Control device, control method and system

Abstract

This control device comprises: an acquiring unit for acquiring, as a first inlet pressure, a pressure value of first steam on a first inlet side as seen from a first regulating valve of a first turbine that rotates using the first steam, which is supplied from the first inlet via the first regulating valve, and acquiring, as a second inlet pressure, a pressure value of second steam on a second inlet side as seen from a second regulating valve of a second turbine that rotates on the same rotating shaft as the first turbine using the second steam, which is supplied from the second inlet via the second regulating valve; and a control unit for regulating an opening degree of the first regulating valve and an opening degree of the second regulating valve in accordance with the first inlet pressure and the second inlet pressure.

Description

[Technical field]

[0001] The present disclosure relates to a control device, a control method, and a system. This application claims priority based on Japanese Patent Application No. 2021-194470 filed on November 30, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] In an extraction or mixed pressure steam turbine, there is a problem that the thrust force applied to the rotor must be suppressed within an allowable value (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 167907 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a control device, a control method, and a system that can control the thrust force in a steam turbine within an allowable value. [Means for solving the problem]

[0005] In order to solve the above problems, the control device of the present disclosure includes an acquisition unit that acquires, as a first inlet pressure, a pressure value of the first steam on the first inlet side as viewed from the first control valve of a first turbine that rotates using first steam supplied from a first inlet via a first control valve, and acquires, as a second inlet pressure, a pressure value of the second steam on the second inlet side as viewed from the second control valve of a second turbine that rotates on the same rotating shaft as the first turbine using second steam supplied from a second inlet via a second control valve, and a control unit that adjusts the valve opening of the first control valve and the valve opening of the second control valve in accordance with the first inlet pressure and the second inlet pressure.

[0006] The control method according to the present disclosure includes the steps of acquiring, as a first inlet pressure, a pressure value of the first steam on the first inlet side as viewed from a first control valve of a first turbine that rotates using first steam supplied from a first inlet via a first control valve, and acquiring, as a second inlet pressure, a pressure value of the second steam on the second inlet side as viewed from a second control valve of a second turbine that rotates on the same rotating shaft as the first turbine using second steam supplied from a second inlet via a second control valve, and adjusting a valve opening of the first control valve and a valve opening of the second control valve in accordance with the first inlet pressure and the second inlet pressure.

[0007] The system according to the present disclosure includes a first regulating valve, a second regulating valve, a first turbine that rotates using first steam supplied from a first inlet via the first regulating valve, a second turbine that rotates on the same rotating shaft as the first turbine using second steam supplied from a second inlet via the second regulating valve, an acquisition unit that acquires a pressure value of the first steam on the first inlet side from the first regulating valve as a first inlet pressure and acquires a pressure value of the second steam on the second inlet side from the second regulating valve as a second inlet pressure, and a control unit that adjusts a valve opening of the first regulating valve and a valve opening of the second regulating valve in accordance with the first inlet pressure and the second inlet pressure. Effect of the Invention

[0008] According to the control device, control method, and system disclosed herein, the thrust force in a steam turbine can be controlled within an allowable value. [Brief description of the drawings]

[0009] [Figure 1] 1 is a system diagram of a system according to a first embodiment of the present disclosure. [Diagram 2] 4 is a schematic diagram for explaining an example of operation of the control device according to the first embodiment of the present disclosure. FIG. [Diagram 3] 2 is a block diagram for explaining a configuration example of a control device according to the first embodiment of the present disclosure. FIG. [Figure 4] 2 is a block diagram for explaining a configuration example of a control device according to the first embodiment of the present disclosure. FIG. [Diagram 5] 4 is a schematic diagram for explaining an example of operation of the control device according to the first embodiment of the present disclosure. FIG. [Figure 6] 4 is a schematic diagram for explaining an example of operation of the control device according to the first embodiment of the present disclosure. FIG. [Figure 7] 11 is a schematic diagram for explaining an example of the operation of the control device according to the second embodiment of the present disclosure. FIG. [Figure 8] 10 is a flowchart showing an operation example of a control device according to a second embodiment of the present disclosure. [Figure 9] FIG. 13 is a schematic diagram for explaining a control device according to a third embodiment of the present disclosure. [Figure 10] FIG. 1 is a schematic block diagram illustrating a configuration of a computer according to at least one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a control device, a control method, and a system according to an embodiment of the present disclosure will be described with reference to the drawings. Note that in each drawing, the same or corresponding components are designated by the same reference numerals and descriptions thereof will be omitted as appropriate.

[0011] First Embodiment (Systems and Control Units) A configuration and operation example of a system and a control device according to the first embodiment of the present disclosure will be described with reference to Figs. 1 to 6. Fig. 1 is a system diagram of a system according to the first embodiment of the present disclosure. Figs. 2 and 5 to 6 are schematic diagrams for explaining an operation example of a control device according to the first embodiment of the present disclosure. Figs. 3 and 4 are block diagrams for explaining a configuration example of a control device according to the first embodiment of the present disclosure.

[0012] FIG. 1 shows an example of a system diagram in the case where the system according to the first embodiment of the present disclosure is applied to a gas turbine combined cycle power plant (GTCC). The system 1 shown in FIG. 1 includes a gas turbine 10, a heat recovery steam generator 20, a steam turbine 30, a generator 34, a condenser 35, and a control device 100. The steam turbine 30 includes a high-pressure steam turbine 31, an intermediate-pressure steam turbine 32, and a low-pressure steam turbine 33, and a rotating shaft 36 of each of the turbines 31, 32, and 33. The generator 34 is driven by each of the turbines 10, 31, 32, and 33 to generate electricity. The condenser 35 converts the steam exhausted from the low-pressure steam turbine 33 and the like back into water.

[0013] The gas turbine 10 includes a compressor 11, a combustor 12, a turbine 13, a fuel flow control valve 14, and a rotating shaft 15. The compressor 11 compresses outside air to generate compressed air. The combustor 12 mixes fuel gas with the compressed air and burns the mixture to generate high-temperature combustion gas. The turbine 13 is driven by the combustion gas. The fuel flow control valve 14 adjusts the flow rate of fuel supplied to the combustor 12. The rotating shaft 15 is the rotating shaft of the compressor 11 and the turbine 13. A fuel line that supplies fuel from a fuel supply source to the combustor 12 is connected to the combustor 12. The fuel line is provided with the fuel flow control valve 14. An exhaust port of the turbine 13 is connected to the heat recovery steam generator 20 by an exhaust line 56.

[0014] The heat recovery boiler 20 includes a high-pressure steam generating section 21, an intermediate pressure steam generating section 22, a reheating section 23, and a low-pressure steam generating section 24. The heat recovery boiler 20 generates steam using heat from the exhaust gas discharged from the gas turbine 10. The high-pressure steam generating section 21 includes a drum 21a and a heat exchanger 21b, and generates high-pressure steam to be supplied to the high-pressure steam turbine 31. The intermediate pressure steam generating section 22 includes a drum 22a and a heat exchanger 22b, and generates intermediate pressure steam to be supplied to the intermediate pressure steam turbine 32. The reheating section 23 heats the steam discharged from the intermediate pressure steam generating section 22, etc. The low pressure steam generating section 24 includes a drum 24a and a heat exchanger 24b, and generates low pressure steam to be supplied to the low pressure steam turbine 33.

[0015] The high pressure steam generating section 21 and the steam inlet 311 of the high pressure steam turbine 31 are connected by a high pressure main steam line 41 that guides high pressure steam to the high pressure steam turbine 31 via a high pressure steam stop valve 42 and a high pressure main steam control valve 43. The high pressure main steam line 41 is connected to an intermediate pressure main steam line 62 via a high pressure steam turbine bypass valve 63. A steam outlet of the high pressure steam turbine 31 is connected to an intermediate pressure main steam line 44 via a check valve 64, and is connected to a condenser 35 via a ventilator valve 66. The intermediate pressure main steam line 44 merges with the intermediate pressure main steam line 61 from the intermediate pressure steam generating section 22 at the steam inlet side of the reheat section 23. A steam outlet side of the reheat section 23 is connected to a steam inlet 321 of the intermediate pressure steam turbine 32 by the intermediate pressure main steam line 62 via an intermediate pressure steam stop valve 45 and an intermediate pressure main steam control valve 46. The intermediate pressure main steam line 62 is connected to the condenser 35 via an intermediate pressure steam turbine bypass valve 65. A steam inlet 331 of the low-pressure steam turbine 33 is connected to a steam outlet of the intermediate-pressure steam turbine 32 by an intermediate-pressure turbine exhaust line 54, and is also connected to the low-pressure steam generating section 24 by a low-pressure main steam line 51 that guides the low-pressure steam to the low-pressure steam turbine 33 via a low-pressure steam stop valve 52 and a low-pressure main steam control valve 53. A condenser 35 is connected to the steam outlet of the low-pressure steam turbine 33. A feedwater line 55 that guides the condensate to the heat recovery boiler 20 is connected to the condenser 35.

[0016] The high pressure main steam control valve 43 adjusts the amount of steam flowing into the high pressure steam turbine 31 under the control of the control device 100. The intermediate pressure main steam control valve 46 adjusts the amount of steam flowing into the intermediate pressure steam turbine 32 under the control of the control device 100. The low pressure main steam control valve 53 adjusts the amount of steam flowing into the low pressure steam turbine 33 under the control of the control device 100. In addition, the high pressure main steam control valve 43, the intermediate pressure main steam control valve 46 and the low pressure main steam control valve 53 adjust the valve opening based on a valve opening command value (hereinafter referred to as valve opening command value) sent from the control device 100.

[0017] A pressure gauge 71 measuring high-pressure main steam is provided upstream of the high-pressure main steam control valve 43. A pressure gauge 72 measuring reduced-pressure steam is provided downstream of the high-pressure main steam control valve 43. The pressure gauge 72 measures the pressure value of high-pressure steam on the steam inlet 311 side as viewed from the high-pressure main steam control valve 43. A pressure gauge 73 measuring medium-pressure main steam is provided upstream of the medium pressure main steam control valve 46. A pressure gauge 74 measuring reduced-pressure medium-pressure steam is provided downstream of the medium pressure main steam control valve 46. The pressure gauge 74 measures the pressure value of medium-pressure steam on the steam inlet 321 side as viewed from the medium pressure main steam control valve 46. A pressure gauge 75 measuring low-pressure main steam is provided upstream of the low pressure main steam control valve 53. A pressure gauge 76 measuring reduced-pressure low-pressure steam is provided downstream of the low pressure main steam control valve 53. The pressure gauge 76 measures the pressure value of the low pressure steam on the steam inlet 331 side as viewed from the low pressure main steam control valve 53 .

[0018] In the following explanation and drawings, the pressure value of the high-pressure steam on the steam inlet 311 side measured by the pressure gauge 72 is also referred to as the HPST inlet pressure. Also, the pressure value of the intermediate-pressure steam on the steam inlet 321 side measured by the pressure gauge 74 is also referred to as the IPST inlet pressure. Also, the high-pressure main steam control valve 43 is also referred to as the HPCV. Also, the intermediate-pressure main steam control valve 46 is also referred to as the IPCV. Also, the high-pressure main steam control valve 43 and the intermediate-pressure main steam control valve 46 are also referred to as the HP governor valve and the IP governor valve. Incidentally, HPST is an abbreviation for high-pressure steam turbine. IPST is an abbreviation for intermediate pressure steam turbine. HPCV is an abbreviation for High Pressure Steam Control Valve. IPCV is an abbreviation for Intermediate Pressure Steam Control Valve.

[0019] The system 1 includes a plurality of sensors (not shown) for measuring the temperature, pressure, flow rate, number of rotations (rotational speed), and the like of various components.

[0020] The control device 100 is composed of a computer and peripheral devices of the computer, and includes an acquisition unit 101 and a control unit 102 as a functional configuration composed of a combination of hardware such as a computer and software such as a program executed by the computer. The acquisition unit 101 acquires measurement values ​​of various sensors such as pressure gauges 71-76. The control unit 102 controls each unit of the system 1 according to the acquisition results of the acquisition unit 101. In this embodiment, the control unit 102 adjusts the valve opening degree of the HPCV and the valve opening degree of the IPCV according to, for example, the HPST inlet pressure and the IPST inlet pressure. The control unit 102 also receives various types of operation data, instruction data, etc., and generates power by the generator 34 through control of the output of the gas turbine 10, control of the opening and closing of the high-pressure steam stop valve 42, control of the valve aperture of the high-pressure main steam control valve 43, control of the opening and closing of the intermediate-pressure steam stop valve 45, control of the valve aperture of the intermediate-pressure main steam control valve 46, control of the opening and closing of the low-pressure steam stop valve 52, control of the valve aperture of the low-pressure main steam control valve 53, etc. If load shedding occurs due to some kind of abnormality, etc., the control device 100 performs various controls at the time of load shedding.

[0021] (Overview of Steam Turbine Control) In the GTCC system, the feedwater in drums 21a, 22a, and 24a is converted into steam using thermal energy from the exhaust gas of the gas turbine 10, and the steam is passed through a steam turbine 30 to generate electricity. vapor Turbine 31, Intermediate Pressure (IP) vapor Turbine 32 and Low Pressure (LP) vapor Turbine 33, especially high pressure vapor Turbine 31 and intermediate pressure vaporIf the pressures received by the turbine 32 are not balanced, the thrust is forced onto the high-pressure side or the intermediate-pressure side, and in the worst case, thrust burnout occurs, requiring huge costs for replacement. A sudden imbalance between the HPST inlet pressure and the IPST inlet pressure is caused, for example, by the closing operation of the ventilator valve 66 at the start of the steam turbine 30 or the abnormal opening operation of the high-pressure steam turbine bypass valve 63 or the intermediate-pressure steam turbine bypass valve 65. In normal operation, the control device 100 monitors, for example, the main steam pressure (for example, the pressure upstream of the high-pressure main steam control valve 43) and performs pressure control so that the target steam pressure determined from the load of the gas turbine 10 is reached. In this case, for example, when the intermediate-pressure main steam rises above the target value due to the closing operation of the ventilator valve 66, the high-pressure main steam control valve 43 is opened to lower the main steam pressure. Then, the steam exhausted from the steam outlet of the high-pressure steam turbine 31 reaches the steam inlet 321 through the intermediate-pressure main steam lines 44 and 64. In this state, the IPST inlet pressure rises, resulting in thrust imbalance.

[0022] In this embodiment, the control device 100 adjusts the HPCV valve opening and the IPCV valve opening by changing the upper limit of the valve opening command value so that the balance between the HPST inlet pressure and the IPST inlet pressure falls within an allowable range. FIG. 2 shows an overview of the control by the control device 100 according to the HPST inlet pressure and the IPST inlet pressure. In FIG. 2, the horizontal axis represents the HPST inlet pressure and the vertical axis represents the IPST inlet pressure, and the corresponding relationship between the HPST inlet pressure and the IPST inlet pressure that makes the thrust force applied to the rotating shaft 36 appropriate is shown by a broken line as an equilibrium characteristic. In FIG. 2, the white area A1 is the desired operating area, and the shaded areas A2 and A3 are thrust imbalance areas. In the area A2 on the upper side of FIG. 2, the IPST inlet pressure is excessive, and in the area A3 on the lower side, the HPST inlet pressure is excessive. The control device 100 responds to the upper IPST inlet excessive pressure region A2 by throttling the IPCV, and operates with a target operating balance (targeting the balanced characteristics in the figure) by throttling the HPCV in the lower HPST inlet excessive pressure region A3.

[0023] 2 is a range of the relationship between the HPST inlet pressure and the IPST inlet pressure based on the equilibrium characteristic, which is the relationship between the HPST inlet pressure and the IPST inlet pressure that optimizes the thrust force applied to the rotating shaft 36. In this case, the region A1 (range) is a region sandwiched between an upper boundary B_IPST and a lower boundary B_HPST of the region A1 (range) when expressed in orthogonal coordinates with the HPST inlet pressure on the horizontal axis and the IPST inlet pressure on the vertical axis. The control device 100 adjusts the valve opening of the HPCV and the valve opening of the IPCV according to the HPST inlet pressure and the IPST inlet pressure based on the region A1 (range). In this case, the control device 100 adjusts the valve opening of the IPCV based on the upper boundary B_IPST side of the region A1 as a reference, and adjusts the valve opening of the HPCV based on the lower boundary B_HPST side.

[0024] The characteristics and regions shown in Figure 2 may be plotted with the IPST inlet pressure on the horizontal axis and the HPST inlet pressure on the vertical axis, in which case the upper and lower boundaries would be swapped.

[0025] Here, a configuration example of the control unit 102 will be described with reference to Fig. 3 and Fig. 4. Fig. 3 shows a configuration example of a calculation unit 200 that calculates a valve opening command value for the HPCV. Fig. 4 shows a configuration example of a calculation unit 400 that calculates a valve opening command value for the IPCV. The control unit 102 shown in Fig. 1 includes the calculation unit 200 shown in Fig. 3 and the calculation unit 400 shown in Fig. 4.

[0026] The calculation section 200 shown in FIG. 3 includes a valve opening upper limit calculation section 210, a valve opening calculation section 220, and a minimum value selector 230.

[0027] The valve opening calculation unit 220 includes a subtractor 221, a PI controller (proportional and integral controller) 222, and a maximum value selector 224. The subtractor 221 subtracts the high pressure main steam pressure (HP main steam pressure) from the high pressure main steam target pressure (HP main steam target pressure) to calculate the deviation of the HP main steam pressure from the target value. The PI controller 222 receives the deviation calculated by the subtractor 221 as an input and calculates a valve opening command value of the HPCV by PI action (proportional and integral action). The range of the valve opening command value is 0 to 100. The maximum value selector 224 outputs the larger of “0” 223 and the calculated value of the PI controller 222. When the calculated value of the PI controller 222 is 0 or more, the maximum value selector 224 outputs the calculated value of the PI controller 222. The HP main steam target pressure is determined, for example, from the load of the gas turbine 10 and the like as described above. The HP main steam pressure is the pressure upstream of the high pressure main steam control valve 43 measured by the pressure gauge 71. The valve opening calculation unit 220 adjusts the HPCV valve opening command value by feedback control so that the deviation between the HP main steam target pressure and the HP main steam pressure is eliminated. Note that the control element is not limited to PI operation, and may be PID operation (proportional integral differential operation) or may be replaced with a control element that uses a model such as a machine learning model.

[0028] The valve opening upper limit calculation unit 210 includes an HPST inlet pressure threshold calculation unit 211, a subtractor 212, and a PI controller 213. The valve opening upper limit calculation unit 210 calculates the upper limit of the HPCV valve opening. The valve opening upper limit calculated by the valve opening upper limit calculation unit 210 and the HPCV valve opening command value calculated by the valve opening calculation unit 220 are input to a minimum value selector 230, which outputs the smaller value. Therefore, the HPCV valve opening command value output by the calculation unit 200 is limited by the valve opening upper limit calculated by the valve opening upper limit calculation unit 210.

[0029] The HPST inlet pressure threshold calculation unit 211 calculates the HPST inlet pressure threshold based on the measured values ​​of the IPST inlet pressure and the HPST inlet pressure, using the boundary line B_HPST, which is the criterion for adjusting the HPCV valve opening described with reference to Fig. 2. The HPST inlet pressure threshold serves as the criterion for determining whether or not to start adjustment of the upper limit value (PI control), and also serves as a target value for the HPST input pressure when adjusting the upper limit value. For example, as shown in Fig. 5, if the IPST inlet pressure is PL1, the HPST inlet pressure threshold calculation unit 211 calculates the HPST inlet pressure corresponding to the intersection C10 with the boundary line B_HPST as the HPST inlet pressure threshold.

[0030] Subtractor 212 calculates the deviation of the HPST inlet pressure from the HPST inlet pressure threshold by subtracting the HPST inlet pressure from the HPST inlet pressure threshold. PI controller 213 uses the deviation calculated by subtractor 212 as an input and calculates an upper limit of the HPCV valve opening degree by PI action (proportional integral action). Note that the control element is not limited to PI action, and may be PID action (proportional integral differential action) or may be replaced with a control element that uses a model such as a machine learning model.

[0031] As described above, the minimum value selector 230 receives the valve opening upper limit value calculated by the valve opening upper limit value calculation unit 210 and the HPCV valve opening command value calculated by the valve opening calculation unit 220, and outputs the smaller value.

[0032] The calculation section 400 shown in FIG. 4 includes a valve opening upper limit calculation section 410, a valve opening calculation section 420, and a minimum value selector 430.

[0033] The valve opening calculation unit 420 includes a subtractor 421, a PI controller (proportional integral controller) 422, and a maximum value selector 424. The subtractor 421 subtracts from an intermediate pressure main steam target pressure (IP main steam target pressure) Medium pressure main steam pressure(IP main steam pressure) is subtracted from the IP main steam pressure to calculate the deviation of the IP main steam pressure from the target value. The PI controller 422 receives the deviation calculated by the subtractor 421 and calculates the valve opening command value of the IPCV by PI operation. The range of the valve opening command value is 0 to 100. The maximum value selector 424 outputs the larger of “0” 423 and the calculated value of the PI controller 422. When the calculated value of the PI controller 422 is 0 or more, the maximum value selector 424 outputs the calculated value of the PI controller 422. The IP main steam target pressure is determined, for example, from the load of the gas turbine 10 and the like. The IP main steam pressure is the upstream pressure of the intermediate pressure main steam control valve 46 measured by the pressure gauge 73. The valve opening calculation unit 420 adjusts the IPCV valve opening command value by feedback control so that the deviation between the IP main steam target pressure and the IP main steam pressure is eliminated. The control element is not limited to a PI operation, but may be a PID operation or may be replaced with a control element that uses a model such as a machine learning model.

[0034] The valve opening upper limit calculation unit 410 includes an IPST inlet pressure threshold calculation unit 411, a subtractor 412, and a PI controller 413. The valve opening upper limit calculation unit 410 calculates the upper limit of the IPCV valve opening. The valve opening upper limit calculated by the valve opening upper limit calculation unit 410 and the IPCV valve opening command value calculated by the valve opening calculation unit 420 are input to a minimum value selector 430, which outputs the smaller value. Therefore, the IPCV valve opening command value output by the calculation unit 400 is limited by the valve opening upper limit calculated by the valve opening upper limit calculation unit 410.

[0035] The IPST inlet pressure threshold calculation unit 411 calculates the IPST inlet pressure threshold based on the measured values ​​of the IPST inlet pressure and the HPST inlet pressure, using the boundary line B_IPST, which is the criterion for adjusting the valve opening of the IPCV described with reference to Fig. 2. The IPST inlet pressure threshold serves as the criterion for determining whether or not to start adjustment of the upper limit value (PI control), and also serves as a target value for the IPST input pressure when adjusting the upper limit value. For example, as shown in Fig. 6, if the HPST inlet pressure is PH1, the IPST inlet pressure threshold calculation unit 411 calculates the IPST inlet pressure corresponding to the intersection C20 with the boundary line B_IPST as the IPST inlet pressure threshold.

[0036] The subtractor 412 calculates the deviation of the IPST inlet pressure from the IPST inlet pressure threshold by subtracting the IPST inlet pressure from the IPST inlet pressure threshold. The PI controller 413 receives the deviation calculated by the subtractor 412 and calculates the upper limit of the IPCV valve opening degree by PI action (proportional integral action). Note that the control element is not limited to the PI action, and may be replaced with a PID action (proportional integral derivative action) or a control element using a model such as a machine learning model.

[0037] As described above, the minimum value selector 430 inputs the valve opening upper limit value calculated by the valve opening upper limit value calculation unit 410 and the valve opening command value of the IPCV calculated by the valve opening calculation unit 420, and outputs the smaller value.

[0038] (Action and effect) As described above, according to the control device, control method, and system disclosed herein, the HPCV valve opening and IPCV valve opening can be adjusted so that the corresponding relationship between the HPST inlet pressure and the IPST inlet pressure is appropriate, and therefore the thrust force caused by an imbalance between the HPST inlet pressure and the IPST inlet pressure in the steam turbine 30 can be controlled within an allowable value.

[0039] Furthermore, according to this embodiment, even if an event occurs in which the pressure in the system rises (or falls) transiently and the balance is disturbed, such as during start-up of the steam turbine 30, load rejection, runback, load change, ventilator valve closing operation, or abnormal opening of the HP turbine bypass valve, the ST can continue to operate with a normal thrust balance.

[0040] <Second embodiment> A control device according to a second embodiment of the present disclosure will be described with reference to Fig. 7 and Fig. 8. Fig. 7 is a schematic diagram for explaining an operation example of the control device according to the second embodiment of the present disclosure. Fig. 8 is a flowchart showing an operation example of the control device according to the second embodiment of the present disclosure.

[0041] The configuration of the system 1 according to the second embodiment is basically the same as the configuration of the system 1 according to the first embodiment. However, in the second embodiment, the operation of the control unit 102 included in the control device 100 shown in FIG. 1 is partially different from that in the first embodiment.

[0042] An example of the operation of the control unit 102 of the control device 100 of the second embodiment will be described with reference to FIG. 7. In the second embodiment, the control unit 102 selects one of three different modes (1) during normal control, (2) during standby for back pressure control, and (3) during back pressure control to adjust the upper limit value of the HPCV valve opening degree and the upper limit value of the IPCV valve opening degree. FIG. 7 shows an example of the upper limit value of the HPCV opening degree command value, the HPCV opening degree command value, and the time change of the HPST inlet pressure at the start of the gas turbine 10. In the example shown in FIG. 7, after the start, the mode changes in the order of (1) during normal control, (2) during standby for back pressure control, and (3) during back pressure control. Note that the back pressure control is a control that adjusts the upper limit value by the HPST inlet pressure, which is the pressure downstream of the HPCV, and is the same as the control of the upper limit value in the first embodiment. The control based on the pressure downstream of the HPCV is called the back pressure control. The control of the upper limit of the IPCV opening command value is similar to the control of the upper limit of the HPCV opening command value, and the control of the upper limit of the HPCV opening command value will be described below as an example.

[0043] (1) During normal control: When the steam turbine 30 starts up, the heat input to the heat recovery boiler 20 increases along with the load on the gas turbine 10, and therefore the amount of steam increases accordingly, so during normal control the target value of the HPCV valve position command is increased, for example, as a function of the load on the gas turbine 10, to gradually open the HPCV. When the HP and IP side ST inlet pressures are within a preset normal range, the upper limit of the valve position command is kept constant at the maximum opening.

[0044] (2) During back pressure control standby: When the HPST inlet pressure approaches the HPST inlet pressure threshold determined by the boundary line B_HPST shown in Fig. 5 and the HPST inlet pressure exceeds the HPST inlet pressure threshold, the valve opening upper limit is changed to the current valve opening + α1. By keeping the upper limit at the current valve opening + α1, it becomes possible to close the valve quickly when the HPST inlet pressure is about to deviate from the allowable range.

[0045] (3) During back pressure control: When an event such as the closing operation of the ventilator valve 66 or the abnormal opening of the high pressure steam turbine bypass valve 63 occurs and the pressure in the system suddenly changes and is about to deviate from the range, the HPCV valve is closed based on the upper limit value output by the valve opening upper limit value calculation unit 210, as in the first embodiment, and the correspondence relationship between the HPST inlet pressure and the IPST inlet pressure can be kept within the normal range.

[0046] In the example shown in Fig. 7, normal control is executed from time t0 to t1. At time t1, the HPST input pressure becomes equal to or higher than an HPST input pressure threshold (not shown), and the rear pressure control standby state is entered. Then, at time t2, the HPST input pressure becomes equal to or higher than the HPST target pressure, and the rear pressure control is executed.

[0047] During normal control, the upper limit of the HPCV valve opening command value indicated by the two-dot chain line is constant at the maximum opening. Also, during normal control, the HPCV valve opening command value is set toward the HPST target pressure indicated by the one-dot chain line, and the HPST input pressure rises. When back pressure control is on standby, the upper limit of the HPCV valve opening command value is set to the current valve opening + α1%. Then, during back pressure control, PI control of the upper limit is started, and the HPCV valve opening is suppressed at the upper limit. Note that the HPCV valve opening in the case of front pressure control without back pressure control continues to rise, for example, as indicated by the dashed line. Here, front pressure control is control based on the pressure upstream of the HPCV.

[0048] Next, the flow of processing in the control unit 102 of the control device 100 of the second embodiment will be described with reference to Fig. 8. In Fig. 8, the HPCV is represented as an HP governor valve, and the IPCV is represented as an IP governor valve. The control unit 102 of the second embodiment executes, in parallel, the adjustment of the valve opening degree of the HPCV (HP governor valve) by the processing of steps S11 to S18 and the adjustment of the valve opening degree of the IPCV (IP governor valve) by the processing of steps S21 to S28.

[0049] When the control is started, the control unit 102 calculates the HPST inlet pressure threshold based on the IPST inlet pressure, using the boundary line B_HPST in the correspondence relationship between the HPST input pressure and the IPST input pressure shown in FIG. 5 as a reference (step S11). The process of step S11 is executed at a predetermined time interval. Next, the control unit 102 judges whether the HPST inlet pressure is equal to or higher than the HPST inlet pressure threshold (step S12). If the HPST inlet pressure is not equal to or higher than the HPST inlet pressure threshold (step S12: NO), the control unit 102 sets the valve opening upper limit to a maximum value and executes the HP governor valve normal control (step S13), and returns to step S11. If the HPST inlet pressure is equal to or higher than the HPST inlet pressure threshold (step S12: YES), the control unit 102 sets the valve opening upper limit to the current opening + α1, transitions to an HP governor valve back pressure control standby state (step S14), and judges whether the HPST inlet pressure is equal to or higher than the target pressure (step S15).

[0050] If the HPST inlet pressure is not equal to or greater than the target pressure (step S15: NO), the control unit 102 returns the process to step S11. If the HPST inlet pressure is equal to or greater than the target pressure (step S15: YES), the control unit 102 executes HP governor valve post pressure control (step S16) and determines whether the HPST inlet pressure is less than the HPST inlet pressure threshold (step S17). If the HPST inlet pressure is not less than the HPST inlet pressure threshold (step S17: NO), the control unit 102 calculates the HPST inlet pressure threshold (step S18) and executes the process of step S16 after a predetermined time. If the HPST inlet pressure is less than the HPST inlet pressure threshold (step S17: YES), the control unit 102 returns the process to step S11.

[0051] In addition, when the control is started, in parallel with the above process, the control unit 102 calculates the IPST inlet pressure threshold based on the HPST inlet pressure using the boundary line B_IPST in the correspondence relationship between the HPST input pressure and the IPST input pressure shown in FIG. 6 as a reference (step S21). The process of step S21 is executed at a predetermined time interval. Next, the control unit 102 judges whether the IPST inlet pressure is equal to or higher than the IPST inlet pressure threshold (step S22). If the IPST inlet pressure is not equal to or higher than the IPST inlet pressure threshold (step S22: NO), the control unit 102 sets the valve opening upper limit to a maximum value and executes the IP governor valve normal control (step S23), and returns to step S21. If the IPST inlet pressure is equal to or higher than the IPST inlet pressure threshold (step S22: YES), the control unit 102 sets the valve opening upper limit to the current opening + α2, transitions to an IP governor valve back pressure control standby state (step S24), and judges whether the IPST inlet pressure is equal to or higher than the target pressure (step S25). Note that α2 is a constant value on the IPST inlet pressure side corresponding to α1.

[0052] If the IPST inlet pressure is not equal to or greater than the target pressure (step S25: NO), the control unit 102 returns the process to step S21. If the IPST inlet pressure is equal to or greater than the target pressure (step S25: YES), the control unit 102 executes IP governor valve post pressure control (step S26) and determines whether the IPST inlet pressure is less than the IPST inlet pressure threshold (step S27). If the IPST inlet pressure is not less than the IPST inlet pressure threshold (step S27: NO), the control unit 102 calculates the IPST inlet pressure threshold (step S28) and executes the process of step S26 after a predetermined time. If the IPST inlet pressure is less than the IPST inlet pressure threshold (step S27: YES), the control unit 102 returns the process to step S21.

[0053] As described above, according to the control device, control method, and system disclosed herein, the HPCV valve opening and IPCV valve opening can be adjusted so that the corresponding relationship between the HPST inlet pressure and the IPST inlet pressure is appropriate, and therefore the thrust force caused by an imbalance between the HPST inlet pressure and the IPST inlet pressure in the steam turbine 30 can be controlled within an allowable value.

[0054] According to the present embodiment, the control unit 102 selectively sets the upper limit of the HPCV valve opening degree and the IPCV valve opening degree to the maximum value of each valve opening degree, the HPST inlet pressure, and IPST Inlet Pressure The upper limit of the HPCV valve opening and the upper limit of the IPCV valve opening are adjusted by increasing the current values ​​of the HPST inlet pressure and the IPST inlet pressure by a predetermined amount (α1 or α2) or by setting the respective values ​​based on the region A1. With this configuration, the valves can be quickly closed when the HPST inlet pressure or the IPST inlet pressure is about to deviate from the allowable range.

[0055] <Third embodiment> A control device according to a third embodiment of the present disclosure will be described with reference to Fig. 9. Fig. 9 is a schematic diagram for explaining the control device according to the third embodiment of the present disclosure.

[0056] The third embodiment presents a procedure for determining the thrust balance target range (area A1 in FIG. 2) shown in the first embodiment. In the third embodiment, the area A1 (range) is determined by the following procedure.

[0057] (S1) Find multiple points C1 where the HPST inlet pressure and IPST inlet pressure combination balances the thrust forces of the HPST and IPST.

[0058] (S2) Find the maximum allowable thrust force range (HP side bias, IP side bias) when the ST inlet pressure is biased to the HP side or IP side from point C1 where the thrust forces are balanced. In the example shown in Figure 9, find the range where the HPST inlet pressure at combination point C1 is biased by ΔHP1 and ΔHP2, and the range where the IPST inlet pressure at point C1 is biased by ΔIP1 and ΔIP2. Find the range where the HPST inlet pressure is biased and the IPST inlet pressure is biased in the same way for each point C1. Then, determine the area A1a between the boundary lines M_HPST and M_IPST shown by dashed lines so that the range where the HPST inlet pressure is biased and the range where the IPST inlet pressure is biased at each point C1 are not exceeded.

[0059] (S3) The boundary line B_HPST and boundary line B_IPST of the region A1 are determined by subtracting a constant γ (adjustment term) from the boundary line M_HPST and boundary line M_IPST between the HPST inlet pressure and the IPST inlet pressure obtained in (S2).

[0060] 2 corresponds to the region A1a where the thrust force is equal to or less than the maximum allowable value when either the HPST inlet pressure or the IPST inlet pressure is biased from the combination point C1 of the HPST inlet pressure and the IPST inlet pressure where the thrust force due to the HPST and the thrust force due to the IPST are balanced. Also, the control unit 102 adjusts the HPCV valve opening and the IPCV valve opening in accordance with the HPST inlet pressure and the IPST inlet pressure, using the region A1 (range) obtained by subtracting a predetermined constant γ from the boundary of the region A1a toward the inside of the region A1a as a reference.

[0061] According to this embodiment, it is possible to suppress the thrust force within a restricted range.

[0062] (Other embodiments) Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the gist of the present disclosure are also included.

[0063] Computer Configuration FIG. 10 is a schematic block diagram illustrating a computer configuration according to at least one embodiment. The computer 90 comprises a processor 91, a main memory 92, a storage 93, and an interface 94. The above-mentioned control device 100 is implemented in a computer 90. The operations of the above-mentioned processing units are stored in the form of a program in a storage 93. The processor 91 reads the program from the storage 93, loads it in a main memory 92, and executes the above-mentioned processing in accordance with the program. The processor 91 also secures storage areas in the main memory 92 corresponding to the above-mentioned storage units in accordance with the program.

[0064] The program may be for realizing a part of the functions to be performed by the computer 90. For example, the program may be for realizing the functions by combining with other programs already stored in the storage or by combining with other programs implemented in other devices. In another embodiment, the computer may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions to be realized by the processor may be realized by the integrated circuit.

[0065] Examples of the storage 93 include a hard disk drive (HDD), a solid state drive (SSD), a magnetic disk, a magneto-optical disk, a compact disc read only memory (CD-ROM), a digital versatile disc read only memory (DVD-ROM), and a semiconductor memory. The storage 93 may be an internal medium directly connected to the bus of the computer 90, or an external medium connected to the computer 90 via an interface 94 or a communication line. In addition, when the program is distributed to the computer 90 via a communication line, the computer 90 that receives the program may load the program into the main memory 92 and execute the above-mentioned process. In at least one embodiment, the storage 93 is a non-transitory tangible storage medium.

[0066] <Additional Notes> The control device 100 described in each embodiment can be understood, for example, as follows.

[0067] (1) The control device 100 according to the first embodiment includes an acquisition unit 101 that acquires, as a first inlet pressure, a pressure value of the first steam on the first inlet side as viewed from the first control valve of a first turbine (high-pressure steam turbine 31) that rotates using a first steam (high-pressure steam) supplied from a first inlet (steam inlet 311) via a first control valve (high-pressure main steam control valve 43), and acquires, as a second inlet pressure, a pressure value of the second steam on the second inlet side as viewed from the second control valve of a second turbine (intermediate-pressure steam turbine 32) that rotates on the same rotating shaft 36 as the first turbine using a second steam supplied from a second inlet (steam inlet 321) via a second control valve (intermediate-pressure main steam control valve 46), and a control unit 102 that adjusts a valve aperture of the first control valve and a valve aperture of the second control valve according to the first inlet pressure and the second inlet pressure. According to this embodiment and each of the following embodiments, the thrust force in the steam turbine can be controlled within a permissible value.

[0068] (2) The control device 100 of a second aspect is the control device of (1), in which the control unit 102 adjusts the valve aperture of the first control valve and the valve aperture of the second control valve in response to the first inlet pressure and the second inlet pressure, based on a predetermined range (area A1) for the correspondence based on the correspondence relationship (balanced characteristic) between the first inlet pressure and the second inlet pressure in which the thrust force applied to the rotating shaft 36 is appropriate. According to this aspect, the valve aperture of the first control valve and the valve aperture of the second control valve can be adjusted so that the correspondence relationship between the first inlet pressure and the second inlet pressure becomes appropriate, and therefore the thrust force caused by the imbalance between the first inlet pressure and the second inlet pressure in the steam turbine 30 can be controlled within an allowable value.

[0069] (3) A third aspect of the control device 100 is the control device 100 of (2), wherein, when the range (area A1) is represented in orthogonal coordinates with one of the first inlet pressure and the second inlet pressure on the horizontal axis and the other of the first inlet pressure and the second inlet pressure on the vertical axis, the control unit 102 adjusts one of the first control valve and the second control valve based on an upper boundary (B_IPST) side of the range as a reference, and adjusts the other of the first control valve and the second control valve based on a lower boundary (B_HPST) side of the range as a reference.

[0070] (4) A fourth aspect of the control device 100 is the control device 100 of (2) or (3), and the range (region A1) corresponds to a region A1a in which the thrust force is equal to or less than a maximum allowable value when either the first inlet pressure or the second inlet pressure is biased from a combination (C1) of the first inlet pressure and the second inlet pressure in which the thrust force due to the first turbine and the thrust force due to the second turbine are balanced.

[0071] (5) A fifth aspect of the control device 100 is the control device 100 of (4), wherein the control unit 102 adjusts the valve opening degree of the first control valve and the valve opening degree of the second control valve in accordance with the first inlet pressure and the second inlet pressure, with the range (area A1) being an area A1 obtained by subtracting a predetermined constant γ from the boundary of the area A1a toward the inside of the area A1a.

[0072] (6) The control device 100 of a sixth aspect is the control device 100 of any one of (2) to (5), in which the control unit 102 adjusts the valve aperture of the first control valve and the valve aperture of the second control valve in response to the first inlet pressure and the second inlet pressure by adjusting an upper limit value of the valve aperture of the first control valve and an upper limit value of the valve aperture of the second control valve. , No. This can be easily combined with feedback control of the pressure upstream of the first control valve by the first control valve, feedback control of the pressure upstream of the second control valve by the second control valve, etc.

[0073] (7) A seventh aspect of the control device 100 is the control device 100 of (6), in which the control unit 102 adjusts the upper limit values ​​of the valve aperture of the first control valve and the valve aperture of the second control valve by selectively setting the upper limit values ​​of the valve aperture of the first control valve and the valve aperture of the second control valve to the maximum value of each valve aperture, each value increased by a predetermined amount (α1, α2) from the current values ​​of the first inlet pressure and the second inlet pressure, or each value based on the range (area A1). According to this aspect, the responsiveness of control based on the upper limit values ​​can be improved. [Industrial Applicability]

[0074] According to each aspect of the present invention, the thrust force in a steam turbine can be controlled within an allowable value. [Explanation of symbols]

[0075] 1. System 10. Gas turbine 11...Compressor 12…Combustor 13…Turbine 14...Fuel flow control valve 20...Waste heat recovery boiler 21…High pressure steam generator 22...Medium pressure steam generator 23...Reheating section 24…Low pressure steam generating section 30…Steam turbine 31...High pressure steam turbine 32...Intermediate pressure steam turbine 33...Low pressure steam turbine 34…Generator 35…Condenser 41…High pressure main steam line 42...High pressure steam stop valve 43...High pressure main steam control valve 44, 61, 62...Medium pressure main steam line 45...Medium pressure steam stop valve 46...Medium pressure main steam control valve 51…Low pressure main steam line 52...Low pressure steam stop valve 53...Low pressure main steam control valve 54...Intermediate pressure turbine exhaust line 55…Water supply line 56…Exhaust line 63...High pressure steam turbine bypass valve 65...Intermediate pressure steam turbine bypass valve 66...Ventilator valve 71, 72, 73, 74, 75, 76…Pressure gauge 100...Control device 101…Acquisition Department 102...Control unit

Claims

1. an acquisition unit that acquires, as a first inlet pressure, a pressure value of the first steam on the first inlet side as viewed from the first control valve of a first turbine that rotates using first steam supplied from a first inlet via a first control valve, and acquires, as a second inlet pressure, a pressure value of the second steam on the second inlet side as viewed from the second control valve of a second turbine that rotates on the same rotary shaft as the first turbine using second steam supplied from a second inlet via a second control valve; a control unit that adjusts a valve opening degree of the first control valve and a valve opening degree of the second control valve in response to the first inlet pressure and the second inlet pressure; Equipped with the control unit adjusts a valve aperture of the first control valve and a valve aperture of the second control valve in response to the first inlet pressure and the second inlet pressure, based on a predetermined range of the correspondence relationship between the first inlet pressure and the second inlet pressure in which a thrust force applied to the rotating shaft is appropriate, when the range is represented in orthogonal coordinates with one of the first inlet pressure and the second inlet pressure on the horizontal axis and the other of the first inlet pressure and the second inlet pressure on the vertical axis, the control unit adjusts one of the first control valve and the second control valve in a direction to reduce the pressure based on an upper boundary line side of the range, and adjusts the other of the first control valve and the second control valve in a direction to reduce the pressure based on a lower boundary line side of the range. Control device.

2. The range corresponds to a region in which the thrust force is equal to or less than a maximum allowable value when one of the first inlet pressure or the second inlet pressure is biased from a combination of the first inlet pressure and the second inlet pressure in which the thrust force by the first turbine and the thrust force by the second turbine are balanced. The control device according to claim 1 .

3. The control unit adjusts the valve opening degree of the first control valve and the valve opening degree of the second control valve in response to the first inlet pressure and the second inlet pressure, within a range obtained by subtracting a predetermined constant from a boundary of the range toward the inside of the range. The control device according to claim 2.

4. The control unit adjusts an upper limit value of a valve opening degree of the first control valve and an upper limit value of a valve opening degree of the second control valve, thereby adjusting the valve opening degree of the first control valve and the valve opening degree of the second control valve in response to the first inlet pressure and the second inlet pressure. The control device according to any one of claims 1 to 3.

5. The control unit adjusts the upper limit value of the valve opening degree of the first control valve and the upper limit value of the valve opening degree of the second control valve by selectively setting each upper limit value of the valve opening degree of the first control valve and the second control valve to any one of a maximum value of each valve opening degree, each value increased by a predetermined amount from each current value of the first inlet pressure and the second inlet pressure, or each value based on the range. The control device according to claim 4.

6. acquiring, as a first inlet pressure, a pressure value of the first steam on the first inlet side as viewed from the first control valve of a first turbine that rotates using first steam supplied from a first inlet via a first control valve, and acquiring, as a second inlet pressure, a pressure value of the second steam on the second inlet side as viewed from the second control valve of a second turbine that rotates on the same rotary shaft as the first turbine using second steam supplied from a second inlet via a second control valve; adjusting a valve opening degree of the first control valve and a valve opening degree of the second control valve in response to the first inlet pressure and the second inlet pressure, in the adjusting step, a valve aperture of the first control valve and a valve aperture of the second control valve are adjusted in response to the first inlet pressure and the second inlet pressure, based on a predetermined range of the correspondence relationship between the first inlet pressure and the second inlet pressure in which a thrust force applied to the rotating shaft is appropriate; In the adjusting step, when the range is represented by an orthogonal coordinate system with one of the first inlet pressure and the second inlet pressure on the horizontal axis and the other of the first inlet pressure and the second inlet pressure on the vertical axis, one of the first control valve and the second control valve is adjusted in a direction to reduce the pressure based on an upper boundary line side of the range, and the other of the first control valve and the second control valve is adjusted in a direction to reduce the pressure based on a lower boundary line side of the range. Control methods.

7. A first control valve; A second control valve; a first turbine that rotates using first steam supplied from a first inlet via the first control valve; a second turbine that rotates on the same rotary shaft as the first turbine by using second steam supplied from a second inlet via the second control valve; an acquisition unit that acquires a pressure value of the first steam on the first inlet side as viewed from the first control valve as a first inlet pressure, and acquires a pressure value of the second steam on the second inlet side as viewed from the second control valve as a second inlet pressure; a control unit that adjusts a valve opening degree of the first control valve and a valve opening degree of the second control valve in response to the first inlet pressure and the second inlet pressure; Equipped with the control unit adjusts a valve aperture of the first control valve and a valve aperture of the second control valve in response to the first inlet pressure and the second inlet pressure, based on a predetermined range of the correspondence relationship between the first inlet pressure and the second inlet pressure in which a thrust force applied to the rotating shaft is appropriate, when the range is represented in orthogonal coordinates with one of the first inlet pressure and the second inlet pressure on the horizontal axis and the other of the first inlet pressure and the second inlet pressure on the vertical axis, the control unit adjusts one of the first control valve and the second control valve in a direction to reduce the pressure based on an upper boundary line side of the range, and adjusts the other of the first control valve and the second control valve in a direction to reduce the pressure based on a lower boundary line side of the range. system.

8. An acquisition unit which acquires, as a first inlet pressure, the pressure value of the first steam on the first inlet side as viewed from the first control valve of a first turbine which rotates using first steam supplied from a first inlet via a first control valve, and acquires, as a second inlet pressure, the pressure value of the second steam on the second inlet side as viewed from the second control valve of a second turbine which rotates on the same rotating shaft as the first turbine using second steam supplied from a second inlet via a second control valve; a control unit that adjusts a valve opening degree of the first control valve and a valve opening degree of the second control valve in response to the first inlet pressure and the second inlet pressure, the control unit adjusts a valve aperture of the first control valve and a valve aperture of the second control valve in response to the first inlet pressure and the second inlet pressure, based on a predetermined range of the correspondence relationship between the first inlet pressure and the second inlet pressure in which a thrust force applied to the rotating shaft is appropriate, the control unit adjusts an upper limit value of a valve aperture of the first control valve and an upper limit value of a valve aperture of the second control valve in response to the first inlet pressure and the second inlet pressure, the control unit selectively adjusts the upper limit values ​​of the valve opening degree of the first control valve and the valve opening degree of the second control valve to any one of the maximum values ​​of the valve opening degrees, values ​​increased by a predetermined amount from the current values ​​of the first inlet pressure and the second inlet pressure, or values ​​based on the range. Control device.

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