Control device, fuel supply system for gas turbine, control method, and program

Abstract

To provide a technique for suppressing control delay during a load change of flow rate control of water to be mixed with fuel to be supplied to a combustor.SOLUTION: A control device controls a flow rate of water to be supplied to a fuel supply system in a system having the fuel supply system for supplying fuel to a combustor of a gas turbine and a water supply system for supplying water to the fuel supply system. The control device includes: a determination section that determines whether an operating state of the gas turbine is during a load change or a static state; a selection section that selects calculation of the flow rate of the water on the basis of a load command value of the gas turbine when the operating state is determined to be during the load change; and a control section that controls the flow rate of the water on the basis of the load command value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control device, a fuel supply system for a gas turbine, a control method, and a program. [Background technology]

[0002] Patent Document 1 discloses a control device that supplies water or steam in addition to fuel to a combustor of a gas turbine. Conventionally, the water injection flow rate to the combustor has been set according to the actual load, which is a measured load value of the gas turbine. In this type of control, the actual load is checked and then the water injection flow rate is set according to the actual load. This means that the control of the water injection flow rate tends to lag behind load changes. Furthermore, during load changes, the water injection flow rate changes according to the actual load, and the change in the water injection flow rate causes the actual load to fluctuate. This causes the load and the water injection flow rate to influence each other and fluctuate, resulting in hunting and potentially combustion oscillation. Depending on the severity of the combustion oscillation, the gas turbine may trip. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-127098 Summary of the Invention [Problem to be solved by the invention]

[0004] Provides a technology to suppress delays in control of water injection flow rate during load changes.

[0005] The present disclosure provides a control device, a fuel supply system for a gas turbine, a control method, and a program that can solve the above-mentioned problems. [Means for solving the problem]

[0006] A control device according to the present disclosure is a control device for controlling the flow rate of water supplied to a fuel supply system, the fuel supply system including a fuel supply system that supplies fuel to a combustor of a gas turbine and a water supply system that supplies water to the fuel supply system, and is equipped with a determination unit that determines whether the operating state of the gas turbine is undergoing a load change or is in a static state, a selection unit that, when it is determined that the operating state is undergoing a load change, selects to calculate the water flow rate based on a load command value of the gas turbine, and a control unit that controls the water flow rate based on the load command value.

[0007] A fuel supply system for a gas turbine according to the present disclosure includes a fuel supply system that supplies fuel to a combustor of the gas turbine, a water supply system that supplies water to the fuel supply system, and the above-described control device.

[0008] A control method according to the present disclosure is a control method for controlling a flow rate of water supplied to a fuel supply system in a fuel supply system that includes a fuel supply system that supplies fuel to a combustor of a gas turbine and a water supply system that supplies water to the fuel supply system, the control method determining whether the operating state of the gas turbine is undergoing a load change or a static state, and if it is determined that the operating state is undergoing a load change, selecting to calculate the water flow rate based on a load command value of the gas turbine, and controlling the water flow rate based on the load command value.

[0009] A program according to the present disclosure causes a computer to execute a process for controlling a flow rate of water supplied to a fuel supply system, the fuel supply system including a fuel supply system that supplies fuel to a combustor of a gas turbine and a water supply system that supplies water to the fuel supply system, the process determining whether the operating state of the gas turbine is undergoing a load change or a static state, and if it is determined that the operating state is undergoing a load change, selecting to calculate the water flow rate based on a load command value of the gas turbine, and controlling the water flow rate based on the load command value. [Effects of the Invention]

[0010] According to the control device, the gas turbine fuel supply system, the control method, and the program of the present disclosure, it is possible to suppress a delay in the control of the water injection flow rate during a load change. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic diagram of a supply system for fuel and water supplied to a combustor according to the embodiment. [Figure 2] FIG. 4 is a diagram illustrating an example of control logic for a water ejection flow rate according to the embodiment. [Figure 3] 4 is a flowchart illustrating an example of water injection flow rate control according to the embodiment. [Figure 4] FIG. 1 is a diagram illustrating an example of a hardware configuration of a water injection flow rate control device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Embodiment> Hereinafter, the method for controlling the water injection flow rate of the present disclosure will be described with reference to the drawings. (composition) FIG. 1 is a schematic diagram of a fuel supply system according to an embodiment. A combustor 7 of a gas turbine is provided with nozzles 3a and 3b, and a mixed fuel obtained by mixing fuel (oil) and water is supplied from the nozzles 3a and 3b. A fuel supply system 1 for supplying fuel and a water supply system 4 for supplying water are provided upstream of the nozzles 3a and 3b, and the water supply system 4 supplies water to the fuel supply system 1. The fuel flowing through the fuel supply system 1 is evenly distributed by a flow distributor 2 and supplied to the nozzles 3a and 3b through fuel supply systems 1a and 1b. The water supply system 4 distributes the water to water supply systems 4a and 4b, which are connected to the fuel supply systems 1a and 1b at confluences 8a and 8b downstream of the flow distributor 2, respectively. In the fuel supply system 1a, fuel oil and water are mixed at the confluence 8a, and the mixed mixed fuel is injected into the combustor 7 from the nozzle 3a. In the fuel supply system 1b, fuel and water are mixed at a junction 8b, and the mixed fuel is injected from a nozzle 3b into the combustor 7. The water injection flow rate control device 10 controls the pump 5 and the valve 6 provided in the water supply system 4 so that a desired flow rate of water is supplied to the fuel supply systems 1a and 1b. The water flow rate is determined according to the load of the gas turbine. Conventionally, the water flow rate has been determined according to the actual load (measured load value) of the gas turbine. However, this control can cause a control delay when the operating state of the gas turbine is in a transient state of load change (e.g., during frequency response or load change), which can destabilize the load control of the gas turbine. Therefore, in this embodiment, the flow rate of water supplied to the fuel supply systems 1a and 1b (referred to as the water injection flow rate) is controlled so that water according to the load can be supplied without delay in response to load changes.

[0013] 2 shows an example of a water injection flow rate control device 10 according to an embodiment. The water injection flow rate control device 10 includes an actual load input / output unit 11, a change detection unit 12, a load command value input / output unit 13, a selection unit 14, a flow rate calculation unit 15, and a control unit 16.

[0014] The actual load input / output unit 11 acquires a measurement value (actual load) of the gas turbine load measured by a sensor or the like, and outputs the actual load to the selection unit 14. The actual load input / output unit 11 is provided with a filter circuit that smoothes fluctuations in the actual load, and outputs the actual load from which the fluctuations have been removed by the filter circuit to the selection unit 14.

[0015] The change detection unit 12 acquires the system frequency of the power system to which the generator driven by the gas turbine is connected and a load command value (GT LOAD DEMAND) issued by a gas turbine control device (not shown), and detects changes in the system frequency and the load command value. For example, the change detection unit 12 determines that the load has changed (detects a load change) if the load command value has changed by a predetermined threshold or more, and determines that the system frequency has changed (detects a system frequency change) if the system frequency has changed by a predetermined threshold or more. When detecting a load change or a system frequency change, the change detection unit 12 outputs a signal indicating that a change in the load or the like has been detected (referred to as a change detection signal) to the selection unit 14. When not detecting a change in the load or the like, the change detection unit 12 does not output a change detection signal. Changes in the frequency system are often instantaneous, but control responding to the change in the frequency system takes time, and load changes occur during that control. Therefore, when the change detection unit 12 detects a change in the frequency system, it continues to output a change detection signal to the selection unit 14 for a while (tens of seconds to several minutes, for example, one minute) after detecting the change. Regarding changes in the load command value (GT LOAD DEMAND), the change detection unit 12 outputs a change detection signal only when it detects a change in the load command value.

[0016] There are several operation modes for gas turbines, such as an operation mode in which the gas turbine operates at a predetermined load, an operation mode (governor mode) for stabilizing the system frequency, etc. In any operation mode, the change detection unit 12 monitors the load command value (GT LOAD DEMAND) and detects its changes. The change detection unit 12 monitors the system frequency and determines whether there is a change in the system frequency only when the gas turbine is operating in governor mode.

[0017] The load command value input / output unit 13 acquires a load command value (GT LOAD DEMAND) for the gas turbine from a gas turbine control device (not shown), and outputs the acquired load command value (GT LOAD DEMAND) to the selection unit 14.

[0018] The selection unit 14 acquires the actual load from the actual load input / output unit 11 and the load command value (GT LOAD DEMAND) from the load command value input / output unit 13, selects one of them, and outputs the selected value to the flow rate calculation unit 15. Specifically, if the selection unit 14 has acquired a change detection signal from the change detection unit 12, it selects the load command value (GT LOAD DEMAND), and otherwise selects the actual load. Furthermore, the selection unit 14 calculates the difference between the actual load and the load command value (GT LOAD DEMAND), and if the absolute value of the calculated difference is equal to or greater than a predetermined value, it selects the actual load even if it has acquired a change detection signal from the change detection unit 12. This is to avoid the possibility that combustion oscillation may occur before there is a control delay in the water injection flow rate in response to a load change if the water injection flow rate is determined based on the load command value (GT LOAD DEMAND) even though the load command value (GT LOAD DEMAND) is too far from the actual load. The selection unit 14 selects either the load command value (GT LOAD DEMAND) or the actual load based on the presence or absence of a change detection signal and the degree of deviation between the load command value (GT LOAD DEMAND) and the actual load, and outputs the selected load value to the flow rate calculation unit 15.

[0019] The flow rate calculation unit 15 acquires the load value output from the selection unit 14 and calculates the water injection flow rate according to the load. The flow rate calculation unit 15 is equipped with a correspondence map between the load magnitude and the water injection flow rate, a function for calculating the water injection flow rate from the load, and so on, and calculates the water injection flow rate according to the load by inputting the actual load or load command value (GT LOAD DEMAND) acquired from the selection unit 14 into this function. The flow rate calculation unit 15 outputs the calculated water injection flow rate to the control unit 16.

[0020] The control unit 16 adjusts the rotation speed of the pump 5 and the opening of the valve 6 based on the water injection flow calculated by the flow rate calculation unit 15, so that water is supplied to the fuel supply systems 1a, 1b at a flow rate according to the load. For example, the control unit 16 holds a control table that associates the rotation speed of the pump 5 and the opening of the valve 6 with the water injection flow rate, and controls the pump 5 etc. by referring to this control table.

[0021] (operation) Next, the operation of the water injection flow rate control device 10 of this embodiment will be described. 7 is a flowchart showing an example of water injection flow rate control according to the embodiment. The selection unit 14 acquires an actual load and a load command value (GT LOAD DEMAND) (step S1). The selection unit 14 acquires the actual load from the actual load input / output unit 11 and acquires the load command value (GT LOAD DEMAND) from the load command value input / output unit 13. Next, the change detection unit 12 determines whether the operating state of the gas turbine is undergoing a load change or a static state (step S2). For example, the change detection unit 12 monitors the load command value (GT LOAD DEMAND), and determines that the operating state of the gas turbine is undergoing a load change when the load command value (GT LOAD DEMAND) changes by a predetermined value or more per unit time. Alternatively, when the gas turbine is operating in governor mode, the change detection unit 12 monitors the grid frequency, and determines that the operating state of the gas turbine is undergoing a load change when the grid frequency changes by a predetermined value or more per unit time. When a change in the system frequency is detected, the change detection unit 12 determines that the operating state of the gas turbine is in a load change state for a certain period of time after the detection of the change. When the operating state is determined to be in a static state rather than in a load change state (step S2; No), the selection unit 14 outputs the actual load to the flow rate calculation unit 15. In this case, the process proceeds to step S5, which will be described later.

[0022] If it is determined that the operating state is a load change state (step S2; Yes), the selection unit 14 determines whether the difference between the actual load and the load command value (GT LOAD DEMAND) is within a predetermined value (step S3). If the difference between the actual load and the load command value (GT LOAD DEMAND) is greater than the predetermined value (step S3; No), the selection unit 14 outputs the actual load to the flow rate calculation unit 15. The flow rate calculation unit 15 calculates the water injection flow rate based on the actual load (step S5). The flow rate calculation unit 15 outputs the calculated water injection flow rate to the control unit 16.

[0023] If the difference between the actual load and the load command value (GT LOAD DEMAND) is within a predetermined value (step S3; Yes), the selection unit 14 outputs the load command value (GT LOAD DEMAND) to the flow rate calculation unit 15. The flow rate calculation unit 15 calculates the water injection flow rate based on the load command value (GT LOAD DEMAND) (step S4). The flow rate calculation unit 15 outputs the calculated water injection flow rate to the control unit 16.

[0024] Next, the control unit 16 controls the pump 5 and the like based on the water injection flow rate calculated by the flow rate calculation unit 15 (step S6). Next, the water injection flow rate control device 10 determines whether to end the control of the water injection flow rate (step S7). For example, if the operation of the gas turbine is to be stopped, the water injection flow rate control device 10 determines to end the control, and otherwise determines to continue the control. If the control is to be ended (step S7; Yes), the processing of FIG. 3 is ended. If the control is to be continued (step S7; No), the processing from step S1 is repeated.

[0025] 3, when the operating state of the gas turbine switches from a static state to a changing load, the water injection flow rate control is switched from the water injection flow rate control based on the actual load to the water injection flow rate control based on the load command value (GT LOAD DEMAND), and when the operating state of the gas turbine switches from a changing load to a static state, the water injection flow rate control is switched from the water injection flow rate control based on the load command value (GT LOAD DEMAND) to the water injection flow rate control based on the actual load. This makes it possible to achieve stable load control while avoiding control delays in the water injection flow rate control.

[0026] (effect) Because the actual load is a value obtained by controlling each component of the gas turbine based on the load command value (GT LOAD DEMAND), setting the water injection flow rate based on the actual load during load changes inevitably results in delays in water injection control. Furthermore, if the grid frequency changes during governor mode operation, the gas turbine load is changed to stabilize the grid frequency. In this case, setting the water injection flow rate based on the actual load also results in control delays. In contrast, according to this embodiment, when the load or grid frequency changes, the water injection flow rate is controlled based on the load command value (GT LOAD DEMAND) rather than the actual load. This allows the water injection flow rate to be set in accordance with load changes, thereby suppressing control delays. Furthermore, hunting between the load and the water injection flow rate and combustion oscillation can be avoided. Furthermore, when the operating state returns to a static state, the water injection flow rate is controlled based on the actual load. This enables stable control, just as in the past.

[0027] In the above embodiment, water is mixed with the fuel supplied from the nozzle to the combustor, but steam may be mixed with the fuel instead of water and injected into the combustor from the nozzle. The control of this embodiment can be applied to a fuel supply system of a gas turbine in which water or steam is mixed with the fuel and supplied to the combustor.

[0028] FIG. 4 is a diagram showing an example of the hardware configuration of a water injection flow rate control device 10 according to an embodiment. A computer 900 includes a CPU 901, a main memory device 902, an auxiliary memory device 903, an input / output interface 904, and a communication interface 905. The water injection flow rate control device 10 described above is implemented in the computer 900. The above-described functions are stored in the auxiliary memory device 903 in the form of a program. The CPU 901 reads the program from the auxiliary memory device 903, loads it into the main memory device 902, and executes the above-described processing in accordance with the program. The CPU 901 also allocates a memory area in the main memory device 902 in accordance with the program. The CPU 901 also allocates a memory area in the auxiliary memory device 903 for storing data being processed in accordance with the program.

[0029] A program for implementing all or part of the functions of the water injection flow rate control device 10 may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed to perform processing by each functional unit. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. Furthermore, if a WWW system is used, the term "computer system" also includes the homepage provision environment (or display environment). Furthermore, the term "computer-readable recording medium" refers to portable media such as CDs, DVDs, and USBs, as well as storage devices such as hard disks built into the computer system. Furthermore, if the program is distributed to the computer 900 via a communication line, the computer 900 that receives the program may load the program into the main storage device 902 and execute the above-described processing. Furthermore, the program may be for implementing part of the above-described functions, or may be capable of implementing the above-described functions in combination with a program already stored in the computer system.

[0030] As described above, several embodiments according to the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as defined in the claims, as well as in the scope and spirit of the invention.

[0031] <Additional Notes> The control device, the fuel supply system of the gas turbine, the control method, and the program described in the embodiments can be understood, for example, as follows.

[0032] (1) A control device (water injection flow rate control device 10) according to a first aspect is a control device for controlling the flow rate of water supplied to a fuel supply system 1 in a fuel supply system that includes a fuel supply system 1 that supplies fuel to a combustor of a gas turbine and a water supply system 4 that supplies water to the fuel supply system 1, and is equipped with a determination unit (change detection unit 12) that determines whether the operating state of the gas turbine is undergoing a load change or is in a static state, a selection unit 14 that, when it is determined that the operating state is undergoing a load change, selects to calculate the water flow rate based on a load command value of the gas turbine, and a control unit 16 that controls the water flow rate based on the load command value. This makes it possible to suppress delays in the control of the water injection flow rate during load changes.

[0033] (2) A control device according to a second aspect is a control device according to (1), wherein, when it is determined that the operating state is not undergoing a load change, the selection unit selects to calculate the water flow rate based on the actual load of the gas turbine, and the control unit controls the water flow rate based on the actual load. This allows the water injection flow rate to be controlled in the same way as before, which has a proven track record.

[0034] (3) A control device according to a third aspect is a control device according to (1) to (2), wherein the selection unit selects to calculate the water flow rate based on the actual load if the difference between the actual load of the gas turbine and the load command value is greater than a predetermined value, even if the operating state is determined to be a load change state. This makes it possible to avoid combustion oscillation.

[0035] (4) A control device according to a fourth aspect is a control device according to (1) to (3), wherein the selection unit determines, when the operating state switches from a static state to a load change state, to switch from a control that calculates the water flow rate based on the actual load of the gas turbine to a control that calculates the water flow rate based on the load command value. This allows the water injection flow rate control to be quickly switched to control during load change when the operating state of the gas turbine changes from a static state to an operating state in which the load fluctuates.

[0036] (4') A control device according to the fourth aspect is a control device according to any one of (1) to (4), wherein the selection unit determines, when the operating state switches from a load changing state to a static state, to switch from a control that calculates the water flow rate based on the load command value of the gas turbine to a control that calculates the water flow rate based on the actual load. This allows the water injection flow rate control to be quickly switched to control for the static state when the operating state of the gas turbine changes from a load changing state to a static state.

[0037] (5) A control device according to a fifth aspect is the control device of (1) to (4), wherein the determining unit determines that the operating state is a load change state when a load command value of the gas turbine changes by a threshold value or more. This makes it possible to avoid a control delay in the water injection flow rate control when the load on the gas turbine is intentionally changed.

[0038] (6) A control device according to a sixth aspect is a control device according to any one of (1) to (5), wherein the determination unit determines that the operating state is in a load change state when the system frequency of the power system to which the gas turbine is connected changes by more than a threshold value. This makes it possible to avoid a control delay in the water injection flow rate control during load changes due to frequency control for system stabilization.

[0039] (7) A control device according to a seventh aspect is the control device of (6), wherein, when the system frequency changes by more than a threshold value, the determination unit determines that the operating state is in a load change state for a certain period of time after the change is detected. This makes it possible to avoid a control delay in the water injection flow rate control during load changes due to frequency control for system stabilization.

[0040] (8) A fuel supply system of a gas turbine according to an eighth aspect includes a fuel supply system that supplies fuel to a combustor of the gas turbine, a water supply system that supplies water to the fuel supply system, and a control device described in any one of (1) to (7).

[0041] (9) A control method according to a ninth aspect is a control method for controlling a flow rate of water supplied to a fuel supply system in a fuel supply system that includes a fuel supply system that supplies fuel to a combustor of a gas turbine and a water supply system that supplies water to the fuel supply system, the control method determining whether the operating state of the gas turbine is undergoing a load change or a static state, and if it is determined that the operating state is undergoing a load change, selecting to calculate the flow rate of water based on a load command value of the gas turbine, and controlling the flow rate of water based on the load command value.

[0042] (10) A program according to a tenth aspect causes a computer to execute a process for controlling a flow rate of water supplied to a fuel supply system, the fuel supply system including a fuel supply system that supplies fuel to a combustor of a gas turbine and a water supply system that supplies water to the fuel supply system, the program determining whether the operating state of the gas turbine is undergoing a load change or a static state, and if it is determined that the operating state is undergoing a load change, selecting to calculate the flow rate of water based on a load command value of the gas turbine, and controlling the flow rate of water based on the load command value. [Explanation of symbols]

[0043] 1, 1a, 1b...Fuel supply system 2...Flow distributor 3a, 3b Nozzle 4, 4a, 4b...Water supply system 5. Pump 6 Valve 7. Combustor 10. Water injection flow control device 11. Actual load input / output section 12. Change detection unit 13...Load command value input / output section 14. Selection section 15...Flow rate calculation section 16 Control section 900···Computer 901 CPU 902...Main memory 903...Auxiliary storage device 904 Input / Output Interface 905···Communication Interface

Claims

1. 1. A control device for controlling a flow rate of water supplied to a fuel supply system in a fuel supply system including a fuel supply system that supplies fuel to a combustor of a gas turbine and a water supply system that supplies water to the fuel supply system, the control device comprising: a determination unit that determines whether the operating state of the gas turbine is in a load change state or a static state; a selection unit that selects, when the operating state is determined to be a load change state, to calculate the water flow rate based on a load command value of the gas turbine; a control unit that controls the flow rate of the water based on the load command value; A control device comprising:

2. the selection unit, when it is determined that the operating state is not during a load change, selects to calculate the water flow rate based on an actual load of the gas turbine; and The control unit controls the flow rate of the water based on the actual load. The control device according to claim 1 .

3. the selection unit selects to calculate the water flow rate based on the actual load if a difference between an actual load of the gas turbine and the load command value is greater than a predetermined value even when the operating state is determined to be a load change state. The control device according to claim 1 or 2.

4. when the operating state switches from a static state to a load changing state, the selection unit determines to switch from control in which the water flow rate is calculated based on an actual load of the gas turbine to control in which the water flow rate is calculated based on the load command value. The control device according to claim 1 .

5. the determination unit determines that the operating state is a load change state when a load command value of the gas turbine changes by a threshold value or more. The control device according to claim 1 or 2.

6. the determination unit determines that the operating state is a load change state when a system frequency of an electric power system to which the gas turbine is connected changes by a threshold value or more. The control device according to claim 1 or 2.

7. When the system frequency changes by a threshold value or more, the determination unit determines that the operating state is in a load change state for a certain period of time from the detection of the change. The control device according to claim 6.

8. a fuel supply system for supplying fuel to a combustor of the gas turbine; a water supply system that supplies water to the fuel supply system; The control device according to claim 1 or 2; A fuel supply system for a gas turbine comprising:

9. 1. A control method for controlling a flow rate of water supplied to a fuel supply system in a system including a fuel supply system that supplies fuel to a combustor of a gas turbine and a water supply system that supplies water to the fuel supply system, the method comprising: determining whether the operating state of the gas turbine is in a load change state or a static state; selecting, when it is determined that the operating state is a load change state, to calculate the water flow rate based on a load command value of the gas turbine; controlling the flow rate of the water based on the load command value; Control method.

10. On the computer, 1. A process for controlling a flow rate of water supplied to a fuel supply system in a system including a fuel supply system that supplies fuel to a combustor of a gas turbine and a water supply system that supplies water to the fuel supply system, the process comprising: determining whether the operating state of the gas turbine is in a load change state or a static state; selecting, when it is determined that the operating state is a load change state, to calculate the water flow rate based on a load command value of the gas turbine; a process of controlling the flow rate of the water based on the load command value; A program that executes the following.

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