JPS623174A - Operation stop of pump in pump waterwheel - Google Patents

Abstract

PURPOSE:To stably stop a pump waterwheel by reducing the revolution speed of the pump waterwheel when a stop instruction is transmitted and by closing- controlling a guide vane and disconnecting the pump waterwheel from an electric power system when the opening degree reaches a prescribed opening degree. CONSTITUTION:A Francis-type pump waterwheel is equipped with a plurality of flow-rate adjusting guide vanes 2 in the outer peripheral side flow passage of a runner 1, and each guide vane 2 is opening/closing-controlled by a guide vane controller 4 through an operating mechanism 3. A power generating motor 6 is directly connected to the runner 1 through a main shaft 5, and said motor 6 is controlled by a variable speed controller 7. When a stop instruction is generated, the revolution speed of the power generation motor 6, namely of the pump waterwheel is reduced to a prescribed revolution speed from a rated revolution speed N0 until a prescribed revolution speed reduction rate is realized, and the guide vane 2 is closing-controlled. Then, the pump waterwheel is disconnected from an electric power system, and the guide vane 2 is perfectly closed to stop the pump waterwheel.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a guide vane for flow rate adjustment and a method for stopping pump operation of a pump water turbine equipped with a variable speed control device.

(Technical date of the invention and its problems) In general, a cylinder equipped with a guide vane for flow adjustment and adjustment.
.

When stopping the pump water turbine from pumping operation, first send a stop command to the guide vane control device to control the guide vane a1 and reduce the amount of pumped water.

In both cases, the pump-turbine is disconnected from the power system when the guide vane opening reaches a predetermined small opening, before the pump-turbine enters the secondary flow region with vibration and noise in the low-flow region. Then, the guide vane is completely closed and the pump turbine is stopped.

In this way, in the conventional stopping method, in order to avoid operation in the secondary flow area where the pump turbine is vibrating and noisy, the guide vane is disconnected from the power grid at a specific opening before it is fully opened. However, in general, bomb turbines, especially Francis type pump turbines, which are often used in pumped storage power plants,
Due to its hydraulic characteristics, the pump shaft input at the opening before the guide vane reaches its fully open state is the pump shaft input during operation at the normal guide vane appropriate opening (the guide vane opening at the highest efficiency point at a certain lift). Although it is smaller than that, it is only about 70% at most, so it does not decrease much.

Disconnecting a pump-turbine from the power system with such a large shaft input has an extremely large impact on the power system, especially in the case of a large-capacity pump-turbine, causing power fluctuations and power frequency fluctuations, resulting in significant damage to consumers. There is a risk of damage.

Conventionally, the generator motor directly connected to the pump turbine in a pumped storage power plant has generally been operated at a constant rotation speed using a synchronous machine from the viewpoint of operational control and economic efficiency.

However, with recent advances in power electronics technology, it has become possible to variable speed control the rotation speed of the generator motor, that is, the rotation speed of the pump water turbine, by using, for example, a frequency conversion device (thyristor). Various proposals have been made regarding control methods for operating hydraulic machines such as pump-turbines capable of variable speed control in steady-state water turbine or pump operation (for example, Japanese Patent Laid-Open No. 48-2
1045, JP-A-57-113971, JP-A-58-1
8595, Japanese Patent Application Laid-Open No. 58-222981), but no suitable method has been found for stopping the pump from the operating state.

As described above, in a pump water turbine equipped with a flow ω adjustment guide vane and a variable speed control device, no control method has yet been proposed for stably stopping the pump operation state without affecting the power system.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for stopping the pump operation of a pump water turbine equipped with a guide vane for flow rate adjustment and a variable speed control device, which stops the pump operation without adversely affecting the electric power system. .

[Summary of the invention]

The method for stopping pump operation of a pump-turbine according to the present invention is applied to a pump-turbine equipped with a guide vane for adjusting the flow that is opened and closed by a guide vane control device, and a variable speed control device for adjusting the rotation speed, during pump operation. When a stop command is issued to the variable speed control device, the stop command is first transmitted to the variable speed control device to reduce the rotational speed of the pump turbine to a predetermined rate of decrease, and at the same time, the stop command is transmitted to the guide vane control device to guide the pump turbine. The vane is controlled to close, and when the input to the pump-turbine decreases and the guide vane opening reaches a preset opening degree, the pump-turbine is disconnected from the power system, and the guide vane is controlled to fully open to control the pump-turbine. It is characterized by stopping.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a 7-runcis type pump-turbine to which the present invention is applied and a generator-motor directly connected to it.
are installed in a circular row of blades, and each guide vane is controlled to open and close by a guide vane control device 4 via a guide vane operation mechanism 3. The runner is directly connected to a generator motor 6 via the main shaft 5, and a variable speed control device 7 is electrically connected to this generator motor, and this variable speed control device controls the rotational speed of the generator motor n6 and, by extension, the pump water turbine. The rotation speed of the runner is controlled.

When a stop command is issued during pump operation of the pump-turbine configured as described above, as shown in the operation control block diagram of FIG. 2, the stop command is first transmitted to the variable speed control device 7, and the rotational speed of the pump turbine is the rated rotational speed N. At the same time, a stop command is transmitted to the guide vane control device 4, and the guide vane 2 is controlled to close via the guide vane operating mechanism 3. After that, when the rotational speed reaches the rotational speed N1 that matches the predetermined reduction rate (in this case, the rotational speed reduction rate is N / No) and the guide vane opening reaches the predetermined small opening. The pump-turbine is disconnected from the electric power system, and all guide vanes 2 are controlled to stop the pump-turbine.

FIG. 3 shows temporal changes in guide vane opening, rotational speed, and pump shaft input in the above-described stopping method according to the present invention and in the conventional stopping method.

That is, when a stop command is issued to the pump-turbine, the guide vane 2 is controlled to close at a closing operation speed determined by the guide vane control device 4, so that the guide vane control according to the conventional method and the present invention is It must be.

However, in the present invention, the rotational speed of the pump-turbine is reduced by a predetermined reduction rate N2/No, so the rotational speed becomes N1. If a hydraulically similar operation is performed here, the shaft input will change by the cube of the rotational speed according to the hydraulic similarity law, so if the pump import in the conventional method has an uncoupled opening at al, the rotational speed Decrease rate N1/
If No is set to 0.8, P = 0.512X
P2, and the pump shaft human force P1 at the time of disconnection is approximately half of the pump shaft human force P2 at the time of disconnection according to the conventional method.

As described above, according to the present invention, it is possible to reduce the shaft input when the parallel is disconnected, so that the influence on the power system can be sufficiently reduced.

(Effects of the Invention) As described above, according to the method for stopping pump operation of a pump-turbine of the present invention, it is possible to reduce the pump shaft input at the time of decoupling, thereby reducing power fluctuations applied to the power grid and accompanying frequency fluctuations. The generation of electricity can be suppressed and a stable power supply becomes possible. Furthermore, since the rotational speed of the pump-turbine is reduced from the rated value at the same time as the stop command and the pump-turbine is disconnected from the rated value, the time required to stop the pump-turbine can be shortened compared to the conventional method. In other words, it is possible to shorten the time required to change the operation mode, which is an important mission of pump-turbines, and the transition time from pump operation to water turbine operation, which is especially important, and it is possible to quickly respond to power supply in emergencies, thereby increasing the diversity of power supply. It can greatly contribute to the development of

Furthermore, since the rotation speed reduction rate can be set arbitrarily in accordance with the hydraulic characteristics of the pump-turbine, the strength of the power system, etc., it is possible to select an economical control device.

Furthermore, it also reduces water pressure fluctuations that occur during shutdown operations, greatly improving the reliability of equipment over long periods of operation.

As described above, according to the present invention, it is possible to obtain a method for stopping the pump operation of a pump-turbine that is simple, stable, and reliable.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram illustrating a Francis type pump-turbine and generator motor to which the present invention is applied, Fig. 2 is an operation control block diagram showing an embodiment of the present invention, and Fig. 3 is a guide according to the present invention and a conventional method. It is a diagram showing how the vane opening degree 81 rotation speed N and the pump shaft input P change over time. DESCRIPTION OF SYMBOLS 1...Runner, 2...Guide vane, 3...Guide vane operation mechanism, 4...Guide vane control device, 5
...Main shaft, 6...Generating power 1FJJ machine, 7...Variable speed control device. Applicant's agent Kiyoshi Inomata Figure 1 Male Figure 2 Figure 3

Claims (1)

[Claims] 1. In a pump turbine equipped with a guide vane for flow rate adjustment that is opened and closed by a guide vane control device and a variable speed control device that can adjust the rotation speed, when a stop command is issued during pump operation, the stop command is first issued. is transmitted to the variable speed control device to reduce the rotational speed of the pump-turbine to a predetermined reduction rate, and at the same time, a stop command is transmitted to the guide vane control device to control the guide vane to close, so that the input to the pump-turbine is controlled to close. The pump-turbine is characterized in that when the guide vane opening reaches a predetermined opening, the pump-turbine is disconnected from the power system and the guide vanes are fully closed to stop the pump-turbine. How to stop pump operation.