GAS TURBINE CONTROL UNIT AND GAS TURBINE CONTROL METHOD

Abstract

A gas turbine control device (20) comprising: a governor control unit (25) configured to calculate, based on a frequency (F) of a power system to which a generator (16) is connected, which generates electrical power by being driven by a gas turbine (10), a governor fuel flow rate command value (GVCSO) indicating a first command value control signal output (CSO) for controlling a fuel input amount, which increases an output of the gas turbine (10) as the frequency (F) decreases, a first CSO calculation unit (24) configured to calculate a first fuel flow rate command value (LDCSO) indicating a second command value control signal output (CSO) for controlling the fuel input amount so that the output of the gas turbine (10) corresponds to a target output, and a second CSO calculation unit (23) configured to calculate an upper limit value (LRCSO) of the first fuel flow rate command value (LDCSO), wherein the second CSO calculation unit (23) is configured to calculate the upper limit value (LRCSO) of the first fuel flow rate command value based on a deviation obtained by subtracting a second limit value from an estimated value of a turbine inlet temperature of the gas turbine (10), the second limit value relating to the estimated value and being set such that the estimated value does not exceed a first limit value of the turbine inlet temperature, wherein the first CSO calculation unit (24) is configured to determine whether the calculated first fuel flow rate command value (LDCSO) is equal to or greater than the upper limit value (LRCSO) and, in this case, to output the upper limit value (LRCSO) to a command value selection unit (26), otherwise to output the calculated first fuel flow rate command value (LDCSO) to the command value selection unit (26), and wherein the command value selection unit (26) is configured to output the smaller value of the governor fuel flow rate command value (GVCSO) obtained from the governor control unit (25) and either the calculated first fuel flow rate command value (LDCSO) or the upper limit value (LRCSO) obtained from the first CSO calculation unit (24) to a control valve (17-19) to control the fuel flow rate.

Description

The present invention relates to a gas turbine control apparatus and a gas turbine control method.Apparatuses for monitoring a gas turbine inlet temperature to control a gas turbine are shown in JP 2007-71 144 A and JP H08-135 406 A. When the gas turbine inlet temperature exceeds a threshold, components such as the combustor and the turbine constituting the gas turbine are liable to be damaged. Therefore, it is necessary to control the gas turbine inlet temperature so as not to exceed the threshold value.A generator of a power generation plant is operated by the above-described gas turbine, the generator being connected to a power system. An increase in the load of the power system sometimes causes the frequency in the power system to drop significantly. With such marked frequency reduction, there is a concern that the ratio of the fuel flow rate to the gas turbine output will increase rapidly, resulting in a rapid increase in the gas turbine inlet temperature.From JP 2002-38 972 A, a gas turbine control apparatus and a gas turbine control method are known in which a load limiting CSO (LDCSO) command value and corresponding signal, respectively, whose upper limit is LRCSO, is outputted. A lower value selection circuit outputs a smaller value of a regulator CSO signal and the load limiting CSO, and thereby the increase of the regulator CSO signal is limited, the load limiting CSO serving as the upper limit of the regulator COS signal. The LRCSO, which is the upper limit of the load limiting CSO (LDCSO), is a fixed value.It is an object of the present invention to provide a gas turbine control apparatus and a gas turbine control method which can solve the above-mentioned problem.According to the present invention there is provided a gas turbine controller having the features of claim 1 and a gas turbine control method having the features of claim 7.In the gas turbine control apparatus, the second CSO control unit may calculate the upper limit value of the first fuel flow rate command value that has attenuated an increase in the upper limit value of the first fuel flow rate command value when the deviation is equal to or greater than a predetermined deviation at which the estimated value of the turbine inlet temperature exceeds the first limit value.In the gas turbine control apparatus, the second CSO control unit may fix the upper limit value of the first fuel flow rate command value to a currently calculated upper limit value when the deviation is equal to or greater than the predetermined deviation.In the gas turbine control apparatus, the second CSO calculation unit may fix the upper limit value of the first fuel flow rate command value to a predetermined upper limit value when the deviation is equal to or greater than the predetermined deviation.In the gas turbine control apparatus, the second CSO calculation unit may fix the upper limit value of the first fuel flow rate command value to a value corresponding to the deviation when the deviation is equal to or greater than the predetermined deviation.According to the present invention there is also provided a gas turbine controller having the features of claim 6 and a gas turbine control method having the features of claim 8.According to the present invention, a rapid increase in the ratio of the fuel flow rate to the gas turbine output when a rapid frequency drop occurs in the power system connected to a gas turbine driven generator can be attenuated. This may reduce the possibility that the turbine inlet temperature exceeds the threshold. FIG. 1 is a system diagram of a gas turbine plant according to the present embodiment. FIG. 2 is a functional block diagram of the gas turbine control apparatus according to the first embodiment. FIG. 3 is a diagram illustrating a process flow of the gas turbine control apparatus according to the first embodiment. FIG. 4 is a functional block diagram of the gas turbine control apparatus according to the second embodiment. FIG. 5 is a diagram illustrating a process flow of the gas turbine control apparatus according to the second embodiment.Hereinafter, a gas turbine plant including a gas turbine controller according to a first embodiment will be described with reference to the drawings.FIG. 1 is a system diagram of a gas turbine plant according to the present embodiment.As illustrated in FIG. 1, the gas turbine plant of the present embodiment is provided with a gas turbine 10, a generator 16 that generates electric power by being driven by the gas turbine 10, a gas turbine controller 20 that controls the gas turbine 10, and a supply device 40 that supplies fuel to the gas turbine 10. The gas turbine 10 and the generator 16 are connected by a rotor 15.The gas turbine 10 is formed by inserting a compressor 11 that compresses air to generate compressed air, a combustor 12 that mixes and burns the compressed air and fuel to generate combustion gas of high temperature, a turbine 13 that is driven by the combustion gas, and the like. The turbine inlet temperature described below refers to the temperature of the inlet at which the high-temperature combustion gas discharged from the combustor 12 enters the turbine 13.The compressor 11 is provided with an inlet guide vane (IGV) 14. The IGV 14 adjusts the amount of air flowing into the compressor 11.The combustor 12 is connected to a fuel supply device 40 that supplies fuel such as fuel gas to the combustor 12 via fuel supply systems. The combustor 12 is supplied with fuel from the plurality of fuel supply systems. Between the fuel supply device 40 and the combustor 12, control valves 17 to 19 for adjusting the fuel supply amount for each fuel supply system are provided.FIG. 2 is a functional block diagram of the gas turbine control apparatus according to the present embodiment.The gas turbine controller 20 is a computer, and may be constituted by a storage unit such as a read only memory (ROM), a random access memory (RAM), a hard disk drive (HDD), and the like, and hardware such as a CPU (central processing unit) and communication interfaces.The CPU of the gas turbine control apparatus 20 executes a stored control program based on a user operation. Thereby, the gas turbine control apparatus 20 has functions of a turbine inlet temperature estimation unit 21, a deviation calculation unit 22, an LRCSO calculation unit 23, an LDCSO calculation unit 24, a controller control unit 25, and a command value selection unit 26. Although the gas turbine control apparatus 20 actually has other functions than the functional units illustrated in FIG. 2 by executing the control program, only functional units illustrated in FIG. 2 will be described for convenience of description.The turbine inlet temperature estimation unit 21 inputs parameters such as a plurality of measurement values S 1, S 2, and S 3, and calculates an estimated value of the turbine inlet temperature using these parameters.The deviation calculation unit 22 calculates a deviation from the turbine inlet temperature estimation value by subtracting a second threshold value related to the estimation value set so that the estimation value does not exceed a first turbine inlet temperature threshold value from the turbine inlet temperature estimation value. The first threshold is a value indicating that damage occurs to the components constituting the turbine 13 when the turbine inlet temperature increases to or above this value. The second threshold is a value provided so that the turbine inlet temperature does not become equal to or greater than the first threshold, and is a threshold of the estimated value of the turbine inlet temperature.The LRCSO calculation unit 23 (second CSO calculation unit) calculates the upper limit value of the first fuel flow rate command value calculated by the LDCSO calculation unit 24. The LRCSO calculation unit 23 calculates the upper limit value of the first fuel flow rate command value based on the deviation obtained by subtracting the second limit value from the estimated value of the turbine inlet temperature.Specifically, the LRCSO calculation unit 23 calculates the upper limit value (LRCSO) of the LDCSO (first fuel flow rate command value) for attenuating an increase in the upper limit value (LRCSO) of the LDCSO when the deviation calculated by the deviation calculation unit 22 is equal to or greater than a predetermined deviation at which it is determined that the estimated value of the turbine inlet temperature may exceed the first limit value.For example, when the deviation calculated by the deviation calculation unit 22 is equal to or greater than a predetermined deviation, the LRCSO calculation unit 23 fixes the upper limit value (LRCSO) of the LDCSO to the currently calculated upper limit value. The upper limit value (LRCSO) calculated by the LRCSO calculation unit 23 is a value that moves up and down depending on each input parameter related to the gas turbine 10, and fixes this value.When the deviation calculated by the deviation calculation unit 22 is equal to or greater than the predetermined deviation, the LRCSO calculation unit 23 may fix the upper limit value of the first fuel flow rate command value to a predetermined upper limit value. The predetermined upper limit value is a value of the fuel flow rate command value for ensuring that the actual turbine inlet temperature does not exceed the first limit value.When the deviation calculated by the deviation calculation unit 22 is equal to or greater than a predetermined deviation, the LRCSO calculation unit 23 may fix the upper limit value of the first fuel flow rate command value to a value corresponding to the deviation. That is, the value corresponding to the deviation is a value of the fuel flow rate command value for preventing the actual turbine inlet temperature from exceeding the first threshold value.The LDCS calculation unit 24 (first CSO calculation unit) calculates the LDCSO (first fuel flow rate command value) indicating a CSO (Control Signal Output) for controlling the fuel input amount so that the output of the gas turbine 10 corresponds to a target output. The LDCSO calculation unit 24 calculates a CSO that does not exceed the value of the LRCSO that is the upper limit value of the LDCSO calculated by the LRCSO calculation unit 23.The controller control unit 25 (third CSO calculation unit) inputs a frequency F of the power system to which the generator 16 is connected. The controller control unit 25 calculates, based on the frequency F, a fuel flow rate command value (CSO) that increases the output as the frequency decreases. The fuel flow rate command value calculated by the controller control unit 25 is referred to as GVCSO.The command value selection unit 26 compares the GVCSO obtained by the controller control unit 25 with the LDCSO obtained by the LDCSO calculation unit 24, and outputs the smaller value than a CSO. The CSO is output to the control valves 17 to 19 to control the fuel flow rate.FIG. 3 is a diagram illustrating a process flow of the guest turbine control device according to the first embodiment.Next, operations of the guest turbine control system according to the first embodiment will be described.The controller control unit 25 acquires information of the frequency F of the power system. The controller control unit 25 inputs the value of the frequency F into a GVCSO calculation formula to calculate the GVCSO (step S 101). The controller control unit 25 outputs the calculated GVCSO to the command value selection unit 26. The GVCSO calculation formula is a formula for calculating a fuel flow rate command value (CSO) that increases the output at the time of frequency lowering based on the frequency F.The turbine inlet temperature estimation unit 21 acquires various parameters. The turbine inlet temperature estimation unit 21 inputs the various parameters into a formula for calculating an estimated value of the turbine inlet temperature to calculate an estimated value (step S 102). The turbine inlet temperature estimation unit 21 outputs the estimation value to the deviation calculation unit 22. The deviation calculation unit 22 subtracts the second threshold value from the estimated value to calculate a deviation (step S 103). The deviation calculation unit 22 outputs the deviation obtained by subtracting the second threshold from the estimated value to the LRCSO calculation unit 23.The LRCSO calculation unit 23 determines whether the obtained deviation is equal to or greater than 0 (S 104). When the deviation is equal to or greater than 0, the LRCSO calculation unit 23 performs control to attenuate an increase in the value of the LRCSO (step S 105). If the deviation is less than 0, the LRCSO calculation unit 23 calculates a normal LRCSO value (step S 106). The calculation of the normal LRCSO value is a value obtained by adding a predetermined bias value or the like to the CSO selected and output by the command value selection unit 26. For example, the LRCSO can be usually calculated by the formula LRCSO = CSO + x%. When the deviation is equal to or greater than 0, the LRCSO calculation unit 23 fixes the upper limit value of the LDCSO to the LRCSO currently calculated.When the deviation calculated by the deviation calculation unit 22 is equal to or greater than 0, the LRCSO calculation unit 23 may fix the LRCSO to a predetermined value. When the deviation calculated by the deviation calculation unit 22 is equal to or greater than 0, the LRCSO calculation unit 23 may fix the LRCSO to a value corresponding to the deviation.The LDCSO calculation unit 24 inputs parameters and calculates the LDCSO (step S 107). The parameters to be input include a load limit setting value and the generator output. The LDCSO calculation unit 24 compares the load limit setting value (the upper limit value or target value set for the load of the generator output) with the generator output, and performs a feedback operation that calculates the LDCSO to match the values to each other. Further, the LDCSO calculation unit 24 acquires the LRCSO. The LDCSO calculation unit 24 determines whether the calculated LDCSO is equal to or greater than the LRCSO (step S 108). When the calculated LDCSO is equal to or greater than the LRCSO, the LDCSO calculation unit 24 outputs the LRCSO as the LDCSO to the command value selection unit 26 (step S 109). When the calculated LDCSO is smaller than the LRCSO, the LDCSO calculation unit 24 outputs the calculated LDCSO to the command value selection unit 26 (step S 110).The command value selection unit 26 compares the GVCSO obtained by the controller control unit 25 with the LDCSO obtained by the LDCSO calculation unit 24. The command value selection unit 26 outputs the smaller value of the GVCSO and LDCSO than a CSO (step S 111). The CSO is output to the control valves 17 to 19 to control the fuel flow rate.According to the above-described flow of the first embodiment, the gas turbine controller 20 may determine whether to attenuate the value of the LRCSO using the estimated value of the turbine inlet temperature obtained by the estimation process. Therefore, even if a rapid frequency drop occurs in the power system connected to the generator 16, and thereby the ratio of the fuel flow rate to the turbine output rapidly increases, an increase in the LRCSO, which is the upper limit value of the LDCSO, can be suppressed. Consequently, the value of the CSO that the command value selection unit 26 selects and outputs can be attenuated.Next, a gas turbine control apparatus according to a second embodiment will be described.A gas turbine plant including a gas turbine controller 30 according to the second embodiment is the same as that of FIG. 1.FIG. 4 is a functional block diagram of the gas turbine control apparatus according to the second embodiment.The gas turbine controller 30 is also a computer, and may be constituted by a storage unit such as a read only memory (ROM), a random access memory (RAM), a hard disk drive (HDD), and the like, and hardware such as a CPU (Central Processing Unit) and communication interfaces.The CPU of the gas turbine controller 30 executes a stored control program based on a user operation. Thereby, the gas turbine control apparatus 30 has functions of a turbine inlet temperature estimation unit 31, a deviation calculation unit 32, a T1TCSO calculation unit 33, an LRCSO calculation unit 34, an LDCSO calculation unit 35, a controller calculation unit 36, and a command value selection unit 37. Although the gas turbine controller 30 actually has other functions than the functional units illustrated in FIG. 4 by executing the control program, only the functional units illustrated in FIG. 4 will be described for convenience of description.The turbine inlet temperature estimation unit 31 inputs parameters such as a plurality of measurement values S 1, S 2, and S 3, and calculates an estimated value of the turbine inlet temperature using these parameters. The turbine inlet temperature may be estimated using a well-known formula.The deviation calculation unit 32 calculates a deviation by subtracting a second threshold value related to the estimated value selected such that the estimated value does not exceed a first threshold value of the turbine inlet temperature from the estimated value of the turbine inlet temperature. The first threshold is a value indicating that damage to the components constituting the gas turbine 10 may occur when the turbine inlet temperature increases to or above this value. The second threshold is a value provided so that the turbine inlet temperature does not become equal to or greater than the first threshold, and is a threshold of the estimated value of the turbine inlet temperature.When the deviation is not equal to or greater than a predetermined deviation, the T1CSSO calculation unit 33 (second CSO calculation unit in the second embodiment) calculates a T1CSSO (a second fuel flow rate command value) by adding a predetermined value to a post-selected fuel flow rate command value selected and output by the command value selection unit 37. The T1TCSO calculation unit 33 calculates the T1TCSO (the second fuel command value) that suppresses the post-selected fuel flow rate command value when the deviation is equal to or greater than a predetermined deviation.The LRCSO calculation unit 34 calculates the upper limit value of the LDCSO (first fuel flow rate command value) calculated by the LDCSO calculation unit 35.The LDCSO calculation unit 35 (first CSO calculation unit in the second embodiment) calculates the LDCSO (first fuel flow rate command value) indicating a CSO (control signal output "Control signal Output") for controlling a fuel input amount so that the output of the gas turbine 10 corresponds to a target output. The LDCSO calculation unit 35 calculates a CSO that does not exceed the limit value of the LRCSO, which is the upper limit value of the LDCSO calculated by the LRCSO calculation unit 34.The controller control unit 36 (third CSO calculation unit) inputs a frequency F of the power system to which the generator 16 is connected. The controller control unit 36 calculates, based on the frequency F, a fuel flow rate command value (CSO) that increases the output as the frequency decreases. The fuel flow rate command value calculated by the control control unit 36 is referred to as GVCSO.The command value selection unit 37 compares the GVCSO obtained by the controller control unit 36, the LDCSO obtained by the LDCSO calculation unit 35, and the T1RDSO obtained by the T1RDSO calculation unit 33, and outputs the smallest value as a CSO. The CSO is output to the control valves 17 to 19 to control the fuel flow rate.FIG. 5 is a diagram illustrating a process flow of the gas turbine control apparatus according to the second embodiment.Next, operations of the gas turbine control apparatus 30 according to the second embodiment will be described.The controller control unit 36 acquires information of the frequency F of the power system. The controller control unit 36 inputs the value of the frequency F into a GVCSO calculation formula to calculate the GVCSO (step S 201). The controller control unit 36 outputs the calculated GVCSO to the command value selection unit 37. The GVCSO calculation formula is a formula for calculating a fuel flow rate command value (CSO) that increases the output at the time of frequency decrease based on the frequency F.The turbine inlet temperature estimation unit 31 acquires various parameters. The turbine inlet temperature estimation unit 31 inputs the various parameters into a formula for calculating an estimated value of the turbine inlet temperature T 1T to calculate an estimated value (step S 202). The turbine inlet temperature estimation unit 31 outputs the estimation value to the deviation calculation unit 32. The deviation calculation unit 32 subtracts the second threshold value from the estimated value to calculate a deviation (step S 203). That is, the deviation calculated by the deviation calculation unit 32 is a value obtained by subtracting the second threshold value related to an estimated value set such that the estimated value does not exceed the first threshold value of the turbine inlet temperature from the estimated value of the turbine inlet temperature T 1T. The deviation calculation unit 32 outputs the calculated deviation to the T1TCSO calculation unit 33. In the calculation of step S 202, the estimation value may be calculated using a publicly known calculation formula.The T1TCSO calculation unit 33 determines whether the obtained deviation is equal to or greater than 0 (step S 204). Under normal conditions where the obtained deviation is less than 0, the T1TCSO calculation unit 33 acquires various parameters for the T1TCSO calculation formula and the CSO selected by the command value selection unit 37, and calculates the T1TCSO with a value larger than the CSO (step S 205). When the obtained deviation is equal to or greater than 0, the T1TCSO calculation unit 33 calculates the T1TCSO that attenuates the CSO selected and output by the command value selection unit 37 (step S 206). The T1TCSO calculation unit 33 outputs the calculated T1TCSO to the command value selection unit 37. In the process of step S 206, for example, the T1TCSO calculation unit 33 calculates and outputs a value obtained by multiplying the CSO by a rate-limited (a limit of the rate of change of the CSO, particularly the rate of increase) from the moment when the deviation exceeds 0, as the T1TCSO. In order to achieve the object that the change rate increase becomes 0 as an example, the T1TCSO calculation unit 33 makes the value of the CSO that is last input a fixed value, and by outputting this value, sets the value T1TCSO so as not to increase any more.The LRCSO calculation unit 34 calculates an upper limit value (LRCSO) of the LDCSO indicating a value obtained by adding a predetermined bias value or the like to the CSO selected and output by the command value selection unit 37 (step S 207). The LRCSO calculation unit 34 outputs the calculated upper limit value (LRCSO) of the LDCSO to the LDCSO calculation unit 35.The LDCSO calculator 35 outputs each parameter to calculate the LDCSO (step S 208). A specific example of the calculation of the LDCSO is the same as that in the first embodiment. The LDCSO calculation unit 35 also acquires the LRCSO. The LDCSO calculator 35 determines whether the calculated LDCSO is equal to or greater than the LRCSO. When the calculated LDCSO is smaller than the LRCSO, the LDCSO calculation unit 35 outputs the calculated LDCSO to the command value selection unit 37. When the calculated LDCSO is equal to or greater than the LRCSO, the LDCSO calculation unit 35 outputs the LRCSO as the LDCSO to the command value selection unit 37.The command value selection unit 37 compares the GVCSO obtained by the controller control unit 36, the LDCSO obtained by the LDCSO calculation unit 35, and the T1RDSO obtained by the T1RDSO calculation unit 33. The command value selection unit 37 outputs the smallest value among the GVCSO, the LDCSO, and the T1RDSO as a CSO (step S 209). The CSO is output to the control valves 17 to 19 to control the fuel flow rate.According to the process of the second embodiment described above, when the deviation of the estimated turbine inlet temperature T 1T from the second threshold value exceeds a predetermined value, the gas turbine controller 30 calculates a value of the T 1CSSO for attenuating an increase in the CSO selected by the command value selection unit 37 and outputs the value to the command value selection unit 37. Therefore, even if a rapid frequency drop occurs in the power system connected to the generator 16, whereby the ratio of the fuel flow rate to the gas turbine output rapidly increases, an increase in the CSO selected by the command value selection unit 37 can be attenuated with the calculated T1TCSO.The aforementioned gas turbine controller may include a computer system therein. A program for causing the gas turbine controller to execute the processes described above is stored in a computer readable storage medium on the gas turbine controller, and the computer of the apparatus reads and executes the program, thereby performing the aforementioned processes. Here, the computer readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, and the like. Alternatively, the computer program may be decentralized through a communication link and the computers may execute the program upon receiving the distribution.In addition, the above-mentioned program may be a program for achieving a part of a function of each process described above. Moreover, the above-mentioned program may be a so-called difference file program (differential program) capable of executing the above-described functions in combination with a program already loaded in the computer system.The present invention relates to a gas turbine control apparatus and a gas turbine control method.List of reference characters20, 30 Gas turbine control apparatus 21, 31 Turbine inlet temperature estimation unit 22, 32 Deviation calculation unit 23, 24 LRCSO calculation unit 24, 35 LGCSO calculation unit 25, 36 Controller control unit 26, 37 Command value selection unit 33 T1TCSO calculation unit 40 Supply device

Claims

A gas turbine control apparatus (20) comprising: a controller control unit (25) configured to calculate, based on a frequency (F) of a power system to which a generator (16) that generates electric power by being driven by a gas turbine (10), a controller fuel flow rate command value (GVCSO) indicating a first command value control signal output (CSO) for controlling a fuel input amount that increases an output of the gas turbine (10) as the frequency (F) decreases; a first CSO calculation unit (24) configured to calculate a first fuel flow rate command value (LDCSO), which indicates a second command value control signal output (CSO) for controlling the fuel input amount so that the output of the gas turbine (10) corresponds to a target output, and a second CSO calculation unit (23) configured to calculate an upper limit value (LRCSO) of the first fuel flow rate command value (LDCSO), wherein the second CSO calculation unit (23) is configured to calculate the upper limit value (LRCSO) of the first fuel flow rate command value based on a deviation obtained by subtracting a second limit value from an estimated value of a turbine inlet temperature of the gas turbine (10), the second limit value referring to the estimated value and being set so as to:, wherein the estimated value does not exceed a first limit value of the turbine inlet temperature, wherein the first CSO calculating unit (24) is configured to determine whether the calculated first fuel flow rate command value (LDCSO) is equal to or greater than the upper limit value (LRCSO), and in this case, to output the upper limit value (LRCSO) to a command value selecting unit (26), otherwise, to output the calculated first fuel flow rate command value (LDCSO) to the command value selecting unit (26), and wherein the command value selecting unit (26) is configured to output the smaller value from the regulator fuel flow rate command value (GVCSO) obtained from the regulator control unit (25), and outputting either the calculated first fuel flow rate command value (LDCSO) or the upper limit value (LRCSO) obtained from the first CSO calculation unit (24) to a control valve (17-19) to control the fuel flow rate.The gas turbine control apparatus (20) according to claim 1, wherein the second CSO calculation unit (23) is configured to calculate the upper limit value (LRCSO) of the first fuel flow rate command value that suppresses an increase in the upper limit value (LRCSO) of the first fuel flow rate command value when the deviation is equal to or greater than a predetermined deviation at which it is determined that the estimated value of the turbine inlet temperature exceeds the first limit value.The gas turbine control apparatus (20) according to claim 2, wherein the second CSO calculation unit (23) is configured to fix the upper limit value (LRCSO) of the first fuel flow rate command value to a currently calculated upper limit value when the deviation is equal to or greater than the predetermined deviation.The gas turbine control apparatus (20) according to claim 2, wherein the second CSO calculation unit (23) is configured to fix the upper limit value (LRCSO) of the first fuel flow rate command value to a predetermined upper limit value when the deviation is equal to or greater than the predetermined deviation.The gas turbine control apparatus (20) according to claim 2, wherein the second CSO calculation unit (23) is configured to fix the upper limit value (LRCSO) of the first fuel flow rate command value to a value corresponding to the deviation when the deviation is equal to or greater than the predetermined deviation.A gas turbine control apparatus (30) comprising: a controller control unit (36) configured to calculate, based on a frequency (F) of a power system to which a generator (16) that generates electric power by being driven by a gas turbine (10), a controller fuel flow rate command value (GVCSO) indicating a first command value control signal output (CSO) for controlling a fuel input amount that increases an output of the gas turbine (10) as the frequency (F) decreases; a first CSO calculation unit (35) configured to calculate a first fuel flow rate command value (LDCSO), which indicates a second command value control signal output (CSO) for controlling the fuel input amount such that an output of the gas turbine (10) corresponds to a target output, and a second CSO calculation unit (34, 33) configured to calculate an upper limit value (LRCSO) of the first fuel flow rate command value (LDCSO) and to calculate a deviation by subtracting a second limit value from an estimated value of a turbine inlet temperature (T1T) of the gas turbine (10), the second limit value referring to the estimated value and being set such that the estimated value does not exceed a first limit value of the turbine inlet temperature (T1T), wherein the second CSO calculation unit (34, 33) is configured to:, to calculate a second fuel flow rate command value (T1TCSO) by adding a predetermined value to a post-selected fuel flow rate command value currently selected from a plurality of fuel flow rate command values including the first fuel flow rate command value (LDCSO), when the deviation is not equal to or greater than a predetermined deviation at which it is determined that the estimated value of the turbine inlet temperature (T1T) exceeds the first threshold value, and wherein the second CSO calculation unit (34, 33) is configured to calculate a second fuel command value attenuating the post-selected fuel flow rate command value when the deviation is equal to or greater than the predetermined deviation, wherein the first CSO calculation unit (35) is configured to:, to determine whether the calculated first fuel flow rate command value (LDCSO) is equal to or greater than the upper limit value (LRCSO) and, in this case, to output the upper limit value (LRCSO) to a command value selection unit (37), otherwise to output the calculated first fuel flow rate command value (LDCSO) to the command value selection unit (37), and wherein the command value selection unit (37) is configured to output the smallest value from the regulator fuel flow rate command value (GVCSO) obtained from the regulator control unit (36) and from either the calculated first fuel flow rate command value (LDCSO) or the upper limit value (LRCSO), which are obtained from the first CSO calculation unit (35) and output from the second fuel flow rate command value (T1CSSO) obtained from the second CSO calculation unit (34, 33) to a control valve (17-19) to control the fuel flow rate.A gas turbine control method comprising: calculating, by a controller control unit (25), based on a frequency (F) of a power system to which a generator (16) that generates electric power by being driven by a gas turbine (10), a controller fuel flow rate command value (GVCSO) indicating a first command value control signal output (CSO) for controlling an input fuel amount that increases an output of the gas turbine (10) as the frequency (F) decreases; calculating, by a first CSO calculation unit (24), a first fuel flow rate command value (LDCSO) indicating a second command value control signal output (CSO) for controlling the input fuel amount, such that the output of the gas turbine (10) corresponds to a target output, and calculating, by a second CSO calculation unit (23), an upper limit value (LRCSO) of the first fuel flow rate command value (LDCSO), the second CSO calculation unit (23) calculating the upper limit value (LRCSO) of the first fuel flow rate command value based on a deviation obtained by subtracting a second limit value from an estimated value of a turbine inlet temperature of the gas turbine (10), the second limit value referring to the estimated value and being set such that the estimated value does not exceed the first limit value of the turbine inlet temperature, the first CSO calculation unit (24) determining that, whether the calculated first fuel flow rate command value (LDCSO) is equal to or greater than the upper limit value (LRCSO) and, in this case, outputs the upper limit value (LRCSO) to a command value selection unit (26), otherwise outputs the calculated first fuel flow rate command value (LDCSO) to the command value selection unit (26), and wherein the command value selection unit (26) outputs the smaller one of the regulator fuel flow rate command value (GVCSO) obtained from the regulator control unit (25) and either the calculated first fuel flow rate command value (LDCSO) or the upper limit value (LRCSO), which are obtained from the first CSO calculating unit (24), are output to a control valve (17-19) to control the fuel flow rate.A gas turbine control method comprising: calculating, by a controller control unit (36), based on a frequency (F) of a power system to which a generator (16) that generates electric power by being driven by a gas turbine (10), a controller fuel flow rate command value (GVCSO) indicating a first command value control signal output (CSO) for controlling a fuel input amount that increases an output of the gas turbine (10) as the frequency (F) decreases; calculating, by a first CSO calculation unit (35), a first fuel flow rate command value indicating a second command value control signal output (CSO) for controlling a fuel input amount such that an output of a gas turbine corresponds to a target output; and calculating, a second CSO calculating unit (34,33) calculating a deviation by subtracting a second threshold value from an estimated value of a turbine inlet temperature (T1T) of the gas turbine (10), the second threshold value referring to the estimated value and being set such that the estimated value does not exceed the first threshold value of the turbine inlet temperature (T1T), calculating a second fuel flow rate command value (T1RDSO) by adding a predetermined value to a post-selected fuel flow rate command value currently selected from a plurality of fuel flow rate command values including the first fuel flow rate command value (LDCSO), when the deviation is not equal to or greater than a predetermined deviation determined to be, wherein the estimated value of the turbine inlet temperature (T1T) exceeds the first threshold value, and calculating a second fuel command value that attenuates the post-selected fuel flow rate command value when the deviation is equal to or greater than the predetermined deviation, wherein the first CSO calculating unit (35) determines whether the calculated first fuel flow rate command value (LDCSO) is equal to or greater than the upper threshold value (LRCSO), and in this case, outputs the upper threshold value (LRCSO) to a command value selecting unit (37), otherwise outputs the calculated first fuel flow rate command value (LDCSO) to the command value selecting unit (37), and wherein the command value selection unit (37) outputs the smallest value among the controller fuel flow rate command value (GVCSO) obtained by the controller control unit (36) and either the calculated first fuel flow rate command value (LDCSO) or the upper limit value (LRCSO) obtained by the first CSO calculation unit (35) and the second fuel flow rate command value (T1RDSO) obtained by the second CSO calculation unit (34, 33) to a control valve (17-19) to control the fuel flow rate.

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