JP2856416B2 - Control method of suppression valve - Google Patents

Description

Description: Object of the Invention (Industrial Application Field) The present invention relates to a method for controlling the operation of a hydraulic machine of a hydroelectric power plant, and in particular, to release pressurized water to the hydraulic machine when the hydraulic machine is stopped in an emergency. The present invention relates to a control method for operating a suppression valve.

(Prior Art) FIG. 4 shows an overall view of the vicinity of a hydraulic machine of a conventional hydroelectric power plant. The hydraulic water from the upper pond 1 is guided by the penstock 2, flows into a casing 4 provided with a water turbine 3 (for example, a Francis turbine) as a hydraulic machine, and is discharged to a water discharge garden 6 through a discharge pipe 5. The water wheel 3 receives pressure water and rotates. The water turbine 3 is directly connected to a synchronous generator 8 via a transmission shaft 7. The electric power generated by the synchronous generator 8 is transmitted to the power system 9. Further, a speed detector 11 is provided via another transmission shaft 10 provided coaxially with the synchronous generator 8.

Guide vanes 12 are provided in the casing 4,
The pressure water guided to the water wheel 3 which is a hydraulic machine can be controlled. The guide vane 12 is opened by a guide vane servomotor 13.
The control of the guide vane servomotor 13 is performed by a water turbine governor 14 and a regulator 15. The return amount of the guide vane servomotor 13 is fed back to the water turbine governor 14 by a wire 16 or a rod.

Further, when the pressure water guided to the water turbine 3 by the guide vane 12 is restricted, the pressure
20 are provided. The pressure control device 20 includes a pressure control valve 22 for releasing pressurized water through the discharge pipe 21 to the water discharge yard 6, a pressure distribution valve 23 for controlling pressure oil for operating the pressure control valve 22, and a pressure distribution valve 23. Link mechanism 23 to work
A dashpot cylinder 25 for mechanically controlling the movement of the link mechanism 24 is provided. The detailed operation of the pressure suppressor 20 will be described later.

As described above, normally, three hydraulic machines are directly connected to the synchronous generator 8 operated at a constant speed. If the rotation speed of the synchronous generator 8 deviates from the rating, the rotation speed is detected by the speed detector 11 (SSG or PMG, etc.), and the turbine vane governor 14 controls the guide vane 12 by an amount corresponding to the difference between the rotation speeds. The opening can be changed. As a result, the output of the water turbine 3 is changed, and the rotation speed is controlled to the rated value.

However, for example, if there is a lightning strike on the transmission line of the power system parallel to the hydroelectric power plant equipped with such a hydropower plant, the power line outside the hydropower plant will be protected in order to protect the electrical equipment of the hydropower plant. In, the connection of the transmission line is cut off. As a result, the turbine load is cut off, and the load suddenly changes from the previous value to zero instantaneously. In this case, if guide vane 12
If not closed, the turbine 3 will overspeed and reach the unconstrained speed. Then, the guide vane 12 is closed at an appropriate speed. By setting the appropriate speed, both the increase in water pressure and the increase in speed caused by closing the guide vane 12 can be suppressed to below the allowable values. However, if the guide vane 12 is closed too early, the speed rise will be small, but the water pressure fluctuation will be large. Conversely, if the guide vanes 12 are closed too late, the fluctuations in hydraulic pressure will decrease, but the fluctuations in speed will increase. Then, in order to keep the water pressure fluctuation and the speed fluctuation below a certain value, the moment of inertia of a rotating part such as a water turbine is increased. However, the moment of inertia increases as the head of the upper pond 1 and the casing 4 becomes higher and the penstock 2 becomes longer. Therefore, when the head or penstock length is increased to a certain extent or more, instead of increasing the moment of inertia, a pressure suppressor 20 is provided to release pressure water that would have been guided to the hydraulic machine.

In the existing hydroelectric power plant, the pressure suppressor 20 cannot be removed unless the penstock 2 and the casing 4 are renewed. Further, as described above, the pressure suppressor 20 has a great effect in suppressing an increase in water pressure. Therefore, it can be said that the pressure suppressor 20 is an important component for the hydraulic machine. The control method of controlling the pressure suppressor 20 to suppress the increase in the water pressure and the speed is an important technique for the existing hydroelectric power plant.

Next, the pressure suppressor 20 will be described in detail with reference to FIGS. As described above, the guide vane servomotor 13 is actuated by the regulator 15 and the water turbine governor 14 due to the fact that the load is cut off by lightning or the like or the abnormality of the turbine is detected, and the guide vane 12 starts the rapid closing operation. Then, the movement of the guide vane servomotor 13 is transmitted as a rotational force to the shaft 27 via the link 26 of the link mechanism 24, and the arm 28 fixed to the shaft 27 rotates counterclockwise in the drawing. The dashpot 25 pin-connected to the tip of the arm 28 is also quickly pulled upward. At this time, since the oil in the cylinder 29 of the dashpot 25 has no time to flow downward from the top through the small hole 31 of the piston 30, the piston 30 is rapidly pulled up integrally with the cylinder 29 of the dashpot 25. . The right end of a floating lever 32 of the link mechanism 24 is connected to the piston 30 with a pin, and the floating lever 32 is lifted with the left end as a fulcrum. Then, the pilot valve 33 pin-connected to the middle of the floating lever 32 is lifted upward.

The operation of the pilot valve 33 is shown in FIG. 6 in which a part of FIG. 5 is enlarged. That is, the lower end of the pilot valve 33 normally seals the escape hole 41 for allowing the pressure oil on the upper side of the piston 40 of the pressure distribution valve 23 to escape. become. This allows the pressure oil above the piston 40 to escape to the escape hole 41
Through, the hydraulic pressure below the piston 40 prevails and the piston 40 rises. With the rise of this piston 40,
The cylinder side port 42 in which the piston 40 is closed opens. A piston 44 is present in the pressure control cylinder 43 adjacent to the pressure distribution valve 23 via the cylinder side port 42 (see FIG. 4), and the pressure oil above the piston 44 is supplied to the cylinder side port.
The oil is discharged through the oil distribution pipe 45 through the pressure distribution valve 23 via 42. Therefore, the piston 44 of the pressure control cylinder 43 is lifted by the water pressure on the casing 4 side, and the pressure control valve 22 is opened.
Thereby, the pressurized water in the casing 4 is discharged to the water discharge garden 6.

After the suppression valve 22 is opened in accordance with the rapid closing operation of the guide vane 12 in this manner, the suppression valve 22 is closed again. This operation will be described. That is, the pressure oil in the dashpot cylinder 29 flows through the small hole 31 of the piston 30,
Gently lowers relative to the dashpot cylinder 29 by its own weight. The movement of this piston 30 is a floating lever
The pilot valve 33 is pushed down to its original position via the valve 32, so that the lower end of the pilot valve 33
Figure) is closed again and the so-called wrap is formed again. Chamber 46 below piston 40 of pressure distribution valve 23 and piston side port
42 is connected, and both are always supplied with pressurized oil. The lower room 46 has a smaller area than the upper room 47. Therefore, when the wrap is formed, the supplied pressure oil pushes down the piston 40 again. When the piston 40 is pushed down, the piston-side port 48 communicates with the cylinder-side port 42, and the pressure oil is supplied to the upper side of the piston 44 of the pressure-control device cylinder 43. As a result, the piston 44 that has overcome the water pressure again falls, and the suppression valve 22 is closed.

As described above, in response to the sudden closing operation of the guide vane 12, the control valve 22 is opened to release the pressurized water in response to the sudden closing operation of the guide vane 12, and then the control valve 22 is gradually closed. The relationship between the opening degree of the guide vane 12 and the water pressure generated in the relation between the opening degree of the suppression valve 22 at this time is indicated by a dotted line in FIG.

FIG. 7 shows the degree of opening of the guide vane 12 and the control valve 22 and the rotation speed of the turbine 3 when the turbine, which is a hydraulic machine, is restarted after being stopped. That is, the guide vanes 12 start to open, and when they are fully opened, the rotation speed of the water turbine 3 starts to increase. When the rotation speed of the turbine 3 reaches 70%, the guide vane is slightly closed if the hydroelectric generator is not loaded (dotted line in the figure). Further, with this slightly closing operation, the pressure control valve 22 is slightly opened.

(Problems to be Solved by the Invention) In the conventional technology described above, the control of the suppression valve 22 is performed mechanically, and a link is provided for this mechanical control.
Link mechanisms such as 26, shaft 27, arm 28, dashpot 25, and floating lever 32 are required, and this link mechanism generates friction and backlash as it ages, and maintenance to prevent and repair them is required. It was not easy.

Further, as shown by the dotted line in FIG. 2, a phenomenon of dead time or overshoot occurs between the movement of the guide vane 12 and the movement of the pressure control valve 22. These are caused by the mechanical control, and are disadvantageous for suppressing the water pressure fluctuation and the speed fluctuation. Furthermore, if there is a large water pressure fluctuation or a speed fluctuation, a large amount of energy for mechanically controlling the control valve is required.

The present invention has been made in view of the above technical background, and has as its object to provide a control method of a pressure-reducing valve that is easy to maintain and can suppress fluctuations in water pressure and speed.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a guide vane servomotor that adjusts an opening degree of a guide vane that guides pressurized water to a hydraulic machine of a hydroelectric power plant. Means for electrically detecting the opening degree of the guide vane, and attaching a second detection means to a pressure control valve for releasing pressurized water to the hydraulic machine, and electrically detecting the opening degree of the pressure control valve, The guide vane is suddenly closed in response to the sudden stop signal of the hydraulic machine, and the guide vane opening detected by the first detection means and the pressure suppression valve opening detected by the second detection means are sent to an arithmetic unit. Based on the detection signal of the guide vane opening, the arithmetic unit calculates an opening to be taken by the pressure-suppressing valve with respect to the guide vane opening during the rapid closing operation. And the second (2) The control valve opening is controlled so as to match the calculated opening by comparing the control valve opening detected by the detecting means, so that the guide vane is fully closed and the control valve is fully opened at the same time. Then, the closing operation of the pressure suppression valve is started to fully close the pressure suppression valve.

In addition, the present invention provides a guide vane servomotor that adjusts the opening of a guide vane that guides pressurized water to a hydraulic machine of a hydroelectric power plant by attaching first detection means to electrically detect the opening of the guide vane. A second detecting means is attached to the pressure control valve for releasing the pressurized water to the hydraulic machine, the opening of the pressure control valve is electrically detected, and the guide vane is rapidly closed in response to the sudden stop signal of the hydraulic machine. And the guide vane opening detected by the first detecting means and the second
The control valve opening detected by the detecting means is input to a calculation device, and the calculation device should take the control vane opening with respect to the guide vane opening during the rapid closing operation based on the detection signal of the guide vane opening. An opening is calculated, and the calculated opening of the suppression valve is compared with the opening of the suppression valve detected by the second detection means, and the opening of the suppression valve is adjusted to match the calculated opening. By controlling, the control valve is fully opened almost at the same time when the maximum value of the first wave of the water pressure rise caused by the guide vane fully closed reaches the upper pond of the hydroelectric power plant, and thereafter, the control valve is closed. It is characterized in that the closing operation is started to fully close the pressure suppression valve.

(Operation) Performs electrical control instead of conventional mechanical control to facilitate maintenance. In addition, the opening to be taken by the control valve is calculated with respect to the guide vane opening during the rapid closing operation, and according to the calculated valve opening, the control vane is fully opened at the same time as the guide vane is fully closed, and then the control valve is closed. By operating and fully closing again (see FIG. 2), dead time and overshoot which existed conventionally can be eliminated.

Further, by following the calculated valve opening degree, when the maximum value of the first wave of the hydraulic pressure rise caused by the guide vane fully closing is predicted, the suppression valve is fully opened at the same time, and then the suppression valve is closed and fully closed again ( Thus, the water pressure fluctuation and the speed fluctuation can be suppressed lower.

(Embodiment) A first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. The same parts as in FIG. 4 showing the conventional example are denoted by the same reference numerals.

The pressurized water in the upper pond 1 is guided to the penstock 2 and flows into the casing 4. In the casing 4, a water turbine 3 as a hydraulic machine is provided.
(For example, a Francis turbine) is provided and is directly connected to the synchronous generator 8 via the transmission shaft 7. The power generated by the synchronous generator 8 is transmitted to the power system 9. A speed detector 11 is attached to a transmission shaft 10 provided coaxially with the synchronous generator 8.
Is provided.

A guide vane 12 for controlling the pressure water guided to the water wheel 3 is provided in the casing 4. The guide vane 12 is opened and closed by a guide vane servomotor 13. The guide vane servomotor 13 is operated by pressure oil sent from the water turbine governor 14.
The water turbine governor 14 operates according to a command from the regulator 15. The guide vane servomotor 13 is provided with an operation transformer 50 as a first detecting means so that the guide vane opening can be detected. In addition, the operation transformer
A potentiometer may be attached instead of 50. This detection signal is input to the regulator 15.

The pressure suppressor 20 for releasing the pressure water to the water turbine 3 is provided with a pressure water release pipe.
The pressure control valve 22 includes a pressure control valve 22 for releasing the pressure control valve 21 and a pressure distribution valve 23 for opening and closing the pressure control valve 22. The pressure control valve 22 is provided with an operation transformer 51 as a second detection means, so that the opening of the pressure control valve 22 can be detected. The second detecting means may be a potentiometer instead of the operation transformer 51. This detection signal is input to the regulator 15.

In the regulator 15, a relationship curve representing the opening degree of the pressure control valve corresponding to the opening degree of the guide vane during the rapid closing operation is predetermined and stored. Further, it has a function of an arithmetic unit for calculating the opening degree of the control valve corresponding to the opening degree of the guide vane input from the signal from the operation transformer 50 as the first detecting means from the relation curve.

In addition, a limit switch (not shown) is provided also as the operation transformer 50 as the first detection means or separately, so that the fully closed state of the guide vane 12 can be detected.

The pressurized water that has rotated the water wheel 3 is discharged to the water discharge garden 6 through the discharge pipe 5. The pressure water released to the relief pipe 21 through the suppression valve 22 is discharged to the water discharge yard 6. An open signal or a close signal is sent from the regulator 15 to the converter 52 so that the pilot valve 33 can be moved up and down.

Hereinafter, the operation of the present embodiment will be described. For example, if there is a lightning strike on the transmission line of the power system and the connection of the transmission line is interrupted, or if an abnormality of the turbine due to a failure of the hydraulic system of the hydraulic machine is detected, the emergency stop signal (emergency stop signal) In response to the sudden stop signal, the converter (not shown) of the water turbine governor 14 operates in the closing direction, switches the main pressure distribution valve (not shown) from the neutral state to the closing direction, and the hydraulic pressure is applied to the guide vane servomotor. It is supplied to 13 closing ports. This allows the guide vane servomotor
13 is operated, and the guide vane 12 starts the quick closing operation. The guide vane opening before the closing operation of the guide vane 12 and the guide vane opening during the rapid closing operation are detected by the operation transformer 50 as the first detecting means. The regulator 15 to which the detection signal is input is controlled based on the detection signal.
Is calculated. According to the calculated valve opening, the opening signal is output from the regulator 15 to the converter 52.
Be sent to The converter 52 operates in the opening direction and pushes down the pilot valve 33 directly connected to the converter. Thereafter, the pressure distribution valve 23 operates in accordance with the downward movement of the pilot valve 33 in the same manner as in the related art, the pressure oil above the piston 44 of the pressure control cylinder 43 is released, and the pressure control valve 22 starts the opening operation. The opening of the suppression valve, which changes with this opening operation, is determined by the second
And a detection signal is input to the regulator 15. The opening of the suppression valve 22 given by the input detection signal is compared with the calculated opening of the suppression valve. If both openings match,
The closing command given from the regulator 15 to the converter 52 is stopped, and at that moment, the opening degree is maintained. If they do not match, the open command is continuously issued until they match. At this time, before the coincidence occurs, when the limit switch (not shown) for detecting the fully closed state of the guide vane 12 operates,
Again, the suppression valve 22 is held at the opening at that time.

By such electric control of the present embodiment, as shown by the solid line in FIG. 2, it is possible to eliminate the dead time and overshoot which existed conventionally. Ie guide vanes
When the valve 12 is fully open, the control valve 22 is fully closed and the guide vane
When the valve 12 starts the closing operation, the pressure suppression valve 22 starts the opening operation, and the pressure suppression valve 22 is fully opened at the same time when the guide vane is fully closed. Thereafter, the suppression valve 22 starts the closing operation and is fully closed soon.
The water pressure fluctuation generated by such control is as shown in the figure.
It can be kept lower than before.

Next, FIG. 3 shows the control of the second embodiment of the present invention. The overall schematic diagram showing the vicinity of the hydraulic machine is the same as FIG. 1 showing the first embodiment.

As shown in FIG. 3, almost at the same time when the maximum value of the first wave of the hydraulic pressure rise caused by the guide vane fully closed is predicted, the pressure suppression valve 22 is fully closed. Thus, the waveform of the first wave of the hydraulic pressure rise and the polygonal waveform indicating the opening / closing operation of the hydraulic valve have an approximate shape. Thereafter, the suppression valve 22 starts the closing operation and is fully closed again.

This will be described in more detail. When you close guide vane 12,
The pressure wave of the water pressure fluctuation caused by this travels in the penstock 2 at a speed of about 1000 m / s, and the time until the pressure wave reaches the upper pond 1 is t seconds. Waves appear. Therefore, the control valve opening is calculated from the relationship curve and controlled so that the control valve 22 is opened forward after t seconds. By making the waveform of the first wave of the water pressure rise substantially coincide with the broken line waveform of the pressure suppression valve 22,
Water pressure rise can be suppressed lower. Further, immediately after this, by simultaneously operating the suppression valve 22, the rate of decrease in the water pressure following the increase in the water pressure can be reduced.

When the conventional vane shown in FIG. 7 is started, when the guide vane is slightly closed from the guide vane starting opening (solid line in FIG. 7) to the guide vane no-load opening (dotted line in FIG. 7), the pressure control valve 22 is closed. Although the opening time of the pressure control valve is slightly reduced, the opening operation of the pressure control valve is performed only when the water turbine is suddenly stopped, as in the present embodiment. This makes it possible to prevent energy loss due to discharge of the pressure water caused by a small opening of the pressure control valve, or damage to the pressure control device due to cavitation, friction, earth and sand friction, and the like.

(Effects of the Invention) As described above, according to the control method of the pressure-suppressing valve of the present invention, electric control is performed instead of conventional mechanical control. It is no longer necessary, and there is no need to worry about friction and backlash caused by aging, and maintenance is facilitated.

In addition, control for fully opening the pressure suppression valve at the same time as the guide vane is fully closed (see FIG. 2) or control for fully opening the pressure suppression valve almost at the same time when the maximum value of the first wave of the water pressure rise caused by the fully closed guide vane is predicted (Refer to FIG. 3), the fluctuation of the water pressure can be suppressed lower, and the fluctuation of speed can be suppressed.

[Brief description of the drawings]

FIG. 1 is an overall schematic view of the vicinity of a hydraulic machine used in a control method of a pressure control valve according to the present invention, FIG. 2 is a view showing control performed in the above embodiment, and FIG. 3 is a second embodiment of the present invention. Fig. 4 is an overall schematic view of the vicinity of the conventional hydraulic machine, Fig. 5 is an enlarged view of the vicinity of the pressure distribution valve 23 in Fig. 4, and Fig. 6 is an enlarged view of a part of Fig. 5. Fig. 7 shows Fig. 4
It is a figure which shows the control at the time of starting taken in a figure. 1 ... upper pond, 3 ... water turbine (hydraulic machine), 4 ... casing, 7 ... transmission shaft, 8 ... synchronous generator, 9 ... power system, 10 ... transmission shaft, 11 ... speed detection , Guide vane, 13 Guide vane servo motor, 14 Turbine governor, 15 Regulator, 20 Control device, 22 Pressure control valve, 23 Pressure control valve, 24 Link mechanism, 25 Dashpot, 26 Link, 27 Shaft, 28 Arm, 29
... Dashpot cylinder, 30 ... Piston, 32 ... Floating lever, 33 ... Pilot valve, 40 ... Piston, 42 ... Cylinder port, 48 ... Piston port, 50,51 ... Transformer, 52 ... Converter.

Claims (2)

(57) [Claims] A first detecting means attached to a guide vane servomotor for adjusting an opening of a guide vane for guiding pressurized water to a hydraulic machine of a hydroelectric power plant, and electrically detecting the opening of the guide vane; A second detection unit is attached to a pressure control valve that releases pressurized water to the hydraulic machine to electrically detect the opening of the pressure control valve, and upon receiving a sudden stop signal of the hydraulic machine, rapidly closes the guide vane. At the same time, the guide vane opening detected by the first detecting means and the suppression valve opening detected by the second detecting means are input to a computing device.
Based on the guide vane opening detection signal, the arithmetic unit calculates an opening to be taken by the pressure suppression valve with respect to the guide vane opening during the rapid closing operation. (2) The control valve opening is controlled so as to match the calculated opening by comparing the control valve opening detected by the detecting means, so that the guide vane is fully closed and the control valve is fully opened at the same time. And then starting the closing operation of the suppression valve to fully close the suppression valve. 2. A guide vane servomotor for adjusting the opening of a guide vane for guiding pressurized water to a hydraulic machine of a hydroelectric power station, wherein first detecting means is attached to electrically detect the opening of the guide vane. A second detection unit is attached to a pressure control valve that releases pressurized water to the hydraulic machine to electrically detect the opening of the pressure control valve, and upon receiving a sudden stop signal of the hydraulic machine, rapidly closes the guide vane. At the same time, the guide vane opening detected by the first detecting means and the suppression valve opening detected by the second detecting means are input to a computing device.
Based on the guide vane opening detection signal, the arithmetic unit calculates an opening to be taken by the pressure suppression valve with respect to the guide vane opening during the rapid closing operation. (2) The first wave of the water pressure rise caused by the guide vane fully closed by controlling the opening of the pressure suppression valve so as to match the calculated opening by comparing the opening with the pressure suppression valve detected by the detecting means. It is characterized in that the suppression valve is fully opened almost at the same time when the maximum value of the hydropower plant reaches the upper pond, and then the closing operation of the suppression valve is started to fully close the suppression valve. Control method of the control valve.