position of the bypass line 23, a desuperheater 26 is provided, which can regulate the temperature of the steam flowing into the steam turbine 30. The desuperheater 26 has a sprayer 26s, which can spray water mist in the main steam line 21 at a position on the side of the waste heat recovery boiler 20 than the branching position of the bypass line 23, and a spray amount regulating valve 26v, which can regulate the spray amount of water from the sprayer 26s.

[0046] The steam turbine device S further has a ST output meter 45, which can sense the steam turbine output as the electric power generated by the ST generator 37, a ST rotation speed meter 46, which senses the rotation speed of the steam turbine rotor 33, a temperature meter 47, which can sense the temperature of the steam flowing in the main steam line 21, and a pressure meter 48, which can sense the pressure of the steam flowing in the main steam line 21. The temperature meter 47 and the pressure meter 48 are disposed in the main steam line 21 at a position on the side of the steam turbine 30 than the branching position of the bypass line 23 and on the side of the waste heat recovery boiler 20 than the steam regulating valve 22.

[0047] The control device 50 is a computer. The control device 50 is provided with a CPU (Central Processing Unit) 60 that performs various kinds of arithmetic operations, a memory 57 that is a work area or the like of the CPU 60, an auxiliary storage device 58 such as a hard disk drive device, a manual input device (input device) 51 such as a keyboard and a mouse, a display device (output device) 52, an input / output interface 53 of the manual input device 51 and the display device 52, a device interface (input device) 54 for performing transmission and reception of data with various kinds of equipment, a communication interface (input / output device) 55 for communicating with the outside through a network N, and a storage / reproduction device (input / output device) 56 that performs storage processing and reproduction processing of data with respect to a disk-type storage medium D. The device interface 54 receives sensing data from the GT output meter 41, the GT rotation meter 42, the ST output meter 45, the ST rotation meter 46, the temperature meter 47, and the pressure meter 48. Further, the device interface 54 transmits control data to each of the circuit breakers 18, 38, the fuel regulating valve 16, the stop valve 22a, the control valve 22b, the bypass valve 24, and the spray amount regulating valve 26v.

[0048] A control program 58p of the combined cycle unit is stored in advance in the auxiliary storage device 58. The control program 58p has embedded therein a startup control program 58pa that controls startup of the combined cycle unit. The control program 58p is introduced into the auxiliary storage device 58 from the disk-type storage medium D, for example, via the storage / reproduction device 56. Further, in a case where the control program 58p has already been stored in the auxiliary storage device 58 and the startup control program in the control program 58p is updated, a new startup control program 58pa is introduced into the auxiliary storage device 58 from the disk-type storage medium D, for example, via the storage / reproduction device 56. Note that the program can be introduced into the auxiliary storage device 58 from an external device via the communication interface 55.

[0049] The CPU 60 functionally has a startup control section 60g of the gas turbine equipment G and a startup control section 60s of the steam turbine equipment S. The startup control section 60g of the gas turbine equipment G has a GT startup mode reception section 61, a GT startup time fuel control section 62, and a GT incorporation instruction section 63. The startup control section 60s of the steam turbine equipment S has an ST output control section 71, a steam pressure control section 72, a bypass control section 73, an ST incorporation instruction section 74, a steam temperature control section 75, a venting instruction section 76, a steam supply stop instruction section 77, a thermal stress estimation section 78, and a thermal stress judgment section 79. These respective functional sections 61 to 63 and 71 to 79 each function by causing the CPU 60 to execute the startup control program 58pa stored in the auxiliary storage device 58. Note that the functional content of these respective functional sections 61 to 63 and 71 to 79 will be described in the course of describing the operation of the control device 50.

[0050] Next, the operation of the control device 50 described above will be described in accordance with the flowchart shown in Figure 3 and Figure 4

[0051] In the present embodiment, as the startup mode of the gas turbine 10, there are a GT quick startup mode and a GT normal startup mode. The GT quick startup mode is a mode in which the output of the gas turbine 10 is increased to the rated output regardless of the state of the steam turbine 30 and the gas turbine 10 is quickly started. The GT normal startup mode is a mode in which the gas turbine 10 is not quickly started. Therefore, first, the operation of the control device 50 at the time of the GT normal startup mode will be described in accordance with the flowchart shown in Figure 3

[0052] First, the GT startup mode receiving section 61 of the control device 50 receives from the outside the startup mode of the gas turbine 10 (S10: GT startup mode receiving step). When the GT startup mode receiving section 61 receives the GT normal startup mode, the GT startup time fuel control section 62 executes a GT normal startup process (S11N). In the GT normal startup process (S11N), the GT startup time fuel control section 62 instructs the fuel regulating valve 16 of the flow rate of the fuel supplied to the gas turbine 10 so that the rotational speed of the gas turbine 10 sensed by the GT rotational speed meter 42 as shown in Figure 5 follows a pre-set rotational speed change pattern (solid line in Figure 5 ) until the GT generator 17 is incorporated into the power system 1. As a result, in the process in which the rotational speed of the gas turbine 10 shown by the rotational speed change pattern has a tendency to increase, the flow rate of the fuel supplied to the gas turbine 10 increases. Therefore, in this process, the temperature of the steam generated from the waste heat recovery boiler 20 gradually increases, and the amount of generation of this steam gradually increases. Further, in the GT normal startup process (S11N), during the period from the incorporation of the GT generator 17 into the power system 1 to the time when the gas turbine output reaches the rated output Pgn, the GT startup time fuel control section 62 instructs the fuel regulating valve 16 of the flow rate of the fuel supplied to the gas turbine 10 so that the gas turbine output sensed by the GT output meter 41 as shown in Figure 5 follows a pre-set normal output change pattern (long dashed line in Figure 5 ). As a result, in the process in which the gas turbine output shown by the normal output change pattern has a tendency to increase, the flow rate of the fuel supplied to the gas turbine 10 increases. Therefore, in this process, the temperature of the steam generated from the waste heat recovery boiler 20 gradually increases, and the amount of generation of this steam gradually increases.

[0053] In the execution of the GT normal startup process (S11N), as Figure 5 ​​As shown, when the rotational speed of gas turbine 10 ( Figure 5 When the GT generator 17 reaches the rated speed Nn (as shown by the solid line in the diagram), the GT connection indicator 63 of the control device 50 instructs the GT circuit breaker 18 to electrically connect the GT generator 17 to the power system 1 (S12: GT connection process). As a result, the GT generator 17 is connected to the power system 1, and the gas turbine output can be detected by the GT output meter 41.

[0054] When the GT generator 17 is connected to the power system 1, as described above, as part of the GT normal start-up procedure (S11N), during GT start-up, the fuel control unit 62 instructs the fuel regulating valve 16 on the flow rate of fuel supplied to the gas turbine 10, so that the gas turbine output sensed by the GT output meter 41 changes according to a preset normal output variation pattern. This normal output variation pattern is as follows: Figure 5 As shown, it is set to maintain the low output Pga for a specified time when the gas turbine output reaches a low output Pga that is lower than the rated output Pgn. Therefore, as part of the GT's normal start-up procedure (S11N), when the gas turbine output ( Figure 5 When the low output Pga is reached (as shown by the long dashed line in the middle), the fuel control unit 62 at GT start-up instructs the fuel regulating valve 16 to supply the flow rate of fuel to the gas turbine 10 in order to maintain the low output Pga (S11Na).

[0055] like Figure 5 As shown, the typical output variation pattern is set such that after maintaining a low output Pga for a specified time, the gas turbine output gradually increases from the low output Pga to the rated output Pgn. Therefore, as part of the GT normal start-up procedure (S11N), during GT start-up, the fuel control unit 62 instructs the fuel regulating valve 16 on the flow rate of fuel supplied to the gas turbine 10 so that after maintaining the low output Pga for a specified time, the gas turbine output ( Figure 5 The output gradually increases from the long dashed line in the middle to the rated output Pgn. By the operation of the fuel control unit 62 when the GT starts, the gas turbine output reaches the rated output Pgn (S13).

[0056] During the period when the gas turbine output is maintained at the low output Pga and the period when the gas turbine output is increased from the low output Pga to the rated output Pgn, when the thermal stress generated in the steam turbine 30 reaches the preset thermal stress or more, as a part of the GT normal startup procedure (SllN), the GT startup time fuel control section 62 adjusts the gas turbine output regardless of the normal output change pattern (SllNb). Specifically, when the thermal stress generated in the steam turbine 30 reaches the preset thermal stress or more, the GT startup time fuel control section 62 instructs the fuel regulating valve 16 to temporarily reduce the flow rate of the fuel supplied to the gas turbine 10. As a result, the temperature, pressure, and flow rate of the steam flowing into the steam turbine 30 are reduced, and the thermal stress generated in the steam turbine 30 is less than the preset thermal stress. When the thermal stress generated in the steam turbine 30 is less than the preset thermal stress, the GT startup time fuel control section 62 again instructs the fuel regulating valve 16 to the flow rate of the fuel supplied to the gas turbine 10 so that the gas turbine output changes in accordance with the normal output change pattern.

[0057] As described above, when the fuel is supplied to the gas turbine 10, the steam is generated from the waste heat recovery boiler 20. The steam temperature control section 75 of the control device 50 instructs the desuperheater 26 so that the temperature of the steam sensed by the thermometer 47 is the preset temperature or less until at least the steam turbine output reaches the rated output (S20: steam temperature control procedure). When the spray amount adjusting valve 26v of the desuperheater 26 receives this instruction, the spray amount of the water from the sprayer 26s to the main steam line 21 reaches the spray amount corresponding to the instruction. As a result, in the main steam line 21, the temperature of the steam at the position on the steam turbine 30 side from the position where the desuperheater 26 is provided is the preset temperature or less.

[0058] Further, when the pressure of the steam sensed by the pressure gauge 48 reaches the preset value (which can not be a fixed value) or more, the bypass control section 73 of the control device 50 instructs the bypass valve 24 to open until at least the steam turbine output reaches the rated output (S21: bypass control procedure). Therefore, during the period from when the steam is generated from the waste heat recovery boiler 20 to when at least the steam turbine output reaches the rated output, when the pressure of the steam sensed by the pressure gauge 48 reaches the preset value or more, the bypass valve 24 opens, and a part of the steam from the waste heat recovery boiler 20 is sent to the condenser 34 via the bypass line 23.

[0059] When the temperature of the steam sensed by the thermometer 47 reaches above the preset temperature, the admission instructing portion 76 of the control device 50 instructs the opening of the valve of the steam regulating valve 22 so as to start the supply of steam to the steam turbine 30 (S22: admission process). As a result, the steam generated in the waste heat recovery boiler 20 flows into the steam turbine 30 via the main steam line 21 and the steam regulating valve 22. The steam turbine 30 starts to be driven by the steam. The admission process (S22) is basically executed after the GT incorporation process (S12).

[0060] When the admission process (S22) is executed, the thermal stress estimating portion 78 of the control device 50 estimates the thermal stress generated in the steam turbine 30 during at least until the steam turbine output reaches the rated output (S23: thermal stress estimating process). In the steam turbine rotor 33, when the steam starts to flow into the steam turbine 30 in the vicinity of the inlet near portion near the steam inlet, a high thermal stress is generated. The thermal stress estimating portion 78 estimates the thermal stress of the inlet near portion. Specifically, the thermal stress estimating portion 78 first estimates the temperature of the current inlet near portion from the temperature of the steam sensed by the thermometer 47, and calculates the temperature difference from the temperature of the inlet near portion estimated before a prescribed time. Then, the thermal stress estimating portion 78 calculates the thermal stress of the inlet near portion based on the temperature difference, the shape of the inlet near portion, and the Young's modulus or the expansion coefficient of the material forming the inlet near portion, and the like. The thermal stress estimated by the thermal stress estimating portion 78 is used when the above-described gas turbine output is adjusted (SllNb).

[0061] When the admission process (S22) is executed, the steam pressure control portion 72 of the control device 50 instructs the opening degree of the control valve 22b of the steam regulating valve 22 so as to gradually increase the flow rate of the steam flowing into the steam turbine 30, and instructs the opening degree of the bypass valve 24 so as to raise the pressure of the steam sensed by the pressure gauge 48 according to a preset pressure change pattern (S24: steam pressure control process).

[0062] In the execution of the steam pressure control process (S24), when the rotational speed (N) of the steam turbine 30 reaches the rated rotational speed Nn (single-dot chain line in FIG. 6), the ST incorporation instructing portion 74 of the control device 50 instructs the electrical connection of the ST generator 37 to the power system 1 by the ST breaker 38 (S26: ST incorporation process). As a result, the ST generator 37 is incorporated into the power system 1, and the steam turbine output can be detected by the ST output meter 45. Figure 5

[0063] After the execution of the ST incorporation process (S26), the steam pressure control process (S24) is further executed, as shown in FIG. 6, until the steam turbine output (double-dot chain line in FIG. 6) reaches the rated output Psn. Figure 5 Figure 5 ​​​

[0064] The above completes the startup of the gas turbine 10 in the GT normal startup mode and the startup of the steam turbine 30.

[0065] Next, the operation of the control device 50 in the GT quick startup mode will be described with reference to the flowchart shown in FIG. 6. Figure 4

[0066] First, the GT startup mode receiving section 61 of the control device 50 receives the startup mode of the gas turbine 10 from the outside (S10: GT startup mode receiving step). When the GT quick startup mode is received by the GT startup mode receiving section 61, the GT startup time fuel control section 62 executes the GT quick startup process (S11Q). In this GT quick startup process (S11Q), as in the GT normal startup process (S11N), the GT startup time fuel control section 62 instructs the fuel regulating valve 16 to the flow rate of the fuel supplied to the gas turbine 10 so that the rotational speed of the gas turbine 10 sensed by the GT tachometer 42 as shown in FIG. 5 (solid line in FIG. 5) changes according to the pre-set rotational speed change pattern until the GT generator 17 is incorporated into the power system 1. As a result, in the process in which the rotational speed of the gas turbine 10 shown by the rotational speed change pattern has a tendency to increase, the flow rate of the fuel supplied to the gas turbine 10 increases. Therefore, in this process, the temperature of the steam generated from the waste heat recovery boiler 20 gradually increases, and the amount of the steam generated gradually increases. Figure 5 Figure 5 In the GT quick startup process (S11Q), during the period from the incorporation of the GT generator 17 into the power system 1 to the gas turbine output reaching the rated output, the GT startup time fuel control section 62 instructs the fuel regulating valve 16 to the flow rate of the fuel supplied to the gas turbine 10 so that the gas turbine output sensed by the GT output meter 41 as shown in FIG. 5 (short dashed line in FIG. 5) changes according to the pre-set quick output change pattern. This quick output change pattern is set to linearly change the gas turbine output with respect to the passage of time in the present embodiment. As a result, with the passage of time, the flow rate of the fuel supplied to the gas turbine 10 gradually increases. Therefore, in this process, the temperature of the steam generated from the waste heat recovery boiler 20 gradually increases, and the amount of the steam generated gradually increases. Figure 5 Figure 5 In the execution of the GT quick startup process (S11Q), when the rotational speed of the gas turbine 10 reaches the rated rotational speed Nn as shown in FIG. 5, the GT incorporation instructing section 63 of the control device 50 instructs the GT breaker 18 to electrically connect the GT generator 17 to the power system 1 (S12: GT incorporation step). As a result, the GT generator 17 is incorporated into the power system 1, and the gas turbine output can be detected by the GT output meter 41.

[0067] In the execution of the GT quick startup process (S11Q), when the rotational speed of the gas turbine 10 reaches the rated rotational speed Nn as shown in FIG. 5, the GT incorporation instructing section 63 of the control device 50 instructs the GT breaker 18 to electrically connect the GT generator 17 to the power system 1 (S12: GT incorporation step). As a result, the GT generator 17 is incorporated into the power system 1, and the gas turbine output can be detected by the GT output meter 41. Figure 5 In the execution of the GT quick startup process (S11Q), when the rotational speed of the gas turbine 10 reaches the rated rotational speed Nn as shown in FIG. 5, the GT incorporation instructing section 63 of the control device 50 instructs the GT breaker 18 to electrically connect the GT generator 17 to the power system 1 (S12: GT incorporation step). As a result, the GT generator 17 is incorporated into the power system 1, and the gas turbine output can be detected by the GT output meter 41.​​​

[0068] After execution of the GT incorporation process (S12), a GT quick startup process (S11Q) is also executed, as shown in Fig. 1. Figure 5 As shown in Fig. 1, the gas turbine output (Pgt) reaches the rated output Pgn. Figure 5

[0069] As described above, when fuel is supplied to the gas turbine 10, steam is generated from the waste heat recovery boiler 20. In the case where the GT quick startup mode is accepted by the GT startup mode acceptance section 61, as well as in the case where the GT normal startup mode is accepted by the GT startup mode acceptance section 61, the steam temperature control section 75 of the control device 50 instructs the desuperheater to make the temperature of the steam sensed by the thermometer 47 be below the preset temperature until at least the steam turbine output reaches the rated output (S20: steam temperature control process). When the spray amount adjusting valve 26v of the desuperheater 26 receives this instruction, the amount of water sprayed from the sprayer 26s toward the main steam pipeline 21 reaches the amount of spray corresponding to the instruction. As a result, the temperature of the steam at the position on the steam turbine 30 side of the position where the desuperheater 26 is provided in the main steam pipeline 21 is below the preset temperature.

[0070] Further, when the pressure of the steam sensed by the pressure gauge 48 reaches above the preset value (which can not be a fixed value), the bypass control section 73 of the control device 50 instructs the bypass valve 24 to open until at least the steam turbine output reaches the rated output (S21: bypass control process). Therefore, during the period from the start of generation of steam from the waste heat recovery boiler 20 to at least the steam turbine output reaching the rated output, when the pressure of the steam sensed by the pressure gauge 48 reaches above the preset value, the bypass valve 24 opens, and a part of the steam from the waste heat recovery boiler 20 is sent to the condenser 34 via the bypass pipeline 23.

[0071] When the temperature of the steam sensed by the thermometer 47 reaches above the preset temperature, the venting instruction section 76 of the control device 50 instructs the steam regulating valve 22 to open so as to start supplying steam to the steam turbine 30 (S22: venting process). As a result, the steam generated in the waste heat recovery boiler 20 flows into the steam turbine 30 via the main steam pipeline 21 and the steam regulating valve 22. The steam turbine 30 starts driving by the steam. This venting process (S22) is executed after the execution of the above-described GT incorporation process (S12) and the gas turbine output reaches the rated output Pgn (S13), that is, after the end of the GT quick startup process (S11Q).

[0072] ​When the ventilation process (S22) is executed, as in the case where the GT normal start mode is accepted by the GT start mode acceptance section 61, the thermal stress estimation section 78 of the control device 50 estimates the thermal stress generated in the steam turbine 30 during a period until the output of the steam turbine reaches the rated output (S23: thermal stress estimation process).

[0073] The steam supply stop instruction section 77 of the control device 50 executes a steam supply stop process (S25) during a period from the start of the supply of steam to the steam turbine 30 to the execution of the ST incorporation process (S26) described later. In this steam supply stop process (S25), the steam supply stop instruction section 77 first determines whether the thermal stress estimated in the thermal stress estimation process (S23) reaches the second thermal stress or more, which is set in advance (S25a). Then, when it is determined that the thermal stress estimated by the thermal stress estimation process (S23) reaches the second thermal stress or more, which is set in advance, the steam supply stop instruction section 77 instructs the closing of the steam regulating valve 22 so as to stop the supply of steam to the steam turbine 30 (S25b).

[0074] Therefore, in the present embodiment, during a period from the start of the supply of steam to the steam turbine 30 to the execution of the incorporation process, even when the thermal stress of the second thermal stress or more is generated in the steam turbine 30, the generation time of the thermal stress can be suppressed to a minimum, and the deterioration of the steam turbine 30 caused by the thermal stress can be suppressed to a minimum.

[0075] After the execution of the steam supply stop process (S25), the above-described ventilation process (S22) is executed again.

[0076] After the execution of the ventilation process (S22), when the thermal stress estimated in the thermal stress estimation process (S23) does not reach the second thermal stress or more, which is set in advance, and the rotational speed (N) of the steam turbine 30 reaches the rated rotational speed Nn (single-dotted line in FIG. 6), the ST incorporation instruction section 74 of the control device 50 instructs the electrical connection of the ST generator 37 to the power system 1 by the ST circuit breaker 38 (S26: ST incorporation process). As a result, the ST generator 37 is incorporated into the power system 1, and the steam turbine output can be detected by the ST output meter 45. Figure 3

[0077] ​When the ST incorporation process (S26) is executed, the ST output control section 71 of the control device 50 executes an ST output control process (S27). As a part of the ST output control process (S27), the ST output control section 71 instructs the opening degree of the control valve 22b to control the flow rate of the steam flowing into the steam turbine 30 so that the output of the ST generator 37, that is, the steam turbine output increases in accordance with a target output change pattern (S27a). This target output change pattern is set so that the thermal stress generated in the steam turbine 30 does not reach a first thermal stress set in advance. Note that this first thermal stress can be the same value as the second thermal stress described above, but can also be a different value from the second thermal stress described above. As described above, even if the control is performed in such a manner that the steam turbine output increases in accordance with this target output change pattern, there can be a case where the thermal stress generated in the steam turbine 30 reaches the first thermal stress or more. Therefore, as a part of the ST output control process (S27), the ST output control section 71 determines whether the thermal stress estimated in the thermal stress estimation process (S23) reaches the first thermal stress or more set in advance (S27b). Then, when it is determined that the thermal stress estimated in the thermal stress estimation process (S23) reaches the first thermal stress or more set in advance, as a part of the ST output control process (S27), the ST output control section 71 instructs the opening degree of the control valve 22b to adjust the flow rate of the steam flowing into the steam turbine 30 so that the change in the steam turbine output is smaller than that indicated by the target output change pattern (S27c). At this time, the ST output control section 71 controls the flow rate of the steam flowing into the steam turbine 30 so as to temporarily maintain the steam turbine output.

[0078] In the execution of the ST output control process (S27), the thermal stress determination section 79 of the control device 50 executes a thermal stress determination process (S28). The thermal stress determination section 79 determines in the thermal stress determination process (S28) whether or not a thermal stress stable state is present, the thermal stress stable state being a state where the amount of change per unit time of the thermal stress estimated in the thermal stress estimation process (S23) is smaller than a change amount set in advance, and the current thermal stress is smaller than the first thermal stress.

[0079] When it is determined in the thermal stress determination process (S28) that the thermal stress stable state is not present, the ST output control process (S27) is continued. On the other hand, when it is determined in the thermal stress determination process (S28) that the thermal stress stable state is present, the ST output control process (S27) ends, and the steam pressure control section 72 of the control device 50 executes a steam pressure control process (S29). In this steam pressure control process (S29), the steam pressure control section 72 controls the flow rate of the steam flowing into the steam turbine 30 so that the steam pressure of the steam flowing into the steam turbine 30 is maintained at a target steam pressure set in advance. Figure 5The steam pressure control process (S24) is also explained. The steam pressure control section 72 instructs the opening degree of the control valve 22b of the steam regulating valve 22 so that the flow rate of the steam flowing into the steam turbine 30 gradually increases, and instructs the opening degree of the bypass valve 24 so that the pressure of the steam sensed by the pressure gauge 48 increases according to the pre-set pressure change pattern.

[0080] By executing this steam pressure control process (S29), as shown in Figure 5 the steam turbine output (Psn) reaches the rated output Psn. Figure 5

[0081] Thus, the startup of the gas turbine 10 and the startup of the steam turbine 30 in the GT fast startup mode are completed.

[0082] In the present embodiment, in the case where the GT startup mode acceptance section 61 accepts the GT normal startup mode, the gas turbine output (Pgn) is maintained at the low output Pga lower than the rated output Pgn for a predetermined time, as explained using Figure 5 the long dashed line in Figure 5 in order not to increase the thermal stress generated in the steam turbine 30.

[0083] Further, the steam supply amount per unit time to the steam turbine 30 has a positive correlation with respect to the steam turbine output. In addition, in the initial stage during the startup of the steam turbine 30 (during a predetermined time from ST), the thermal stress of the steam turbine 30 has a positive correlation with respect to the steam turbine output. Therefore, in the present embodiment, in the case where the GT startup mode acceptance section 61 accepts the GT fast startup mode, the flow rate of the steam flowing into the steam turbine 30 is controlled based on the steam turbine output sensed by the ST output gauge 45 so that the thermal stress generated in the steam turbine 30 does not reach the pre-set thermal stress or more. Therefore, in the present embodiment, in the case where the GT startup mode acceptance section 61 accepts the GT fast startup mode, it is not necessary to maintain the gas turbine output at the low output Pga for a predetermined time as in the case where the GT normal startup mode is accepted.

[0084] Therefore, in the present embodiment, in the case where the GT startup mode acceptance section 61 accepts the GT fast startup mode, it is possible to suppress the thermal stress generated in the steam turbine 30, and as shown in Figure 6 compared to the case where the GT normal startup mode is accepted, it is possible to shorten the time until the gas turbine output (Psn) reaches the rated output Psn. Figure 6 ​The time for which the gas turbine output is maintained at the low output is the time for which the gas turbine output is maintained at the rated output Pgn (indicated by a short broken line in FIG. 6). In other words, in the present embodiment, in the case where the GT quick start mode is accepted by the GT start mode accepting section 61, thermal stress generated in the steam turbine 30 can be suppressed, and the time for which the gas turbine output is maintained at the rated output Pgn can be shortened compared to the case where the gas turbine output is maintained at the low output for the prescribed time.

[0085] "Second Embodiment"

[0086] Referring to ​ The present embodiment will be described.

[0087] As ​ shown in FIG. 7, the combined cycle unit of the present embodiment is provided with a first gas turbine device Ga, a second gas turbine device Gb, a steam turbine device Sa, and a control device 50a.

[0088] The first gas turbine device Ga and the second gas turbine device Gb are the same as the gas turbine device G in the first embodiment. Therefore, the first gas turbine device Ga is provided with a first gas turbine 10a, a first GT generator 17a, a first GT breaker 18a, a first waste heat recovery boiler 20a, and a first stack 29a. Further, the second gas turbine device Gb is provided with a second gas turbine 10b, a second GT generator 17b, a second GT breaker 18b, a second waste heat recovery boiler 20b, and a second stack 29b.

[0089] With respect to the first gas turbine device Ga, the steam turbine device Sa of the present embodiment is provided with, as shared devices with the first gas turbine device Ga, the first waste heat recovery boiler 20a, a steam turbine 30, an ST generator 37, an ST breaker 38, a condenser 34, a feed water pump 35, a first main steam line 21a, a steam regulating valve 22, a bypass line 23, a bypass valve 24, a feed water line 36, a first desuperheater 26a, an ST output meter 45, an ST speed meter 46, a temperature meter 47, and a pressure meter 48, as with the steam turbine device S in the first embodiment. The first main steam line 21a connects a steam outlet of the first waste heat recovery boiler 20a and a steam inlet of the steam turbine 30.

[0090] The steam turbine apparatus Sa of this embodiment further includes a second waste heat recovery boiler 20b as a shared device with the second gas turbine apparatus Gb, a second main steam line 21b, a second desuperheater 26b, a first switching valve 28a, and a second switching valve 28b. The second main steam line 21b connects a steam outlet of the second waste heat recovery boiler 20b and a steam inlet of the steam turbine 30. Thus, the second main steam line 21b and a portion of the first main steam line 21a on the steam turbine 30 side share each other. Here, the portion of the second main steam line 21b and the first main steam line 21a that share each other is referred to as a shared main steam line 21c. Further, in the second main steam line 21b, a portion other than the shared main steam line 21c is referred to as a second main steam dedicated line 21bd, and in the first main steam line 21a, a portion other than the shared main steam line 21c is referred to as a first main steam dedicated line 21ad.

[0091] The steam regulating valve 22 is provided in the shared main steam line 21c. The second switching valve 28b is provided in the second main steam dedicated line 21bd. In the first main steam dedicated line 21ad, the first switching valve 28a is provided at a position on the first waste heat recovery boiler 20a side than a branching position of the bypass line 23.

[0092] In a case where the first gas turbine 10a is started and the second gas turbine 10b is not started, the first switching valve 28a is in an open state and the second switching valve 28b is in a closed state. Thus, by the start of the first gas turbine 10a, steam generated in the first waste heat recovery boiler 20a flows into the steam turbine 30 via the first main steam line 21a. Further, when the pressure of the steam sensed by the pressure gauge 48 becomes high, the bypass valve 24 opens, and a portion of the steam generated in the first waste heat recovery boiler 20a is sent to the condenser 34 via the bypass line 23.

[0093] In a case where the first gas turbine 10a is not started and the second gas turbine 10b is started, the first switching valve 28a is in a closed state and the second switching valve 28b is in an open state. Thus, by the start of the second gas turbine 10b, steam generated in the second waste heat recovery boiler 20b flows into the steam turbine 30 via the second main steam line 21b. Further, when the pressure of the steam sensed by the pressure gauge 48 becomes high, the bypass valve 24 opens, and a portion of the steam generated in the second waste heat recovery boiler 20b is sent to the condenser 34 via the bypass line 23.

[0094] Further, in a case where the first gas turbine 10a and the second gas turbine 10b are started, the first switching valve 28a and the second switching valve 28b are in an open state together. Therefore, by the start of the first gas turbine 10a, the steam generated in the first waste heat recovery boiler 20a flows into the steam turbine 30 via the first main steam line 21a, and the steam generated in the second waste heat recovery boiler 20b flows into the steam turbine 30 via the second main steam line 21b. Further, when the pressure of the steam sensed by the pressure gauge 48 becomes high, the bypass valve 24 opens, and a part of the steam generated in the first waste heat recovery boiler 20a or a part of the steam generated in the second waste heat recovery boiler 20b is sent to the condenser 34 via the bypass line 23.

[0095] Like the control device 50 of the first embodiment, the control device 50a is a computer. The control device 50a functionally has a start control section of the first gas turbine device Ga, a start control section of the second gas turbine device Gb, and a start control section of the steam turbine device S. The start control section of the first gas turbine device Ga and the start control section of the second gas turbine device Gb are each the same configuration as the start control section 60g in the control device 50 of the first embodiment. Further, the start control section of the steam turbine device S is substantially the same configuration as the start control section 60s in the control device 50 of the first embodiment. However, the start control section of the steam turbine device S in the present embodiment further has a switching control section that controls the opening and closing of the first switching valve 28a and the second switching valve 28b.

[0096] In the present embodiment, also like the first embodiment, in a case where the GT quick start mode is accepted by the GT start mode acceptance section 61, thermal stress generated in the steam turbine 30 can be suppressed, and the time until the gas turbine output becomes the rated output Pgn can be shortened compared to a case where the GT normal start mode is accepted.

[0097] The combined cycle unit of the present embodiment is a device that has two gas turbine devices Ga, Gb with respect to one steam turbine device S. However, the combined cycle unit can also be a device that has three or more gas turbine devices G with respect to one steam turbine device S.

[0098] "Modified Example"

[0099] The control device 50, 50a of each of the above embodiments each has a GT startup mode receiving section 61, and when the GT startup mode receiving section 61 receives a GT quick startup mode, a GT quick startup process (S11Q) is executed, and when the GT startup mode receiving section 61 receives a GT normal startup mode, a GT normal startup process (S11N) is executed. However, the GT startup mode receiving section 61 can not be present in the control device. In this case, the control device executes the same GT startup process as the GT quick startup process (S11Q) in each of the above embodiments.

[0100] The control device 50, 50a of each of the above embodiments is constituted by one computer. However, the control device can be constituted by a computer for a gas turbine facility and a computer for a steam turbine facility. In this case, the two computers need to be able to communicate with each other via a local network or the like. Further, the control device can be constituted by a controller having only the function of the bypass control section 73, a controller having only the function of the steam temperature control section 75, in addition to the computer having the functions of the GT startup fuel control section 62, the ST output control section 71, the steam pressure control section 72, and the like.

[0101] The above describes the preferred embodiments of the present application and modifications thereof, but the present application is not limited to these embodiments and modifications. Additions, omissions, substitutions, and other changes can be made to the structure without departing from the spirit of the present application. The present application is not limited by the above description, but is limited only by the claims.

[0102] "Postscript"

[0103] The startup method of the combined cycle unit in the above embodiments is grasped, for example, in the following manner.

[0104] (1) The startup method of the combined cycle unit in the first aspect is applied to the following combined cycle unit.

[0105] The combined cycle unit includes a gas turbine 10 that is driven by supply of fuel; a waste heat recovery boiler 20 that generates steam using heat of exhaust gas discharged from the gas turbine 10; a steam turbine 30 that is driven by steam from the waste heat recovery boiler 20; a condenser 34 that restores steam discharged from the steam turbine 30 to water; and a generator that generates electric power by driving of the steam turbine 30.

[0106] In the startup method of the combined cycle unit, the following procedures are executed: a gas turbine startup procedure in which fuel is supplied to the gas turbine 10 to increase the output of the gas turbine 10 to a rated output; a bleeder procedure (S22) in which, when the temperature of the steam from the waste heat recovery boiler 20 reaches a preset temperature or more, the supply of steam to the steam turbine 30 is started; a merging procedure (S26) in which, after the bleeder procedure (S22), when the rotational speed of the steam turbine 30 reaches a rated rotational speed, the generator is merged into the power system 1; an ST output control procedure (S27) in which, after the merging of the generator, the flow rate of the steam flowing into the steam turbine 30 is controlled to increase the output of the generator in accordance with a target output change pattern; and a thermal stress estimation procedure (S23) in which the thermal stress generated in the steam turbine 30 is estimated on the basis of the temperature of the steam flowing into the steam turbine 30. In the ST output control procedure (S27), when the thermal stress estimated in the thermal stress estimation procedure (S23) is a preset first thermal stress or more, the flow rate of the steam flowing into the steam turbine 30 is controlled to change the output of the generator less than indicated by the target output change pattern.

[0107] The steam supply amount per unit time to the steam turbine 30 has a positive correlation with the steam turbine output which is the output of the generator. Further, during a prescribed time from when the generator connected to the steam turbine 30 is merged into the power system 1, the thermal stress of the steam turbine 30 has a positive correlation with the steam turbine output. Therefore, in the present aspect, the flow rate of the steam flowing into the steam turbine 30 is controlled on the basis of the steam turbine output so that the thermal stress generated in the steam turbine 30 does not reach a preset thermal stress or more. Therefore, in the present aspect, it is not necessary to maintain the gas turbine output at a low output lower than the rated output for a prescribed time in order to prevent the thermal stress generated in the steam turbine 30 from increasing.

[0108] Therefore, in the present aspect, it is possible to suppress the thermal stress generated in the steam turbine 30 and, compared to maintaining the gas turbine output at a low output for a prescribed time, it is possible to make the time until the gas turbine output becomes the rated output shorter.

[0109] (2) A startup method of a combined cycle unit according to the second aspect,

[0110] In the startup method of the combined cycle unit in the first aspect, in the ST output control procedure (S27), when the thermal stress estimated in the thermal stress estimation procedure (S23) reaches the preset first thermal stress or more, the flow rate of the steam flowing into the steam turbine 30 is controlled to temporarily maintain the output of the generator.

[0111] (3) A method for starting up a combined cycle unit according to the third aspect,

[0112] In the method for starting up a combined cycle unit according to the first aspect or the second aspect, a bypass control step (S21) is further performed, in which when the pressure of the steam flowing into the steam turbine 30 reaches a value set in advance or more, a part of the steam from the waste heat recovery boiler 20 is not supplied to the steam turbine 30 but is sent to the condenser 34.

[0113] In the present aspect, it is possible to avoid the pressure of the steam flowing into the steam turbine 30 from exceeding a pressure set in advance.

[0114] (4) A method for starting up a combined cycle unit according to the fourth aspect,

[0115] In the method for starting up a combined cycle unit according to any one of the first aspect to the third aspect, a steam temperature control step (S20) is further performed, in which the temperature of the steam from the waste heat recovery boiler 20 is controlled so that the temperature of the steam flowing into the steam turbine 30 reaches a temperature set in advance or less.

[0116] In the present aspect, it is possible to avoid the temperature of the steam flowing into the steam turbine 30 from exceeding a temperature set in advance.

[0117] (5) A method for starting up a combined cycle unit according to the fifth aspect,

[0118] In the method for starting up a combined cycle unit according to any one of the first aspect to the fourth aspect, a steam supply stop step (S25) is further performed, in which during a period from the start of the supply of the steam to the steam turbine 30 to the performance of the incorporation step (S26), when the thermal stress estimated in the thermal stress estimation step (S23) reaches a second thermal stress set in advance or more, the supply of the steam to the steam turbine 30 is stopped.

[0119] In the present aspect, during a period from the start of the supply of the steam to the steam turbine 30 to the performance of the incorporation step (S26), even when a thermal stress of the second thermal stress or more is generated in the steam turbine 30, it is possible to suppress the generation time of the thermal stress to a minimum and to suppress the deterioration of the steam turbine 30 caused by the thermal stress to a minimum.

[0120] (6) A method for starting up a combined cycle unit according to the sixth aspect,

[0121] In the startup method of the combined cycle unit in any one of the first to fifth aspects, the target output change pattern used in the ST output control step (S27) is set so that thermal stress generated in the steam turbine 30 does not reach the first thermal stress set in advance.

[0122] (7) A startup method of a combined cycle unit in a seventh aspect,

[0123] In the startup method of the combined cycle unit in any one of the first to sixth aspects, the following steps are further performed: a thermal stress judgment step (S28) of judging whether or not a thermal stress stable state is present, the thermal stress stable state being a state in which a change amount per unit time of the thermal stress estimated in the thermal stress estimation step (S23) is smaller than a change amount set in advance, and the thermal stress is smaller than the first thermal stress set in advance; and a steam pressure control step (S24) of, in the thermal stress judgment step (S28), when it is judged that the thermal stress stable state is present, ending the ST output control step (S27), and controlling a pressure of steam flowing into the steam turbine 30 so that the pressure of the steam flowing into the steam turbine 30 is maintained within a range set in advance.

[0124] (8) A startup method of a combined cycle unit in an eighth aspect,

[0125] In the startup method of the combined cycle unit in any one of the first to seventh aspects, the gas turbine startup step is a GT quick startup step (S11Q) of increasing the output of the gas turbine 10 to the rated output regardless of the state of the steam turbine 30.

[0126] (9) A startup method of a combined cycle unit in a ninth aspect,

[0127] In the startup method of the combined cycle unit in the eighth aspect, the GT quick startup step (S11Q) is ended before the aeration step (S22).

[0128] (10) A startup method of a combined cycle unit in a tenth aspect,

[0129] In the startup method of the combined cycle unit in the eighth or ninth aspect, a GT startup mode reception step (S10) of receiving whether or not the gas turbine 10 is to be quickly started is further performed. When a GT quick startup mode of quickly starting the gas turbine 10 is received in the GT startup mode reception step (S10), the GT quick startup step (S11Q), the aeration step (S22), the merging step (S26), the ST output control step (S27), and the thermal stress estimation step (S23) are performed.

[0130] (11) The starting method of a combined cycle unit according to the eleventh aspect,

[0131] In the starting method of a combined cycle unit according to the tenth aspect, when a GT normal starting mode in which the gas turbine 10 is not rapidly started is accepted in the GT starting mode acceptance process (S10), the following processes are executed: a GT normal starting process (S11N) in which fuel is supplied to the gas turbine 10 so that the output of the gas turbine 10 is increased to a rated output; an admission process (S22) in which, when the temperature of steam from the waste heat recovery boiler 20 reaches a preset temperature or more, the supply of steam to the steam turbine 30 is started; a merging process (S26) in which, after the admission process (S22), when the rotational speed of the steam turbine 30 reaches a rated rotational speed, the generator is merged into the power system 1; and a steam pressure control process (S24) in which, after the generator is merged, the pressure of steam flowing into the steam turbine 30 is controlled so that the pressure of steam flowing into the steam turbine 30 is increased in accordance with a target pressure change pattern. In the GT normal starting process (S11N), before the output of the gas turbine 10 reaches the rated output, the flow rate of fuel supplied to the gas turbine 10 is adjusted so that the output of the gas turbine 10 is temporarily maintained at a preset low output that is less than the rated output.

[0132] In the present aspect, the GT normal starting process (S11N) can be executed in addition to the GT rapid starting process (S11Q).

[0133] (12) The starting method of a combined cycle unit according to the twelfth aspect,

[0134] In the starting method of a combined cycle unit according to the eleventh aspect, when a GT normal starting mode in which the gas turbine 10 is not rapidly started is accepted in the GT starting mode acceptance process (S10), the thermal stress estimation process (S23) is executed. In the GT normal starting process (S11N), when the thermal stress estimated in the thermal stress estimation process (S23) reaches a preset thermal stress or more, the flow rate of fuel supplied to the gas turbine 10 is temporarily reduced so that the output of the gas turbine 10 is temporarily reduced.

[0135] In the present aspect, in the GT normal starting process (S11N), the thermal stress generated in the steam turbine 30 can be avoided from being increased.

[0136] The combined cycle unit in the above-described embodiments is, for example, grasped in the following manner.

[0137] (13) A combined cycle unit according to the thirteenth aspect, comprising:

[0138] A gas turbine 10 that can be driven by supplying fuel; a waste heat recovery boiler 20 that can generate steam using heat of exhaust gas discharged from the gas turbine 10; a steam turbine 30 that can be driven by steam from the waste heat recovery boiler 20; a condenser 34 that restores steam discharged from the steam turbine 30 to water; a generator 37 that can generate electric power by driving of the steam turbine 30; a circuit breaker 38 that electrically connects and disconnects the generator 37 to and from an electric power system 1 according to an instruction from the outside; a fuel regulating valve 16 that can regulate a flow rate of fuel supplied to the gas turbine 10; a main steam line 21 that conducts steam from the waste heat recovery boiler 20 to the steam turbine 30; a steam regulating valve 22 that is provided in the main steam line 21 and can regulate a flow rate of steam flowing into the steam turbine 30; a thermometer 47 that is provided in the main steam line 21 on the waste heat recovery boiler 20 side than the steam regulating valve 22 and can sense a temperature of steam flowing in the main steam line 21; a tachometer 46 that can sense a rotational speed of the steam turbine 30; an output meter 45 that can sense an output as an amount of electric power generated by the generator 37; and a control device 50. The control device 50 has a startup fuel control section 62 that instructs the fuel regulating valve 16 to start supplying fuel to the gas turbine 10 and instructs a flow rate of fuel supplied to the gas turbine 10 so that an output of the gas turbine 10 increases to a rated output; a bleeder instructing section 76 that instructs the steam regulating valve 22 to open when a temperature of steam sensed by the thermometer 47 reaches a temperature set in advance or more so as to start supplying steam to the steam turbine 30; a merging instructing section 74 that instructs the circuit breaker 38 to electrically connect the generator 37 to the electric power system 1 when a rotational speed sensed by the tachometer reaches a rated rotational speed of the steam turbine 30; an ST output control section 71 that instructs the steam regulating valve 22 to the steam regulating valve 22 to regulate a flow rate of steam flowing into the steam turbine 30 so that an output sensed by the output meter 45 increases according to a target output change pattern after the generator 37 is electrically connected to the electric power system 1; and a thermal stress estimating section 78 that estimates thermal stress generated in the steam turbine 30 based on a temperature of steam sensed by the thermometer 47. The ST output control section 71 instructs the steam regulating valve 22 to regulate a flow rate of steam flowing into the steam turbine 30 so that a change in the output sensed by the output meter 45 is smaller than that indicated by the target output change pattern when the thermal stress estimated by the thermal stress estimating section 78 reaches a value set in advance or more.

[0139] In the present aspect, as with the startup method of the combined cycle unit in the first aspect, thermal stress generated in the steam turbine 30 can be suppressed, and the time until the gas turbine output becomes the rated output can be shortened compared to the case where the gas turbine output is maintained at the low output for the prescribed time.

[0140] (14) The combined cycle unit in the fourteenth aspect,

[0141] In the combined cycle unit in the thirteenth aspect, further provided are a pressure gauge 48 provided in the main steam line 21 on the waste heat recovery boiler 20 side from the position at which the steam regulating valve 22 is provided, capable of sensing the pressure of the steam flowing in the main steam line 21; a bypass line 23 extending in the main steam line 21 from a position on the waste heat recovery boiler 20 side from the position at which the steam regulating valve 22 is provided, conducting steam from the waste heat recovery boiler 20 to the condenser 34; and a bypass valve 24 provided in the bypass line 23, capable of adjusting the flow rate of the steam flowing in the bypass line 23. The control device 50 has a bypass control section 73 that instructs the opening of the bypass valve 24 when the pressure of the steam sensed by the pressure gauge 48 reaches a value set in advance or more.

[0142] In the present aspect, as with the startup method of the combined cycle unit in the third aspect, the pressure of the steam flowing into the steam turbine 30 can be prevented from exceeding a pressure set in advance.

[0143] (15) The combined cycle unit in the fifteenth aspect,

[0144] In the combined cycle unit in the thirteenth aspect or the fourteenth aspect, further provided is an attemperator 26 capable of adjusting the temperature of the steam flowing into the steam turbine 30 in the main steam line 21 on the waste heat recovery boiler 20 side from the position at which the steam regulating valve 22 is provided. The control device 50 has a steam temperature control section 75 that instructs the attemperator 26 so that the temperature of the steam sensed by the thermometer 47 is a temperature set in advance or less.

[0145] In the present aspect, as with the startup method of the combined cycle unit in the fourth aspect, the temperature of the steam flowing into the steam turbine 30 can be prevented from exceeding a temperature set in advance.

[0146] The startup control procedure of the combined cycle unit in the above-described embodiments is grasped, for example, in the following manner.

[0147] (16) The startup control procedure of the combined cycle unit in the sixteenth aspect is applied to the following combined cycle unit.

[0148] The combined cycle unit has: a gas turbine 10 that can be driven by supplying fuel; a waste heat recovery boiler 20 that can generate steam using heat of exhaust gas discharged from the gas turbine 10; a steam turbine 30 that can be driven by steam from the waste heat recovery boiler 20; a condenser 34 that restores steam discharged from the steam turbine 30 to water; a generator 37 that can generate electric power by driving of the steam turbine 30; a circuit breaker 38 that electrically connects and disconnects the generator 37 to and from an electric power system 1 according to an instruction from the outside; a fuel regulating valve 16 that can regulate a flow rate of fuel supplied to the gas turbine 10; a main steam line 21 that conducts steam from the waste heat recovery boiler 20 to the steam turbine 30; a steam regulating valve 22 that is provided in the main steam line 21 and can regulate a flow rate of steam flowing into the steam turbine 30; a thermometer 47 that is provided in the main steam line 21 on the waste heat recovery boiler 20 side than the steam regulating valve 22 and can sense a temperature of steam flowing in the main steam line 21; a tachometer 46 that can sense a rotational speed of the steam turbine 30; and an output meter 45 that can sense an output that is an amount of generated electric power by the generator 37.

[0149] The combined cycle unit has: a gas turbine 10 that can be driven by supplying fuel; a waste heat recovery boiler 20 that can generate steam using heat of exhaust gas discharged from the gas turbine 10; a steam turbine 30 that can be driven by steam from the waste heat recovery boiler 20; a condenser 34 that restores steam discharged from the steam turbine 30 to water; a generator 37 that can generate electric power by driving of the steam turbine 30; a circuit breaker 38 that electrically connects and disconnects the generator 37 to and from an electric power system 1 according to an instruction from the outside; a fuel regulating valve 16 that can regulate a flow rate of fuel supplied to the gas turbine 10; a main steam line 21 that conducts steam from the waste heat recovery boiler 20 to the steam turbine 30; a steam regulating valve 22 that is provided in the main steam line 21 and can regulate a flow rate of steam flowing into the steam turbine 30; a thermometer 47 that is provided in the main steam line 21 on the waste heat recovery boiler 20 side than the steam regulating valve 22 and can sense a temperature of steam flowing in the main steam line 21; a tachometer 46 that can sense a rotational speed of the steam turbine 30; and an output meter 45 that can sense an output that is an amount of generated electric power by the generator 37.

[0150] By executing the startup control program of the present scheme in the computer, as with the startup method of the combined cycle unit in the first scheme, thermal stress generated in the steam turbine 30 can be suppressed, and the time until the gas turbine output becomes the rated output can be shortened compared with the case where the gas turbine output is maintained at the low output for the prescribed time.

[0151] Industrial applicability

[0152] In one scheme of the present disclosure, thermal stress generated in the steam turbine can be suppressed, and the gas turbine output can be brought to the rated output in a short time.

[0153] Explanation of reference numerals

[0154] 1: power system

[0155] G: gas turbine device

[0156] Ga: first gas turbine device

[0157] Gb: second gas turbine device

[0158] 10: gas turbine

[0159] 10a: first gas turbine

[0160] 10b: second gas turbine

[0161] 11: compressor

[0162] 12: turbine

[0163] 13: gas turbine rotor

[0164] 14: combustor

[0165] 15: fuel line

[0166] 16: fuel regulating valve

[0167] 17: GT generator

[0168] 17a: first GT generator

[0169] 17b: second GT generator

[0170] 18: GT breaker

[0171] 18a: first GT breaker

[0172] 18b: second GT breaker

[0173] 19: power line

[0174] S, Sa: steam turbine device

[0175] 20: waste heat recovery boiler

[0176] 20a: first waste heat recovery boiler

[0177] 20b: second waste heat recovery boiler

[0178] 21: main steam line

[0179] 21a: first main steam line

[0180] 21b: second main steam line

[0181] 21c: shared main steam line

[0182] 21ad: first main steam dedicated line

[0183] 21bd: second main steam dedicated line

[0184] 22: steam regulating valve

[0185] 22a: stop valve

[0186] 22b: control valve

[0187] 23: bypass line

[0188] 24: bypass valve

[0189] 25: flue

[0190] 26: desuperheater

[0191] 26a: first desuperheater

[0192] 26b: second desuperheater

[0193] 26s: atomizer

[0194] 26v: atomizing valve

[0195] 28a: first switching valve

[0196] 28b: second switching valve

[0197] 29: stack

[0198] 29a: first stack

[0199] 29b: second stack

[0200] 30: steam turbine

[0201] 33: steam turbine rotor

[0202] 34: condenser

[0203] 35: feed water pump

[0204] 36: water supply line

[0205] 37: ST generator

[0206] 38: ST circuit breaker

[0207] 39: power line

[0208] 41: GT output meter

[0209] 42: GT tachometer

[0210] 45: ST output meter

[0211] 46: ST tachometer

[0212] 47: temperature meter

[0213] 48: pressure meter

[0214] 50, 50a: control device

[0215] 51: manual input device

[0216] 52: display device

[0217] 53: input / output interface

[0218] 54: device interface

[0219] 55: communication interface

[0220] 56: storage / reproduction device

[0221] 57: memory

[0222] 58: auxiliary storage device

[0223] 58p: control program

[0224] 58pa: startup control program

[0225] 60: CPU

[0226] 60g: startup control section of gas turbine equipment

[0227] 61: GT startup mode accepting section

[0228] 62: GT startup time fuel control section

[0229] 63: GT incorporation instruction section

[0230] 60s: startup control section of steam turbine equipment

[0231] 71: ST output control section

[0232] 72: steam pressure control section

[0233] 73: bypass control section

[0234] 74: ST incorporation instruction section

[0235] 75: steam temperature control section

[0236] 76: ventilation instruction section

[0237] 77: steam supply stop instruction section

[0238] 78: thermal stress estimation section

[0239] 79: thermal stress determination section

Claims

1. A method for starting up a combined cycle power unit, the combined cycle power unit comprising: a gas turbine capable of being driven by a fuel supply; a waste heat recovery boiler capable of generating steam using the heat from exhaust gas discharged from the gas turbine; a steam turbine capable of being driven by steam from the waste heat recovery boiler; a condenser for restoring steam discharged from the steam turbine back into water; and a generator capable of generating electricity by driving the steam turbine, wherein... The following procedures are performed in the startup method of a combined cycle unit: The gas turbine start-up process involves supplying fuel to the gas turbine, increasing its output to the rated output. In the ventilation process, when the temperature of the steam from the waste heat recovery boiler reaches or exceeds a preset temperature, steam is supplied to the steam turbine. In the process of integration, after the ventilation process, when the speed of the steam turbine reaches the rated speed, the generator is integrated into the power system; The ST output control process controls the flow rate of steam flowing into the steam turbine after it is connected to the generator, so that the output of the generator increases according to the target output change pattern. as well as The thermal stress estimation process estimates the thermal stress generated in the steam turbine based on the temperature of the steam flowing into the steam turbine. In the ST output control process, when the thermal stress estimated in the thermal stress estimation process reaches or exceeds the preset first thermal stress, the flow rate of steam flowing into the steam turbine is controlled so that the change in the generator output is less than the change shown in the target output change pattern.

2. The start-up method for a combined cycle unit according to claim 1, wherein, In the ST output control process, when the thermal stress estimated in the thermal stress estimation process reaches or exceeds the preset first thermal stress, the flow rate of steam flowing into the steam turbine is controlled in order to temporarily maintain the output of the generator.

3. The start-up method for a combined cycle unit according to claim 1 or 2, wherein, A bypass control process is also performed, in which when the pressure of the steam flowing into the steam turbine reaches or exceeds a preset value, a portion of the steam from the waste heat recovery boiler is not supplied to the steam turbine but is instead sent to the condenser.

4. The start-up method for a combined cycle unit according to claim 1 or 2, wherein, The process also includes a steam temperature control step, which controls the temperature of the steam from the waste heat recovery boiler to ensure that the temperature of the steam flowing into the steam turbine is below a preset temperature.

5. The start-up method for a combined cycle unit according to claim 1 or 2, wherein, The steam supply stop procedure is also performed, wherein during the period from the start of steam supply to the steam turbine to the execution of the integration procedure, when the thermal stress estimated in the thermal stress estimation procedure reaches or exceeds a predetermined second thermal stress, the steam supply to the steam turbine is stopped.

6. The start-up method for a combined cycle unit according to claim 1 or 2, wherein, The target output variation pattern used in the ST output control process is set such that the thermal stress generated in the steam turbine will not reach the preset first thermal stress.

7. The start-up method for a combined cycle unit according to claim 1 or 2, wherein, The following procedures are also performed: The thermal stress assessment process determines whether the system is in a stable thermal stress state. This stable state is defined as a state where the estimated change in thermal stress per unit time, as determined in the thermal stress estimation process, is less than a pre-set change, and the thermal stress is less than the pre-set first thermal stress. In the steam pressure control process, when the thermal stress judgment process determines that the thermal stress is in a stable state, the ST output control process ends, and the pressure of the steam flowing into the steam turbine is controlled so that the pressure of the steam flowing into the steam turbine is maintained within a preset range.

8. The start-up method for a combined cycle unit according to claim 1 or 2, wherein, The gas turbine start-up procedure is a GT rapid start-up procedure that increases the output of the gas turbine to the rated output regardless of the condition of the steam turbine.

9. The start-up method for a combined cycle unit according to claim 8, wherein, The GT quick start procedure ends before the ventilation procedure.

10. The start-up method for a combined cycle unit according to claim 8, wherein, It also performs a process of accepting whether to quickly start the gas turbine in GT start mode. When accepting the GT fast start mode for the gas turbine in the GT start mode acceptance process, the GT fast start process, the gas supply process, the integration process, the ST output control process, and the thermal stress estimation process are executed.

11. The start-up method for a combined cycle unit according to claim 10, wherein, When accepting a GT normal start-up mode (which does not quickly start the gas turbine) during the GT start-up mode acceptance process, the following steps are performed: The GT typically starts up the gas turbine by supplying fuel to it, thereby increasing the gas turbine's output to its rated output. In the ventilation process, when the temperature of the steam from the waste heat recovery boiler reaches or exceeds a preset temperature, steam is supplied to the steam turbine. In the integration process, after the ventilation process, when the steam turbine reaches its rated speed, the generator is integrated into the power system; and The steam pressure control process, after being connected to the generator, controls the pressure of the steam flowing into the steam turbine so that the pressure of the steam flowing into the steam turbine increases according to a target pressure change pattern. During the GT normal start-up process, before the gas turbine output reaches the rated output, the flow rate of fuel supplied to the gas turbine is adjusted so that the gas turbine output is temporarily maintained at a preset low output below the rated output.

12. The start-up method for a combined cycle unit according to claim 11, wherein, When the GT start-up mode acceptance process accepts a GT normal start-up mode that does not rapidly start the gas turbine, the thermal stress estimation process is executed. In the GT normal start-up process, when the thermal stress estimated in the thermal stress estimation process reaches or exceeds the preset thermal stress, the flow rate of fuel supplied to the gas turbine is temporarily reduced so as to temporarily reduce the output of the gas turbine.

13. A combined cycle power unit, the combined cycle power unit comprising: Gas turbines are driven by fuel. Waste heat recovery boilers can utilize the heat from the exhaust gases from the gas turbine to generate steam; The steam turbine can be driven by steam from the waste heat recovery boiler; A condenser that converts the steam discharged from the steam turbine back into water; The generator is capable of generating electricity by driving the steam turbine. A circuit breaker that connects the generator to the power system from the outside according to instructions, and disconnects the generator from the power system from the outside according to instructions; A fuel regulating valve is used to regulate the flow rate of fuel supplied to the gas turbine; The main steam pipeline transmits steam from the waste heat recovery boiler to the steam turbine; A steam regulating valve, located on the main steam pipeline, is used to regulate the flow rate of steam flowing into the steam turbine. A thermometer is installed in the main steam pipeline on the side closer to the waste heat recovery boiler than the steam regulating valve, and is capable of sensing the temperature of the steam flowing in the main steam pipeline. A tachometer is used to sense the rotational speed of the steam turbine; The output meter can sense the output as the amount of electricity generated by the generator. as well as Control device, The control device has: During startup, the fuel control unit instructs the fuel regulating valve to begin supplying fuel to the gas turbine and instructs the flow rate of the fuel supplied to the gas turbine so that the output of the gas turbine increases to the rated output; The ventilation indicator, when the temperature of the steam sensed by the thermometer reaches or exceeds a preset temperature, instructs the steam regulating valve to open so as to start supplying steam to the steam turbine; The indicator unit, when the rotational speed sensed by the tachometer reaches the rated rotational speed of the steam turbine, instructs the circuit breaker to electrically connect the generator to the power system; The ST output control unit, after the generator is electrically connected to the power system, instructs the steam regulating valve to control the flow rate of steam flowing into the steam turbine, so that the output sensed by the output meter increases according to a target output change pattern; and The thermal stress estimation unit estimates the thermal stress generated in the steam turbine based on the temperature of the steam sensed by the thermometer. When the thermal stress estimated by the thermal stress estimation unit reaches or exceeds a preset value, the ST output control unit instructs the steam regulating valve to control the flow rate of steam flowing into the steam turbine, so that the change in output sensed by the output meter is less than the change shown in the target output change pattern.

14. The combined cycle unit according to claim 13, wherein, It also has: A pressure gauge is installed in the main steam pipeline on the side closer to the waste heat recovery boiler than the steam regulating valve, and can sense the pressure of the steam flowing in the main steam pipeline. A bypass line extends from a position closer to the waste heat recovery boiler than the position where the steam regulating valve is located in the main steam line, and conducts steam from the waste heat recovery boiler to the condenser. as well as A bypass valve, located in the bypass line, is used to regulate the flow rate of steam flowing in the bypass line. The control device has a bypass control unit that instructs the bypass valve to open when the pressure of the steam sensed by the pressure gauge reaches or exceeds a preset value.

15. The combined cycle unit according to claim 13 or 14, wherein, It also includes a desuperheater, which regulates the temperature of the steam flowing into the steam turbine in the main steam pipeline, at a position closer to the waste heat recovery boiler than where the steam regulating valve is located. The control device includes a steam temperature control unit that instructs the desuperheater to bring the steam temperature sensed by the thermometer below a preset temperature.

16. A storage medium storing a startup control program for a combined cycle unit, the combined cycle unit comprising: Gas turbines are driven by fuel. Waste heat recovery boilers can utilize the heat from the exhaust gases from the gas turbine to generate steam; The steam turbine can be driven by steam from the waste heat recovery boiler; A condenser that converts the steam discharged from the steam turbine back into water; The generator is capable of generating electricity by driving the steam turbine. A circuit breaker that connects the generator to the power system from the outside according to an instruction, and disconnects the generator from the power system from the outside according to an instruction. A fuel regulating valve is used to regulate the flow rate of fuel supplied to the gas turbine; The main steam pipeline transmits steam from the waste heat recovery boiler to the steam turbine; A steam regulating valve, located on the main steam pipeline, is used to regulate the flow rate of steam flowing into the steam turbine. A thermometer is installed in the main steam pipeline on the side closer to the waste heat recovery boiler than the steam regulating valve, and is capable of sensing the temperature of the steam flowing in the main steam pipeline. A tachometer is used to sense the rotational speed of the steam turbine; as well as The output meter can sense the output as the power generated by the generator, wherein, The startup control program for the combined cycle unit causes the computer to perform the following procedures: In the gas turbine start-up process, the fuel regulating valve is instructed to begin supplying fuel to the gas turbine, and the flow rate of the fuel supplied to the gas turbine is indicated so that the output of the gas turbine increases to the rated output; In the ventilation process, when the temperature of the steam sensed by the thermometer reaches or exceeds a preset temperature, the steam regulating valve is instructed to open so that steam can be supplied to the steam turbine. In the process of integration, when the rotational speed sensed by the tachometer reaches the rated speed of the steam turbine, the circuit breaker is instructed to electrically connect the generator to the power system; In the ST output control process, after the generator is electrically connected to the power system, the steam regulating valve is instructed to control the flow rate of steam flowing into the steam turbine, so that the output sensed by the output meter increases according to the target output change pattern. as well as The thermal stress estimation process estimates the thermal stress generated in the steam turbine based on the temperature of the steam sensed by the thermometer. In the ST output control process, when the thermal stress estimated in the thermal stress estimation process reaches or exceeds a preset value, the steam regulating valve is instructed to control the flow rate of steam flowing into the steam turbine, so that the change in output sensed by the output meter is less than the change shown in the target output change pattern.

17. A computer program product comprising a startup control program for a combined cycle unit, the combined cycle unit comprising: Gas turbines are driven by fuel. Waste heat recovery boilers can utilize the heat from the exhaust gases from the gas turbine to generate steam; The steam turbine can be driven by steam from the waste heat recovery boiler; A condenser that converts the steam discharged from the steam turbine back into water; The generator is capable of generating electricity by driving the steam turbine. A circuit breaker that connects the generator to the power system from the outside according to an instruction, and disconnects the generator from the power system from the outside according to an instruction. A fuel regulating valve is used to regulate the flow rate of fuel supplied to the gas turbine; The main steam pipeline transmits steam from the waste heat recovery boiler to the steam turbine; A steam regulating valve, located on the main steam pipeline, is used to regulate the flow rate of steam flowing into the steam turbine. A thermometer is installed in the main steam pipeline on the side closer to the waste heat recovery boiler than the steam regulating valve, and is capable of sensing the temperature of the steam flowing in the main steam pipeline. A tachometer is used to sense the rotational speed of the steam turbine; as well as The output meter can sense the output as the power generated by the generator, wherein, The startup control program for the combined cycle unit causes the computer to perform the following procedures: In the gas turbine start-up process, the fuel regulating valve is instructed to begin supplying fuel to the gas turbine, and the flow rate of the fuel supplied to the gas turbine is indicated so that the output of the gas turbine increases to the rated output; In the ventilation process, when the temperature of the steam sensed by the thermometer reaches or exceeds a preset temperature, the steam regulating valve is instructed to open so that steam can be supplied to the steam turbine. In the process of integration, when the rotational speed sensed by the tachometer reaches the rated speed of the steam turbine, the circuit breaker is instructed to electrically connect the generator to the power system; In the ST output control process, after the generator is electrically connected to the power system, the steam regulating valve is instructed to control the flow rate of steam flowing into the steam turbine, so that the output sensed by the output meter increases according to the target output change pattern. as well as The thermal stress estimation process estimates the thermal stress generated in the steam turbine based on the temperature of the steam sensed by the thermometer. In the ST output control process, when the thermal stress estimated in the thermal stress estimation process reaches or exceeds a preset value, the steam regulating valve is instructed to control the flow rate of steam flowing into the steam turbine, so that the change in output sensed by the output meter is less than the change shown in the target output change pattern.

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