Plant control device, plant control method and plant control program

Abstract

To enable good plant efficiency while avoiding a situation where a temperature T of steam supplied to a steam turbine exceeds an upper limit temperature.SOLUTION: This disclosure relates to a plant control device for controlling a plant including a steam turbine that can be driven by steam generated by using exhaust heat of a gas turbine and a steam temperature regulation section for regulating a temperature of steam supplied from a steam generating facility to the steam turbine. The plant control device sets a temperature target value corresponding to the temperature of the steam to be supplied to the steam turbine, and controls the steam temperature regulation section so that the steam temperature becomes the temperature target value. Setting of the temperature target value is performed so as to change a tolerance corresponding to a temperature upper limit value of the steam on the basis of operation information including a temporal change of a control target value corresponding to at least one of a load and rotational frequency of the gas turbine.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a plant control device, a plant control method, and a plant control program. [Background technology]

[0002] A combined cycle plant is known that improves energy efficiency by combining a gas turbine and a steam turbine. In the combined cycle plant, the exhaust heat of the gas turbine (e.g., the heat contained in the exhaust gas of the gas turbine) is recovered, for example, by a heat recovery boiler, and the recovered exhaust heat is used to generate steam. The steam generated in the heat recovery boiler is supplied to a steam turbine, and the steam turbine is driven using the exhaust heat from the gas turbine.

[0003] In this type of combined cycle plant, the steam temperature is adjusted by controlling an attemperator that injects spray water onto the steam supplied to the steam turbine so that the temperature of the steam supplied to the steam turbine does not exceed an upper limit temperature defined by specifications, etc. The amount of spray water injected from the attemperator is controlled so that the temperature of the steam supplied to the steam turbine is equal to or lower than a temperature target value that is set with a margin for the upper limit temperature. For example, Patent Document 1 proposes steam temperature control in which the temperature target value is set lower than during normal operation at plant startup so that the steam temperature does not overshoot and exceed the upper limit temperature at plant startup. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 09-105503 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, the temperature of the steam supplied to the steam turbine is controlled by adjusting the amount of spray water injected so that the temperature becomes a preset target temperature value. This target temperature value is set to include a sufficient margin with respect to the upper limit temperature so that the steam temperature does not exceed the upper limit temperature even in a transient state in which the operating state (e.g., load) of the plant changes over time.

[0006] In order to more reliably prevent the steam temperature from exceeding the upper limit temperature, it is preferable to set a large tolerance included in the temperature target value. On the other hand, if the tolerance included in the temperature target value is increased, the temperature target value will be lowered, and the steam temperature supplied to the steam turbine, which is the object of control, will also be lowered, resulting in a decrease in plant efficiency.

[0007] At least one embodiment of the present disclosure has been developed in consideration of the above-mentioned circumstances, and aims to provide a plant control device, a plant control method, and a plant control program that can achieve good plant efficiency while preventing the temperature of steam supplied to a steam turbine from exceeding an upper limit temperature. [Means for solving the problem]

[0008] In order to solve the above problems, a plant control device according to at least one embodiment of the present disclosure includes: a gas turbine capable of being driven by fuel gas produced by combustion of fuel; a steam generating facility for generating steam using exhaust heat from the gas turbine; a steam turbine that can be driven by the steam supplied from the steam generating facility; a steam temperature adjusting unit for adjusting a temperature of the steam supplied from the steam generating facility to the steam turbine; A plant control device for controlling a plant comprising: a temperature target value setting unit for setting the temperature target value corresponding to the temperature; a temperature control unit for controlling the steam temperature adjusting unit so that the temperature becomes the temperature target value; Equipped with The temperature target value setting unit sets the temperature target value so as to change a tolerance with respect to an upper temperature value of the steam based on operating information including a time change of a control target value corresponding to at least one of a load or a rotation speed of the gas turbine.

[0009] In order to solve the above problem, a plant control method according to at least one embodiment of the present disclosure includes: a gas turbine capable of being driven by fuel gas produced by combustion of fuel; a steam generating facility for generating steam using exhaust heat from the gas turbine; a steam turbine that can be driven by the steam supplied from the steam generating facility; a steam temperature adjusting unit for adjusting a temperature of the steam supplied from the steam generating facility to the steam turbine; A plant control method for controlling a plant comprising: setting the temperature target value corresponding to the temperature; controlling the steam temperature adjusting unit so that the temperature becomes the temperature target value; Equipped with The temperature target value is set so as to change a tolerance for the upper temperature limit value of the steam based on operation information including a time change in a control target value corresponding to at least one of a load or a rotation speed of the gas turbine.

[0010] In order to solve the above problem, a plant control program according to at least one embodiment of the present disclosure includes: a gas turbine capable of being driven by fuel gas produced by combustion of fuel; a steam generating facility for generating steam using exhaust heat from the gas turbine; a steam turbine that can be driven by the steam supplied from the steam generating facility; a steam temperature adjusting unit for adjusting a temperature of the steam supplied from the steam generating facility to the steam turbine; A plant control program for controlling a plant comprising: A computer device includes: setting the temperature target value corresponding to the temperature; controlling the steam temperature adjusting unit so that the temperature becomes the temperature target value; It is possible to execute The temperature target value is set so as to change a tolerance for the upper temperature limit value of the steam based on operation information including a time change in a control target value corresponding to at least one of a load or a rotation speed of the gas turbine. Effect of the Invention

[0011] According to at least one embodiment of the present disclosure, it is possible to provide a plant control device, a plant control method, and a plant control program that can achieve good plant efficiency while preventing the temperature of steam supplied to a steam turbine from exceeding an upper limit temperature. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram of a combined cycle plant according to an embodiment. FIG. [Diagram 2] FIG. 1 is a block diagram of a plant control device according to an embodiment. [Diagram 3] FIG. 1 is an explanatory diagram showing input / output characteristics of a general first-order lag function. [Figure 4] 3 is a correspondence diagram showing the relationship between the tolerance and the plant efficiency for each temperature target value set in the temperature target value setting unit in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0014] First, a configuration of a combined cycle plant 1, which is an example of a plant to be controlled by a plant control device 100 according to at least one embodiment of the present disclosure, will be described. Fig. 1 is a schematic configuration diagram of a combined cycle plant 1 according to one embodiment.

[0015] The combined cycle plant 1 includes a gas turbine 10, a heat recovery boiler 20 for generating steam using exhaust gas EG from the gas turbine 10, a steam turbine 60 that can be driven by steam from the heat recovery boiler 20, and a condenser 40 for converting the steam from the steam turbine 60 back into water.

[0016] The gas turbine 10 includes a compressor 11 for compressing combustion air, and a turbine 15 driven by combustion gas generated by mixing and burning the combustion air compressed by the compressor 11 with fuel supplied from a fuel supply system. The rotors of the compressor 11 and the turbine 15 are connected to each other to form a gas turbine rotor 19.

[0017] The steam turbine 60 includes a high-pressure steam turbine HP, an intermediate-pressure steam turbine IP, and a low-pressure steam turbine LP. The high-pressure steam turbine HP, the intermediate-pressure steam turbine IP, and the low-pressure steam turbine LP have their respective rotating shafts connected to one another to form a steam turbine rotor 61. The steam turbine rotor 61 is integrally connected to the gas turbine rotor 19 described above. The steam that has completed its work in the steam turbine 60 is returned to condensation in the condenser 40.

[0018] The condensate from the condenser 40 can be supplied to the heat recovery steam generator 20 via a condensate supply line 62. A low-pressure feed water pump 63 is provided on the condensate supply line 62, and the amount of condensate supplied to the heat recovery steam generator 20 can be adjusted.

[0019] A make-up water tank 42 is connected to the condenser 40 via a make-up water supply line 41. A make-up water supply pump 43 is installed in the make-up water supply line 41, so that make-up water can be supplied from the make-up water tank 42 when the condenser 40 runs short of condensed water.

[0020] The heat recovery boiler 20 has a configuration for recovering and effectively utilizing heat (exhaust heat) contained in the exhaust gas EG from the gas turbine 10. The heat recovery boiler 20 includes a low-pressure economizer 21, a low-pressure evaporator 22, a high-pressure primary economizer 23, an intermediate-pressure economizer 24, an intermediate-pressure evaporator 25, a low-pressure superheater 26, a high-pressure secondary economizer 27, an intermediate-pressure superheater 28, a high-pressure evaporator 29, a high-pressure primary superheater 30, a primary reheater 31, a secondary reheater 32, and a high-pressure secondary superheater 33 as components for utilizing the heat recovered from the exhaust gas EG.

[0021] The exhaust gas from which heat has been recovered in the heat recovery steam generator 20 is discharged to the outside through a chimney 34.

[0022] In the heat recovery boiler 20, the feed water (condensate) from the condenser 40 is first heated by the low-pressure economizer 21. At least a portion of the feed water heated by the low-pressure economizer 21 is stored in the low-pressure drum 44. The low-pressure evaporator 22 is connected to the low-pressure drum 44, and steam can be generated from at least a portion of the water stored in the low-pressure drum 44. The steam generated in the low-pressure evaporator 22 is returned to the low-pressure drum 44.

[0023] Furthermore, the feedwater heated by the low-pressure economizer 21 is supplied to a high-pressure feedwater pump 45 and a medium-pressure feedwater pump 46. The medium-pressure feedwater pump 46 pressurizes the feedwater to a first pressure P1, and the high-pressure feedwater pump 45 pressurizes the feedwater to a second pressure P2 (>first pressure P1) higher than the first pressure. The feedwater pressurized to the second pressure P2 by the high-pressure feedwater pump 45 is heated by the high-pressure primary economizer 23 and the high-pressure secondary economizer 27, and then supplied to the high-pressure drum 47. The feedwater pressurized to the first pressure P1 by the medium-pressure feedwater pump 46 is heated by the medium-pressure economizer 24, and then supplied to the medium-pressure drum 48. The high pressure water supply pump 45 and the medium pressure water supply pump 46 may be integrally constructed.

[0024] The high-pressure evaporator 29 is connected to the high-pressure drum 47, and steam can be generated from at least a portion of the water stored in the high-pressure drum 47. The steam generated in the high-pressure evaporator 29 is returned to the high-pressure drum 47. The steam extracted from the high-pressure drum 47 is superheated by the high-pressure primary superheater 30 and the high-pressure secondary superheater 33, and supplied to the high-pressure steam turbine HP. A first attemperator 49a is provided between the high-pressure primary superheater 30 and the high-pressure secondary superheater 33. The first attemperator 49a is an example of a steam temperature adjustment unit for adjusting the temperature of the steam supplied to the high-pressure steam turbine HP.

[0025] In this embodiment, the first attemperator 49a can adjust the steam temperature by spraying spray water onto the steam. A part of the water supplied by the high-pressure feed water pump 45 can be supplied as spray water to the first attemperator 49a via a first spray water supply line 51a connected to an outlet of the high-pressure feed water pump 45. A flow rate control valve 52a for adjusting the flow rate of the spray water supplied to the first attemperator 49a is provided on the first spray water supply line 51a. The opening degree of the flow rate control valve 52a is controlled based on a control signal from a plant control device 100, which will be described later, so that the amount of attemperator desuperheating by the first attemperator 49a can be adjusted.

[0026] The steam that has completed its work in the high-pressure steam turbine HP is heated by the primary reheater 31 and the secondary reheater 32, and then supplied to the intermediate-pressure steam turbine IP. A second attemperator 49b is provided between the primary reheater 31 and the secondary reheater 32. The second attemperator 49b is an example of a steam temperature adjustment unit for adjusting the temperature of the steam supplied to the intermediate-pressure steam turbine IP.

[0027] In this embodiment, the second attemperator 49b can adjust the steam temperature by injecting spray water onto the steam. A part of the water supplied by the high-pressure feed water pump 45 can be supplied as spray water to the second attemperator 49b via a second spray water supply line 51b connected to an outlet of the high-pressure feed water pump 45. A flow rate control valve 52b for adjusting the flow rate of the spray water supplied to the second attemperator 49b is provided on the second spray water supply line 51b. The opening degree of the flow rate control valve 52b is controlled based on a control signal from a plant control device 100, which will be described later, so that the amount of attemperator reduction by the second attemperator 49b can be adjusted.

[0028] The intermediate-pressure evaporator 25 is connected to the intermediate-pressure drum 48, and is capable of generating steam from at least a portion of the water stored in the intermediate-pressure drum 48. The steam generated in the intermediate-pressure evaporator 25 is returned to the intermediate-pressure drum 48. A portion of the steam extracted from the intermediate-pressure drum 48 is heated by the intermediate-pressure superheater 28, supplied to an outlet flow passage of the high-pressure steam turbine HP, and supplied to the intermediate-pressure steam turbine IP via the primary reheater 31 and the secondary reheater 32.

[0029] The low-pressure evaporator 22 is connected to the low-pressure drum 44, and steam can be generated from at least a portion of the water stored in the low-pressure drum 44. The steam generated in the low-pressure evaporator 22 is returned to the low-pressure drum 44. A portion of the steam extracted from the low-pressure drum 44 is heated by the low-pressure superheater 26 and supplied to an outlet flow passage of the intermediate-pressure steam turbine IP, and then supplied to the low-pressure steam turbine LP. The steam that has completed work in the low-pressure steam turbine LP is returned to the condenser 40.

[0030] Next, a plant control device 100 for controlling the combined cycle plant 1 having the above configuration will be described. The plant control device 100 is composed of, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, for example, and the CPU reads the program into the RAM or the like and executes information processing and arithmetic processing to realize various functions. The program may be installed in a ROM or other storage medium in advance, provided in a state stored in a computer-readable storage medium, or distributed via a wired or wireless communication means. The computer-readable storage medium may be a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

[0031] 2 is a block diagram of a plant control device 100 according to an embodiment. The plant control device 100 adjusts the amount of heat reduction by the first attemperator 49a and the second attemperator 49b by controlling the opening degrees of the flow rate control valves 52a and 52b in the combined cycle plant 1 having the above-described configuration, thereby controlling the temperature of steam supplied to the steam turbine 60. To achieve such a function, the plant control device 100 includes a temperature acquisition unit 102, a control target value acquisition unit 104, an operation information generation unit 106, a temperature target value setting unit 108, and a temperature control unit 110.

[0032] In the following explanation, we will representatively describe the case where the first attemperator 49a, of the first and second attemperators 49b that are temperature adjustment units possessed by the combined cycle plant 1, is used as the control target of the plant control device 100 to control the steam temperature. However, unless otherwise specified, the same applies to the case where the second attemperator 49b is used as the control target to control the steam temperature.

[0033] The temperature acquisition unit 102 is configured to acquire the temperature T of the steam supplied to the steam turbine 60. Specifically, when the first attemperator 49a is the control target, the temperature acquisition unit 102 acquires the temperature T detected by a temperature sensor (not shown) installed in a flow path (between the first attemperator 49a and the high-pressure steam turbine HP) through which the steam whose temperature has been reduced by the first attemperator 49a flows. In this case, the temperature sensor may be installed in the flow path between the first attemperator 49a and the high-pressure secondary superheater 33, or may be installed between the high-pressure secondary superheater 33 and the high-pressure steam turbine HP.

[0034] Furthermore, when the second attemperator 49a is the control target, the temperature acquisition unit 102 acquires a temperature T detected by a temperature sensor (not shown) installed in a flow path (between the second attemperator 49a and the high-pressure steam turbine HP) through which the steam whose temperature has been reduced by the second attemperator 49a flows. In this case, the temperature sensor may be installed in the flow path between the second attemperator 49b and the secondary reheater 32, or between the secondary reheater 32 and the intermediate-pressure steam turbine IP.

[0035] The control target value acquisition unit 104 is configured to acquire a control target value Vc corresponding to at least one of the load L and the rotation speed R of the gas turbine 10. That is, the control target value Vc may be a load target value corresponding to the load L, or a rotation speed target value corresponding to the rotation speed R. The control target value Vc is continuously acquired by the control target value acquisition unit 104 at predetermined time intervals dt, and is used by the operation information generation unit 106 to generate operation information.

[0036] The driving information generating unit 106 is configured to generate driving information Id based on the time change of the control target value Vc acquired by the control target value acquiring unit 104. The driving information generating unit 106 generates the driving information Id as the difference between the control target value Vc and an output value obtained by inputting the control target value Vc to a first first-order lag function LAG1 and a second first-order lag function LAG2.

[0037] The first first-order lag function LAG1 and the second first-order lag function LAG2 are each a first-order lag function having a set time constant T. Here, Fig. 3 is an explanatory diagram showing the input / output characteristics of a general first-order lag function LAG. The first-order lag function LAG can obtain an output value Y shown in the following formula for an input value X having a time difference dt between steps, and outputs Y(n) → Y(n-1) when the time constant T is larger than the time difference dt between steps, and outputs Y(n) → X(n) when the time constant T is smaller than the time difference dt between steps. Y(n)=Y(n-1)+{X(n)-Y(n-1)}×dt / (T+dt) The driving information Id thus generated by the driving information generating unit 106 serves as an index indicating the amount of fluctuation C of the control target value Vc during a predetermined period. In this embodiment, as an example, the time difference dt is 0.1 seconds, and the time constants T of the first and second first-order lag functions LAG1 and LAG2 are both 10 seconds. In this case, since the time constants T are larger than the time difference dt in the first and second first-order lag functions LAG1 and LAG2, they each output a value close to the output value Y(n-1) of the previous step for the input value X(n). Therefore, the operation information Id, which is the difference between the control target value Vc and the output values ​​of the first and second first-order lag functions LAG1 and LAG2, indicates the time change (amount of fluctuation) of the control target value Vc. It is not necessary to provide two first-order lag functions, and a single first-order lag function or three or more first-order lag functions may be provided.

[0038] The temperature target value setting unit 108 is configured to set a temperature target value Tt corresponding to the temperature T. In the temperature target value setting unit 108, first, the operation information Id generated by the operation information generating unit 106 is input to a fluctuation amount determining unit 112. The fluctuation amount determining unit 112 specifies a fluctuation amount C of the control target value Vc based on the operation information Id, and determines whether or not the fluctuation amount C is equal to or greater than a preset reference value C1. As an example, it is determined whether the positive fluctuation amount of the fluctuation amount C of the control target value Vc is equal to or greater than a reference value C1, and at the same time, it is determined whether the negative fluctuation amount is equal to or greater than the reference value C1. In other words, it is determined whether the absolute value of the fluctuation amount C of the control target value Vc is equal to or greater than the reference value C1.

[0039] The temperature target value selection unit 114 selects the temperature target value Tt based on the determination result of the fluctuation amount determination unit 112. In this embodiment, a first temperature target value Tt1 corresponding to the case where the fluctuation amount C is equal to or greater than the reference value C1, and a second temperature target value Tt2 corresponding to the case where the fluctuation amount C is less than the reference value C1 are prepared in advance as candidates for the temperature target value Tt. The temperature target value selection unit 114 selects either the first temperature target value Tt1 or the second temperature target value Tt2 as the temperature target value Tt based on the determination result of the fluctuation amount determination unit 112.

[0040] Furthermore, the target temperature value selection unit 114 may set a second target temperature value Tt2 as the target temperature value Tt when the amount of fluctuation C remains less than the reference value C1 for a predetermined period of time. As an example, if the state in which the fluctuation amount C is less than the reference value C1 continues for a predetermined period or more, the second temperature target value Tt2 is selected, and otherwise the first temperature target value Tt1 is selected. More specifically, if the temperature target value selection unit 114 receives an input value output from the fluctuation amount determination unit 112 when the state in which the fluctuation amount C is less than the reference value C1 continues for a predetermined period or more, the second temperature target value Tt2 is selected, and if the temperature target value selection unit 114 does not receive the input value, the first temperature target value Tt1 is selected. With this configuration, it is possible to set the temperature target value more safely and effectively improve the plant efficiency at an appropriate timing.

[0041] The temperature target value Tt is set to include a tolerance for the upper temperature limit value T0 of the steam supplied to the steam turbine 60, and thereby the temperature control unit 110 controls the steam temperature to be the temperature target value Tt within a range that does not exceed the upper temperature limit value T0. Fig. 4 is a correspondence diagram showing the relationship between the tolerance and the plant efficiency for each temperature target value set in the temperature target value setting unit 103 in Fig. 2. The second temperature target value Tt2, which corresponds to the case where the fluctuation amount C is less than the reference value C1, is set to have a smaller tolerance than the first temperature target value Tt1, which corresponds to the case where the fluctuation amount C is equal to or greater than the reference value C1.

[0042] In the above embodiment, the temperature target value Tt is switched based on whether the fluctuation amount C of the control target value Vc is equal to or greater than the reference value C1, but the temperature target value Tt may be switched based on other conditions. For example, when a condition for determining whether the operation state of the combined cycle plant 1 is stable (specifically, whether the shaft start-up of the plant combined cycle plant 1 is completed, whether oil heating operation is not in progress, whether fuel switching is not in progress, whether there is a stop command, whether the gas turbine load is equal to or less than a predetermined value, etc.) is not satisfied, a first temperature target value Tt1 having a large margin for the temperature upper limit value T0 may be set, and when the condition is satisfied, a second temperature target value Tt2 having a small margin for the temperature upper limit value T0 may be set.

[0043] As another example, even if the state in which the fluctuation amount C is less than the reference value C1 continues for a predetermined time, the temperature target value selection unit 114 may set a first temperature target value Tt1 with a large margin if the other switching conditions described above are not satisfied, and may set a second temperature target value Tt2 with a small margin if the other switching conditions described above are also satisfied. With this configuration, the temperature target value can be set more safely, and the plant efficiency can be effectively improved at an appropriate timing.

[0044] The temperature control unit 110 is configured to control the first attemperator 49a and the second attemperator 49b, which are steam temperature adjustment units, so that the temperature T acquired by the temperature acquisition unit 102 becomes the temperature target value Tt set by the temperature target value setting unit 108. Specifically, a difference between the temperature T acquired by the temperature acquisition unit 102 and the temperature target value Tt set by the temperature target value setting unit 108 is input to the PI controller 118, and a control signal SC corresponding to the difference is output. The control signal SC is used to adjust the opening of the flow rate control valve 52a or the flow rate control valve 52b, which is the control target, and thereby the temperature T of the steam supplied to the steam turbine 60 by the first attemperator 49a or the second attemperator 49b is controlled to become the temperature target value Tt.

[0045] As described above, in the temperature target value setting unit 108, when the fluctuation amount C is equal to or larger than the reference value C1, A first temperature target value Tt1 including a relatively large first tolerance t1 is set as the temperature target value Tt. In this case, in a situation in which the steam temperature is likely to change due to a large fluctuation amount C, the tolerance included in the temperature target value Tt can be increased, thereby preferably preventing the steam temperature from exceeding the upper temperature limit value T0. On the other hand, when the fluctuation amount C is less than the reference value C1, the temperature target value setting unit 108 sets a second temperature target value Tt2 including a relatively small second tolerance t2 as the temperature target value Tt. In this case, in a situation in which the steam temperature is unlikely to change due to a small fluctuation amount C, the tolerance included in the temperature target value Tt can be decreased, thereby increasing the steam temperature within a range that does not exceed the upper temperature limit value T0, and effectively improving plant efficiency.

[0046] As described above, according to the above embodiment, it is possible to achieve good plant efficiency while preventing the temperature T of the steam supplied to the steam turbine 60 from exceeding the upper limit temperature T0.

[0047] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate.

[0048] The contents described in each of the above embodiments can be understood, for example, as follows.

[0049] (1) A plant control device according to one embodiment includes: a gas turbine capable of being driven by fuel gas produced by combustion of fuel; a steam generating facility for generating steam using exhaust heat from the gas turbine; a steam turbine that can be driven by the steam supplied from the steam generating facility; a steam temperature adjusting unit for adjusting a temperature of the steam supplied from the steam generating facility to the steam turbine; A plant control device for controlling a plant comprising: a temperature target value setting unit for setting the temperature target value corresponding to the temperature; a temperature control unit for controlling the steam temperature adjusting unit so that the temperature becomes the temperature target value; Equipped with The temperature target value setting unit sets the temperature target value so as to change a tolerance with respect to an upper temperature value of the steam based on operating information including a time change of a control target value corresponding to at least one of a load or a rotation speed of the gas turbine.

[0050] According to the above aspect (1), the temperature of steam supplied to the steam turbine is controlled to be a temperature target value that is set to include a margin with respect to a temperature upper limit value defined by the specifications of the steam turbine, etc. The margin included in the temperature target value is changed based on operation information including a time change in a control target value corresponding to at least one of the load or rotation speed of the gas turbine, and thus the temperature target value is variably set according to the operating state of the plant. By changing the temperature target value according to the operating state of the plant in this manner, it is possible to improve plant efficiency while preventing the temperature of the steam supplied to the steam turbine from exceeding the temperature target value.

[0051] (2) In another embodiment, in the above embodiment (1), The temperature target value setting unit is when it is determined that the amount of fluctuation of the control target value is equal to or greater than a reference value based on the operating information, a first temperature target value including a first tolerance is set as the temperature target value; When it is determined that the amount of fluctuation is less than the reference value, a second temperature target value including a second tolerance smaller than the first tolerance is set as the temperature target value.

[0052] According to the above aspect (2), when it is determined based on the operation information that the amount of change in the control target value during a predetermined period is equal to or greater than the reference value, a first temperature target value including a relatively large first tolerance is set as the temperature target value. As a result, in a situation in which the steam temperature is likely to change due to a large amount of change in the control target value, the tolerance included in the temperature target value is increased, thereby making it possible to suitably prevent the steam temperature from exceeding the upper temperature limit. On the other hand, when it is determined based on the operation information that the amount of change in the control target value during a predetermined period is less than the reference value, a second temperature target value including a relatively small second tolerance is set as the temperature target value. As a result, in a situation in which the steam temperature is unlikely to change due to a small amount of change in the control target value, the tolerance included in the temperature target value is reduced, thereby making it possible to increase the steam temperature within a range that does not exceed the upper temperature limit, thereby effectively improving plant efficiency.

[0053] (3) In another embodiment, in the above embodiment (2), The target temperature value setting unit sets the second target temperature value as the target temperature value when a state in which the amount of fluctuation is less than the reference value continues for a predetermined time.

[0054] According to the above aspect (3), by setting a second temperature target value including a second tolerance smaller than the first tolerance, on the condition that the state in which the fluctuation amount of the control target value is less than the reference value continues for a predetermined time, it is possible to set the temperature target value more safely and to effectively improve plant efficiency at an appropriate timing.

[0055] (4) In another embodiment, in any one of the above (1) to (3), The operating information is generated based on the difference between the control target value and a result of inputting the control target value into a first-order lag function.

[0056] According to the above aspect (4), it is possible to suitably generate operating information including a time change in the control target value, based on the difference between the control target value and a result of inputting the control target value to a first-order lag function.

[0057] (5) In another embodiment, in any one of the above (1) to (4), The steam temperature adjusting unit is a desuperheater capable of adjusting the temperature by adjusting the amount of spray water injected onto the steam.

[0058] According to the above aspect (5), the steam temperature adjusting unit is configured as an attemperator that can adjust the temperature of the steam supplied to the steam turbine to a target temperature value by adjusting the amount of spray water injected into the steam.

[0059] (6) A plant control method according to one aspect includes the steps of: a gas turbine capable of being driven by fuel gas produced by combustion of fuel; a steam generating facility for generating steam using exhaust heat from the gas turbine; a steam turbine that can be driven by the steam supplied from the steam generating facility; a steam temperature adjusting unit for adjusting a temperature of the steam supplied from the steam generating facility to the steam turbine; A plant control method for controlling a plant comprising: setting the temperature target value corresponding to the temperature; controlling the steam temperature adjusting unit so that the temperature becomes the temperature target value; Equipped with The temperature target value is set so as to change a tolerance for the upper temperature limit value of the steam based on operation information including a time change in a control target value corresponding to at least one of a load or a rotation speed of the gas turbine.

[0060] According to the above aspect (6), the temperature of the steam supplied to the steam turbine is controlled to be a temperature target value that is set to include a margin with respect to a temperature upper limit value defined by the specifications of the steam turbine, etc. The margin included in the temperature target value is changed based on operation information that includes a time change in a control target value corresponding to at least one of the load or rotation speed of the gas turbine, and thus the temperature target value is variably set according to the operating state of the plant. By changing the temperature target value in this manner according to the operating state of the plant, it is possible to improve plant efficiency while preventing the temperature of the steam supplied to the steam turbine from exceeding the temperature target value.

[0061] (7) A plant control program according to one embodiment of the present invention comprises: a gas turbine capable of being driven by fuel gas produced by combustion of fuel; a steam generating facility for generating steam using exhaust heat from the gas turbine; a steam turbine that can be driven by the steam supplied from the steam generating facility; a steam temperature adjusting unit for adjusting a temperature of the steam supplied from the steam generating facility to the steam turbine; A plant control program for controlling a plant comprising: A computer device includes: setting the temperature target value corresponding to the temperature; controlling the steam temperature adjusting unit so that the temperature becomes the temperature target value; It is possible to execute The temperature target value is set so as to change a tolerance for the upper temperature limit value of the steam based on operation information including a time change in a control target value corresponding to at least one of a load or a rotation speed of the gas turbine.

[0062] According to the above aspect (7), the temperature of the steam supplied to the steam turbine is controlled to be a temperature target value that is set to include a margin with respect to a temperature upper limit value defined by the specifications of the steam turbine, etc. The margin included in the temperature target value is changed based on operation information including a time change in a control target value corresponding to at least one of the load or rotation speed of the gas turbine, and thus the temperature target value is variably set according to the operating state of the plant. By changing the temperature target value in this manner according to the operating state of the plant, it is possible to improve plant efficiency while preventing the temperature of the steam supplied to the steam turbine from exceeding the temperature target value. [Explanation of symbols]

[0063] 1. Combined cycle plant 10. Gas Turbine 11 Compressor 12 Combustor 15 Turbine 19 Gas turbine rotor 20. Waste heat recovery boiler 21 Low-pressure economizer 22 Low pressure evaporator 23 High-pressure primary economizer 24 Medium pressure economizer 25 Medium pressure evaporator 26 Low pressure superheater 27 High pressure secondary economizer 28 Intermediate pressure superheater 29 High-pressure evaporator 30 High pressure primary superheater 31 Primary reheater 32 Secondary reheater 33 High pressure secondary superheater 34 Chimney 40 Condenser 41 Make-up water supply line 42 Water Supply Tank 43 Make-up water supply pump 44 Low Pressure Drum 47 High Pressure Drum 48 Medium Pressure Drum 49a 1st desuperheater 49b 2nd desuperheater 60 Steam Turbine 61 Steam turbine rotor 62 Condensate supply line 63 Low pressure water supply pump 100 Control device 102 Temperature acquisition section 102 104 Control target value acquisition unit 106 Driving information generation unit 108 Temperature target value setting section 110 Temperature control unit 112 Fluctuation amount determination unit 114 Temperature target value selection section 118 PI Controller

Claims

1. a gas turbine capable of being driven by fuel gas produced by combustion of fuel; a steam generating facility for generating steam using exhaust heat from the gas turbine; a steam turbine that can be driven by the steam supplied from the steam generating facility; a steam temperature adjusting unit for adjusting a temperature of the steam supplied from the steam generating facility to the steam turbine; A plant control device for controlling a plant comprising: a temperature target value setting unit for setting the temperature target value corresponding to the temperature; a temperature control unit for controlling the steam temperature adjusting unit so that the temperature becomes the temperature target value; Equipped with the temperature target value setting unit sets the temperature target value so as to change a tolerance with respect to an upper temperature limit value of the steam based on operation information including a time change of a control target value corresponding to at least one of a load or a rotation speed of the gas turbine.

2. The temperature target value setting unit is when it is determined that the amount of fluctuation of the control target value is equal to or greater than a reference value based on the operating information, a first temperature target value including a first tolerance is set as the temperature target value; 2 . The plant control device according to claim 1 , wherein, when it is determined that the amount of fluctuation is less than the reference value, a second temperature target value including a second tolerance smaller than the first tolerance is set as the temperature target value.

3. 3 . The plant control device according to claim 2 , wherein the temperature target value setting unit sets the second temperature target value as the temperature target value when a state in which the amount of fluctuation is less than the reference value continues for a predetermined time.

4. 3. The plant control device according to claim 1, wherein the operation information is generated based on a difference between the control target value and a result of inputting the control target value into a first-order lag function.

5. 3 . The plant control device according to claim 1 , wherein the steam temperature adjusting unit is a desuperheater capable of adjusting the temperature by adjusting an amount of spray water injected onto the steam. 4 .

6. a gas turbine capable of being driven by fuel gas produced by combustion of fuel; a steam generating facility for generating steam using exhaust heat from the gas turbine; a steam turbine that can be driven by the steam supplied from the steam generating facility; a steam temperature adjusting unit for adjusting a temperature of the steam supplied from the steam generating facility to the steam turbine; A plant control method for controlling a plant comprising: setting the temperature target value corresponding to the temperature; controlling the steam temperature adjusting unit so that the temperature becomes the temperature target value; Equipped with a temperature target value is set so as to change a tolerance with respect to an upper temperature value of the steam based on operation information including a time change of a control target value corresponding to at least one of a load or a rotation speed of the gas turbine.

7. a gas turbine capable of being driven by fuel gas produced by combustion of fuel; a steam generating facility for generating steam using exhaust heat from the gas turbine; a steam turbine that can be driven by the steam supplied from the steam generating facility; a steam temperature adjusting unit for adjusting a temperature of the steam supplied from the steam generating facility to the steam turbine; A plant control program for controlling a plant comprising: A computer device includes: setting the temperature target value corresponding to the temperature; controlling the steam temperature adjusting unit so that the temperature becomes the temperature target value; It is possible to execute a temperature target value is set so as to change a tolerance with respect to an upper temperature limit value of the steam based on operation information including a time change of a control target value corresponding to at least one of a load or a rotation speed of the gas turbine.

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