Control device for gas turbine, gas turbine facility, method for controlling gas turbine, and control program for gas turbine

Abstract

This control device for a gas turbine connected to a power generator capable of linking to a power system is configured to be able to switch operation modes of the gas turbine between a normal operati

Description

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

[0001] This disclosure relates to a gas turbine control device, a gas turbine facility, a gas turbine control method, and a gas turbine control program. This application claims priority based on Japanese Patent Application No. 2021-139624, filed with the Japan Patent Office on August 30, 2021, the contents of which are incorporated herein by reference.

[0002] 2. Description of the Related Art Gas turbine systems, which drive a turbine with combustion gases produced by burning fuel, typically include a compressor for compressing the fuel gas or oxidant gas (such as air).

[0003] Patent Document 1 discloses a gas turbine equipped with a gas compressor for compressing gas fuel supplied to a combustor. Patent Document 1 also describes that in order to prevent surging of the gas compressor, the gas turbine is operated so that the pressure ratio (compression ratio) of the gas compressor does not exceed a limit value, and that if the pressure ratio of the gas compressor exceeds the limit value, operation of the gas turbine is stopped immediately to protect the equipment.

[0004] International Publication No. 2012 / 132062

[0005] A gas turbine unit to which a generator is connected normally operates in an operation mode (normal operation mode) in which the generator is rotationally driven by the gas turbine. However, when there is no demand for power generation, the unit may operate in an operation mode (reverse power operation mode) in which the gas turbine is rotationally driven by the generator that receives power supply from an external source and functions as a motor.

[0006] In reverse power operation of a gas turbine, the generator assists in driving the turbine, allowing the fuel supply to be reduced to a level that does not cause the gas turbine to misfire. However, because the fuel supply is reduced in this manner, the pressure ratio (compression ratio) of the compressor is reduced compared to normal operation. When the compressor pressure ratio is reduced during reverse power operation, the fluid flow velocity in the rear stages of the compressor increases, significantly deviating from the design flow velocity conditions during normal operation (such as rated operation). This can cause stronger forced vibration of the compressor blades, potentially increasing the risk of damage to the compressor blades.

[0007] In view of the above circumstances, at least one embodiment of the present invention aims to provide a gas turbine control device, gas turbine equipment, a gas turbine control method, and a gas turbine control program that can suppress the occurrence of damage to a compressor.

[0008] A gas turbine control device according to at least one embodiment of the present invention is a gas turbine control device coupled to a generator that can be connected to an electric power grid, wherein the gas turbine is configured to be able to switch its operation mode between a normal operation mode in which the gas turbine drives the generator to rotate, and a reverse power operation mode in which the gas turbine is driven to rotate by the generator that receives electric power from the electric power grid and operates as a motor, and the gas turbine control device comprises: an index acquisition unit configured to acquire an index that indicates a pressure ratio of a compressor of the gas turbine; and a signal output unit configured to output a signal to protect the compressor when the index becomes less than a threshold value while the gas turbine is operating in the reverse power operation mode.

[0009] Moreover, a gas turbine facility according to at least one embodiment of the present invention includes: a gas turbine coupled to a generator that can be connected to an electric power grid; and the above-described control device configured to control the gas turbine.

[0010] Furthermore, at least one embodiment of the present invention provides a method for controlling a gas turbine coupled to a generator that can be connected to an electric power grid, wherein the gas turbine is configured to be able to switch its operation mode between a normal operation mode in which the gas turbine drives and rotates the generator, and a reverse power operation mode in which the gas turbine is driven and rotated by the generator that receives electric power from the electric power grid and operates as a motor, and the method includes the steps of: acquiring an index indicating a pressure ratio of a compressor of the gas turbine; and outputting a signal to protect the compressor when the index becomes less than a threshold value while the gas turbine is operating in the reverse power operation mode.

[0011] Furthermore, a control program for a gas turbine according to at least one embodiment of the present invention is a control program for a gas turbine connected to a generator that can be connected to an electric power grid, wherein the gas turbine is configured to be able to switch its operation mode between a normal operation mode in which the gas turbine drives the generator to rotate, and a reverse power operation mode in which the gas turbine is driven to rotate by the generator that receives electric power from the electric power grid and operates as a motor, and the control program is configured to cause a computer to execute the steps of: acquiring an index that indicates a pressure ratio of a compressor of the gas turbine; and outputting a signal to protect the compressor when the index becomes less than a threshold value while the gas turbine is operating in the reverse power operation mode.

[0012] According to at least one embodiment of the present invention, there are provided a gas turbine control device, a gas turbine facility, a gas turbine control method, and a gas turbine control program that are capable of suppressing the occurrence of damage to a compressor.

[0013] FIG. 1 is a schematic diagram of a gas turbine constituting a gas turbine facility according to an embodiment. FIG. 2 is a schematic diagram of a gas turbine facility according to an embodiment. FIG. 3 is a schematic diagram of a gas turbine facility according to an embodiment. FIG. 4 is a diagram for explaining a method for controlling a gas turbine according to an embodiment. FIG. 5 is a diagram for explaining a method for controlling a gas turbine according to an embodiment. FIG. 6 is a diagram for explaining a method for controlling a gas turbine according to an embodiment.

[0014] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0015] (Configuration of Gas Turbine Facility) Fig. 1 is a schematic diagram of a gas turbine constituting a gas turbine facility according to an embodiment. Figs. 2 and 3 are schematic diagrams of the gas turbine facility according to an embodiment.

[0016] As shown in FIG. 2 , a gas turbine facility 100 according to one embodiment includes a gas turbine 1 connected to a generator 30 and a control device 50 for controlling the gas turbine 1 .

[0017] As shown in Figures 1 and 2, the gas turbine 1 includes a compressor 2 for generating compressed air, a combustor 4 for generating combustion gas using the compressed air and fuel, and a turbine 6 configured to be rotationally driven by the combustion gas.

[0018] 1, the compressor 2 includes a plurality of stator vanes 16 fixed to the compressor casing 10 side, and a plurality of moving blades 18 implanted in the rotor 8 so as to be arranged alternately with respect to the stator vanes 16. Air taken in from an air intake 12 is sent to the compressor 2, and this air is compressed as it passes through the plurality of stator vanes 16 and the plurality of moving blades 18, thereby becoming high-temperature, high-pressure compressed air.

[0019] The combustors 4 are supplied with fuel and compressed air generated by the compressor 2, and the fuel is combusted in the combustors 4 to generate combustion gas, which is a working fluid for the turbine 6. As shown in Fig. 1 , the gas turbine 1 has a plurality of combustors 4 arranged in a casing 20 along the circumferential direction around a rotor 8 (rotor axis O).

[0020] The turbine 6 has a combustion gas passage 28 formed by the turbine casing 22, and includes a plurality of stator vanes 24 and rotor blades 26 provided in the combustion gas passage 28. The stator vanes 24 are fixed to the turbine casing 22 side, and a plurality of the stator vanes 24 arranged along the circumferential direction of the rotor 8 constitute a stator vane row. The rotor blades 26 are implanted in the rotor 8, and a plurality of the rotor blades 26 arranged along the circumferential direction of the rotor 8 constitute a rotor blade row. The stator vane rows and rotor blade rows are arranged alternately in the axial direction of the rotor 8.

[0021] In the turbine 6, the combustion gas from the combustor 4 that flows into the combustion gas passage 28 passes through the plurality of stator vanes 24 and the plurality of rotor blades 26, thereby driving the rotor 8 to rotate about the rotor axis O, which in turn drives the generator connected to the rotor 8 to generate electricity. After driving the turbine 6, the combustion gas is discharged to the outside via an exhaust chamber 29.

[0022] As shown in Fig. 2, the gas turbine 1 is connected to a generator 30 via a rotor 8 (rotating shaft). The generator 30 can be connected to an electric power system 32. A switch 31 is provided between the generator 30 and the electric power system 32, so that the connection state between the generator 30 and the electric power system 32 can be switched.

[0023] The generator 30 is capable of generating electricity by being rotationally driven by the gas turbine 1, and is also capable of receiving power from the power grid 32 to function as a motor and rotationally drive the gas turbine 1.

[0024] 2 , fuel stored in a fuel storage unit 34 is supplied to the combustor 4 via a fuel supply line 33. It is not necessary to provide the fuel storage unit 34 in the gas turbine facility, and fuel can be supplied from a remote location via the fuel supply line 33. The fuel supply line 33 is provided with a fuel control valve 36 for adjusting the flow rate of fuel (fuel supply amount) supplied to the combustor 4. Although not shown, it is possible to use, for example, two or more fuel control valves 36 to adjust the fuel supply amounts to the pilot nozzle and main nozzle of the combustor 4 and the pilot ratio.

[0025] 2, an inlet guide vane (IGV) 40 for adjusting the intake air amount of the compressor 2 is provided at the inlet of the compressor 2. The opening degree of the IGV 40 is configured to be adjustable by an inlet guide vane control unit including an actuator 42.

[0026] The gas turbine 1 is provided with a first measuring unit 44 for measuring the inlet pressure of the compressor 2. The gas turbine 1 is also provided with a second measuring unit 46 for measuring the outlet pressure of the compressor 2. The first measuring unit 44 and the second measuring unit 46 may each be a pressure sensor. A signal indicating the inlet pressure detected by the first measuring unit 44 and a signal indicating the outlet pressure detected by the second measuring unit 46 are each sent to the control device 50.

[0027] The first measuring unit 44 is configured to measure the pressure at the inlet of the compressor 2 or at a position upstream of the inlet. The first measuring unit 44 may be configured to measure, for example, atmospheric pressure. The second measuring unit 46 is configured to measure the pressure at a position between the outlet of the compressor 2 and the inlet of the combustor 4. The second measuring unit 46 may be configured to measure, for example, the pressure of an air passage in the casing 20 that houses the combustor 4.

[0028] The gas turbine 1 is configured to be able to switch its operation mode between a normal operation mode and a reverse power operation mode.

[0029] The normal operation mode is an operation mode in which the gas turbine 1 rotationally drives the generator 30. In the normal operation mode, the electric power generated by the generator 30 is normally supplied to the electric power grid 32.

[0030] On the other hand, the reverse power operation mode is an operation mode in which the generator 30 receives power supply from the power grid 32 and operates as a motor to assist in the rotational drive of the gas turbine 1. The gas turbine 1 may be operated in the reverse power operation mode for the purpose of supplying exhaust gas to a destination while reducing fuel consumption. During operation in the reverse power mode, the generator 30 assists in driving the turbine 6 of the gas turbine 1, so the amount of fuel supplied to the gas turbine 1 can be reduced compared to operation in the normal operation mode.

[0031] The control device 50 is configured to control the gas turbine 1 based on the inlet pressure of the compressor 2 detected by the first measuring unit 44 and / or the outlet pressure of the compressor 2 detected by the second measuring unit 46. As shown in Fig. 3 , the control device 50 includes an index acquiring unit 52, a signal output unit 54, a switching signal receiving unit 56, and an operation control unit 58.

[0032] The index acquiring unit 52 is configured to acquire an index indicating the pressure ratio of the compressor 2. Here, the pressure ratio of the compressor 2 is the ratio between the outlet pressure and the inlet pressure of the compressor 2. The index acquiring unit 52 may acquire, as the index indicating the pressure ratio, a ratio P2 / P1 between the measured value P2 of the outlet pressure detected by the second measuring unit 46 and the measured value P1 of the inlet pressure detected by the first measuring unit 44. Alternatively, the index acquiring unit 52 may acquire, as the index indicating the pressure ratio, the measured value P2 of the outlet pressure detected by the second measuring unit 46. This is because the inlet pressure of the compressor 2 is approximately the same as atmospheric pressure and can be considered to be approximately constant.

[0033] The signal output unit 54 is configured to output a signal for protecting the compressor 2 when the indicator indicating the above-mentioned pressure ratio becomes less than (or equal to or less than) the threshold value while the gas turbine 1 is operating in the reverse power operation mode.

[0034] The signal output unit 54 may be configured to send, to an operation control unit 58 described later, a signal for stopping the gas turbine 1 or a signal for switching the operation mode of the gas turbine 1 from the reverse power operation mode to the normal operation mode, as a signal for protecting the compressor 2. Alternatively, the signal output unit 54 may be configured to send, to the alarm output unit 62, a signal for outputting an alarm, as a signal for protecting the compressor 2. Note that the alarm output unit 62 may include a device (such as a display or a speaker) for outputting visual or audio information indicating the alarm.

[0035] The switching signal receiving unit 56 is configured to receive a signal for switching the operation mode of the gas turbine 1 from the normal operation mode to the reverse power operation mode or from the reverse power operation mode to the normal operation mode. The switching signal receiving unit 56 may be configured to receive a signal for switching the operation mode from the switching signal input unit 60. The switching signal input unit 60 may include a terminal device that can be operated by an operator, and may include, for example, an operation mode switching button, a keyboard, or a mouse.

[0036] The operation control unit 58 is configured to control the gas turbine 1 based on the signal for protecting the compressor 2 from the signal output unit 54 or the signal for switching the operation mode from the switching signal receiving unit 56. The operation control unit 58 may be configured to control, for example, the opening degree of the fuel control valve 36 or the pilot ratio control unit 38 for adjusting the fuel supply to the combustor 4, or the operation amount of the actuator 42 for adjusting the opening degree of the inlet guide vane 40, based on the above-mentioned signals.

[0037] The control device 50 includes a computer equipped with a processor (such as a CPU), a main memory device (such as a memory device; such as a RAM), an auxiliary memory device, and an interface. The control device 50 receives signals from the first measurement unit 44, the second measurement unit 46, or the switching signal input unit 60 via the interface. The processor is configured to process the signals received in this manner. The processor is also configured to process a program loaded in the main memory device. This realizes the functions of each of the functional units (such as the index acquisition unit 52) ​​described above.

[0038] The processing contents of the control device 50 are implemented as programs executed by the processor. The programs may be stored in, for example, an auxiliary storage device. When the programs are executed, they are loaded into the main storage device. The processor reads the programs from the main storage device and executes the instructions contained in the programs.

[0039] (Gas Turbine Control Flow) Hereinafter, a control method for the gas turbine 1 according to some embodiments will be described with reference to Figures 4 to 6. Note that, although a case where the above-described gas turbine 1 is controlled using the above-described control device 50 will be described below, in some embodiments, the control method for the gas turbine may be executed using another device, or some of the procedures described below may be performed manually. Figures 4 to 6 are diagrams for explaining a control method for the gas turbine 1 according to one embodiment, and are graphs showing an example of time changes in the load during gas turbine operation, the gas turbine rotation speed set value (target rotation speed), the fuel supply amount set value (fuel command value), and the pilot fuel ratio.

[0040] 4 to 6, the gas turbine 1 is operated in a normal operation mode at a load L0 until time t0. At time t0, the rotation speed setting value of the gas turbine 1 is S0, the fuel supply setting value is F0, and the fuel pilot ratio is R0.

[0041] 4 to 6 , at time t0, preparations for switching the operation mode of the gas turbine 1 to the reverse power operation mode are initiated based on an instruction from the operator of the gas turbine facility 100, etc. From time t0, the set value of the rotation speed of the gas turbine 1 is reduced, thereby reducing the set value of the fuel supply rate. As a result, the load of the gas turbine also decreases from L0. The set value of the fuel supply rate may be determined based on the deviation between the actual rotation speed of the gas turbine 1 and the set value of the rotation speed. If the generator 30 is connected to the power grid 32, the actual rotation speed of the gas turbine 1 is maintained within approximately the same range as the frequency of the power grid 32, and therefore the set value of the fuel supply rate based on the deviation described above will be reduced.

[0042] From time t0, the pilot fuel ratio or the IGV opening may be adjusted as appropriate to prevent misfires due to a decrease in the fuel supply amount. For example, as shown in Figures 4 to 6, the pilot fuel ratio may be increased from R0.

[0043] At time t1, the load of the gas turbine 1 becomes the minimum load Lmin in the normal operation mode (i.e., the amount of fuel supplied to the combustor 4 becomes the minimum supply amount Fmin in the normal operation mode). At time t1, the pilot ratio is R1 (>R0). This operating condition is maintained from time t1 until time t2, which is a specified period later.

[0044] At time t2, for example, an operator operates the switching signal input unit 60, which sends a signal to the control device to switch the operation mode of the gas turbine 1 from the normal operation mode to the reverse power operation mode. This initiates switching from the normal operation mode to the reverse power operation mode. Upon receiving the signal to switch the operation mode, the control device 50 controls the pilot ratio control unit 38 via the operation control unit 58 to increase the pilot ratio.

[0045] At time t3, the control device 50 controls the pilot ratio control unit 38 so that the increase in the pilot ratio stops. After time t3, the pilot ratio is maintained at R2 (>R1). The pilot ratio R2 is a pilot ratio that allows transition to the reverse power operation mode. Furthermore, at time t3, the control device 50 may control the actuator 42 so that the opening of the IGV 40 becomes an opening appropriate for the reverse power operation mode. In this way, at time t3, the conditions for transition to the reverse power operation mode, such as the pilot ratio, are met.

[0046] From time t3, the control device 50 further reduces the rotation speed set value from Smin. As the rotation speed set value decreases, the difference between the set value and the actual rotation speed (which depends on the frequency of the power grid 32) further increases, and therefore the set value of the fuel supply amount further decreases. The control device 50 controls the fuel adjustment valve 36 based on the set value of the fuel supply amount. As a result, the load on the gas turbine 1 also further decreases from the minimum load Lmin in the normal operation mode.

[0047] At time t4, the load on the gas turbine 1 becomes zero. By continuing to decrease the rotation speed setting value at time t4, the setting value of the fuel supply amount to the combustor 4 continues to decrease. After time t4, power is supplied from the power grid 32 to the generator 30, and the generator 30 operates as a motor to assist in the rotational drive of the gas turbine 1. In other words, reverse power operation of the gas turbine 1 is started.

[0048] After time t4, control is performed to further decrease the set value of the fuel supply rate. The set value of the fuel supply rate after time t4 may be determined based on, for example, the deviation between the actual rotation speed of the gas turbine and the rotation speed set value, or may be decreased until it reaches a minimum value determined by another method.

[0049] During operation in the reverse power mode from time t4 onwards, the index acquisition unit 52 of the control device 50 acquires an index indicating the pressure ratio of the compressor 2 (for example, the ratio P2 / P1 between the measured value P2 of the outlet pressure of the compressor 2 detected by the second measurement unit 46 and the measured value P1 of the inlet pressure detected by the first measurement unit 44, or the measured value P2 of the outlet pressure detected by the second measurement unit 46). In addition, the signal output unit 54 compares the index with a threshold value, and when the index becomes less than the threshold value (or equal to or less than the threshold value) (time t Ａ ), and outputs a signal to protect the compressor 2. In the examples of FIGS. Ａ When this happens, the rotation speed setting value is S Ａ The set value of the fuel supply amount is F Ａ is.

[0050] In the exemplary embodiment shown in FIG. Ａ At time t Ａ At time t Ａ The set value of the fuel supply amount and the set value of the rotation speed may be decreased at a constant rate starting from this value to reach zero within a predetermined time.

[0051] In the exemplary embodiment shown in FIG. Ａ In the above, the signal output unit 54 sends, to the operation control unit 58, a signal for switching the operation mode of the gas turbine 1 from the reverse power operation mode to the normal operation mode, as a signal for protecting the compressor 2. The operation control unit 58 switches the operation mode of the gas turbine 1 from the reverse power operation mode to the normal operation mode.

[0052] In the example shown in FIG. Ａ Time t after a specified period from Ｂ The set value of the fuel supply amount and the set value of the rotation speed are Ａ While maintaining the value at time t Ｂ Thereafter, the procedure may be reversed from the preparation for switching the operation mode from the normal operation mode to the reverse power operation mode, which has already been described.

[0053] That is, at time t Ｂ From time t5, the rotation speed setting is increased, thereby increasing the fuel supply rate setting. This increases the load on the gas turbine 1. At time t5, the load on the gas turbine 1 becomes zero. After time t5, the generator 30 is rotationally driven by the gas turbine 1. That is, operation of the gas turbine 1 in the normal operation mode is resumed. At time t6, the rotation speed setting becomes Smin and the fuel supply rate setting becomes Fmin, and the pilot ratio is reduced from R2 while maintaining the rotation speed setting Smin. At time t7, the pilot ratio R2 becomes a value appropriate for increasing the fuel supply rate. At time t8, the rotation speed setting is increased, and the fuel supply rate is increased. This increases the gas turbine load. At time t9, the rotation speed setting increases to S0 and the gas turbine load increases to L0, completing the transition of the gas turbine 1 to the normal operation mode.

[0054] In the exemplary embodiment shown in FIG. Ａ At time t Ａ After the alarm is output at time t Ａ The set value S of the fuel supply amount at Ａ , and the rotation speed setting value FＡ is maintained for a predetermined time. In some embodiments, after the alarm is output, control may be performed to stop the gas turbine 1 or to switch the operation mode to the normal operation mode.

[0055] During reverse power operation of the gas turbine 1, the generator 30 assists in driving the turbine 6, so that the amount of fuel supplied to the gas turbine 1 can be reduced to a level at which the gas turbine 1 does not misfire. Meanwhile, during reverse power operation of the gas turbine 1, the amount of fuel supplied is reduced in this manner, so that the pressure ratio (compression ratio) of the compressor 2 is reduced compared to normal operation. If the pressure ratio of the compressor 2 is reduced during reverse power operation, the fluid flow velocity in the rear stages of the compressor 2 increases, resulting in a significant deviation from the design flow velocity conditions during normal operation (such as rated operation), which may cause stronger forced vibration of the compressor blades and increase the risk of damage to the compressor blades.

[0056] In this regard, according to the device or method of the above-described embodiment, when an index indicating the pressure ratio of the compressor 2 of the gas turbine 1 becomes less than a threshold value while the gas turbine 1 is operating in the reverse power operation mode, a signal for protecting the compressor 2 is output. Here, the signal for protecting the compressor 2 is, for example, a signal for stopping the gas turbine 1, a signal for switching the operation mode of the gas turbine 1 from the reverse power operation mode to the normal operation mode, or a signal for outputting an alarm. Therefore, by controlling the operation of the gas turbine 1 based on this signal, it is possible to suppress the occurrence of damage to the compressor 2 (e.g., damage to compressor blades due to increased vibration of the compressor blades) that would be caused by performing reverse power operation when the pressure ratio of the compressor 2 is too low.

[0057] In some embodiments, the pressure ratio P2 / P1 of the compressor calculated based on the measured value P2 of the outlet pressure of the compressor 2 and the measured value P1 of the inlet pressure of the compressor 2 is acquired as the index. Alternatively, in some embodiments, the measured value P2 of the outlet pressure of the compressor 2 is acquired as the index. In this manner, an appropriate index can be acquired as an index indicating the pressure ratio of the compressor 2. Furthermore, a signal for protecting the compressor 2 is output based on this index, so that occurrence of damage to the compressor 2 can be effectively suppressed.

[0058] The contents described in each of the above embodiments can be understood, for example, as follows.

[0059] (1) A gas turbine control device (50) according to at least one embodiment of the present invention is a control device for a gas turbine (1) coupled to a generator (30) that can be connected to an electric power system (32), wherein the gas turbine is configured to be able to switch its operation mode between a normal operation mode in which the gas turbine rotationally drives the generator and a reverse power operation mode in which the gas turbine is rotationally driven by the generator that receives electric power from the electric power system and operates as a motor, and the gas turbine includes: an index acquisition unit (52) configured to acquire an index indicating a pressure ratio of a compressor (2) of the gas turbine; and a signal output unit (54) configured to output a signal for protecting the compressor when the index becomes less than a threshold value during operation of the gas turbine in the reverse power operation mode.

[0060] According to the configuration (1) above, when an index indicating the pressure ratio of the compressor of the gas turbine falls below a threshold value while the gas turbine is operating in the reverse power operation mode, a signal for protecting the compressor is output. Therefore, by controlling the operation of the gas turbine based on the signal, it is possible to suppress damage to the compressor (for example, damage to compressor blades due to increased vibration of the compressor blades) caused by performing reverse power operation when the compressor pressure ratio is too low.

[0061] (2) In some embodiments, in the configuration of (1) above, the index acquisition unit is configured to acquire a measured value P2 of the outlet pressure of the compressor and a measured value P1 of the inlet pressure of the compressor, and to acquire a ratio P2 / P1 of the measured value P2 of the outlet pressure to the measured value P1 of the inlet pressure as the index.

[0062] According to the configuration (2) above, the compressor pressure ratio P2 / P1 calculated based on the measured value P2 of the compressor outlet pressure and the measured value P1 of the compressor inlet pressure is acquired as an index. Therefore, an appropriate index can be acquired as an index indicating the compressor pressure ratio. Furthermore, a signal for protecting the compressor is output based on this index, so that damage to the compressor can be effectively suppressed.

[0063] (3) In some embodiments, in the configuration of (1) above, the index acquisition unit is configured to acquire a measured value P2 of the outlet pressure of the compressor and acquire the measured value P2 of the outlet pressure as the index.

[0064] In a typical gas turbine, the compressor inlet pressure is nearly equal to atmospheric pressure and is therefore nearly constant, so the compressor outlet pressure can serve as an indicator of the compressor pressure ratio (the ratio of the outlet pressure to the inlet pressure). In this regard, according to the configuration of (3) above, the measured value P2 of the compressor outlet pressure is acquired as an index, so that an appropriate index can be acquired as an index showing the compressor pressure ratio. Furthermore, a signal for protecting the compressor is output based on this index, so that damage to the compressor can be effectively suppressed.

[0065] (4) In some embodiments, in the configuration of any one of (1) to (3) above, the signal output unit is configured to output, as the signal, a signal for stopping the gas turbine.

[0066] According to the configuration of (4) above, a signal for stopping the gas turbine is output when the index indicating the pressure ratio of the compressor falls below the threshold value. Therefore, by stopping the gas turbine based on this signal, it is possible to suppress damage to the compressor that would otherwise be caused by performing reverse power operation when the pressure ratio of the compressor is too low.

[0067] (5) In some embodiments, in the configuration of any one of (1) to (3) above, the signal output unit is configured to output, as the signal, a signal for switching the operation mode of the gas turbine from the reverse power operation mode to the normal operation mode.

[0068] According to the configuration of (5) above, a signal for switching the operation mode of the gas turbine to the normal operation mode is output when the index indicating the pressure ratio of the compressor becomes less than the threshold value. Therefore, by switching the operation mode of the gas turbine based on the signal, it is possible to suppress damage to the compressor that would be caused by performing reverse power operation when the pressure ratio of the compressor is too low.

[0069] (6) In some embodiments, in the configuration of any one of (1) to (3) above, the signal output unit is configured to output a signal for outputting an alarm as the signal.

[0070] According to the configuration of (6) above, a signal for outputting an alarm is output when the index indicating the pressure ratio of the compressor falls below a threshold value. Therefore, by outputting an alarm based on the signal, for example, an operator can stop the gas turbine or switch the operation mode of the gas turbine to the normal operation mode, thereby suppressing damage to the compressor that would otherwise be caused by performing reverse power operation when the compressor pressure ratio is too low.

[0071] (7) A gas turbine facility (100) according to at least one embodiment of the present invention comprises: a gas turbine (1) including a compressor (2) for compressing air, a combustor (4) for generating combustion gas by a combustion reaction between the compressed air from the compressor and fuel, and a turbine (6) driven by the combustion gas from the combustor, the gas turbine being connected to a generator (30) that can be connected to an electric power system (32); and a control device (50) according to any one of (1) to (6) above, configured to control the gas turbine.

[0072] According to the configuration of (7) above, when an index indicating the pressure ratio of the compressor of the gas turbine falls below a threshold value while the gas turbine is operating in the reverse power operation mode, a signal for protecting the compressor is output. Therefore, by controlling the operation of the gas turbine based on the signal, it is possible to suppress damage to the compressor (for example, damage to compressor blades due to increased vibration of the compressor blades) caused by performing reverse power operation when the compressor pressure ratio is too low.

[0073] (8) A control method for a gas turbine (1) according to at least one embodiment of the present invention is a control method for a gas turbine coupled to a generator (30) connectable to an electric power grid (32), wherein the gas turbine is configured to be able to switch its operation mode between a normal operation mode in which the gas turbine drives the generator to rotate and a reverse power operation mode in which the gas turbine is driven to rotate by the generator operating as a motor by receiving electric power from the electric power grid, and the control method includes the steps of: acquiring an index indicating a pressure ratio of a compressor (2) of the gas turbine; and outputting a signal to protect the compressor when the index becomes less than a threshold value during operation of the gas turbine in the reverse power operation mode.

[0074] According to the method (8) above, when an index indicating the pressure ratio of the compressor of the gas turbine falls below a threshold value while the gas turbine is operating in the reverse power operation mode, a signal for protecting the compressor is output. Therefore, by controlling the operation of the gas turbine based on the signal, it is possible to suppress damage to the compressor (for example, damage to compressor blades due to increased vibration of the compressor blades) caused by performing reverse power operation when the compressor pressure ratio is too low.

[0075] (9) A control program for a gas turbine (1) according to at least one embodiment of the present invention is a control program for a gas turbine connected to a generator (30) connectable to an electric power system (32), wherein the gas turbine is configured to be able to switch its operation mode between a normal operation mode in which the gas turbine drives the generator to rotate and a reverse power operation mode in which the gas turbine is driven to rotate by the generator, which receives electric power from the electric power system and operates as a motor, and the control program is configured to cause a computer to execute the steps of: acquiring an index indicating a pressure ratio of a compressor (2) of the gas turbine; and outputting a signal to protect the compressor when the index becomes less than a threshold value during operation of the gas turbine in the reverse power operation mode.

[0076] According to the program of (9) above, when an index indicating the pressure ratio of the compressor of the gas turbine falls below a threshold value while the gas turbine is operating in the reverse power operation mode, a signal for protecting the compressor is output. Therefore, by controlling the operation of the gas turbine based on the signal, it is possible to suppress damage to the compressor (for example, damage to compressor blades due to increased vibration of the compressor blades) caused by performing reverse power operation when the compressor pressure ratio is too low.

[0077] The above describes an embodiment of the present invention, but the present invention is not limited to the above-described embodiment, and also includes forms in which the above-described embodiment is modified, or forms in which these forms are appropriately combined.

[0078] In this specification, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions expressing that things are in an equal state, such as "identical," "equal," and "homogeneous," not only express a state in which there is a strict equivalence, but also express a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions expressing shapes such as a rectangular shape or a cylindrical shape not only express shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

[0079] DESCRIPTION OF SYMBOLS 1 Gas turbine 2 Compressor 4 Combustor 6 Turbine 8 Rotor 10 Compressor casing 12 Air intake 16 Stator vane 18 Moving blade 20 Casing 22 Turbine casing 24 Stator vane 26 Moving blade 28 Combustion gas passage 29 Exhaust chamber 30 Generator 31 Switch 32 Power system 33 Fuel supply line 34 Fuel storage section 36 Fuel control valve 38 Pilot ratio control section 40 Inlet guide vane 42 Actuator 44 First measurement section 46 Second measurement section 50 Control device 52 Index acquisition section 54 Signal output section 56 Switching signal reception section 58 Operation control section 60 Switching signal input section 62 Alarm output section 100 Gas turbine equipment O Rotor axis

Claims

1. A control device for a gas turbine connected to a generator that can be connected to an electric power grid, wherein the gas turbine is configured to be able to switch its operation mode between a normal operation mode in which the gas turbine drives the generator to rotate, and a reverse power operation mode in which the gas turbine is driven to rotate by the generator that receives electric power from the electric power grid and operates as a motor, the control device for a gas turbine comprising: an index acquisition unit configured to acquire an index that indicates a pressure ratio of a compressor of the gas turbine; and a signal output unit configured to output a signal to protect the compressor when the index becomes less than a threshold value while the gas turbine is operating in the reverse power operation mode.

2. A gas turbine control device according to claim 1, wherein the index acquisition unit is configured to acquire a measured value P2 of the outlet pressure of the compressor and a measured value P1 of the inlet pressure of the compressor, and to acquire a ratio P2 / P1 of the measured value P2 of the outlet pressure to the measured value P1 of the inlet pressure as the index.

3. A gas turbine control device according to claim 1, wherein the index acquisition unit is configured to acquire a measured value P2 of the outlet pressure of the compressor and to acquire the measured value P2 of the outlet pressure as the index.

4. A gas turbine control device according to any one of claims 1 to 3, wherein the signal output unit is configured to output, as the signal, a signal for stopping the gas turbine.

5. The gas turbine control device according to any one of claims 1 to 3, wherein the signal output unit is configured to output, as the signal, a signal for switching the operation mode of the gas turbine from the reverse power operation mode to the normal operation mode.

6. A gas turbine control device according to any one of claims 1 to 3, wherein the signal output unit is configured to output a signal for outputting an alarm as the signal.

7. A gas turbine facility comprising: a compressor for compressing air; a combustor for generating combustion gas by a combustion reaction between the compressed air from the compressor and fuel; and a turbine driven by the combustion gas from the combustor, the gas turbine being connected to a generator that can be connected to an electric power grid; and a control device according to any one of claims 1 to 3 that is configured to control the gas turbine.

8. A control method for a gas turbine connected to a generator that can be connected to an electric power grid, wherein the gas turbine is configured to be able to switch its operation mode between a normal operation mode in which the gas turbine drives the generator to rotate, and a reverse power operation mode in which the gas turbine is driven to rotate by the generator that receives electric power from the electric power grid and operates as a motor, the control method for a gas turbine comprising: a step of acquiring an index that indicates a pressure ratio of a compressor of the gas turbine; and a step of outputting a signal to protect the compressor when the index becomes less than a threshold value while the gas turbine is operating in the reverse power operation mode.

9. A control program for a gas turbine connected to a generator that can be connected to an electric power grid, wherein the gas turbine is configured to be able to switch its operation mode between a normal operation mode in which the gas turbine drives the generator to rotate, and a reverse power operation mode in which the gas turbine is driven to rotate by the generator that receives electric power from the electric power grid and operates as a motor, the control program for a gas turbine causing a computer to execute the steps of: acquiring an index indicating a pressure ratio of a compressor of the gas turbine; and outputting a signal to protect the compressor when the index becomes less than a threshold value while the gas turbine is operating in the reverse power operation mode.

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