Gas turbine startup control device

Abstract

A gas turbine control device is provided with a fuel flow rate command value calculation unit and a fuel flow rate control unit. The fuel flow rate command value calculation unit calculates a fuel flow rate command value by proportional-integral control based on a deviation between a rotational speed of a gas turbine and a target rotational speed or a deviation between an output of the gas turbine and a target output load. The fuel flow rate control unit controls the flow rate of fuel with respect to the gas turbine on the basis of the fuel flow rate command value. The fuel flow rate command value calculation unit calculates a fuel flow rate command value such that the output of the gas turbine increases at a first rate of change in a first output band, and calculates a fuel flow rate command value such that the output of the gas turbine increases at a second rate of change that is smaller than the first rate of change in a second output band that is a higher output band than the first output band. The integral gain in the first output band of the proportional-integral control is set to be smaller than the integral gain in the second output band.

Description

Technical Field

[0001] The present invention relates to a gas turbine start control device.

[0002] This application claims the priority based on Japanese Patent Application No. 2022-202992 filed with the Japan Patent Office on December 20, 2022, and incorporates its content herein. Background Art

[0003] When starting a gas turbine, after raising the rotational speed of the gas turbine in a stopped state to a target speed (e.g., rated speed), an initial load is applied to the gas turbine. The initial load applied to the gas turbine is preset, and after applying the initial load, the load of the gas turbine is controlled to gradually increase toward the target load over time.

[0004] Typically, the load transition of the gas turbine after applying the initial load is controlled to increase with a substantially constant change amount (i.e., proportionally) with respect to the passage of time. Therefore, it takes time for the load of the gas turbine to reach the target load. To address this problem, in Patent Document 1, the start time is shortened by making the load change amount during gas turbine startup variable according to the load band.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2010-121598 Summary of the Invention

[0008] Technical Problem to be Solved by the Invention

[0009] In the above Patent Document 1, the load change amount during gas turbine startup is made variable according to the load band. In particular, the startup control is performed in such a way that the load change amount in the low load band becomes larger. Therefore, in Patent Document 1, although the startup time of the gas turbine can be temporarily shortened by having a large load change amount in the low load band, since the change in the load change amount corresponding to the load band is achieved by a single controller, the output of the gas turbine (in other words, the output of the generator connected to the gas turbine) may become unstable.

[0010] In addition, in order to shorten the startup time of the gas turbine, a significant change in the amount of initial load applied can also be considered. However, from the viewpoint of appropriately maintaining the operation of the gas turbine, there is an upper limit set for the amount of initial load applied, and there is a limitation that it cannot be set too large.

[0011] At least one embodiment of the present invention has been completed in view of the above circumstances, and an object thereof is to provide a gas turbine start control device capable of stably maintaining the output of a gas turbine and completing the start of the gas turbine in a short time.

[0012] Means for Solving Technical Problems

[0013] To solve the above problems, a gas turbine start control device according to at least one embodiment of the present invention is a control device for a gas turbine, which includes:

[0014] A fuel flow command value calculation unit that calculates a fuel flow command value by proportional-integral control based on the deviation between the rotational speed of the gas turbine and the target rotational speed or the deviation between the output of the gas turbine and the target output load; and

[0015] A fuel flow control unit that controls the flow rate of fuel to the gas turbine according to the fuel flow command value,

[0016] The fuel flow command value calculation unit calculates the fuel flow command value such that the output of the gas turbine increases at a first rate of change in a first output band (Output Band), and calculates the fuel flow command value such that the output of the gas turbine increases at a second rate of change smaller than the first rate of change in a second output band, which is an output band higher than the first output band,

[0017] The integral gain in the first output band of the proportional-integral control is smaller than the integral gain in the second output band.

[0018] Advantages of the Invention

[0019] According to at least one embodiment of the present invention, it is possible to provide a gas turbine start control device capable of stably maintaining the output of a gas turbine and completing the start of the gas turbine in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a diagram showing a schematic configuration of a single-shaft combined cycle power generation system according to one embodiment.

[0021] Figure 2 is showing Figure 1 of the functional configuration of the gas turbine start control device.

[0022] Figure 3 is a flowchart showing a start control method according to one embodiment.

[0023] Figure 4 is showing in Figure 3An example of the transition of the generator output and the fuel flow command value after the determination of the completion of the speed increase control in step S101.

[0024] Figure 5 Is Figure 4 A comparative example.

[0025] Figure 6 Is a comparative example showing the transition of the generator output and the fuel flow command value under the start control of a typical gas turbine.

[0026] Figure 7 Is to show Figure 2 A block diagram of the functional structure of the first fuel flow command value calculation unit.

[0027] Figure 8 Is to show Figure 2 A block diagram of the functional structure of the second fuel flow command value calculation unit.

[0028] Figure 9 Is to show the Figure 7 And Figure 8 A graph showing the transition of the fuel flow command value during the corresponding start control.

[0029] Figure 10 Is to show Figure 2 Another example of the block diagram of the functional structure possessed by the fuel flow command value calculation unit.

[0030] Figure 11 Is to show Figure 10 A block diagram of the internal structure of the proportional-integral controller.

[0031] Figure 12 Specifies Figure 11 An example of a function defining the relationship between the integral component and the generator output.

[0032] Figure 13 Is Figure 12 A modified example. Detailed implementation manners

[0033] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the structures described or illustrated as embodiments are not intended to limit the scope of the present invention thereto, but are merely illustrative examples.

[0034] First, with reference to Figure 1 , a single-shaft combined cycle power generation system 100 having a gas turbine 3 which is a control object of a gas turbine start control device 50 according to at least one embodiment of the present invention will be described. Figure 1 Is a diagram showing the schematic structure of a single-shaft combined cycle power generation system 100 according to an embodiment.

[0035] The single-shaft combined cycle power generation system 100 includes a burner 11 that supplies combustion gas to the gas turbine 3, a flow control valve 10 provided in the fuel flow path that supplies fuel to the burner 11, a gas turbine start control device 50 that implements start control of the gas turbine 3, a compressor 1, a condenser 7, a condensate pump 8, a waste heat recovery boiler 9, and a steam control valve 12. In addition, an inlet guide vane control valve (IGV control valve) 2 is provided on the pipe that supplies air or the like to the compressor 1, and the inlet guide vane control valve 2 controls the angle of the inlet guide vane for adjusting the flow rate of the working fluid such as air. Further, the gas turbine 3, the steam turbine 6, and the generator 5 are connected in a single shaft.

[0036] In this structure, compressed air compressed by the compressor 1 and fuel whose flow rate is adjusted by the flow control valve 10 are supplied to the burner 11, and these are mixed and burned to generate combustion gas. This combustion gas flows into the gas turbine 3 and acts as power for rotating the gas turbine 3. Thereby, the rotational force of the gas turbine 3 is transmitted to the generator 5, and the generator 5 generates electricity.

[0037] The combustion gas that has completed work in the gas turbine 3 is led as exhaust gas to the waste heat recovery boiler 9 downstream thereof, and is released into the atmosphere through a chimney (not shown) or the like. In the waste heat recovery boiler 9, steam is generated from the water supply (condensate) from the condenser 7 using the heat recovered from the exhaust gas. This steam is led to the steam turbine 6 through the steam control valve 12. The steam led to the steam turbine 6 rotates the steam turbine 6. The rotational force of the steam turbine 6 is transmitted to the generator 5 and is used for the power generation of the generator 5.

[0038] In addition, in the following description, the output of the generator 5 is treated as the output of the gas turbine 3 (that is, the output of the generator 5 and the output of the gas turbine 3 are substantially synonymous).

[0039] The steam turbine 6 expands and does work by the steam supplied from the waste heat recovery boiler 9 to drive the generator 5, and at the same time supplies the steam that has completed expansion work to the condenser 7 through a flow path. The condenser 7 condenses the steam supplied from the steam turbine 6 and makes it into condensate. This condensate flows through the flow path 8 by the condensate pump and is supplied to the waste heat recovery boiler 9. This condensate is required when steam is generated in the waste heat recovery boiler 9.

[0040] The gas turbine starting control device 50 is a control unit for implementing the starting control of the gas turbine 3, and is composed of, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. And a series of processes for realizing various functions, as an example, are stored in a storage medium or the like in the form of a program, and the CPU reads the program into the RAM or the like and executes information processing and arithmetic processing to realize various functions. In addition, the program can also be applied in a manner of being pre-installed in the ROM or other storage media, in a manner of being provided in a state stored in a computer-readable storage medium, in a manner of being transmitted via wired or wireless communication means, etc. The computer-readable storage medium refers to a magnetic disk, an optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, etc.

[0041] Figure 2 represents Figure 1 a block diagram of the functional structure of the gas turbine starting control device 50. The gas turbine starting control device 50 includes a fuel flow command value calculation unit 20 and a fuel flow control unit 30.

[0042] The fuel flow command value calculation unit 20 obtains a state quantity related to the operating state of the gas turbine 3 (such as the rotational speed R of the gas turbine 3 or the output P of the generator 5) as an input signal, and outputs a fuel flow command value CSO obtained by calculation. In the present embodiment, the fuel flow command value calculation unit 20 is configured to calculate the fuel flow command value CSO by proportional-integral control based on the deviation between the rotational speed R of the gas turbine 3 and the target rotational speed Rref or the deviation between the output P of the gas turbine 3 and the target output Pref. And the fuel flow control unit 30 is configured to control the opening degree of the flow regulating valve 10 by inputting the fuel flow command value CSO from the fuel flow command value calculation unit 20 and controlling the fuel flow rate to the burner 11 according to the fuel flow command value CSO.

[0043] The fuel flow command value calculation unit 20 includes a first fuel flow command value calculation unit 20a, a second fuel flow command value calculation unit 20b, and a low value selection unit 20c. In the first fuel flow command value calculation unit 20a, the rotational speed R of the gas turbine 3 in the input signal is input, and a first fuel flow command value CSO1, which is one of the candidates for the fuel flow command value CSO, is output. In the first fuel flow command value calculation unit 20a, a target value of the rotational speed R (hereinafter, "target rotational speed Rref") is input, and as will be described later, the first fuel flow command value CSO1 is calculated based on the deviation between the rotational speed R and the target rotational speed Rref. As will be described later, the first fuel flow command value CSO1 is processed as the fuel flow command value CSO in the first output band.

[0044] In the second fuel flow command value calculation unit 20b, the generator output P in the input signal is input, and a second fuel flow command value CSO2, which is one of the candidates for the fuel flow command value CSO, is output. In the second fuel flow command value calculation unit 20b, a target value of the generator output P (hereinafter, "target output Pref") is input, and as will be described later, the second fuel flow command value CSO2 is calculated based on the deviation between the generator output P and the target output Pref. As will be described later, the second fuel flow command value CSO2 is processed as the fuel flow command value CSO in the second output band.

[0045] The first fuel flow command value CSO1 calculated in the first fuel flow command value calculation unit 20a and the second fuel flow command value CSO2 calculated in the second fuel flow command value calculation unit 20b are respectively input to the low value selection unit 20c. In the low value selection unit 20c, the lower one of the first fuel flow command value CSO1 and the second fuel flow command value CSO2 is selected as the fuel flow command value CSO and output from the fuel flow command value calculation unit 20.

[0046] Next, a start control method implemented by the gas turbine start control device 50 having the above structure will be described. Figure 3 is a flowchart showing a start control method according to an embodiment, Figure 4 is shown in Figure 3 After it is determined in step S101 that the speed increase control has been completed, an example of the transition of the generator output P and the fuel flow command value CSO is shown.

[0047] First, the gas turbine start control device 50 performs a speed increase control on the gas turbine 3 in a stopped state under a no-load condition (step S100). During the speed increase control, the gas turbine 3 is in a no-load state where no load is applied (that is, a state where the generator output P is zero), and the speed increase is performed to increase the rotational speed R of the gas turbine 3 in the stopped state toward a preset target speed, that is, the rated speed Rmax.

[0048] Next, the gas turbine start control device 50 determines whether the speed increase control in step S100 has been completed (step S101). In step S101, when the rotational speed R of the gas turbine 3 reaches a preset target speed, i.e., the rated speed Rmax, it is determined that the speed increase control has been completed. If the speed increase control is completed (step S101: YES), the rotational speed R of the gas turbine 3 is controlled to maintain the target speed, i.e., the rated speed Rmax.

[0049] Next, an initial load is applied to the gas turbine 3 in a no-load state that has completed the speed increase control (step S102). The amount of the initial load applied in step S102 is preset. As an example, it can be set in consideration of the actual situation of the steam turbine 6. For example, in the steam turbine 6, in order to avoid the idling wind loss caused by the reverse power from the generator 5, a certain amount of load needs to be ensured as the initial load. On the other hand, from the viewpoint of the restriction of the increase in the thermal load caused by the metal temperature mismatch, it is preferable that the initial load is below a specified upper limit. Considering such conditions, the amount of the initial load applied can be appropriately set.

[0050] In addition, in Figure 4 , the initial load is applied at time t1, and the generator output P becomes the initial output P0 corresponding to the initial load.

[0051] Next, after the initial load is applied, since the generator output P is in the relatively low first output band, the gas turbine start control device 50 uses the first fuel flow command value CSO1 to control the fuel flow as the fuel flow command value CSO (step S103). At this time, as will be described in detail later, the first fuel flow command value CSO1 is set to be smaller than the second fuel flow command value CSO2, and thus the low value selection unit 20c selects the first fuel flow command value CSO1 as the fuel flow command value CSO.

[0052] In step S103, the first fuel flow command value calculation unit 20a that calculates the first fuel flow command value CSO1 selected as the fuel flow command value CSO calculates the first fuel flow command value CSO1 through proportional control based on the deviation between the rotational speed R and the target speed Rref. Assuming that proportional-integral control is adopted in the first fuel flow command value calculation unit 20a instead of proportional control, as in Figure 5 the comparative example shown, the generator output P will become unstable. Therefore, in the first fuel flow command value calculation unit 20a, the first fuel flow command value CSO1 is calculated through proportional control, and thus even if the change rate of the fuel flow command value CSO with respect to time is set to be large, stability can be ensured.

[0053] Next, the gas turbine startup control device 50 determines whether the generator output P has reached a preset reference value Ps (step S104). When the generator output P is less than the reference value Ps (step S104: No), the process returns to step S103, and the increase in the generator output P based on the first fuel flow command value CSO1 continues.

[0054] On the other hand, when switching from the first output band to the second output band because the generator output P reaches the reference value Ps (step S104: No), the gas turbine startup control device 50 uses the second fuel flow command value CSO2 as the fuel flow command value CSO to control the fuel flow (step S105). At this time, as will be described in detail later, the second fuel flow command value CSO2 is set to be less than the first fuel flow command value CSO1, and thus the low value selection unit 20c selects the second fuel flow command value CSO2 as the fuel flow command value CSO.

[0055] In step S105, the second fuel flow command value calculation unit 20b that calculates the second fuel flow command value CSO2 selected as the fuel flow command value CSO calculates the second fuel flow command value CSO2 by proportional-integral control based on the deviation between the generator output P and the target output Pref. In step S105, since the generator output P exceeds the reference value Ps and becomes large enough, in the second fuel flow command value calculation unit 20b, even if the second fuel flow command value CSO2 is calculated by proportional control and by proportional-integral control, stability can be ensured.

[0056] Next, the gas turbine startup control device 50 determines whether the generator output P has reached a preset target output Pe (step S106). When the generator output P is less than the target output Pe (step S106: No), the process returns to step S105, and the increase in the generator output P based on the second fuel flow command value CSO2 continues. On the other hand, when the generator output P reaches the target output Pe (step S106: No), the gas turbine startup control device 50 ends a series of startup controls and transfers to steady-state operation.

[0057] Here, Figure 6 is a comparative example showing the transition of the generator output P and the fuel flow command value CSO under the startup control of the typical gas turbine 3. In Figure 6In the comparative example shown, after the initial load is applied at time t1, start-up control is performed by fuel flow control in which the aforementioned second fuel flow command value CSO2 is set as the fuel flow command value CSO. That is, in this comparative example, the fuel control after the initial load is applied is performed only by the second fuel flow command value CSO2 throughout the output range. At this time, assuming that the change amount of the second fuel flow command value CSO2 with respect to time is too large, the control becomes unstable, so it is necessary to suppress the change amount of the fuel flow command value CSO to be relatively small. Therefore, there is a problem that the start-up time until the generator output P reaches the target output Pe becomes long.

[0058] In contrast, in the aforementioned embodiment, in the first output range corresponding to the time from time t1 to time t2 when the initial load is applied, fuel flow control is performed in which the first fuel flow command value CSO1 is set as the fuel flow command value CSO. The first fuel flow command value CSO1 is calculated by proportional control in the first fuel flow command value calculation unit 20a, so even if the change amount with respect to time becomes large, the control is less likely to become unstable. Therefore, as Figure 4 shown, by increasing the change amount (the first change amount) in the first output range from time t1 to time t2 compared to the change amount (the second change amount) in the second output range after time t2, it is possible to effectively shorten the start-up time until the generator output P reaches the target output.

[0059] In this way, in the fuel flow command value calculation unit 20, the fuel flow command value SOC is calculated by proportional-integral control according to the output range. In the above embodiment, in the first output range, the first fuel flow command value SOC1 calculated by proportional control by the first fuel flow command value calculation unit 20a is treated as the fuel flow command value SCO. Here, proportional control is substantially equivalent to the case where the integral gain Ki is set to zero in proportional-integral control. Therefore, instead of proportional control, the first fuel flow command value calculation unit 20a can calculate the first fuel flow command value SOC1 by proportional-integral control with a non-zero integral gain Ki within a range smaller than the integral gain Ki in the proportional-integral control when the second fuel flow command value calculation unit 20b calculates the second fuel flow command value SOC2 in the second output range (in other words, in the first output range, the first fuel flow command value SOC1 can be calculated by proportional-integral control with an integral gain Ki smaller than that in the second output range).

[0060] Next, with reference to Figures 7 - 9 , the internal structures of the first fuel flow command value calculation unit 20a and the second fuel flow command value calculation unit 20b will be described. Figure 7 It shows Figure 2Block diagram of the functional structure of the first fuel flow command value calculation unit 20a Figure 8 It shows Figure 2 Block diagram of the functional structure of the second fuel flow command value calculation unit 20b Figure 9 It shows the relationship with Figure 7 and Figure 8 Graph showing the change in the fuel flow command value CSO during start-up control

[0061] As Figure 7 shown, in the first fuel flow command value calculation unit 20a, the state variables related to the operating state of the gas turbine 3, namely the rotational speed R and the target rotational speed Rref corresponding to the rotational speed R, are respectively input. The deviation ΔR between the rotational speed R and the target rotational speed Rref is input to the proportional controller 22. The proportional controller 22 outputs the first fuel flow command value CSO1 corresponding to the deviation ΔR.

[0062] Furthermore, the first fuel flow command value calculation unit 20a is provided with a switch T1 for switching the first fuel flow command value CSO1 output from the first fuel flow command value calculation unit 20a between the output value of the proportional controller 22 and the first tracking value Vt1. The first tracking value Vt1 is a value obtained by adding the first offset value Vb1 to the fuel flow command value CSO output from the fuel flow command value calculation unit 20.

[0063] The switch T1 switches according to its switching state. Specifically, when in the first output band because the generator output P is less than the reference value Ps between times t1 and t2 as shown in Figure 4 , the switch T1 switches so that the first fuel flow command value CSO1 output from the proportional controller 22 is directly output. On the other hand, when in the second output band because the generator output P exceeds the reference value Ps after time t2 as shown in Figure 4 , the switch T1 switches to output the first tracking value Vt1.

[0064] As Figure 8 shown, in the second fuel flow command value calculation unit 20b, the state variables related to the operating state of the gas turbine 3, namely the generator output P and the target output Pref corresponding to the generator output P, are respectively input. The deviation ΔP between the generator output P and the target output Pref is input to the proportional-integral controller 26. The proportional-integral controller 26 outputs the second fuel flow command value CSO2 corresponding to the deviation ΔP.

[0065] Further, the second fuel flow command value calculation unit 20b includes a switch T2 for switching the second fuel flow command value CSO2 output from the second fuel flow command value calculation unit 20b between the output value of the proportional-integral controller 26 and the second tracking value Vt2. The second tracking value Vt2 is a value obtained by adding a second offset value Vb2 to the fuel flow command value CSO output from the fuel flow command value calculation unit 20.

[0066] The switch T2 switches according to its switching state. Specifically, when in the first output band because the generator output P is less than the reference value Ps between times t1 and t2 as shown in Figure 4 , the switch T2 switches to output the second tracking value Vt2. On the other hand, when in the second output band because the generator output P exceeds the reference value Ps after time t2 as shown in Figure 4 , it switches so that the second fuel flow command value CSO2 output from the proportional-integral controller 26 is directly output.

[0067] As shown in Figure 9 , during the period from the initial load application time t1 to time t2, the first fuel flow command value CSO1 is output from the first fuel flow command value calculation unit 20a. On the other hand, the second tracking value Vt2 (= fuel flow command value CSO + second offset value Vb2) is output from the second fuel flow command value calculation unit 20b as the second fuel flow command value CSO2. Therefore, during the period from time t1 to time t2 when in the first output band, the first fuel flow command value CSO1 is less than the second fuel flow command value CSO2, so the first fuel flow command value CSO1 is used as the fuel flow command value CSO.

[0068] After time t2, the first tracking value Vt1 (= fuel flow command value CSO + first offset value Vb1) is output from the first fuel flow command value calculation unit 20a. On the other hand, the second fuel flow command value CSO2 is output from the second fuel flow command value calculation unit 20b. Therefore, after time t2 when in the second output band, the second fuel flow command value CSO2 is less than the first fuel flow command value CSO1, so the second fuel flow command value CSO2 is used as the fuel flow command value CSO.

[0069] Further, as shown in Figure 9As shown, at time t2 when switching from the first output band to the second output band due to an increase in the generator output P reaching the reference value Ps, the second fuel flow command value CSO2, which is selected as the fuel flow command value CSO in the second output band with a low value, is tracked by the most recent fuel flow command value CSO (in other words, the first fuel flow command value CSO1 selected with a low value in the first output band before switching to the second output band). Thus, before and after the time t2 of switching the output band, the fuel flow command value CSO is continuous, thereby ensuring the stability of control.

[0070] Figure 10 is a diagram showing Figure 2 another example of the functional structure of the fuel flow command value calculation unit 20, Figure 11 is a diagram showing Figure 10 the internal structure of the proportional-integral controller 60. Refer to Figures 2 - 9 , in the above-described embodiment, the fuel flow command value calculation unit 20 has the following structure: either the first fuel flow command value CSO1 calculated by proportional control in the first fuel flow command value calculation unit 20a or the second fuel flow command value CSO2 calculated by proportional-integral control in the second fuel flow command value calculation unit 20b is treated as the fuel flow command value CSO, so that essentially two controllers (a proportional controller and a proportional-integral controller) are used separately. On the other hand, in Figures 10 - 11 the embodiment shown, the difference is that the fuel flow command value calculation unit 20 is configured using a single proportional-integral controller 60.

[0071] In this embodiment, the fuel flow command value calculation unit 20 calculates the fuel flow command value CSO corresponding to the deviation between the gas turbine state quantity and its target value. The gas turbine state quantity is any parameter related to the output of the gas turbine 3, for example, including the gas turbine output, the generator output, the fuel flow command value CSO, the intake air flow, or the gas turbine cylinder pressure. In Figure 10 the embodiment shown, as the gas turbine state quantity, in the gas flow command value calculation unit 20, the rotational speed R or the generator output P is input as the state quantity related to the operating state of the gas turbine 3. The deviation ΔR between the calculated rotational speed R and the separately input target rotational speed Rref is input to the proportional-integral controller 60. And the deviation ΔP between the calculated generator output P and the separately input target output Pref is calculated, and this deviation ΔP is also input to the proportional-integral controller 60. The proportional-integral controller 60 calculates the fuel flow command value CSO corresponding to the input deviation ΔR or ΔP according to proportional-integral control.

[0072] The proportional-integral controller 60 is configured to perform proportional-integral control for calculating a fuel flow command value CSO corresponding to the input gas turbine state quantity, and includes a proportional operation unit 62 and an integral operation unit 64. The proportional operation unit 62 outputs a first operation value by multiplying the deviation ΔR or ΔP input to the proportional-integral controller 60 by a prescribed proportional component (P component). The integral operation unit 64 accumulates the error of the deviation ΔR or ΔP input to the proportional-integral controller 60, and calculates a second operation value by multiplying the accumulated result by an integral component (I component) corresponding to the integral gain Ki. The first operation value and the second operation value are added by an adder 66, and thus output as the fuel flow command value CSO.

[0073] Here, the integral component Ki in the integral operation unit 64 is set to be variable according to the gas turbine state quantity. The relationship between the gas turbine state quantity and the integral gain Ki is defined by a function FX. Here, Figure 12 is a definition Figure 11 of an example of the function FX that defines the relationship between the integral gain Ki and the gas turbine state quantity. When the generator output P, which is an example of the gas turbine state quantity, is less than the reference value Ps and is in the first output band, the integral gain Ki is set to zero. Thereby, the proportional-integral controller 60 substantially functions as a proportional controller. At this time, the proportional-integral controller 60 calculates the aforementioned first fuel flow command value CSO1 as the fuel flow command value CSO according to the input deviation ΔR, and substantially realizes the same function as Figure 2 the first fuel flow command value calculation unit 20a shown.

[0074] On the other hand, when the generator output P, which is the gas turbine state quantity, is greater than or equal to the reference value Ps and is in the second output band, the integral gain Ki is set to a finite value greater than zero according to the function FX. Thereby, the proportional-integral controller 60 substantially functions as a proportional-integral controller. At this time, the proportional-integral controller 60 calculates the aforementioned second fuel flow command value CSO2 as the fuel flow command value according to the input deviation ΔP, and substantially realizes the same function as Figure 2 the second fuel flow command value calculation unit 20b shown.

[0075] And Figure 13 is Figure 12 a modified example. In this modified example, the function FX is set such that the integral gain Ki is small when the generator output P is sufficiently lower than the reference value Ps even in the first output band, and the integral gain Ki is high when the generator output P is sufficiently higher than the reference value Ps even in the second output band. This point is the same as Figure 12is the same as the function FX shown. On the other hand, when the generator output P approaches the reference value Ps, it is set such that the integral gain Ki gradually increases according to the increase in the generator output P, which is different from the function FX shown at this point. By defining the integral gain Ki as a function in this form, it is possible to reduce the deviation of the generator output P from the target load without destabilizing the control in a wide range of load bands including the case where the generator output P approaches the reference value Ps, thereby performing high-precision output control. Figure 12 is different from the function FX shown. By defining the integral gain Ki as a function in this form, it is possible to reduce the deviation of the generator output P from the target load without destabilizing the control in a wide range of load bands including the case where the generator output P approaches the reference value Ps, thereby performing high-precision output control.

[0076] Thus, in the present embodiment, by switching the integral gain Ki in the proportional-integral controller 60 according to the gas turbine state quantity, it is possible to achieve a configuration in which two controllers (a proportional controller and a proportional-integral controller) are substantially used separately in a single proportional-integral controller 60.

[0077] As described above, according to each of the above embodiments, it is possible to realize a gas turbine start control device 50, a gas turbine start control method, and a gas turbine start control program that can complete the start of the gas turbine 3 in a short time.

[0078] In addition, the constituent elements in the above embodiments can be appropriately replaced with well-known constituent elements without departing from the spirit of the present invention, and the above embodiments can be appropriately combined.

[0079] The content described in each of the above embodiments is understood as follows, for example.

[0080] (1) The gas turbine start control device according to one embodiment is a control device for a gas turbine, comprising:

[0081] a fuel flow command value calculation unit that calculates a fuel flow command value by proportional-integral control based on a deviation between the rotational speed of the gas turbine and a target rotational speed or a deviation between the output of the gas turbine and a target output load; and

[0082] a fuel flow control unit that controls the flow rate of fuel to the gas turbine according to the fuel flow command value,

[0083] the fuel flow command value calculation unit calculates the fuel flow command value such that the output of the gas turbine increases at a first change rate in a first output band, and calculates the fuel flow command value such that the output of the gas turbine increases at a second change rate smaller than the first change rate in a second output band that is an output band higher than the first output band,

[0084] the integral gain in the first output band of the proportional-integral control is smaller than the integral gain in the second output band.

[0085] According to the method in (1) above, the flow control of the fuel relative to the gas turbine is performed according to the fuel flow command value calculated by proportional-integral control based on the deviation between the rotational speed of the gas turbine and the target rotational speed or the deviation between the output of the gas turbine and the target output load. The fuel flow command value is calculated in such a way that the change rate of the output of the gas turbine is different through the output band when the output of the gas turbine increases. Specifically, the first change rate in the relatively low first output band is greater than the second change rate in the second output band that is higher than the first output band. Therefore, compared with the case where the output of the gas turbine is increased only at the second change rate, the increase in the output of the gas turbine can be completed quickly, and the start-up time of the gas turbine can be effectively shortened. In particular, by making the integral gain in the first output band smaller than the integral gain in the second output band, the operating state of the gas turbine when the output increases can be effectively stabilized.

[0086] In addition, the proportional-integral control when calculating the fuel flow command value is a concept including proportional control (proportional control) corresponding to the case where the integral gain is zero and proportional-integral control (proportional-integral control) where the integral gain is non-zero, and further includes so-called proportional-integral-derivative control where the derivative gain is non-zero.

[0087] (2) In other methods, in the method in (1) above,

[0088] The fuel flow command value calculation unit includes:

[0089] A first fuel flow command value calculation unit for calculating the fuel flow command value in the first output band, that is, the first fuel flow command value; and

[0090] A second fuel flow command value calculation unit for calculating the fuel flow command value in the second output band, that is, the second fuel flow command value.

[0091] According to the method in (2) above, the fuel flow command value in the first output band of the output of the gas turbine is calculated as the first fuel flow command value, and the fuel flow command value in the second output band of the output of the gas turbine is calculated as the second fuel flow command value.

[0092] (3) In other methods, in the method in (2) above,

[0093] The first fuel flow command value calculation unit includes a proportional controller that calculates the first fuel flow command value based on the deviation between the rotational speed and the target rotational speed.

[0094] The first fuel flow command value calculated as the fuel flow command value when the output of the gas turbine is in the first output band is obtained as the operation result of the proportional controller according to the method of (3) above. Assuming that a proportional-integral controller is used, the stability in the tracking of the output of the gas turbine with respect to the target output becomes low, but by using a proportional controller, stable tracking is obtained.

[0095] (4) In other methods, in the method of (2) above,

[0096] The second fuel flow command value calculation unit includes a proportional-integral controller, and the proportional-integral controller calculates the second fuel flow command value based on the deviation between the output of the gas turbine and the target output.

[0097] According to the method of (4) above, the second fuel flow command value calculated as the fuel flow command when the output of the gas turbine is in the second output band is obtained as the operation result of the proportional-integral controller.

[0098] (5) In other methods, in the method of (2) above, it further includes:

[0099] A low-value selection unit that selects the smaller one of the first fuel flow command value and the second fuel flow command value as the fuel flow command value.

[0100] According to the method of (5) above, the first fuel flow command value and the second fuel flow command value calculated as candidates for the fuel flow command value are selected by the low-value selection unit, and the smaller one is used as the fuel flow command value.

[0101] (6) In other methods, in the method of (5) above,

[0102] When the output of the gas turbine is in the first output band, the second fuel flow command value is set to a first tracking value obtained by adding a first offset value to the fuel flow command value.

[0103] According to the method of (6) above, when the output of the gas turbine is in the relatively low first output band, the second fuel flow command value is set to a first tracking value obtained by adding a first offset value to the fuel flow command value. Thus, the second fuel flow command value is greater than the first fuel flow command value, so in the low-value selection unit, the first fuel flow command value is appropriately selected as the fuel flow command value.

[0104] (7) In other methods, in the method of (5) above,

[0105] When the output of the gas turbine is in the second output band, the first fuel flow command value is set to a second tracking value obtained by adding a second offset value to the fuel flow command value.

[0106] According to the method in (7) above, when the output of the gas turbine is in the relatively high second output band, the first fuel flow command value is set to a second tracking value obtained by adding a second offset value to the fuel flow command value. Thus, the first fuel flow command value is greater than the second fuel flow command value. Therefore, in the low-value selection unit, the second fuel flow command value is appropriately selected as the fuel flow command value.

[0107] (8) In other methods, in any of the methods in (1) to (7) above,

[0108] When the output of the gas turbine switches from the first output band to the second output band, the second fuel flow command value is tracked by the fuel flow command value.

[0109] According to the method in (8) above, when switching from the first output band to the second output band due to an increase in the output of the gas turbine, the second fuel flow command value is tracked by the fuel flow command value. Thus, before and after that, by ensuring the continuity of the fuel flow command value, stable control can be performed.

[0110] (9) In other methods, in the method in (1) above,

[0111] The proportional-integral control makes the integral gain variable according to a gas turbine state quantity related to the output of the gas turbine.

[0112] According to the method in (9) above, by using a proportional-integral controller with an integral gain variable according to a gas turbine state quantity related to the output of the gas turbine, thus, with a single controller, according to the output band, the fuel flow command value for increasing the output of the gas turbine at the first change rate or the second change rate can be calculated.

[0113] (10) In other methods, in the method in (9) above,

[0114] When the output of the gas turbine is in the first output band, the integral gain is set to zero.

[0115] According to the method in (10) above, when the output of the gas turbine is in the first output band, the integral gain is set to zero, so that the proportional-integral controller can be substantially treated as a proportional controller.

[0116] (11) In other ways, in any of the above ways (9) to (10), the integral gain is calculated according to a function that defines the relationship between the gas turbine state quantity and the integral gain.

[0117] According to the way of the above (11), the calculation of the integral gain is carried out using a function that defines the relationship between the specified gas turbine state quantity and the integral gain. Thereby, it is possible to calculate the integral gain corresponding to the gas turbine state quantity related to the integral gain.

[0118] (12) In other ways, in any of the above ways (1) to (11),

[0119] The first change rate is more than 5 times the second change rate.

[0120] According to the way of the above (12), by setting the first change rate to be more than 5 times the second change rate, it is possible to effectively shorten the startup time of the gas turbine.

[0121] Symbol Explanation

[0122] 1 - Compressor, 3 - Gas turbine, 5 - Generator, 6 - Steam turbine, 7 - Condenser, 8 - Condensate pump, 9 - Waste heat recovery boiler, 10 - Flow control valve, 11 - Burner, 12 - Steam control valve, 20 - Fuel flow command value calculation unit, 20a - First fuel flow command value calculation unit, 20b - Second fuel flow command value calculation unit, 20c - Low value selection unit, 30 - Fuel flow control unit, 50 - Gas turbine startup control device, 62 - Proportional operation unit, 64 - Integral operation unit, 66 - Adder, 100 - Single - shaft combined cycle power generation system.

Claims

1. A gas turbine control device, comprising: a fuel flow command value calculation unit configured to calculate a fuel flow command value by proportional-integral control based on a deviation between the rotational speed of the gas turbine and a target rotational speed or a deviation between the output of the gas turbine and a target output load; and a fuel flow control unit configured to control the flow rate of fuel supplied to the gas turbine according to the fuel flow command value, wherein the fuel flow command value calculation unit calculates the fuel flow command value such that the output of the gas turbine increases at a first rate of change in a first output band, and calculates the fuel flow command value such that the output of the gas turbine increases at a second rate of change less than the first rate of change in a second output band higher than the first output band, and an integral gain in the first output band of the proportional-integral control is less than an integral gain in the second output band.

2. The gas turbine control device according to claim 1, wherein the fuel flow command value calculation unit includes: a first fuel flow command value calculation unit configured to calculate a first fuel flow command value, which is the fuel flow command value in the first output band; and a second fuel flow command value calculation unit configured to calculate a second fuel flow command value, which is the fuel flow command value in the second output band.

3. The gas turbine start control device according to claim 2, wherein the first fuel flow command value calculation unit includes a proportional controller that calculates the first fuel flow command value based on a deviation between the rotational speed and the target rotational speed.

4. The gas turbine start control device according to claim 2, wherein the second fuel flow command value calculation unit includes a proportional-integral controller that calculates the second fuel flow command value based on a deviation between the output of the gas turbine and the target output.

5. The gas turbine start control device according to claim 2, further comprising: a low value selection unit that selects the smaller one of the first fuel flow command value and the second fuel flow command value as the fuel flow command value.

6. The gas turbine start control device according to claim 5, wherein when the output of the gas turbine is in the first output band, the second fuel flow command value is set to a first tracking value obtained by adding a first offset value to the fuel flow command value.

7. The gas turbine start control device according to claim 5, wherein when the output of the gas turbine is in the second output band, the first fuel flow command value is set to a second tracking value obtained by adding a second offset value to the fuel flow command value.

8. The gas turbine start control device according to claim 1, wherein when the output of the gas turbine switches from the first output band to the second output band, the second fuel flow command value is tracked by the fuel flow command value.

9. The gas turbine start control device according to claim 1, wherein The proportional-integral control varies the integral gain according to a gas turbine state quantity related to the output of the gas turbine.

10. The gas turbine starting control device according to claim 9, wherein when the output of the gas turbine is in the first output band, the integral gain is set to zero.

11. The gas turbine starting control device according to claim 9, wherein the integral gain is calculated according to a function defining the relationship between the gas turbine state quantity and the integral gain.

12. The gas turbine starting control device according to claim 1, wherein the first change rate is 5 times or more the second change rate.

Images