Power generation turbine control device and method

Abstract

To suppress fluctuation of a system frequency.SOLUTION: A turbine control device 11 generates an opening control signal So of a regulating valve for controlling a rotation speed of a turbine on the basis of an actual rotation speed of the turbine in a power-generating plant and a governor setting signal S set in accordance with electric energy required by a power generator connected to the turbine via a turbine shaft. The turbine control device 11 includes a delay correction limit circuit 117 for suppressing the governor setting signal S in the case where a difference between the governor setting signal S and the opening control signal So is increased when the governor setting signal S is amplified.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a turbine control device and method for power generation.

Background Art

[0002] A turbine in a power generation plant is controlled by a turbine control device. The turbine control device adjusts the steam flow rate supplied to the turbine by opening and closing a control valve provided in a pipe connecting a boiler and the turbine.

[0003] Patent Document 1 discloses a turbine control device including a non-linear governor ratio calculation unit that calculates a rotational speed deviation signal and a non-linear function output.

[0004] Patent Document 2 discloses a turbine control device including a speed control unit that adjusts an adjustment parameter of the rotational speed of a turbine in a power generation plant based on system information.

[0005] These technologies are governor-free improvement technologies that contribute to the system stabilization of a turbine control device for power generation.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The turbine control devices of the above patent documents improve the controllability of governor-free operation by adjusting the non-linear governor ratio inside the turbine control device.

[0008] Incidentally, in recent years, there has been a trend towards increasing power generation using renewable energy sources such as solar and wind power. As a result, the grid frequency has begun to fluctuate (in particular, the frequency (equivalent to turbine rotation speed) gradually increases and then remains high). Consequently, there have been cases where the output signal of the nonlinear adjustment rate and the load setting command become conflicting operation commands, making it impossible to maintain the controllability of governor-free operation.

[0009] Specifically, during the process in which the automatic output control device attempts to increase power output by increasing the load setting command to the turbine control device and increasing the throttle control command, a phenomenon can occur where the grid frequency slowly increases. At this time, the regulating rate (governor control) of the turbine control device operates in the opposite direction, decreasing the throttle control command. Therefore, the automatic output control device and the governor of the turbine control device operate in conflicting directions.

[0010] To stabilize the power grid, output control is performed from the central power station and from the automatic output control devices within the power plant. However, compared to the high-speed calculation and control of the turbine control system's regulating rate (governor), these control methods take longer, and there may be periods when their control operations conflict with those of the turbine control system's regulating rate (governor).

[0011] This invention has been made in view of the above-mentioned problems, and aims to suppress fluctuations in system frequency. [Means for solving the problem]

[0012] To achieve the above objective, the present invention provides a turbine control device that generates an opening control signal for a shadow valve that controls the rotational speed of a turbine in a power plant, based on the actual rotational speed of the turbine and a governor setting signal set according to the amount of power required by a generator connected to the turbine via the turbine shaft, and further comprises a correction unit that suppresses the governor setting signal when the difference between the governor setting signal and the opening control increases. [Effects of the Invention]

[0013] According to the present invention, fluctuations in the system frequency are suppressed.

Brief Description of the Drawings

[0014] [Figure 1] Schematic configuration diagram of a power generation plant. [Figure 2] Schematic block diagram of a turbine control device. [Figure 3] Flowchart of the regulating load control process. [Figure 4] Operation time chart of a power generation plant by a conventional turbine control device. [Figure 5] Operation time chart of a power generation plant by a turbine control device according to an embodiment.

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of a turbine control device and method for power generation according to the present invention will be described with reference to the drawings. Note that the embodiments described below do not limit the invention according to the claims, and not all of the elements and combinations thereof described in the embodiments are essential for the solution means of the invention.

[0016] The above object can be achieved by adding a function of automatically adjusting, without contradiction, a signal from an output control command signal and control at a regulation rate (governor) using a signal in a turbine control device that is operating at high speed.

[0017] FIG. 1 is a schematic configuration diagram of a power generation plant.

[0018] The power generation plant 100 is, for example, a thermal power generation plant. The power generation plant 100 includes a boiler 1, a steam pipe 2, a control valve 3, a turbine 4, a generator 5, a condenser 6, a condensate pump 7, and a turbine control device 11 (an electro-hydraulic governor control device) as an example of a “turbine control device for power generation”.

[0019] The boiler 1 is connected to the turbine 4 via the steam pipe 2. A control valve 3 is provided in the middle of the steam pipe 2. The control valve 3 is opened and closed based on an opening limit signal described later. Thereby, the control valve 3 controls the steam flow rate flowing from the boiler 1 into the turbine 4. That is, the control valve 3 controls the rotational speed of the turbine 4.

[0020] The turbine 4 is connected to the generator 5 via the turbine shaft 8. The turbine 4 may be a steam turbine.

[0021] The generator 5 is connected to other power generation systems via a transmission line not shown. These generator 5, transmission line, and other power generation systems constitute a power grid.

[0022] The turbine control device 11 is connected to the grid information source 20 via a network, and acquires grid information regarding the operating status of the power grid including the power generation plant 100 from the grid information source 20. The grid information may include, for example, the power generation amount of other power generation systems that utilize natural energy such as solar power generation and wind power generation.

[0023] Next, the operation of the power generation plant 100 will be described. The steam generated in the boiler 1 is led to the steam pipe 2, passes through the control valve 3, and generates torque in the turbine 4. The turbine 4 generates electric power in the generator 5.

[0024] The steam discharged from the turbine 4 is condensed in the condenser 6, becomes water, passes through the condensate pump 7, and is sent back to the boiler 1 again. The water sent to the boiler 1 is heated to generate steam. The generated steam is sent out from the boiler 1.

[0025] A gear 9 is provided at one end of the turbine shaft 8 (the left end on the turbine 4 side in FIG. 1). A speed sensor 10 is arranged opposite to the gear 9. The speed sensor 10 detects the rotational speed (actual rotational speed) of the gear 9 and generates a pulse signal. The speed sensor 10 transmits the generated pulse signal to the turbine control device 11.

[0026] The load and speed of the turbine 4 are controlled by the turbine control device 11. The turbine control device 11 controls the load and speed of the turbine 4 by adjusting the throttle valve 3. Note that other detailed valves, etc., have been omitted.

[0027] Next, the turbine control device 11's speed control load control process (steam flow rate control process) for the turbine 4 will be explained with reference to Figures 2 and 3.

[0028] Figure 2 is a schematic block diagram of the turbine control device. Figure 3 is a flowchart of the speed governor load control process.

[0029] The turbine control device 11 includes a subtraction unit 111, a variable adjustment rate calculation unit 112, a gain multiplication unit 113 as an example of a "speed adjustment signal generation unit", an addition unit 114, a load limiter 115, and a low value priority unit (hereinafter referred to as LVG (Low Value Gate)) 116 as an example of a "selection unit". Furthermore, the turbine control device 11 includes a delay correction limit circuit 117 as an example of a "correction unit".

[0030] The turbine control device 11 acquires the actual rotational speed detected by the speed sensor 10 (S31).

[0031] Next, the turbine control device 11 acquires system information from the system information supply source 20 (S32). The turbine control device 11 may perform the process in S32 before the process in S31, or it may perform the process in S32 in parallel with the process in S31.

[0032] Next, the subtraction unit 111 subtracts the actual rotational speed from the preset rated rotational speed to calculate the speed deviation ΔV (S33). The rated rotational speed information may be stored in the memory unit of the turbine control device 11 in advance.

[0033] Next, the variable adjustment rate calculation unit 112 calculates the variable adjustment rate Rv based on the actual rotational speed and system information (S34). The variable adjustment rate Rv is a parameter that changes over time.

[0034] Next, the gain multiplication unit 113 multiplies the speed deviation ΔV calculated in S33 by the reciprocal of the variable adjustment ratio Rv calculated in S34, i.e., the variable gain Gv (=1 / Rv), to calculate the speed adjustment signal ΔSv (=Gv·ΔV) (S35).

[0035] Next, the adder 114 adds the governor setting signal S output from an automatic output control device (not shown) to the speed adjustment signal ΔSv (=Gv·ΔV) calculated in S35 to calculate the speed control load control signal Sv (=S+ΔSv) (S36). The governor setting signal S is set according to the amount of power required by the generator 5 and may be stored in advance in the memory unit of the turbine control device 11.

[0036] Next, the LVG116 outputs the lower of the speed control load control signal Sv (=S+ΔSv) and the load control signal from the load limiter 115 as an opening degree limit signal So to control the opening degree of the throttle valve 3 and the delay correction limit circuit 117 (S37).

[0037] Next, the turbine control device 11 controls the opening degree of the throttle valve 3, i.e., the rotational speed (system frequency) of the turbine 4, based on the opening degree limit signal So (S38).

[0038] Next, the delay correction limit circuit 117 calculates the difference (So-S) between the governor setting signal S and the opening limit signal So, and determines whether the calculated difference increases (So-S>0) (S39).

[0039] If the result of the judgment in S39 is true (S39:YES), the delay correction limit circuit 117 executes the delay correction limit process described later. If the result of the judgment in S39 is false (S39:NO), the delay correction limit circuit 117 terminates the speed control load control process.

[0040] Next, we will explain the delay correction limiting process.

[0041] The delay correction limiting circuit 117 determines that the governor setting signal S and the opening degree limiting signal So are in opposing control directions if, when the governor setting signal S is amplified, the change in the opening degree limiting signal So output by the LVG 116 is in the decreasing direction, or if the increase in the opening degree limiting signal So is small. At this time, the opening degree limiting signal So output by the LVG 116 is subtracted by the speed adjustment signal ΔSv output by the gain multiplication unit 113.

[0042] If the above-mentioned conflicting conditions are determined, the delay correction limit circuit 117 compares the opening degree limit signal So output by the LVG 116 with the governor setting signal S. If the difference (So-S) exceeds a threshold, it applies limit control to the governor setting signal S to suppress the output of a signal increase beyond a certain level.

[0043] Figure 4 is an operating time chart of a power plant using a conventional turbine control system. In Figure 4, the horizontal axis represents time, and the vertical axis represents the output of turbine rotation speed [%] (solid line), governor setting signal S (dashed line), and throttle valve opening (opening limit signal So) (dotted line).

[0044] Conventional turbine control devices do not have a delay correction limit circuit 117. In the case of conventional turbine control devices, as shown in Figure 4, the governor setting signal S is output as is without correction. As a result, the governor setting signal S increases, and the opening limit signal So output from LVG116 decreases, resulting in a state where the governor setting signal S and the opening limit signal So are in conflict.

[0045] Figure 5 is an operating time chart of a power plant using a turbine control device according to an embodiment. In Figure 5, as in Figure 4, the horizontal axis represents time, and the vertical axis represents the output of turbine rotation speed [%] (solid line), governor setting signal S (dashed line), and throttle valve opening (opening limit signal So) (dotted line).

[0046] As shown in Figure 5, the delay correction limiting circuit 117 of the turbine control device 11 either does not output a value above the threshold or delays the value of the governor setting signal S if the governor setting signal S exceeds the threshold. In this way, the delay correction limiting circuit 117 suppresses the difference (Sо-S) between the governor setting signal S and the opening limiting signal So (output value to the control valve 3) output from the LVG 116 to reduce it.

[0047] In this configuration, the turbine control device 11 generates an opening control signal So for the throttle valve 3 that controls the rotational speed of the turbine 4, based on the actual rotational speed of the turbine 4 in the power plant 100 and a governor setting signal S set according to the amount of power required by the generator 5 connected to the turbine 4 via the turbine shaft 8. The turbine control device 11 includes a delay correction limiting circuit 117 that suppresses the governor setting signal S when the difference between the governor setting signal S and the opening control signal So increases when the governor setting signal S is amplified.

[0048] This makes it possible to suppress fluctuations in the rotational speed (system frequency) of the turbine 4 when the governor setting signal S and the opening control signal So are in conflict.

[0049] Furthermore, the delay correction limiting circuit 117 suppresses the governor setting signal S if the difference between the governor setting signal S and the opening control signal So exceeds a threshold. This allows for more appropriate suppression of fluctuations in the rotational speed (system frequency) of the turbine 4.

[0050] Furthermore, the turbine control device 11 includes a subtraction unit 111, a variable regulation rate calculation unit 112, a gain multiplication unit 113, an addition unit 114, and an LVG 116. The subtraction unit 111 calculates the speed deviation ΔV by subtracting the actual rotational speed from the rated rotational speed of the turbine 4. The variable regulation rate calculation unit 112 calculates the variable regulation rate Rv based on the actual rotational speed and system information regarding the operating status of the power system to which the power plant 100 is connected. The gain multiplication unit 113 generates a speed adjustment signal ΔSv based on the calculated speed deviation ΔV and variable regulation rate Rv. The addition unit 114 adds the governor setting signal S to the generated speed adjustment signal ΔSv to generate a speed control load control signal Sv. The LVG 116 outputs the lower of the generated speed control load control signal Sv and the load control signal from the load controller 115 as the opening control signal So. This makes it possible to suppress fluctuations in the rotational speed (system frequency) of the turbine 4 in response to changes in system information.

[0051] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are included.

[0052] In the above embodiment, an example was described in which the governor setting signal S is suppressed when the difference (So-S) between the opening degree limit signal So and the governor setting signal S exceeds a threshold. However, the delay correction limit circuit 117 may also suppress the governor setting signal S when the actual rotational speed increases.

[0053] Specifically, the delay correction limiting circuit 117 reduces the difference between the opening degree limiting signal So and the governor setting signal S (Sо-S) when the speed adjustment signal ΔSv is subtracted from the opening degree limiting signal So due to an increase in the rotational speed (system frequency) of the turbine 4.

[0054] This makes it possible to suppress fluctuations in the rotational speed (system frequency) of the turbine 4 in accordance with the actual rotational speed of the turbine 4. (Note 1) A power generation turbine control device that generates an opening control signal for a throttle valve that controls the rotational speed of a turbine, based on the actual rotational speed of the turbine in the power plant and a governor setting signal set according to the amount of power required by a generator connected to the turbine via the turbine shaft, A power generation turbine control device comprising a correction unit that suppresses the governor setting signal when the difference between the governor setting signal and the opening control signal increases when the governor setting signal is amplified. (Note 2) A power generation turbine control device that generates an opening control signal for a throttle valve that controls the rotational speed of a turbine, based on the actual rotational speed of the turbine in the power plant and a governor setting signal that is set in advance according to the amount of power required by a generator connected to the turbine via the turbine shaft, A power generation turbine control device comprising a correction unit that suppresses the governor setting signal when the difference between the governor setting signal and the opening control signal increases as the actual rotational speed increases. (Note 3) The correction unit suppresses the governor setting signal if the difference between the governor setting signal and the opening control signal exceeds a threshold. A power generation turbine control device as described in (Appendix 1 or 2). (Note 4) A subtraction unit calculates the speed deviation by subtracting the actual rotational speed from the rated rotational speed of the turbine, A variable adjustment rate calculation unit calculates a variable adjustment rate based on the actual rotational speed and system information relating to the operating status of the power grid to which the power plant is connected. A speed adjustment signal generation unit generates a speed adjustment signal based on the calculated speed deviation and the variable adjustment ratio, An adder unit that adds the governor setting signal to the generated speed adjustment signal to generate a speed control load control signal, The system includes a selection unit that outputs the lower of the generated speed-governing load control signal and the load control signal from the load controller as the opening degree control signal. A power generation turbine control device as described in (Appendix 1 or 2). (Note 5) A power generation turbine control method that generates an opening control signal for a throttle valve that controls the rotational speed of a turbine, based on the actual rotational speed of the turbine in the power plant and a governor setting signal set according to the amount of power required by a generator connected to the turbine via the turbine shaft, A power generation turbine method that suppresses the governor setting signal when the governor setting signal is amplified and the difference between the governor setting signal and the opening control signal increases and exceeds a threshold. [Explanation of symbols]

[0055] 3...Control valve, 4...Turbine, 5...Generator, 8...Turbine shaft, 11...Turbine control device, 100...Power plant, 111...Subtraction unit, 112...Variable adjustment rate calculation unit, 113...Gain multiplication unit, 114...Addition unit, 115...Load limiter, 116...LVG, 117...Delay correction limit circuit, Rv...Variable adjustment rate, S...Governor setting signal, So...Opening control signal, Sv...Speed ​​control load control signal, ΔSv...Speed ​​adjustment signal, ΔV...Speed ​​deviation

Claims

1. A power generation turbine control device that generates an opening control signal for a throttle valve that controls the rotational speed of a turbine, based on the actual rotational speed of the turbine in the power plant and a governor setting signal set according to the amount of power required by a generator connected to the turbine via the turbine shaft, A power generation turbine control device comprising a correction unit that, when the governor setting signal is amplified and the difference between the governor setting signal and the opening control signal increases, outputs a corrected governor setting signal with a value less than the first threshold when the governor setting signal exceeds a first threshold.

2. A power generation turbine control device that generates an opening control signal for a throttle valve that controls the rotational speed of a turbine, based on the actual rotational speed of the turbine in the power plant and a governor setting signal set according to the amount of power required by a generator connected to the turbine via the turbine shaft, A power generation turbine control device comprising a correction unit that suppresses the governor setting signal, which, when the actual rotational speed increases and the difference between the governor setting signal and the opening control signal increases, outputs a corrected governor setting signal with a value less than the first threshold when the governor setting signal exceeds a first threshold.

3. The correction unit outputs a corrected governor setting signal with a value less than the first threshold if the difference between the governor setting signal and the opening control signal exceeds the second threshold, or if the governor setting signal exceeds the first threshold. The power generation turbine control device according to claim 1 or 2.

4. A subtraction unit calculates the speed deviation by subtracting the actual rotational speed from the rated rotational speed of the turbine, A variable adjustment rate calculation unit calculates a variable adjustment rate based on the actual rotational speed and system information relating to the operating status of the power grid to which the power plant is connected. A speed adjustment signal generation unit generates a speed adjustment signal based on the calculated speed deviation and the variable adjustment ratio, An adder that generates a speed control load control signal by adding the governor setting signal to the generated speed adjustment signal, wherein if the governor setting signal is corrected by the correction unit, the adder uses the corrected governor setting signal as the governor setting signal to be added, The system includes a selection unit that outputs the lower of the generated speed-governing load control signal and the load control signal from the load controller as the opening degree control signal. The power generation turbine control device according to claim 1 or 2.

5. A power generation turbine control method that generates an opening control signal for a throttle valve that controls the rotational speed of a turbine, based on the actual rotational speed of the turbine in the power plant and a governor setting signal set according to the amount of power required by a generator connected to the turbine via the turbine shaft, A power generation turbine method in which, when the governor setting signal is amplified, the difference between the governor setting signal and the opening control signal increases and exceeds a second threshold, and the governor setting signal exceeds a first threshold, outputs a corrected governor setting signal with a value less than the first threshold.

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