Gas turbine control device, gas turbine control method, and gas turbine control program

Abstract

This gas turbine control device controls a gas turbine comprising a combustor capable of generating combustion gas for driving the gas turbine by cofiring a first fuel and a second fuel. When it is determined that the supply of the second fuel to the combustor is being at least partly shut off, the present device calculates a shutoff-time fuel flow rate to be supplied to the combustor in accordance with a fuel cofiring ratio after the second fuel is at least partly shut off. Moreover, after the second fuel is at least partly shut off, the device outputs a fuel flow rate command value corresponding to the shutoff-time fuel flow rate, before reaching the fuel cofiring ratio.

Description

[Technical Field]

[0001] The present disclosure relates to a gas turbine control device, a gas turbine control method, and a gas turbine control program. This application claims priority based on Japanese Patent Application No. 2022-166116, filed with the Japan Patent Office on October 17, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Gas turbine power generation facilities are known that generate electricity by using combustion gases produced by burning fuel to drive a turbine connected to a generator. In recent years, with growing awareness of environmental issues, natural gas, a clean energy source, is sometimes used as fuel in these types of gas turbine power generation facilities. Natural gas is extracted as raw natural gas from gas fields, etc., and is then liquefied and refined to be used as liquefied natural gas (LNG).

[0003] For example, Patent Document 1 discloses technology relating to a gas turbine that uses a mixture of liquefied natural gas and boil-off gas (BOG), a low-calorie gas generated in liquefied natural gas storage facilities, as fuel for the gas turbine. This document describes that when the supply of boil-off gas is stopped for some reason, causing an increase in the calorific value of the fuel supplied to the gas turbine, the operating state of the gas turbine is stabilized by reducing the flow rate of fuel supplied to the gas turbine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-227886 Summary of the Invention [Problem to be solved by the invention]

[0005] In a gas turbine that burns a mixture of fuel gases with different combustion characteristics, if a part of the fuel gas supply system stops due to some kind of malfunction or defect, the combustion characteristics of the fuel gas change, which can hinder stable operation of the gas turbine. For example, if hydrogen gas, which has a lower calorific value per unit volume than natural gas, is mixed with natural gas and burned in the gas turbine, if at least part of the hydrogen gas supply system stops, the proportion of natural gas, which has a higher calorific value per unit volume, in the fuel supplied to the gas turbine increases. As a result, the turbine heat input increases, which can lead to effects such as overfire, in which the turbine inlet temperature rises sharply.

[0006] In the above-mentioned Patent Document 1, when the supply of boil-off gas mixed with liquefied natural gas is stopped, the fuel flow rate to the gas turbine is reduced to stabilize the operating state of the gas turbine. However, in this document, the fuel flow rate is adjusted to correspond to the change in the calorific value of the fuel supplied to the gas turbine due to the stoppage of the supply of boil-off gas, and it is difficult to suppress sudden phenomena such as overfire.

[0007] At least one embodiment of the present disclosure has been made in consideration of the above-described circumstances, and has an object to provide a gas turbine control device, a gas turbine control method, and a gas turbine control program that are capable of suppressing the influence of a change in the amount of heat input to the turbine when at least a portion of fuel that is supplied to a combustor of the gas turbine and has a low calorific value per unit volume is blocked. [Means for solving the problem]

[0008] In order to solve the above problem, a gas turbine control device according to at least one embodiment of the present disclosure includes: To drive a gas turbine by co-firing a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel. a supply state determination unit for determining a fuel supply state; a cutoff fuel flow rate calculation unit that calculates a cutoff fuel flow rate to be supplied to the combustor in accordance with a fuel mixing ratio after at least a portion of the second fuel is cut off, when it is determined that the combustor is in the supply state in which at least a portion of the second fuel is cut off; a fuel command value output unit for outputting a fuel flow rate command value corresponding to the fuel flow rate at the time of cutoff after at least a portion of the second fuel is cut off and before the fuel mixing ratio is reached; Equipped with.

[0009] In order to solve the above problem, a gas turbine control method according to at least one embodiment of the present disclosure includes: 1. A gas turbine control method for controlling a gas turbine including a combustor capable of generating combustion gas for driving the gas turbine by mixed combustion of a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel, comprising: determining a supply state of the second fuel to the combustor; calculating a cutoff fuel flow rate to be supplied to the combustor in accordance with a fuel mixing ratio after at least a portion of the second fuel is cut off when it is determined that the combustor is in the supply state in which at least a portion of the second fuel is cut off; After at least a portion of the second fuel is cut off and before the fuel mixing ratio is reached, outputting a fuel flow rate command value corresponding to the cut-off fuel flow rate; Equipped with.

[0010] In order to solve the above problem, a gas turbine control program according to at least one embodiment of the present disclosure includes: 1. A gas turbine control program for controlling a gas turbine including a combustor capable of generating combustion gas for driving the gas turbine by mixed combustion of a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel, the program comprising: To the computer device, determining a supply state of the second fuel to the combustor; calculating a cutoff fuel flow rate to be supplied to the combustor in accordance with a fuel mixing ratio after at least a portion of the second fuel is cut off when it is determined that the combustor is in the supply state in which at least a portion of the second fuel is cut off; After at least a portion of the second fuel is cut off and before the fuel mixing ratio is reached, outputting a fuel flow rate command value corresponding to the cut-off fuel flow rate; is possible. [Effects of the Invention]

[0011] According to at least one embodiment of the present disclosure, it is possible to provide a gas turbine control device, a gas turbine control method, and a gas turbine control program that are capable of suppressing the influence of a change in the amount of heat input to the turbine when at least a portion of fuel that is supplied to a combustor of the gas turbine and has a low calorific value per unit volume is blocked. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating a schematic configuration of a gas turbine according to an embodiment. [Figure 2] FIG. 1 is a block diagram showing a functional configuration of a gas turbine control device according to an embodiment. [Figure 3] 1 is a flowchart illustrating a gas turbine control method according to an embodiment. [Figure 4] 4 is a time chart showing the control state of each component of the gas turbine corresponding to FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the configurations described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0014] First, a gas turbine 1 that is a control target of a gas turbine control device 50 according to at least one embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a diagram showing a schematic configuration of a gas turbine 1 according to one embodiment.

[0015] The gas turbine 1 includes a compressor 3 that generates compressed air, a combustor 2 that generates combustion gas by mixing and burning the compressed air generated by the compressor 3 with fuel, a fuel supply system 4 that supplies fuel to the combustor 2, and a turbine 6 that is driven by the combustion gas. The compressor 3 and the turbine 6 are connected to one shaft. In the gas turbine 1 having this configuration, the compressed air compressed by the compressor 3 and the fuel supplied from the fuel supply system 4 are supplied to the combustor 2, and these are mixed and burned to generate combustion gas. This combustion gas flows into the turbine 6 and serves as power to rotate the turbine 6.

[0016] The fuel supply system 4 handles a mixed fuel obtained by mixing a first fuel F1 and a second fuel F2 as the fuel to be supplied to the combustor 2. The second fuel F2 is a fuel having a lower calorific value per unit volume than the first fuel F1. In this embodiment, the first fuel F1 is liquefied natural gas, and the second fuel F2 is hydrogen gas.

[0017] The first fuel F1 is supplied via a first fuel supply line 8 connected to a first fuel supply source 7. The first fuel supply line 8 is provided with a flow meter 10 for detecting the flow rate of the first fuel F1.

[0018] The second fuel F2 is supplied via a second fuel supply line 16 connected to a second fuel supply source 14. The second fuel supply line 16 is provided with a first flow rate adjustment valve 18 for adjusting the flow rate of the second fuel F2 and a shutoff valve 13 for shutting off the second fuel F2.

[0019] The first fuel supply line 8 and the second fuel supply line 16 join each other downstream and are connected to a main fuel supply line 22. The first fuel F1 and the second fuel F2 are mixed by joining at a joining point 25 of the first fuel supply line 8 and the second fuel supply line 16, and the mixed fuel (hereinafter referred to as "mixed fuel Fm" as appropriate) is sent through the main fuel supply line 22. The main fuel supply line 22 is provided with a shutoff valve 24 for shutting off the mixed fuel Fm and a second flow rate adjustment valve 26 for adjusting the flow rate of the mixed fuel Fm.

[0020] The downstream side of the main fuel supply line 22 branches into multiple fuel branch supply lines 28a, 28b, etc. to correspond to multiple fuel injection nozzles (not shown) included in the combustor 2. The multiple fuel injection nozzles may include main fuel injection nozzles, pilot fuel injection nozzles, top hat fuel injection nozzles, etc. In this case, at least some of the main fuel injection nozzles may be grouped together. Each of the multiple fuel branch supply lines 28a, 28b, etc. is provided with a third flow rate adjustment valve 30a, 30b, etc. to adjust the flow rate of the mixed fuel flowing through each line.

[0021] Next, a gas turbine control device 50 for controlling the gas turbine 1 having the above configuration will be described. The gas turbine control device 50 is a control unit for controlling the gas turbine 1 and is composed of, for example, a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, for example. The CPU reads the program into the RAM or the like and executes information processing and arithmetic operations to realize various functions. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0022] 2 is a block diagram showing the functional configuration of a gas turbine control device 50 according to one embodiment. The gas turbine control device 50 includes a shutoff determination unit 19, a fuel flow rate command value calculation unit 20, and a fuel flow rate control unit 29.

[0023] The cutoff determination unit 19 is configured to determine whether or not at least a portion of the second fuel F2 has been cut off in the fuel supply system 4. For example, the cutoff determination unit 19 determines whether or not at least a portion of the second fuel F2 has been cut off based on the open / close state of a cutoff valve 21 provided in the second fuel supply line 16 through which the second fuel F2 flows.

[0024] 1 illustrates a case in which the second fuel F2 is supplied from a single second fuel supply source 14 via a single second fuel supply line 16, and the shutoff valve 13 is closed when the second fuel supply source 14 becomes unable to supply the second fuel F2 for some reason or when a blockage occurs in the second fuel supply line 16. When the shutoff determination unit 19 detects that the second fuel F2 has been shut off based on the open / closed state of the shutoff valve 21, it outputs a shutoff detection signal Sa to that effect.

[0025] In the following description, a situation in which the second fuel F2 is completely shut off will be described as a situation in which the second fuel F2 is shut off, but if, for example, the second fuel supply line 16 branches into multiple lines and the second fuel F2 can be supplied from multiple second fuel supply sources 14, at least a portion of the second fuel F2 may be shut off by closing the shutoff valves 21 provided in some of the second fuel supply lines 16. In this case, the shutoff detection signal Sa can also be treated as a signal corresponding to the amount of shutoff of the second fuel F2, and can be treated equally.

[0026] The fuel flow rate command value calculation unit 20 acquires, as input signals, state quantities (turbine output P, ​​rotation speed R, exhaust temperature EXT, blade path temperature BPT, etc.) related to the operating state of the gas turbine 1, and outputs a fuel flow rate command value CSO determined by calculation. The fuel flow rate command value CSO is input from the fuel flow rate command value calculation unit 20 to a fuel flow rate control unit 29, which adjusts the flow rate of fuel supplied by the fuel supply system 4 based on the fuel flow rate command value CSO.

[0027] The fuel flow rate command value calculation unit 20 includes a first fuel flow rate command value calculation unit 20a, a second fuel flow rate command value calculation unit 20b, a third fuel flow rate command value calculation unit 20c, a fourth fuel flow rate command value calculation unit 20d, and a low value selection unit 20e. The first fuel flow rate command value calculation unit 20a to the fourth fuel flow rate command value calculation unit 20d calculate corresponding first fuel flow rate command values ​​CSO1 to CSO4, respectively. The low value selection unit 20e selects and outputs the smallest one of the first fuel flow rate command value CSO1 to the fourth fuel flow rate command value CSO4 as the fuel flow rate command value SCO.

[0028] The first fuel flow rate command value calculation unit 20a has a normal-state fuel flow rate command value calculation unit 20a1 and a shutoff fuel flow rate command value calculation unit 20a2 which can be switched between each other depending on the operation mode of the gas turbine 1. The switching between the normal-state fuel flow rate command value calculation unit 20a1 and the shutoff fuel flow rate command value calculation unit 20a2 is performed based on a shutoff detection signal Sa input from the shutoff determination unit 19 to the first fuel flow rate command value calculation unit 20a.

[0029] When the fuel supply system 4 is in a normal state (i.e., a state in which the second fuel F2 is not cut off based on the cutoff detection signal Sa), the first fuel flow rate command value calculation unit 20a calculates a first fuel flow rate command value CSO1 using a normal-state fuel flow rate command value calculation unit 20a1. The normal-state fuel flow rate command value calculation unit 20a1 receives the turbine output P and the target turbine output Pref corresponding to the turbine output P, ​​among the input signals to the fuel flow rate command value calculation unit 20, and calculates a first fuel flow rate command value CSO2, which is one candidate for the fuel flow rate command value CSO, based on a deviation ΔP between them.

[0030] The calculation of the first fuel flow rate command value CSO in the normal-state fuel flow rate command value calculation unit 20a1 is performed by preparing a correlation between the deviation ΔP and the first fuel flow rate command value CSO1 in advance, and inputting the deviation ΔP into the correlation to obtain the corresponding first fuel flow rate command value CSO1. This correlation is prepared in advance corresponding to the fuel mixing ratio of the first fuel F1 and the second fuel F2 obtained from the fuel supply system 4.

[0031] When the fuel supply system 4 is in a cutoff state (i.e., a state in which at least a portion of the second fuel F2 is cut off based on the cutoff detection signal Sa), the first fuel flow rate command value calculation unit 20a calculates a first fuel flow rate command value CSO1 using a cutoff fuel flow rate command value calculation unit 20a2. The cutoff fuel flow rate command value calculation unit 20a2 receives the turbine output P and the target turbine output Pref corresponding to the turbine output P, ​​among the input signals to the fuel flow rate command value calculation unit 20, and calculates a first fuel flow rate command value CSO2, which is one candidate for the fuel flow rate command value CSO, based on a deviation ΔP between them.

[0032] The calculation of the first fuel flow rate command value CSO in the cutoff fuel flow rate command value calculation unit 20a2 is performed by preparing a correlation between the deviation ΔP and the first fuel flow rate command value CSO1 in advance, and inputting the deviation ΔP into the correlation to obtain the corresponding first fuel flow rate command value CSO1. This correlation is prepared in advance corresponding to the fuel mixing ratio corresponding to the case where it is assumed that at least a portion of the second fuel F2 is cut off in the fuel supply system 4 in response to the cutoff signal Sa.

[0033] The second fuel flow rate command value calculation unit 20b is configured to calculate a second fuel flow rate command value CSO2, which is one candidate for the fuel flow rate command value CSO. The second fuel flow rate command value calculation unit 20b receives the rotation speed R and the target rotation speed Rref corresponding to the rotation speed R, among the input signals to the fuel flow rate command value calculation unit 20, and calculates the second fuel flow rate command value CSO2 based on the deviation ΔR between them.

[0034] The third fuel flow rate command value calculation unit 20c is configured to calculate a third fuel flow rate command value CSO3, which is one candidate for the fuel flow rate command value CSO. The third fuel flow rate command value calculation unit 20c receives the exhaust gas temperature EXT and the target exhaust gas temperature EXTref corresponding to the exhaust gas temperature EXT, among the input signals to the fuel flow rate command value calculation unit 20, and calculates the third fuel flow rate command value CSO3 based on the deviation ΔEXT between them.

[0035] The fourth fuel flow rate command value calculation unit 20d is configured to calculate a fourth fuel flow rate command value CSO4, which is one candidate for the fuel flow rate command value CSO. The fourth fuel flow rate command value calculation unit 20d receives the blade path temperature BPT and the target blade path temperature BPTref corresponding to the blade path temperature BPT, among the input signals to the fuel flow rate command value calculation unit 20, and calculates the fourth fuel flow rate command value CSO4 based on the deviation ΔBPT between them.

[0036] Next, a turbine control method implemented by the gas turbine control device 50 having the above configuration will be described. Fig. 3 is a flowchart showing a gas turbine control method according to one embodiment, and Fig. 4 is a time chart showing the control states of the components of the gas turbine 1 corresponding to Fig. 3.

[0037] First, the gas turbine control device 50 controls the gas turbine 1 in the normal control mode (step S1). In the normal control mode, the first fuel F1 and the second fuel F2 are both supplied soundly in the fuel supply system 4, and are supplied as a mixed fuel Fm to the combustor 2. In this case, in the first fuel flow rate command value calculation unit 20a, the calculation of the first fuel flow rate command value CSO1 is performed by the normal-state fuel flow rate command value calculation unit 20a1.

[0038] In this embodiment, for ease of explanation, the fuel flow rate command value calculation unit 20a will describe a case where the second fuel flow rate command value CSO2 to the fourth fuel flow rate command value CSO4 are larger than the first fuel flow rate command value CSO1, and therefore the low value selection unit 20e always selects the first fuel flow rate command value CSO1 as the fuel flow rate command value CSO.

[0039] Next, the shutoff determination unit 19 determines whether or not at least a portion of the second fuel F2 has been shut off in the fuel supply system 4 (step S2). In step S2, in the gas turbine 1 controlled in the normal control mode, it is determined whether or not the second fuel F2 has been shut off by monitoring the fuel supply system 4. Such a determination can be made, for example, based on the opening degree of the shutoff valve 21 arranged in the second fuel supply line 16 provided in the fuel supply system 4.

[0040] If the cutoff determination unit 19 determines that at least a portion of the second fuel F2 has been cut off (step S1: YES), the gas turbine control device 50 switches from the normal control mode to the cutoff control mode (step S3). In the cutoff control mode, the calculation of the first fuel flow rate command value CSO1 in the first fuel flow rate command value calculation unit 20a is performed by a cutoff fuel flow rate command value calculation unit 20a2.

[0041] The cutoff fuel flow rate command value calculation unit 20a2 calculates the fuel mixture ratio after the second fuel F2 is cut off, and calculates the cutoff fuel flow rate to be supplied to the combustor 2 corresponding to the fuel mixture ratio, thereby obtaining the first fuel flow rate command value CSO1. In this embodiment, by cutting off the second fuel F2, the fuel mixture ratio after cutoff becomes 100% for the first fuel F1. Therefore, assuming that the mixed fuel Fm is only the first fuel F1, the first fuel flow rate command value CSO1 corresponding to the cutoff fuel flow rate to be supplied to the combustor 2 is calculated.

[0042] The correlation between the fuel flow rate at cutoff and the turbine output is prepared in advance for each fuel mixing ratio. In this embodiment, a correlation corresponding to the fuel mixing ratio when the first fuel F1 is cutoff is prepared in advance, and the fuel flow rate at cutoff corresponding to the current turbine output is calculated based on the correlation.

[0043] In FIG. 4 , when the shutoff determination unit 19 detects the shutoff of the second fuel F2 at time t1, the first fuel flow rate command value CSO1 calculated by the normal fuel flow rate command value calculation unit 20a1 is switched to the first fuel flow rate command value CSO1 calculated by the shutoff fuel flow rate command value calculation unit 20a2. Because the second fuel F2 has a lower calorific value per unit volume than the first fuel F1, the first fuel flow rate command value CSO1 calculated by the shutoff fuel flow rate command value calculation unit 20a2 is lower than the first fuel flow rate command value CSO1 calculated by the normal fuel flow rate command value calculation unit 20a1. Here, there is a predetermined distance between the shutoff valve 13 and the combustor 2 in the fuel supply system 4, and a time lag occurs between the shutoff of the second fuel F2 and the actual increase in the fuel mixture ratio of the first fuel F1 in the combustor 2. In FIG. 4 , the flow rate in the combustor 2 remains unchanged from before shutoff, and the fuel mixture ratio does not change until time t3. On the other hand, the distance between the second flow rate control valve 26, which adjusts the flow rate of the mixed fuel Fm, and the combustor 2 is shorter than the distance between the shutoff valve 13 and the combustor 2. Therefore, by switching to the first fuel flow rate command value CSO1 calculated by the shutoff fuel flow rate command value calculation unit 20a2 immediately after the shutoff valve 13 is shut off, it becomes possible to reduce the heat input to the combustor before the fuel mixing ratio of the first fuel F1 actually increases in the combustor. In Fig. 4, at time t2, when a time lag Δt has elapsed since time t1, the turbine inlet temperature T1T and the gas turbine load GTLoad decrease.

[0044] Next, the gas turbine control device 50 determines whether a predetermined time tp has elapsed since switching to the shutoff control mode (step S4). The predetermined time tp is set to be longer than the time required for the fuel mixture ratio of the first fuel F1 to actually increase in the combustor after the second fuel F2 is shut off at time t1. Therefore, the shutoff control mode remains active from time t1 to the predetermined time tp, thereby reducing the turbine inlet temperature T1T compared to the normal control mode, thereby effectively suppressing the effects of overfire. In FIG. 4, the predetermined time tp is set to be greater than the time difference "t3 - t1." The shutoff of the shutoff valve 13 reduces the fuel flow rate of the second fuel F2, and the effects of the increased fuel mixture ratio of the first fuel F1 appear in the combustor 2 at time t3, resulting in a rapid increase in the turbine inlet temperature T1T and the gas turbine load GTLoad. However, because the flow rate of the mixed fuel is already more limited than before shutoff and the heat input to the combustor 2 is also lower, overfire is effectively suppressed.

[0045] Immediately after the second fuel F2 is shut off, the second fuel F2 that was supplied before the shutoff remains in the main fuel supply line 22 downstream of the junction 25. Therefore, the time t3 at which overfire occurs is delayed by the time required from the time t1 at which the second fuel F2 is shut off until the second fuel F2 remaining in the main fuel supply line 22 is consumed in the combustor 2. In step S4, by continuing the shutoff control mode until the predetermined time tp has elapsed from the time t1, the flow rate of the mixed fuel Fm is limited and the turbine inlet temperature T1T is lowered in advance until the influence of overfire occurs with this time lag, thereby mitigating the influence of overfire.

[0046] Then, when a predetermined time tp has elapsed since the mode was switched to the shutdown control mode (step S4: YES), the gas turbine control device 50 returns the gas turbine 1 from the shutdown control mode to the normal control mode (step S5). When a sufficient period (predetermined time) has elapsed since time t1 in this way, and there is no possibility of an overfire occurring, the control mode of the gas turbine 1 is returned to the normal control mode, thereby enabling a smooth return to normal operation.

[0047] As described above, according to each of the above embodiments, when at least a portion of the second fuel F2 that is mixed with the first fuel F1 is shut off, a fuel flow rate at cutoff corresponding to the mixed-fuel ratio after the cutoff is calculated and reflected in the fuel flow rate command value CSO before a change in the mixed-fuel ratio occurs due to the cutoff. As a result, by setting the fuel flow rate command value CSO to a value corresponding to the mixed-fuel ratio after the cutoff before the influence of the cutoff of at least a portion of the second fuel gas F2 appears in the operating state of the gas turbine 1, it is possible to effectively mitigate the influence even if an overfire occurs.

[0048] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate.

[0049] The contents described in each of the above embodiments can be understood, for example, as follows.

[0050] (1) A gas turbine control device according to one aspect includes: 1. A gas turbine control device for controlling a gas turbine including a combustor capable of generating combustion gas for driving the gas turbine by mixed combustion of a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel, comprising: a supply state determination unit for determining a supply state of the second fuel to the combustor; a cutoff fuel flow rate calculation unit that calculates a cutoff fuel flow rate to be supplied to the combustor in accordance with a fuel mixing ratio after at least a portion of the second fuel is cut off, when it is determined that the combustor is in the supply state in which at least a portion of the second fuel is cut off; a fuel command value output unit for outputting a fuel flow rate command value corresponding to the fuel flow rate at the time of cutoff after at least a portion of the second fuel is cut off and before the fuel mixing ratio is reached; Equipped with.

[0051] According to the above aspect (1), when at least a portion of the second fuel gas that is mixed with the first fuel is shut off, a fuel flow rate at shutoff corresponding to the mixed-fuel ratio after the shutoff is calculated and reflected in the fuel flow rate command value before a change in the mixed-fuel ratio occurs due to the shutoff. As a result, by setting the fuel flow rate command value to a value corresponding to the mixed-fuel ratio after the shutoff before the influence of the shutoff of at least a portion of the second fuel gas appears in the operating state of the gas turbine, even if an overfire occurs, the influence can be effectively mitigated.

[0052] (2) In another embodiment, in the above embodiment (1), The cutoff fuel flow rate calculation unit calculates the cutoff fuel flow rate corresponding to a current output of the gas turbine based on a correlation between the output of the gas turbine and the cutoff fuel flow rate in the case of the fuel mixing ratio.

[0053] According to the above aspect (2), a correlation between the cutoff fuel flow rate and the output of the gas turbine when at least a portion of the second fuel gas is cut off is prepared in advance. When at least a portion of the second fuel gas is cut off in the gas turbine, the cutoff fuel flow rate corresponding to the current output of the gas turbine is calculated based on the correlation.

[0054] (3) In another aspect, in the above aspect (1) or (2), The cutoff fuel flow rate is valid for a predetermined time after it is determined that at least a portion of the second fuel to the combustor is in the cutoff state.

[0055] According to the above aspect (3), the shut-off fuel flow rate calculated when at least a portion of the second fuel gas is shut off is valid for a predetermined period of time, thereby effectively mitigating the effects of overfire even if it occurs during that period.

[0056] (4) In another embodiment, in the above embodiment (3), a target amount calculation unit that calculates a fuel flow rate to be supplied to the combustor based on a target output value and a current output value of the gas turbine, After the predetermined time has elapsed, the fuel command value output unit switches from a shutoff control mode in which the fuel flow rate command value corresponding to the total fuel flow rate to be supplied in accordance with the fuel mixing ratio to a normal control mode in which the fuel flow rate command value is output using the fuel flow rate calculated by the target amount calculation unit.

[0057] According to the above aspect (4), after a predetermined time during which the shutoff fuel flow rate is valid has elapsed, the operating state of the gas turbine can be smoothly returned to normal by switching from the shutoff control mode to the normal control mode.

[0058] (5) In another embodiment, in any one of the above (1) to (4), The first fuel is natural gas and the second fuel is hydrogen gas.

[0059] According to the above aspect (5), in a gas turbine in which natural gas and hydrogen gas are mixed and burned, when at least a portion of the hydrogen gas is cut off, the influence of a change in the amount of heat input to the turbine can be effectively suppressed.

[0060] (6) A gas turbine control method according to one aspect includes: 1. A gas turbine control method for controlling a gas turbine including a combustor capable of generating combustion gas for driving the gas turbine by mixed combustion of a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel, comprising: determining a supply state of the second fuel to the combustor; calculating a cutoff fuel flow rate to be supplied to the combustor in accordance with a fuel mixing ratio after at least a portion of the second fuel is cut off when it is determined that the combustor is in the supply state in which at least a portion of the second fuel is cut off; After at least a portion of the second fuel is cut off and before the fuel mixing ratio is reached, outputting a fuel flow rate command value corresponding to the cut-off fuel flow rate; Equipped with.

[0061] According to the above aspect (6), when at least a portion of the second fuel gas that is mixed with the first fuel is shut off, a fuel flow rate at shutoff corresponding to the mixed-fuel ratio after the shutoff is calculated and reflected in the fuel flow rate command value before a change in the mixed-fuel ratio occurs due to the shutoff. As a result, by setting the fuel flow rate command value to a value corresponding to the mixed-fuel ratio after the shutoff before the influence of the shutoff of at least a portion of the second fuel gas appears in the operating state of the gas turbine, even if an overfire occurs, the influence can be effectively mitigated.

[0062] (7) A gas turbine control program according to one aspect includes: 1. A gas turbine control program for controlling a gas turbine including a combustor capable of generating combustion gas for driving the gas turbine by mixed combustion of a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel, the program comprising: To the computer device, determining a supply state of the second fuel to the combustor; calculating a cutoff fuel flow rate to be supplied to the combustor in accordance with a fuel mixing ratio after at least a portion of the second fuel is cut off when it is determined that the combustor is in the supply state in which at least a portion of the second fuel is cut off; After at least a portion of the second fuel is cut off and before the fuel mixing ratio is reached, outputting a fuel flow rate command value corresponding to the cut-off fuel flow rate; is possible.

[0063] According to the above aspect (7), when at least a portion of the second fuel gas that is mixed with the first fuel is shut off, a fuel flow rate at shutoff corresponding to the mixed-fuel ratio after the shutoff is calculated and reflected in the fuel flow rate command value before a change in the mixed-fuel ratio occurs due to the shutoff. As a result, by setting the fuel flow rate command value to a value corresponding to the mixed-fuel ratio after the shutoff before the influence of the shutoff of at least a portion of the second fuel gas appears in the operating state of the gas turbine, even if an overfire occurs, the influence can be effectively mitigated. [Explanation of symbols]

[0064] 1. Gas turbine 2. Combustor 3. Compressor 4 Fuel supply system 6 Turbine 7 First fuel source 8. First fuel supply line 10 Flow meter 13 Shut-off valve 14 Secondary fuel source 16 Second fuel supply line 18 First flow control valve 19. Shutdown judgment unit 20 Fuel flow command value calculation unit 20a First fuel flow command value calculation unit 20a1 Normal fuel flow command value calculation unit 20a2 Shut-off fuel flow command value calculation unit 20b Second fuel flow command value calculation unit 20c Third fuel flow command value calculation unit 20d Fourth fuel flow command value calculation unit 20e Low value selection section 22 Main fuel supply line 25 Confluence 26 Second flow control valve 28a-28d Fuel branch supply line 29 Fuel flow control unit 30a-30d Third flow control valve 50 Gas turbine control device F1 1st fuel F2 Second Fuel Fm blended fuel

Claims

1. 1. A gas turbine control device for controlling a gas turbine including a combustor capable of generating combustion gas for driving the gas turbine by mixed combustion of a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel, comprising: a supply state determination unit that determines a supply state of the second fuel in a second fuel supply line that supplies the second fuel, on an upstream side of a junction with the first fuel supply line that supplies the first fuel; a cutoff fuel flow rate calculation unit that calculates a cutoff fuel flow rate to be supplied to the combustor in accordance with a fuel mixing ratio after at least a portion of the second fuel is cut off, when it is determined that the combustor is in the supply state in which at least a portion of the second fuel is cut off; a fuel command value output unit configured to output a fuel flow rate command value corresponding to the fuel flow rate at the time of cutoff after at least a portion of the second fuel is cut off and before the fuel mixing ratio is reached; A gas turbine control device comprising:

2. A gas turbine control device as described in claim 1, wherein the supply state determination unit determines the supply state of the second fuel based on the opening degree of a shut-off valve provided in the second fuel supply line.

3. 3. The gas turbine control device according to claim 1, wherein the shutoff time fuel flow rate calculation unit calculates the shutoff time fuel flow rate corresponding to a current output of the gas turbine based on a correlation between an output of the gas turbine and the shutoff time fuel flow rate in the case of the fuel mixing ratio.

4. 3. The gas turbine control device according to claim 1, wherein the shut-off fuel flow rate is valid for a predetermined time after it is determined that the supply of at least a portion of the second fuel to the combustor is in the shut-off state.

5. a target amount calculation unit that calculates a fuel flow rate to be supplied to the combustor based on a target output value and a current output value of the gas turbine, 5. The gas turbine control device according to claim 4, wherein the fuel command value output unit switches, after the predetermined time has elapsed, from a shutoff control mode in which the fuel flow rate command value corresponding to a total fuel flow rate to be supplied in accordance with the fuel mixing ratio to a normal control mode in which the fuel flow rate command value is output using the fuel flow rate calculated by the target amount calculation unit.

6. The gas turbine control device according to claim 1 or 2, wherein the first fuel is natural gas and the second fuel is hydrogen gas.

7. 1. A gas turbine control method for controlling a gas turbine including a combustor capable of generating combustion gas for driving the gas turbine by mixed combustion of a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel, the method comprising: determining a supply state of the second fuel in a second fuel supply line for supplying the second fuel on an upstream side of a junction with a first fuel supply line for supplying the first fuel; calculating a cutoff fuel flow rate to be supplied to the combustor in accordance with a fuel mixing ratio after at least a portion of the second fuel is cut off when it is determined that the combustor is in the supply state in which at least a portion of the second fuel is cut off; After at least a portion of the second fuel is cut off and before the fuel mixing ratio is reached, outputting a fuel flow rate command value corresponding to the cut-off fuel flow rate; A gas turbine control method comprising:

8. 1. A gas turbine control program for controlling a gas turbine including a combustor capable of generating combustion gas for driving the gas turbine by mixed combustion of a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel, the program comprising: To the computer device, determining a supply state of the second fuel in a second fuel supply line for supplying the second fuel on an upstream side of a junction with a first fuel supply line for supplying the first fuel; calculating a cutoff fuel flow rate to be supplied to the combustor in accordance with a fuel mixing ratio after at least a portion of the second fuel is cut off when it is determined that the combustor is in the supply state in which at least a portion of the second fuel is cut off; After at least a portion of the second fuel is cut off and before the fuel mixing ratio is reached, outputting a fuel flow rate command value corresponding to the cut-off fuel flow rate; A gas turbine control program capable of executing the above.

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