JPH04159457A - Method for contolling reversible pumpturbine - Google Patents

Abstract

PURPOSE:To safely and quickly switch operation from the pumping operation to the generating operation without causing violent pulsation, shaft deflection and hydraulic pulsation in a reversible pumpturbine by controlling an opening of a guide vane in accordance with a detection value of a condition of vibration, shaft deflection, pulsation, etc., of the reversible pumpturbine. CONSTITUTION:When a pumping-generating switch command is generated during pumping operation of a reversible pumpturbine, closing action of a guide vane 6 is performed to parallel off a generator-motor 1 from a power system when an opening of the vane reaches a pumping parallel off opening. While the guide vane opening is held to a small opening, a condition of vibration, shaft deflection, pulsation, etc., of the reversible pumpturbine is detected, to start air supply to the reversible pumpturbine, in the case of this detection value smaller than a specified value, and to open-action control the guide vane opening, when a rotational speed is reversed, and operation is transferred from the generating operation to the full-load operation by the generator-motor via a governor control start. On the other hand, in the case of the detection value larger than the specified value, the guide vane is fully closed, and when the rotational speed in a pumping direction is decreased to a low speed, the guide vane is open-actuated to the opening of starting the pumpturbine.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a control method for a pump-turbine, and in particular to a Francis-type pump that allows rapid and reliable transition from pumping operation to power generation operation. Concerning a method of controlling a water turbine.

(Prior Art) A Francis type pump-turbine used in a pumped storage power plant has generally been constructed as shown in FIG.

This pump-turbine consists of a generator motor 1 and a main shaft 2 of the pump-turbine.
A runner 3 attached to the lower end of the main shaft 2 is rotatably housed in a runner chamber 4. A large number of guide vanes 6 are arranged in an annular manner between the runner chamber 4 and a spiral casing 5 provided around the outer periphery of the runner chamber 4. The spiral casing 5 and the upper pond (not shown) are connected by a penstock pipe 7, and a large mouth valve 8 is provided in this pipe. Furthermore, an elbow-shaped suction pipe 9 is connected to the lower part of the runner chamber 4.

The generator motor 1 is electrically connected to a power system bus 12 via a parallel circuit breaker 10 and a main transformer 11 .

In a pumped-storage power plant equipped with a Francis-type pump-turbine configured in this way, when the pump-turbine is shifted from pumping operation to power generation operation in response to power demand, the guide vane is activated by a control command from a control device (not shown). The opening degree of 6 gradually decreases, and when the predetermined opening degree is reached, the generator motor 1 is disconnected from the power system bus 12, and the rotation speed of the pump water turbine, which was operating at the rated rotation speed, gradually decreases. A brake (not shown) of the generator motor 1 is applied and the rotational speed becomes zero. Meanwhile, after the guide vane 6 is fully closed, the inlet valve 8 is fully closed, resulting in a stop. Generally, this downtime is
It takes about 6-7 minutes.

The pumping operation is completely stopped, and in response to a generation operation command, the large mouth valve 8 is fully opened, the guide vane 6 is opened to the starting opening of the generation operation, the rotation speed is increased, and the generator motor 1 is connected to the power grid. A parallel circuit breaker 10 is connected to the bus bar 12 to enable power generation operation. Typically, this startup time requires 3-4 minutes.

In recent years, with the construction of large-capacity thermal power plants and nuclear power plants, pumped storage power plants that receive peak loads must start, stop, and switch to each operation mode as quickly as possible due to their nature. is required. In addition, in the construction of pumped storage power plants, larger capacity and higher head are required, and they are being built and operated one after another, and their responsibility is large, and they are urgently required to respond to power supply and demand balances based on commands from the power system. The recent electric power situation has also required a response when it is necessary to perform power generation operation.

The main responsibilities of a pumped storage power plant are pumping storage operation and power generation operation, but in response to the request for urgent power generation operation from the power grid during pumping storage operation, it is possible to safely, reliably, and urgently generate power from pumped storage operation. The emphasis is on transitioning to driving.

A schematic procedure of a method for controlling a pump-turbine during a rapid changeover from pumping operation to power generation operation in a conventional general pumped storage power plant will be explained with reference to FIGS. 6 and 7.

The idea behind the method of rapidly switching from pumping operation to power generation operation is that after the generator motor is disconnected from the power grid, the rotation speed in the pumping direction is quickly reversed and the rotation speed is shifted to the generation direction. It is considered that the rotational speed can be quickly slowed down by the action of water flowing down from the penstock in the direction of power generation operation, and then reversed to the rotation speed in the direction of power generation operation.

For this reason, the large mouth valve is normally kept open when the pumping operation is shifted to the power generation operation.

Figure 6 shows the block diagram at this time, and Figure 7 shows the input and output of the pump-turbine, the flow rate of the pump-turbine, the rotational speed of the pump-turbine, the opening degree of the guide vane, and the operation of the inlet valve on the vertical axis.
The horizontal axis shows the common required time and each operation.

Rapid switching command from pumping operation to power generation operation during pumping operation (
When pumping storage-power generation switching command) a is issued (time 1.),
A guide vane closing operation is performed, and this opening reaches a preset guide vane opening (pumping and disassembling row opening) (at time t
2). Then, due to the opening signal at this time, the generator motor is disconnected from the power grid, and the input/output input becomes zero (point A).

At this time, the flow rate (amount of pumped water) of the pump-turbine is reduced by gradually closing the guide vane opening.

After decoupling, the guide vane opening is maintained at the pumping decoupling opening. Then, the flow rate in the pumping direction rapidly decreases due to the water flowing down from the penstock in the direction of power generation operation while rotating in the pumping direction, that is, the pump-turbine enters the pump brake region, and at point B, the flow reverses in the direction of power generation. Start. On the other hand, the rotation speed reverses in the pumping direction at time t3 due to the action of this water flow (point C).

After that, the flow rate flows in the direction of power generation, and the rotation speed increases in the direction of power generation, and as a result, the guide vane remains at the turbine starting opening, and the governor control starts at t4.
When the speed reaches this point, control by the speed governor is started, and after being paralleled to the power system bus (time t5) and transitioning to power generation operation, full power generation operation is started (time t6).

(Problem to be solved by the invention) However, in the conventional pump-turbine control method described above,
After disconnection, the flow rate acting on the runner during operation due to rotation in the pumping operation direction flows in the direction of power generation, the rotational speed is in the direction of pumping, and the flow rate is in the direction of power generation.
(see figure), an unstable water flow acts on the pump turbine, causing severe pulsation, shaft vibration, and water pressure pulsation.
There is a problem of damage to the pump-turbine, making it impossible to safely and reliably shift from pumping operation to power generation operation.

As a method for rapid switching from pumping storage operation to power generation operation, the switching time is shortened, but there are problems as a routine switching method, and currently there is no example of this method being implemented safely and reliably.

By the way, in a Francis type pump-turbine, the rotation speed during power generation operation (turbine operation) is N1, the operating head is H1, the flow rate is Q1
When the guide vane opening degree of the pump turbine is a, the relationship between the unit head rotational speed N/fT and the unit head flow rate Q/fπ is as follows.
The characteristic curve becomes as shown in FIG.

In the figure, the guide vane opening degree is a 1 < a 2 < a
There is a relative relationship of 3<a4.

In FIG. 8, the power generation operation (water turbine operation) range is indicated by W1, and the pumping operation (pump operation) range is indicated by P.

The pump brake region where the rotational speed is in the water pumping direction and the flow rate acting on the runner is in the power generation direction is the region shown by K in FIG. This region K is passed through when transitioning from pumping operation to power generation operation, and is accompanied by severe vibrations, shaft vibrations, and water pressure pulsations, and the larger the guide vane opening, the greater the anxiety.

The present invention has been made in consideration of the above-mentioned circumstances, and when switching from pumped storage operation to power generation operation, the pump turbine can quickly shift to power generation operation without severe pulsation, shaft vibration, or water pressure pulsation, and can operate pumped storage operation. It is an object of the present invention to provide a control method for a pump-turbine that can safely, reliably, and rapidly switch from power generation operation to power generation operation.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, a method for controlling a pump-turbine according to the present invention is a method for controlling a pump-turbine when transitioning from pumping operation to power generation operation by a switching command during pumping operation. , After disconnecting the generator motor from the power grid during pumping operation, detect the vibration, shaft runout, pulsation, etc. of the pump turbine, and if the detected values are within preset values, the guide vane The rotational speed of the pump-turbine is kept at a small opening, the rotational speed of the pump-turbine is rapidly reduced, and air is injected into the pump-turbine to reverse the rotational speed of the pump-turbine to the direction of power generation operation. Control the opening degree of the guide vane to shift to power generation operation, and if the detected value of the state of the pump turbine, such as pulsation, shaft vibration, pulsation, etc., is larger than the specified value,
The guide vanes are operated to fully open, and when the rotational speed of the pump-turbine decreases and becomes low in the direction of pumping operation, the guide vanes are controlled to open to shift to power generation operation.

(Function) According to the present invention configured as described above, the pulsation and shaft vibration of the pump-turbine in the region of the pump brake that the generator-motor passes through after it is disconnected from the power system and before it shifts to power generation operation, It is possible to rapidly switch from a water pumping state to a power generation state while suppressing conditions such as pulsation to below a preset specified value.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 3.

In this embodiment, switching control of the pump-turbine from pumping operation to power generation operation is performed according to the block diagram shown in FIG. Figure 2 shows the input/output, flow rate, and flow rate of the pump-turbine at this time.
The rotational speed, guide vane opening degree, operation of the large mouth valve, and each state of the intake valve are shown in correspondence to common times.

During pumping operation of the pump-turbine, when a pumping-generation switching command a is issued (time t1), the guide vanes perform a closing operation, and the preset guide vane opening reaches the pumping-storage separation opening (time t2). ). Then, the generator motor is disconnected from the power system by the signal at this time, and the input pressure of the pump turbine becomes zero (point A).

The guide vane opening degree is further closed by a closing operation, and is controlled and maintained at a small opening degree (point D). During this time, conditions such as vibration, shaft vibration, and pulsation of the pump-turbine are detected, and it is determined whether the detected values are smaller than the specified values set to safely and reliably prevent damage to the pump-turbine. be done.

If this detected value is smaller than the specified value and it is possible to safely and reliably shift to power generation operation, that is, if this judgment is YES, the guide vane opening is maintained at the small opening, and at the same time,
In order to inject air into the pump-turbine, air supply to the pump-turbine is started at time t2), and after a certain period of time, this air supply is stopped.

In this state, the pump passes through the pump brake area of the pump-turbine, which is accompanied by severe vibration, shaft vibration, pulsation, etc. However, as mentioned above, these detected values are smaller than the specified values, and it may be necessary to adjust the guide vane opening at this time. It can be further reduced by keeping the opening small and supplying air to the pump turbine.

When the rotation speed is reversed (point D) while keeping the guide vane opening at a small opening, the opening of the guide vane is controlled to start the water turbine (time t3), and governor control is started (time 1).
4), it is paralleled to the power grid by the generator motor (time t5), and transitions from power generation operation to full load operation (time 16).
).

In the above judgment, if the detected value is larger than the specified value, if the transition to power generation operation is continued, a serious problem will occur in the pump-turbine and the pump-turbine will be damaged. Operate the guide vane opening degree to fully close as shown in . This eliminates the influence of the water flow acting on the runner during rotation in the pumping direction on the pump-turbine in the area where the power generation direction is, protecting the pump-turbine and simultaneously allowing a transition to power generation operation.

When it is detected that the rotational speed in the water pumping direction has become low while the guide vanes remain fully closed, the guide vanes are opened to the opening degree for starting the water turbine. Thereafter, the control of transition to power generation operation is the same as described above, and will therefore be omitted.

FIG. 3 shows the configuration of the main equipment of the pumped storage power plant applied to the above embodiment.

This pumped storage power plant differs from the conventional pumped storage power plant shown in FIG. 5 in that it has an air supply system 16 that includes an air supply valve 13, an air tank 14, and an air compressor 15. A plurality of air supply systems 16 may be provided independently.

The compressed air stored in the air tank 14 from the air compressor 15 is then pumped out to the pump water wheel via the air supply valve 13 to the suction pipe 9.
This is because the water is injected into the upper part of the pump turbine and the upper cover 17 of the pump water wheel.

Note that it goes without saying that the air may be injected into the pump-turbine by only one of the methods described above.

According to the above embodiment, when shifting from pumping operation to power generation operation, it is possible to prevent excessive vibration, shaft vibration, pulsation, etc. from occurring and adversely affecting the pump-turbine, and to do so safely and reliably. can be migrated to without any problem.

In addition, the transition to power generation operation can be reliably performed in about 3 to 4 minutes, meeting this demand.

In addition, an air tank 14 and an air compressor 1 for injecting air (air supply) into the pump-turbine used in this embodiment.
Devices such as No. 5 are usually installed in pumped storage power plants, and it is also possible to use them.

In order to cope with the request for a rapid transition from pumping storage to power generation operation in response to a power generation operation command in the event of an emergency, the guide vane opening is gradually closed after a pumping storage-generation switch command is issued. After the reduction, the control method is changed to disconnect the generator-motor from the power grid, and in order to shorten the switching time, all inputs for pumping operation are shut off using the pumping-storage-generation switching command, and the generator-motor is disconnected from the power system. You can also do it like this. According to this, the guide vane is quickly closed, maintained at a preset small opening degree, and the rotational speed is reversed (switched) to the direction of power generation operation, thereby transitioning to power generation operation.

Cutting off all input to a Francis type pump-turbine instantly cuts off all input from the power grid, and although it may cause disturbance to the power grid, it is appropriate for situations where power generation operations are ordered in an emergency. This is an unavoidable situation. The pump-turbine itself has few problems such as vibration and shaft vibration when all input is cut off, and there are no particular problems in terms of control.

FIG. 4 shows an embodiment in which all inputs are cut off.

The difference between the embodiment shown in Fig. 4 and the embodiment shown in Fig. 1 is that when a pumping storage-generation switching command is issued, all inputs are cut off, the generator motor is disconnected from the power grid, and the guide vane is disconnected. The point is that the guide vane can be operated up to the opening degree (small opening degree).

The subsequent migration method is the same as described above, so the explanation will be omitted.

〔Effect of the invention〕

Since the present invention has the above-described configuration, it is possible to prevent excessive vibration, shaft vibration, pulsation, etc. from occurring in the pump brake area of the pump-turbine passing through when transitioning from pumping operation to power generation operation, thereby improving safety. Moreover, it is possible to reliably shift from pumping operation to power generation operation urgently and stably.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the pump-turbine control method according to the present invention, Fig. 2 is a time chart of each state corresponding to Fig. 1, and Fig. 3 is a schematic configuration of the main parts of the pump-turbine. 4 is a block diagram showing another embodiment of the present invention,
Figure 5 is a diagram equivalent to Figure 3 showing the main parts of a conventional pump-turbine, Figure 6 is a diagram equivalent to Figure 1 showing a conventional pump-turbine control method, and Figure 7 is a diagram corresponding to Figure 6. The state time chart, FIG. 8, is a graph showing the characteristic curve of a Francis type pump-turbine. DESCRIPTION OF SYMBOLS 1... Generator motor, 3... Runner, 4... Runner room, 6... Guide vane, 10... Parallel circuit breaker, 12... Power system bus, 13... Air supply valve, 14
...Air tank, 15...Air compressor, 16...
Air supply system. Applicant's agent Hisarei Hatano Zujuku 4-n

Claims (1)

[Claims] In the control method of a pump-turbine when shifting from pumping operation to generating operation by a switching command during pumping operation, vibration, shaft vibration, pulsation, etc. of the pump-turbine after disconnecting the generator motor from the power grid during pumping operation. If the detected value is within the preset value, the guide vane is kept at a small opening, the rotational speed of the pump-turbine is rapidly reduced, and air is supplied to the pump-turbine. After injection, the rotational speed of the pump-turbine is reversed to the direction of power generation operation, and after this reversal, the opening degree of the guide vane is controlled to shift to power generation operation, and the pulsation, shaft vibration, pulsation, etc. of the pump-turbine are controlled. If the detected state value is larger than the specified value, the guide vane is fully closed, and when the rotational speed of the pump-turbine decreases and the speed becomes low in the direction of pumping operation, the guide vane is controlled to open and shifts to power generation operation. A method of controlling a pump-turbine, characterized in that: