Gas turbine systems and their control methods

Abstract

A gas turbine system and its control method are disclosed. The gas turbine system comprises: a gas turbine having a compressor for generating compressed air, a combustor for burning fuel using compressed air, and a turbine driven by combustion gases generated by combustion of fuel in the combustor; an electric generator capable of being driven by the turbine and capable of providing rotational power to the gas turbine via power supplied from an external source; a fuel flow determination device for determining a set value of a parameter used in controlling the flow rate of fuel supplied to the combustor; and a fuel flow control device for controlling the flow rate of fuel supplied to the combustor based on the set value, wherein in an operating mode in which the electric generator provides rotational power to the turbine, i.e., a reverse electric operation mode, the fuel flow determination device determines the set value in such a way that the fuel flow rate becomes a lower limit value in the reverse electric operation mode.

Description

Technical Field

[0001] This disclosure relates to gas turbine systems and control methods thereof.

[0002] This application asserts priority based on Japan Patent Application No. 2021-053782 filed with the Japan Patent Office on March 26, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] For example, Patent Document 1 describes a technology for generating electricity by driving a generator with a gas turbine.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-47728 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In the normal operating mode where a gas turbine drives a generator, the flow rate (fuel supply) of fuel supplied to the gas turbine combustor is typically controlled based on factors such as the gas turbine's rotational speed, the generator's output, and the gas turbine's exhaust temperature. However, in the reverse-electric operating mode, where the gas turbine is powered by an external power source, performing the same control methods as in the normal operating mode can sometimes fail to adequately control the fuel supply.

[0009] In view of the above, the object of at least one embodiment of this disclosure is to provide a gas turbine system and a control method thereof capable of appropriately controlling the flow rate of fuel supplied to the combustor of a gas turbine in a reverse electric operation mode.

[0010] Solution for solving the problem

[0011] To achieve the above objectives, the gas turbine system disclosed herein comprises: a gas turbine having a compressor for generating compressed air, a combustor for burning fuel using the compressed air, and a turbine driven by combustion gases generated by the combustion of the fuel in the combustor; an electric generator capable of being driven by the turbine and capable of providing rotational power to the gas turbine via power supplied from an external source; a fuel flow determination device for determining a set value of a parameter used in controlling the flow rate of the fuel supplied to the combustor; and a fuel flow control device for controlling the flow rate of the fuel supplied to the combustor based on the set value, wherein in an operating mode in which the electric generator provides rotational power to the gas turbine, i.e., a reverse electric operation mode, the fuel flow determination device determines the set value in such a way that the fuel flow rate becomes a lower limit value in the reverse electric operation mode.

[0012] Furthermore, according to the control method of the gas turbine system disclosed herein, the gas turbine system comprises: a gas turbine having a compressor for generating compressed air, a combustor for burning fuel using the compressed air, and a turbine driven by combustion gases generated by combustion of the fuel in the combustor; an electric generator capable of being driven by the turbine and capable of providing rotational power to the gas turbine via power supplied from an external source; and a fuel flow control device that controls the flow rate based on a set value of a parameter used in controlling the flow rate of the fuel supplied to the combustor, wherein the control method of the gas turbine system includes the step of determining the set value in an operating mode in which the electric generator provides rotational power to the gas turbine, i.e., a reverse electric operation mode, such that the flow rate of the fuel is above a lower limit value in the reverse electric operation mode.

[0013] Invention Effects

[0014] According to the gas turbine system and control method disclosed herein, the flow rate of fuel supplied to the combustor of the gas turbine in reverse electric operation mode can be appropriately controlled. Attached Figure Description

[0015] Figure 1 This is a structural diagram of a gas turbine system according to one embodiment of the present disclosure.

[0016] Figure 2 This is a structural block diagram of a control device for a gas turbine system according to one disclosed embodiment.

[0017] Figure 3 This is a time-series diagram showing the time-varying changes of various items when a gas turbine system according to one embodiment of the present disclosure transitions from a normal operating mode to a reverse electric operating mode. Detailed Implementation

[0018] Hereinafter, a gas turbine system and its control method according to embodiments of the present disclosure will be described based on the accompanying drawings. The embodiments described below represent one aspect of the present disclosure and are not intended to limit the present disclosure; modifications can be made arbitrarily within the scope of the technical concept of the present disclosure.

[0019] <Structure of a gas turbine system according to one embodiment of this disclosure>

[0020] like Figure 1 As shown, a gas turbine system 10 according to one embodiment of this disclosure includes a gas turbine 1, which has: a combustor 4 that burns fuel to generate combustion gases; a compressor 2 that supplies compressed air to the combustor 4 as combustion air; and a turbine 6 that has a rotating shaft 5 shared with the compressor 2 and is configured to be driven by the combustion gases generated by the combustor 4. An electric generator 7 is connected to the rotating shaft 5, and the electric generator 7 is configured to be electrically connected to an external power system 8 of the gas turbine 1. An inlet guide vane (IGV) 3A for adjusting the intake air volume is provided at the inlet of the compressor 2. The opening degree of the IGV 3A is configured to be adjustable by an actuator 3B (inlet guide vane control device).

[0021] The burner 4 is configured to receive fuel from a fuel supply source 11 via a fuel supply line 12. The fuel supply line 12 is equipped with: a fuel control valve 13 (fuel flow control device) for regulating the flow rate (fuel supply amount) of fuel supplied to the burner 4; and a pilot ratio control unit 14 (e.g., a control valve for controlling the fuel supply amount to a pilot nozzle (not shown) and a main nozzle (not shown)) for regulating a pilot ratio, which is the ratio of the fuel supply amount to the pilot nozzle (not shown) to the fuel supply amount to the burner 4. The fuel control valve 13, the pilot ratio control unit 14, and the actuator 3B are electrically connected to a control device 15. Through operations described later, the control device 15 determines a set value for the fuel control valve 13 to control the fuel supply amount to the burner 4. Therefore, the control device 15 constitutes a fuel flow rate determining device for determining the set value of the fuel supply amount to the burner 4.

[0022] like Figure 2 As shown, the control device 15, which is a fuel flow determination device, includes: a first determination unit 21, which is based on the gas turbine 1 in the normal operating mode described later (see reference). Figure 1 ) and electric generator 7 (refer to) Figure 1The system determines the operating conditions of the gas turbine 1, including a first setpoint (based on the rotational speed of the gas turbine 1), a second setpoint (based on the lower limit of the fuel supply in the reverse electric operation mode, described later), and a high-value selection circuit 23, which is electrically connected to the first setpoint 21, the second setpoint 22, and the fuel control valve 13, and selects either the first setpoint or the second setpoint as the setpoint. The first setpoint 21 is configured to receive data on at least the rotational speed of the gas turbine 1. The first setpoint 21 may also receive data on the power generation of the electric generator 7, the temperature of the exhaust gas discharged from the gas turbine 1, etc. Furthermore, the lower limit of the fuel supply in the reverse electric operation mode determined by the second setpoint 22 is a value set in this embodiment to prevent misfire of the burner 4, but it does not necessarily need to be the lowest value within the range capable of preventing misfire; it could be a value with a margin, or a value set to ensure safe operation of the gas turbine system 10 in the reverse electric operation mode.

[0023] The control device 15 comprises, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. As an example, a series of processes for implementing various functions are stored in the storage medium as programs. The CPU reads the program into RAM and performs information processing / analysis, thereby implementing various functions. Alternatively, the program can be pre-installed in ROM, other storage media, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication. Computer-readable storage media include magnetic disks, optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0024] Operation of a gas turbine system according to one embodiment of this disclosure

[0025] Next, the operation of a gas turbine system 10 according to one embodiment of the present disclosure will be described. Figure 1 The gas turbine system 10 can switch between the normal operating mode, in which the turbine 6 drives the electric generator 7, and the reverse electric operating mode, in which the electric generator 7 provides rotational power to the gas turbine 1 through external power supply.

[0026] In normal operation, compressed air is supplied from compressor 2 to burner 4, and fuel is supplied from fuel supply source 11 to burner 4 via fuel supply line 12, whereby the fuel is burned to generate combustion gases. These combustion gases are supplied to turbine 6, which is then driven to rotate. The rotation of turbine 6 is transmitted via rotating shaft 5 to electric generator 7, which then acts as a generator. The electricity generated by electric generator 7 is transmitted to power system 8.

[0027] On the other hand, in the reverse electric operation mode, electricity is supplied from the external power system 8 of the gas turbine 1 to the electric generator 7, which then drives the electric generator 7 as an electric motor. The rotational power generated by the electric generator 7 is provided to the gas turbine 1 to assist its operation. Therefore, the reverse electric operation mode generally consumes less fuel than the normal operation mode.

[0028] <Control method for a gas turbine system according to one embodiment of the present disclosure>

[0029] Next, based on Figure 1 and 2 and Figure 3 The timing diagram illustrates the control method of the gas turbine system 10, particularly the control method of the fuel supply to the burner 4. Figure 3 The timing diagram illustrates the time-dependent changes of various parameters in the gas turbine system 10 as it transitions from normal operating mode to reverse electric operating mode. Prior to time t0, the gas turbine system 10 operates in normal operating mode at a specified load L0. The operator of the gas turbine system 10 begins preparations at time t0 for the switch to reverse electric operating mode at time t2 (described later).

[0030] In part of the process for transitioning to the reverse electric operation mode in this embodiment, the speed setpoint of the gas turbine 1 is reduced, and the setpoint of the parameter determined based on the actual speed and the speed setpoint is also reduced. In normal operation, when the gas turbine system 10 supplies power to the external power system 8, the fuel supply is controlled such that the speed setpoint is not significantly different from the rated frequency of the power system 8. In the gas turbine system 10 of this embodiment, when connected to the power system 8, even if the speed setpoint is reduced, the actual speed is maintained at (or within approximately the same range as) the frequency of the power system 8, and the fuel supply is reduced accordingly.

[0031] Before switching to the reverse electric operation mode, the speed setpoint is gradually decreased from the predetermined value S0 in the normal operation mode, thereby reducing the setpoint of the fuel supply amount transmitted from the first determination unit 21 to the high-value selection circuit 23. As the speed setpoint decreases, the difference between the actual speed (depending on the frequency of the power system 8) and the speed setpoint increases, and the first setpoint determined by the first determination unit 21 decreases.

[0032] The high-value selection circuit 23 selects the larger of the first setting value transmitted from the first decision unit 21 and the second setting value transmitted from the second decision unit 22. Here, in the reverse electric operation mode, the first setting value is larger than the second setting value before the fuel supply reaches its lower limit. Therefore, in the preparation stage for transitioning to the reverse electric operation mode, the high-value selection circuit 23 selects the first setting value as the fuel supply setting value. This is achieved by moving from the speed setting value S0 to the speed setting value S... min The fuel supply setting is reduced from the initial setting F0 towards a setting equivalent to the minimum supply in normal operating mode. min The control device 15 controls the fuel control valve 13 based on a setpoint for the fuel supply quantity, which is used as a parameter in controlling the fuel supply quantity, to reduce the opening of the fuel control valve 13 in a manner corresponding to the reduction in the setpoint for the fuel supply quantity. As a result, the load on the gas turbine system 10 decreases from the initial load L0 to the lowest load L in the normal operating mode. min reduce.

[0033] Furthermore, at time t0, the control device 15 controls the pilot ratio control unit 14 to increase the pilot ratio from the initial pilot ratio R0. This allows the burner 4 to remain in a state less prone to misfire even if the fuel supply to the burner 4 is reduced. Moreover, at time t0, the control device 15 can also adjust the opening of the IGV3A to a level that prevents misfire in the burner 4 by controlling the actuator 3B.

[0034] At time t1, the load on the gas turbine system 10 becomes the lowest load L in normal operating mode. min (That is, the amount of fuel supplied to burner 4 becomes the minimum supply amount F in normal operating mode.) min Before reaching time t1, the leader ratio is raised to a constant value R1. This operating condition is maintained until a predetermined time has elapsed from time t1, i.e., time t2.

[0035] At time t2, for example, the operator of the gas turbine system 10 presses the operation mode switching button, initiating the switch from the normal operation mode to the reverse electric operation mode. The control device 15 starts to increase the pilot ratio by controlling the pilot ratio control unit 14. At time t3, the control device 15 stops increasing the pilot ratio, and after time t3, the pilot ratio remains at R2, which is greater than R1. Alternatively, at time t3, the control device 15 can also control the opening of the IGV3A to a level suitable for the reverse electric operation mode by controlling the actuator 3B. As described above, the control device 15 performs control to ensure that the conditions for transitioning to the reverse electric operation mode, such as the pilot ratio, are met when the operation mode switching button is pressed.

[0036] From the moment t3 when the transition condition to reverse electric operation mode is met, control device 15 further increases the speed setpoint from S. min The speed setpoint decreases, and the difference between the setpoint and the actual speed (depending on the frequency of the power system 8) further increases, thus the fuel supply setpoint decreases further. Control device 15 controls fuel control valve 13 based on the parameter used in controlling the fuel supply, i.e., the fuel supply setpoint, to reduce the opening of fuel control valve 13 in a manner corresponding to the decrease in the fuel supply setpoint. As a result, the gas turbine load also decreases from the minimum load L in normal operating mode. min Further reduction.

[0037] At time t4, the load on the gas turbine system 10 becomes zero, but the fuel supply to the combustor 4 continues to decrease by continuously reducing the speed setpoint. After time t4, electricity is supplied from the power system 8 to the electric generator 7. Therefore, after time t4, the electric generator 7 is driven as an electric motor, and the rotational power generated by the electric generator 7 is supplied to the gas turbine 1.

[0038] At time t5, the speed setpoint decreases to S. GM1 At this time, the first setting value determined by the first decision unit 21 and the second setting value determined by the second decision unit 22 become the same value. Furthermore, the high-value selection circuit 23 further reduces the speed setting value, making the second setting value larger than the first setting value, and selects the second setting value F determined by the second decision unit. GM In this embodiment, considering the frequency variation of the external power system 8, at time t6 after time t5, the speed setpoint is set to a value higher than S. GM1 The lower value is S GM2 When the frequency of the external power system 8 varies and is slightly lower than the rated frequency, the speed of the gas turbine 1 (depending on the frequency of the power system 8) is related to the speed setpoint S. GM2The difference also decreases slightly, and the value of the first setpoint increases. However, if the decrease in the frequency of the power system 8 is within a specified range, the second setpoint remains larger than the first setpoint. Furthermore, the high-value selection circuit 23 selects the second selection value, thus maintaining the lower limit of the fuel supply in the reverse power operation mode. As a result, it is possible to suppress the excessive increase in the fuel supply in the gas turbine system 10 due to the frequency variation of the power system 8. Here, the speed setpoint S is determined by considering the magnitude of the frequency variation of the power system. GM1 With the speed setpoint S GM2 The difference can reduce the fuel supply in reverse electric operation mode to a lower limit (second set value F). GM The state of ) should be maintained appropriately.

[0039] Thus, in the gas turbine system 10 of this embodiment, the flow rate of fuel supplied to the burner 4 of the gas turbine 1 in the reverse electric operation mode can be appropriately controlled.

[0040]

[0041] In this embodiment, the second set value F GM It is a predetermined constant value, but not limited to this method. For example, the second setpoint can also automatically change according to the intake temperature of the gas turbine 1 and the ambient pressure. Additionally, the second setpoint F... GM It can also be a parameter that changes automatically or manually based on the composition of the fuel (calorie content per unit, etc.). However, if the second set value F... GM If the set value is constant, the flow rate of fuel supplied to the combustor 4 of the gas turbine 1 is controlled based on the constant set value in the reverse electric operation mode, thus simplifying the control of fuel flow rate in the reverse electric operation mode.

[0042] In this embodiment, in either the normal operation mode or the reverse power operation mode, the control device 15 has a second decision unit 22 and a high-value selection circuit 23, but it is not limited to this configuration. The second decision unit 22 and the high-value selection circuit 23 may also be configured such that they are disabled as control processing by the control device 15 in the normal operation mode, but become effective as control processing when switching to the reverse power operation mode begins.

[0043] In this embodiment, during the switching process to the reverse power operation mode (in Figure 3In the example, at time t5, it was explained that the first determination unit 21 can be configured to set the speed setting value in a manner where the first setting value is smaller than the second setting value. When the second determination unit 22 and the high-value selection circuit 23 are also present in the normal operating mode, the first determination unit 21 is configured to set the speed setting value in a manner where the first setting value is larger than the second setting value, so that the high-value selection circuit 23 can always select the first setting value as the setting value in the normal operating mode. It should be noted that the second setting value in the normal operating mode and the second setting value in the reverse electric operation mode do not need to be the same; a structure that switches the value according to the switching of the operating mode is also possible. That is, the second setting value in the normal operating mode can be set to be greater than the second setting value in the reverse electric operation mode, or vice versa. Therefore, the flow rate of fuel supplied to the combustor 4 of the gas turbine 1 can be appropriately controlled even in the normal operating mode.

[0044] In this embodiment, a structure is described in which the fuel supply setting is continuously reduced to a second setting (lower limit) by continuously decreasing a first setting value during the transition to the reverse power operation mode. However, a structure in which the fuel supply setting is discontinuously reduced to the second setting (lower limit) during the transition to the reverse power operation mode is also possible. This structure can be implemented, for example, by discontinuously switching the input signal to itself from the first setting value determined by the first determination unit 21 to the second setting value determined by the second determination unit 22 during the transition from the high-value selection circuit 23 to the reverse power operation mode. However, as in this embodiment, by continuously reducing the fuel supply setting to the second setting (lower limit), the risk of misfire can be further reduced.

[0045] In this embodiment, during the reverse electric operation mode, power is supplied from the power system 8 to the electric generator 7 as an external power source from the gas turbine 1, but this method is not limited to it. Excess power from other plants or the like can also be supplied to the electric generator 7.

[0046] The contents described in the above embodiments are as follows.

[0047] [1] A gas turbine system of one scheme, wherein,

[0048] The gas turbine system (10) includes:

[0049] A gas turbine (1) comprising a compressor (2) for generating compressed air, a burner (4) for burning fuel using the compressed air, and a turbine (6) driven by combustion gases generated by the combustion of the fuel in the burner (4);

[0050] An electric generator (7) is capable of being driven by the turbine (6) and can provide rotational power to the gas turbine (1) via external power supply;

[0051] A fuel flow determination device (control device 15) determines the set value of a parameter used in controlling the flow rate of the fuel supplied to the burner (4); and

[0052] A fuel flow control device (fuel control valve 13) controls the flow rate of fuel supplied to the burner (4) based on the set value.

[0053] In the reverse electric operation mode in which the electric generator (7) provides the rotational power to the gas turbine (1), the fuel flow determination device (15) determines the set value in such a way that the fuel flow rate becomes the lower limit value in the reverse electric operation mode.

[0054] According to the gas turbine system disclosed herein, the flow rate of fuel supplied to the gas turbine burner in reverse electric operation mode can be appropriately controlled.

[0055] [2] Another type of gas turbine system is based on the gas turbine system in [1].

[0056] The fuel flow determination device (15) includes:

[0057] The first decision unit (21) determines a first set value as an option for the set value, which is determined at least based on the rotational speed of the gas turbine (1); and

[0058] The second decision unit (22) determines a second set value that serves as the lower limit value in the reverse power operation mode.

[0059] In the reverse power operation mode, the first set value and the second set value are compared, and the larger one is determined as the set value.

[0060] Based on this structure, the flow rate of fuel supplied to the gas turbine burner in reverse electric operation mode can be appropriately controlled.

[0061] [3] Another gas turbine system is based on the gas turbine system in [2].

[0062] When the first decision unit (21) reduces the flow rate of the fuel in a manner that constitutes the reverse power operation mode, it reduces the set value of the rotational speed relative to the frequency of the power supply from the outside.

[0063] Based on this structure, the flow rate of fuel supplied to the gas turbine burner in reverse electric operation mode can be appropriately controlled.

[0064] [4] Another gas turbine system is based on the gas turbine system of [2] or [3].

[0065] The first decision unit (21) determines the speed setting value in the reverse electric operation mode in such a way that the difference between the speed of the gas turbine (1) and the speed setting value is greater than the operation mode in which the electric generator (7) is driven by the turbine (6).

[0066] According to this structure, in normal operating mode, a first setpoint determined at least based on the speed of the gas turbine is set as the setpoint, so the flow rate of fuel supplied to the combustor of the gas turbine in normal operating mode can be appropriately controlled.

[0067] [5] Another gas turbine system is based on any one of the gas turbine systems in [2] to [4].

[0068] In the reverse power operation mode, the first decision unit (21) determines the first setting value in such a way that the first setting value is lower than the second setting value while suppressing the increase in the flow of fuel from the second setting value, which is the lower limit value.

[0069] Based on this structure, the flow rate of fuel supplied to the gas turbine burner in reverse electric operation mode can be appropriately controlled.

[0070] [6] A control method for a gas turbine system, wherein the gas turbine system (10) comprises:

[0071] A gas turbine (1) comprising a compressor (2) for generating compressed air, a burner (4) for burning fuel using the compressed air, and a turbine (6) driven by combustion gases generated by the combustion of the fuel in the burner (4);

[0072] An electric generator (7) capable of being driven by the turbine (6) and capable of providing rotational power to the gas turbine (1) via external power supply; and

[0073] The fuel flow control device (fuel control valve 13) controls the flow based on set values ​​of parameters used in controlling the flow rate of the fuel supplied to the burner (4).

[0074] in,

[0075] The control method of the gas turbine system includes the following steps: in the operation mode in which the electric generator (7) provides the rotational power to the gas turbine (1), i.e., the reverse electric operation mode, the set value is determined in such a way that the flow rate of the fuel is above the lower limit value in the reverse electric operation mode.

[0076] According to the control method of the gas turbine system disclosed herein, the flow rate of fuel supplied to the combustor of the gas turbine in reverse electric operation mode can be appropriately controlled.

[0077] Explanation of reference numerals in the attached figures

[0078] 1…gas turbine;

[0079] 2…compressor;

[0080] 4…burner;

[0081] 6… Turbine;

[0082] 7…electric generator;

[0083] 10… Gas turbine system;

[0084] 13… Fuel control valve (fuel flow control device);

[0085] 15…Control device (fuel flow determination device);

[0086] 21…First Decision Department;

[0087] 22…Second Decision Department.

Claims

1. A gas turbine system, wherein, The gas turbine system includes: A gas turbine comprising a compressor for generating compressed air, a combustor for burning fuel using the compressed air, and a turbine driven by combustion gases generated by combustion of the fuel in the combustor; An electric generator that can be driven by the turbine and can provide rotational power to the gas turbine by power supplied from outside the gas turbine; A fuel flow determination device that determines the set value of a parameter used in controlling the flow rate of the fuel supplied to the burner; and A fuel flow control device that controls the flow rate of fuel supplied to the burner based on the set value. The fuel flow determination device can switch the gas turbine from a normal operating mode in which the turbine drives the electric generator to a reverse electric operating mode in which the electric generator provides the rotational power to the gas turbine. The fuel flow determination device gradually reduces the setpoint speed of the gas turbine during the switching process from the normal operating mode to the reverse electric operating mode. After switching from the normal operating mode to the reverse electric operating mode, the fuel flow determination device determines the set value in such a way that the fuel flow rate becomes the lower limit value in the reverse electric operating mode.

2. The gas turbine system according to claim 1, wherein, The fuel flow determination device includes: The first decision unit determines a first set value as an option for the set value, which is determined at least based on the rotational speed of the gas turbine; and The second decision unit determines a second set value that serves as the lower limit value in the reverse power operation mode. In the reverse power operation mode, the first set value and the second set value are compared, and the larger one is determined as the set value.

3. The gas turbine system according to claim 2, wherein, When the first decision unit reduces the flow rate of fuel in a manner that constitutes the reverse power operation mode, it reduces the set value of the rotational speed relative to the frequency of the power supply from the external source.

4. The gas turbine system according to claim 2 or 3, wherein, The first decision unit determines the speed setting value in the reverse electric operation mode in such a way that the difference obtained by subtracting the speed setting value from the speed of the gas turbine is greater in the case of the reverse electric operation mode than in the case of the normal operation mode.

5. The gas turbine system according to claim 2 or 3, wherein, In the reverse electric operation mode, the first decision unit determines the first setting value in such a way that the first setting value is lower than the second setting value, while suppressing the increase in the flow rate of the fuel from the second setting value, which is the lower limit value.

6. A control method for a gas turbine system, the gas turbine system comprising: A gas turbine comprising a compressor for generating compressed air, a combustor for burning fuel using the compressed air, and a turbine driven by combustion gases generated by combustion of the fuel in the combustor; An electric generator capable of being driven by the turbine and capable of providing rotational power to the gas turbine via external power supply; and A fuel flow control device that controls the flow rate of fuel supplied to the burner based on set values ​​of parameters used in controlling the flow rate of the fuel. in, The control method for the gas turbine system includes the following steps: Switching the gas turbine from its normal operating mode, where the turbine drives the electric generator, to a reverse electric operating mode, where the electric generator supplies rotational power to the gas turbine. During the transition of the gas turbine from the normal operating mode to the reverse electric operating mode, the speed setpoint of the gas turbine is gradually reduced. After switching from the normal operating mode to the reverse electric operating mode, the set value is determined in such a way that the fuel flow rate is above the lower limit value in the reverse electric operating mode.

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