Water pressure rise control device

Abstract

A water pressure rise suppression device that can suppress a rise in water pressure in a penstock. [Solution] The water pressure rise suppression device 1 comprises an opening degree acquisition unit that acquires the opening degree of the guide vane 3 at the time when the guide vane 3 begins to suddenly close, a quick-open drive unit that, in response to the opening degree of the guide vane 3 acquired by the opening degree acquisition unit, drives the control valve 9 to open at a predetermined quick speed using a servo motor 10 so as to suppress the rise in water pressure in the penstock 2 due to the sudden closing of the guide vane 3 from that opening degree, and a slow-close drive unit that drives the control valve 9 to close at a predetermined slow speed using the servo motor 10 to close the valve after the quick-open drive unit has completed suppressing the water pressure rise.

Description

[Technical Field]

[0001] This invention relates to a water pressure rise suppression device for suppressing a water pressure rise in a penstock that occurs in a hydroelectric power plant due to sudden blockage of a guide vane. [Background technology]

[0002] Conventionally, hydroelectric power plants are equipped with guide vanes that control the flow rate of water introduced through a penstock to rotate a water turbine for generating electricity. If the guide vanes are suddenly closed due to a generator being disconnected or a serious malfunction, the flow rate of the introduced water drops sharply, causing a sudden increase in water pressure in the penstock, which can lead to damage to the penstock. Therefore, devices that suppress this increase in water pressure are known (for example, the pressure suppression device described in Patent Document 1).

[0003] In the pressure suppression device of Patent Document 1, the guide vanes are rapidly closed, and the water pressure in the penstock begins to rise rapidly. At the same time, the hydraulic dashpot connected to the turbine's operating arm via a link is raised. In conjunction with this, the switching valve is switched, and the supply of hydraulic pressure oil to the cylinder of the pressure suppression valve servo motor is blocked.

[0004] This connects the oil supply and discharge port to the oil drain pipe via the switching valve, and the hydraulic oil in the cylinder of the control valve servo motor is discharged to the oil collection tank via the oil drain pipe. As a result, the water pressure in the penstock acting on the control valve pushes the valve element of the control valve downward, opening it and discharging the water flowing in the penstock into the drain pipe. This suppresses the increase in water pressure in the penstock and prevents damage to the turbine casing and penstock. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-28427 Summary of the Invention [Problem to be solved by the invention]

[0006] However, according to the pressure control device of Patent Document 1, as described above, when the guide vane is operated to close, the closing operation is transmitted to the pressure control valve via a mechanical transmission mechanism consisting of a link, operating arm, operating rod, dashpot, etc., and the pressure control valve opens, thereby suppressing the increase in water pressure in the water pipeline.

[0007] As a result, the control valve is inactive for a long time between the start of the guide vane closing operation and the start of the control valve opening operation. Furthermore, it is difficult to adjust the control valve opening to match the guide vane opening. Furthermore, because the control valve starts opening after detecting the guide vane closing operation, the control valve cannot be opened instantly when a transient rise in water pressure occurs due to the guide vane closing operation.

[0008] The first object of this invention is to provide a water pressure rise suppression device that can suppress a water pressure rise in the penstock by opening the control valve simultaneously with the start of sudden guide vane closure. The second object is to provide a water pressure rise suppression device that can immediately start opening the control valve to suppress a water pressure rise when a transient water pressure rise occurs in the penstock during parallel operation of generators. [Means for solving the problem]

[0009] The first invention of the water pressure rise suppression device is A water pressure rise suppression device that suppresses a rise in water pressure caused by a sudden blockage of a guide vane in a penstock through which flowing water passes while adjusting the water volume to be supplied to a water turbine that drives a generator, when a load shedding or a serious failure related to the generator occurs, a pressure control valve that opens and closes a pipeline between a branch pipe that communicates with the penstock and a drain pipe that communicates with the outside; a servo motor that drives the pressure control valve to open and close; a control unit for controlling the driving of the servo motor, The control unit an opening degree acquisition unit (blocks B4 and B7 in FIG. 2) that acquires the opening degree of the guide vane at the time when the guide vane starts the sudden closing; a rapid-opening drive unit (blocks B8, B9, B10) that, in response to the opening of the guide vane acquired by the opening acquisition unit, drives the servo motor to open the control valve at a predetermined rapid speed so as to suppress a rise in water pressure in the penstock due to a sudden closing of the guide vane from the acquired opening; The apparatus further includes a slow-closing drive unit (block B11) that drives the control valve to close at a predetermined slow speed by the servo motor after the rapid-open drive unit has completed suppressing the water pressure increase.

[0010] In this case, the quick-opening drive unit may include an opening degree calculation unit (block B8) that calculates the required opening degree of the pressure control valve necessary to suppress an increase in water pressure in the water pressure pipe based on the opening degree acquired by the opening degree acquisition unit, and the quick-opening drive unit may perform the opening drive until the required opening degree is achieved (blocks B9, B10).

[0011] The second invention of the water pressure rise suppression device is A water pressure rise suppression device that suppresses a transient rise in water pressure in a penstock through which flowing water passes, the flowing water being supplied via guide vanes to water turbines for power generation of a plurality of generators, during parallel operation of the generators, a pressure control valve that opens and closes a pipeline between a branch pipe connected to the penstock and a drainage pipe to the outside; a servo motor that drives the pressure control valve to open and close; a control unit for controlling the driving of the servo motor, The control unit a transient rise detection unit (block B16 in FIG. 4) that detects a transient rise in water pressure in the penstock based on whether or not a rise in water pressure in the penstock at a predetermined time interval exceeds a predetermined value; a quick-opening drive unit (blocks B17 and B18) that drives the control valve to quickly open at a predetermined quick speed by the servo motor in response to the transient rise in water pressure detected by the transient rise detection unit in order to suppress the rise in water pressure; The system further includes a slow-closing drive unit (block B19) that drives the control valve to close at a predetermined slow speed by the servo motor after the increase in water pressure has been suppressed by the rapid-opening drive of the control valve. [Effects of the Invention]

[0012] According to the first invention, in response to the acquisition of the guide vane opening degree at the time when the guide vane starts to suddenly close, the control valve is driven to open at a predetermined rapid speed so as to suppress the increase in water pressure in the penstock that would occur when the guide vane suddenly closes from that opening degree. Therefore, the control valve is driven to open rapidly at the same time as the guide vane starts to suddenly close, thereby suppressing the increase in water pressure in the penstock.

[0013] Furthermore, if the rapid-opening drive unit is equipped with an opening degree calculation unit, the control valve is driven to open rapidly until it reaches the required opening degree acquired by the opening degree acquisition unit. Therefore, by appropriately calculating the required opening degree, the opening degree of the control valve relative to the opening degree of the guide vane can be appropriately adjusted.

[0014] According to the second invention, in response to the transient rise detection unit detecting a transient rise in water pressure in the penstock, the control valve is driven to open at a predetermined rapid speed to suppress the rise in water pressure. Therefore, if a transient rise in water pressure occurs in the penstock during parallel operation of the generator, the water pressure rise can be immediately suppressed. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing the main parts of a hydroelectric power plant equipped with a water pressure rise suppression device according to an embodiment of the present invention; [Figure 2] 2 is a block diagram showing the operation of a control unit when a generator is disconnected or a serious fault occurs in the hydroelectric power plant of FIG. 1. FIG. [Figure 3] 1 is a timing chart of main signals observed when load shedding occurs at a hydroelectric power plant. [Figure 4] 1. FIG. 4 is a block diagram showing the operation of the control unit when the water pressure in the penstock rises transiently during parallel operation of the generators in the hydroelectric power plant of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figure 1 shows the main components of a hydroelectric power plant equipped with a water pressure rise suppression device 1 according to one embodiment of the present invention. As shown in Figure 1, in the hydroelectric power plant, water stored at an elevated location is supplied from a penstock 2 to a power-generating water turbine 4, with the water volume being adjusted by a guide vane 3. This rotates the water turbine 4, which in turn rotates the rotor of a generator 5 connected to the water turbine 4, thereby generating electricity.

[0017] The water used to rotate the water turbine 4 is discharged through the draft pipe 6. The amount of electricity generated by power generation is controlled by adjusting the amount of water supplied to the water turbine 4 with the guide vanes 3. Therefore, the generator 5 supplies an amount of electricity corresponding to the opening degree of the guide vanes 3 to the power grid as a load.

[0018] The water pressure rise suppression device 1 has the function of suppressing the rise in water pressure inside the penstock 2 through which the flowing water supplied to the water turbine 4 passes. The rise in water pressure inside the penstock 2 occurs when the guide vanes 3 suddenly close due to load rejection or a major malfunction of the generator 5. That is, when the guide vanes 3 suddenly close, a periodic water pressure rise wave is generated inside the penstock 2 according to the Joukowski equation shown below. ∂P / ∂t=ρα∂V / ∂t where P is the water pressure in the iron pipe [Pa], V is the water flow velocity [m / s], and ρ is the water density [kg / m 3 ], α is the water acceleration [m / s 2 ], t is the blocking time [t].

[0019] From the above Joukowski equation, the amplitude ΔP of the maximum water pressure rise wave when the guide vane 3 is suddenly closed is given by the following equation. ΔP=ρα0ΔV where α0 is the speed of sound in water [m / s], and ΔV is the change in water flow velocity [m / s].

[0020] In order to suppress the rise in water pressure inside the penstock 2 due to such water pressure rise waves, the water pressure rise suppression device 1 includes a pressure control valve 9 that opens and closes the pipeline between a branch pipe 7 connected to the penstock 2 and a drainage pipe 8 connected to the outside, a servo motor 10 that drives the pressure control valve 9 to open and close, and a control unit that controls the drive of the servo motor 10. This control unit can be configured, for example, by a PLC (programmable logic controller). In this embodiment, the control unit is configured by a high-speed PLC.

[0021] The water pressure rise suppression device 1 is provided with a lever 13, one end of which is rotatably fixed to a housing 11 of the water pressure rise suppression device 1 and the other end of which has a weight 12 suspended therefrom. The lower end of a servo motor 10 is fixed to the housing 11, and the upper end of which is rotatably connected to the weight 12 side of the lever 13. The upper end of a rod 14 for moving the pressure control valve 9 up and down is rotatably connected to the one end of the lever 13. The lower end of the rod 14 is fixed to the pressure control valve 9.

[0022] Therefore, the servo motor 10 moves the weight 12 side of the lever 13 up and down, and rotates the lever 13 around the one end thereof, thereby moving the upper end of the rod 14 up and down to open and close the pressure control valve 9. At that time, the weight 12 has the function of reducing the load on the servo motor 10.

[0023] Figure 2 is a block diagram showing the operation of the control unit of the water pressure rise suppression device 1 when the generator 5 is disconnected or a serious fault occurs. In Figure 2, "◯" means logical sum and "□" means logical product. The digital input elements to the high-speed PLC that makes up the control unit are the parallel signal of block B1, the major fault lockout relay signal (all emergency stop signals) of block B2, the major fault lockout relay signal (all emergency stop signals) of block B3, and the main control signal.

[0024] The analog input elements to the high-speed PLC are the opening GVin of the guide vane 3 in block B4, the opening REGin of the pressure control valve 9 in block B5, and the iron pipe water pressure Pin of the iron pipe 2 in block B6.

[0025] Figure 3 shows a timing chart of the main signals observed when load rejection occurs in the generator 5 of a hydroelectric power plant. Figure 3 shows the temporal changes in the generator current I, generator voltage V, iron pipe water pressure P, guide vane opening GA, and pressure control valve opening VA. Figure 3 will be referenced in the following explanation of the control unit in Figure 2.

[0026] As shown in FIG. 2, the condition of block B1 is set to OFF. Therefore, when block B1 receives a parallel-off signal indicating that the generator 5 has been parallel-off, block B1 instantly outputs a parallel-off detection signal Di in response.

[0027] Furthermore, since the condition of block B2 is ON and the condition of block B3 is ON, in the event of a major fault / emergency stop or a major fault / sudden stop, a major fault occurrence detection signal Mb is output. When the parallel-off detection signal Di or the major fault occurrence detection signal Mb is output (time t3 in FIG. 3), the guide vanes 3 begin to suddenly close (see graph curve 15a in FIG. 3).

[0028] In a conventional hydroelectric power plant (a power plant that does not have a water pressure rise suppression device 1), the water pressure in the penstock 2 begins to rise at this time t3 (see graph curve 15b). In this embodiment, therefore, in order to predict and suppress this water pressure rise, processing of blocks B7 to B11 is performed based on the input of blocks B4 to B6.

[0029] First, block B7 acquires the opening GVin of the guide vanes 3. The opening GVin has a value corresponding to the load on the generator 5 immediately before parallel-off (time t1). At time t3, the guide vanes 3 start to rapidly close from this opening GVin (see graph curve 15a).

[0030] At time t3 when this sudden blockage begins, in a conventional hydroelectric power plant (a power plant that does not have a water pressure rise suppression device 1), the water pressure in the penstock 2 will rise as shown by graph curve 15b.

[0031] In this embodiment, in order to predict and suppress this increase in water pressure, the control valve 9 is rapidly opened to the required opening degree Resod (see graph curve 15c) at the same time as the start of the sudden closing of the guide vane 3 (time t3). In block B8, this required opening degree Resod is calculated.

[0032] In block B9, a rapid opening time Opt1 (the time from time t3 to t4) is set for driving the control valve 9 to rapidly open at a predetermined rapid opening speed Rov1 (the slope of the graph curve 15c from time t3 to t4) until the required opening degree Resod is reached, and the servo motor 10 starts driving the control valve 9 to rapidly open. The rapid opening time Opt1 differs for each power plant and is set arbitrarily within a range equal to or less than the rapid opening time corresponding to the maximum speed of the servo motor 10.

[0033] When the rapid-opening time Opt1 has elapsed, the rapid-opening drive is stopped in block B10. At this time, the opening of the pressure control valve 9 is the required opening Resod. In block B10, a time for maintaining this required opening Resod (rapid-opening holding time Rt1) is set. The rapid-opening holding time Rt1 can be determined based on the waveform (graph curve 15d) of the pressure control valve opening VA in FIG. 3 observed when a test load shedding is performed.

[0034] When this sudden-open holding time Rt1 has elapsed, in block B11, slow-closing drive for closing the pressure control valve 9 at a slow speed is started, and a slow-closing drive time Sct1 required for this slow-closing drive is set.

[0035] Similarly, the slow-closing drive time Sct1 can be determined by calculating the slow-down speed from the waveform of the control valve opening VA and, based on this, calculating the time it takes for the control valve opening VA to change from the required opening Resod to the fully closed state. When the set slow-closing drive time Sct1 has elapsed, the closing of the control valve 9 is completed. Note that the sudden-open hold time Rt1 and the slow-closing drive time Sct1 differ for each hydroelectric power plant and can be set to any value.

[0036] Fig. 4 is a block diagram showing the operation of the control unit when the water pressure in the penstock 2 rises transiently during system parallel operation of the generator 5. As shown in Fig. 4, in block B12, the operating condition for parallel operation is set to ON, so an output indicating that parallel operation is in progress is output.

[0037] Block B13 accepts an input of the iron pipe water pressure Pin, which is the water pressure in the iron penstock 2. Block B14 accepts an input of the opening GVin of the guide vane 3. Block B15 accepts an input of the opening REGin of the control valve 9.

[0038] Block B16 detects the occurrence of a transient rise in water pressure in the penstock 2 based on the penstock water pressure Pin. That is, the water pressure value of the penstock 2 is sampled at arbitrary time intervals, and the change in the penstock water pressure value at arbitrary time intervals is measured each time sampling is performed. When the change in the measured penstock water pressure value exceeds a predetermined value, it is determined that a transient rise in water pressure has occurred, and a detection signal Tps indicating this is output.

[0039] In block B17, in response to the detection signal Tps, a rapid-open drive is initiated to open the pressure control valve 9 at a predetermined rapid-open speed Rov2. This rapid-open speed Rov2 is approximately the same as the rapid-open speed Rov1 that occurs when the above-mentioned parallel-off occurs. This rapid-open drive is continued until the water pressure increase is suppressed and the water pressure returns to its original level.

[0040] In block B18, the operation of the control valve 9 is stopped when the water pressure returns to its original level, and a quick-open hold time Rt2 is set to maintain the opening of the control valve 9 at that point. However, the quick-open hold time Rt2 is set to be as short as possible. In block B19, a slow-closing drive time Sct2 is set to close the control valve 9 at a slow speed, and the control valve 9 is closed for the slow-closing drive time Sct2. The values ​​of the quick-open hold time Rt2 and the slow-closing drive time Sct2 in this case are the same as those of the quick-open hold time Rt1 and the slow-closing drive time Sct1 when parallel-off or the like occurs, as described above.

[0041] As described above, according to this embodiment, in response to obtaining the opening degree GVin of the guide vane 3 at the time when the guide vane 3 starts to suddenly close, the control valve 9 is driven to rapidly open at a predetermined rapid-opening speed Rov1 so as to suppress the increase in water pressure in the penstock 2 due to the sudden closing of the guide vane 3 from the opening degree GVin.

[0042] This allows the opening operation of the pressure control valve 9 to begin simultaneously with the start of sudden closure of the guide vanes 3. Therefore, even when there is a transient increase in the water pressure in the penstock 2, the pressure control valve 9 can be opened, thereby reliably suppressing the increase in water pressure in the penstock 2 due to the sudden closure of the guide vanes 3.

[0043] Furthermore, the required opening Resod of the control valve 9 required to suppress the rise in water pressure in the penstock 2 is calculated from the opening GVin of the guide vane 3 using a function of GVin that differs for each load. By appropriately selecting this function, it is possible to easily adjust the opening GVin of the guide vane 3 versus the opening Resod of the control valve 9 according to the load.

[0044] In addition, in response to the detection of a transient increase in water pressure in the penstock 2, the pressure control valve 9 is driven to open rapidly at a predetermined rapid speed in order to suppress the increase in water pressure, so that the transient increase in water pressure in the penstock can be immediately suppressed without delay. [Explanation of symbols]

[0045] 1...water pressure rise suppression device, 2...water penstock, 3...guide vane, 4...water turbine, 5...generator, 6...draft pipe, 7...branch pipe, 8...drain pipe, 9...control valve, 10...servo motor, 11...casing, 12...weight, 13...lever, 14...rod, 15a to 15d...graph curves.

Claims

1. A water pressure rise suppression device that suppresses a rise in water pressure caused by a sudden blockage of a guide vane in a penstock through which flowing water passes, the guide vane being supplied via a guide vane to a water turbine that drives a generator, when a load shedding or a serious failure related to the generator occurs, a pressure control valve that opens and closes a pipeline between a branch pipe that communicates with the penstock and a drain pipe that communicates with the outside; a servo motor that drives the pressure control valve to open and close; a control unit for controlling the driving of the servo motor, The control unit an opening degree acquiring unit that acquires an opening degree of the guide vane at a time when the guide vane starts the sudden closing; a quick-opening drive unit that drives the control valve to open at a predetermined quick speed using the servo motor in response to the opening of the guide vane being acquired by the opening acquisition unit so as to suppress a rise in water pressure in the penstock due to a sudden closing of the guide vane from the acquired opening; A water pressure rise suppression device characterized by comprising a slow closing drive unit that uses the servo motor to drive the control valve to close at a predetermined slow speed to block it after the suppression of the water pressure rise by the quick opening drive unit is completed.

2. The quick-open drive unit is an opening calculation unit that calculates a required opening of the control valve that is necessary to suppress a rise in water pressure in the penstock, based on the opening acquired by the opening acquisition unit; 2. The water pressure increase suppression device according to claim 1, wherein the quick-opening drive unit continues the opening drive until the required opening degree is reached.

3. A water pressure rise suppression device that suppresses a transient rise in water pressure in a penstock through which flowing water passes, the flowing water being supplied via guide vanes to water turbines for power generation of a plurality of generators, during parallel operation of the generators, a pressure control valve that opens and closes a pipeline between a branch pipe that communicates with the penstock and a drain pipe that communicates with the outside; a servo motor that drives the pressure control valve to open and close; a control unit for controlling the driving of the servo motor, The control unit a transient rise detection unit that detects a transient rise in water pressure in the penstock based on whether or not a rise in water pressure in the penstock at a predetermined time interval exceeds a predetermined value; a rapid-opening drive unit that drives the control valve to open at a predetermined rapid speed by the servo motor in response to the transient rise in water pressure detected by the transient rise detection unit in order to suppress the rise in water pressure; A water pressure rise suppression device characterized by having a slow closing drive unit that uses the servo motor to drive the control valve to close at a predetermined slow speed and close it after the rise in water pressure is suppressed by driving the control valve suddenly to open.

Images