JPS5846677B2 - Pump Suishiyano Hogo Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for protecting a pump water turbine, and more particularly to a method for protecting a penstock when the main engine rotates upward in the reverse direction while the pump is in operation.

Pump-turbine generally has different guide vane closing speeds for pump operation and water turbine operation.
Further, the closing speed in each operation mode is a so-called closing speed in which the closing speed is changed in the middle of closing.

The details will be explained with reference to FIG.

First, the water turbine operation mode will be explained.

If the guide vane opening is now 100% and load shedding is performed at this point, that is, if the load on the generator directly connected to the pump-turbine is suddenly cut off, the rotational speed of the pump-turbine will temporarily decrease. to rise.

In the case of a pump-turbine, the diameter of the runner blades is made relatively large to enable reverse rotation of the pump, and the runner shape is designed so that sufficient centrifugal force acts on the water.

For this reason, even if the water turbine is operated in a direction different from the pump operation, if the rotation speed increases, a large centrifugal force will act on the water flowing through the runner, reducing the amount of water flowing into the runner chamber, and eventually causing it to flow backwards. , turn the pump direction flow.

In other words, even if the guide vanes are not closed, if the rotation increases, the flow rate of the water turbine will decrease.

This tendency becomes stronger the higher the head of the pump turbine becomes, and a phenomenon occurs in which the rotation speed increases and immediately after the rotation speed starts to decrease, the flow in the turbine suddenly shifts to flow in the direction of the pump.

As a natural result, the water pressure in the penstock of the pump-turbine increases rapidly.

In particular, when an increase in rotational speed and a sudden closing of the guide vanes occur simultaneously, the flow rate reduction effect due to the pump action and the throttling effect of the guide vanes occur at the same time, causing an abnormal increase in water pressure within the penstock, which is dangerous.

For this reason, conventionally, in the water turbine operation mode, the closing speed of the guide vanes is limited and bent as shown by curve 36 below a certain opening degree (for example, 70%).

For example, if we consider a case where load shedding occurs when the guide vane opening is close to 100%, the guide vanes will close relatively quickly at first, and then at a relatively slow speed by the time the rotation speed exceeds the maximum value and begins to fall. This prevents the above-mentioned abnormal water pressure rise from expanding.

Next, the pump operation mode will be explained.

If the electric motor that is directly connected to the pump-turbine and drives the pump-turbine is turned off during pump operation, if the guide vanes close too late, the water flow that was in the direction of the pump will reverse and shift to the turbine flow. The direction of rotation not only stalls in the direction of the pump, but also eventually reverses, essentially shifting to water turbine operation.

During this period, the backflow and reversal phenomena are accompanied by vibrations and create extremely severe operating conditions for the pump-turbine.

Therefore, as soon as the electric motor is powered off, the guide vanes are closed, and the guide vanes are closed all at once at a relatively fast speed, as shown by curve 35, until nearly fully closed.

The reason for lowering the closing speed by bending near the fully closed position is to reduce the degree of water hammer on the draft side immediately after closing.

As is clear from the above, 1. If the input to the motor is lost during operation in the pump operation mode, but the guide vanes are not closed and reversed and the mode essentially shifts to the water turbine operation mode, the closing pattern of the guide vanes will change. If the pump remains in the pump operation mode, the opening of the guide vanes will be too closed, which can lead to buckling, and the throttling action of the guide vanes will work too much, causing a sudden rise in the water pressure in the penstock, creating an extremely dangerous situation.

The guide vane closing speeds, which have different closing speeds for pump operation and water turbine operation, are determined by a guide vane closing speed selection device.

Conventionally, there are two types of guide vane closing speed selection devices.

In other words, there is a mechanical guide vane closing speed selection device that mechanically detects the guide vane opening position using a cam or the like and operates a guide vane closing speed selection device plunger through a hydraulic switching valve, and the other system controls the guide vane opening position. This is an electric guide vane closing speed selection device that operates the guide vane closing speed selection device plunger electrically captured by a position switch and through a solenoid valve.

A common drawback in these conventional technologies is that the mode selection for pump operation and water turbine operation is only selected manually or automatically in the sequence progression, that is, only by external commands, and the main engine The problem is that so-called self-adaptive mode selection, in which the driving state itself is monitored and fed back to the mode selection device, has not been considered.

For this reason, for example, even if the main engine that has been selected for pump operation is in a state where the rotation speed increases in the reverse direction (hydraulic operation state), the main engine remains in pump operation mode and stops, causing an abnormal pressure increase in the penstock. This can lead to accidents such as bursting of iron pipes.

An object of the present invention is to improve the above-mentioned drawbacks of the prior art and to provide a method for protecting a pump-turbine that is safe under any operating conditions.

That is, the features of the present invention include a reversible runner for operating a pump in forward rotation and operating a water turbine in reverse rotation, and a water amount adjusting means for adjusting the amount of water flowing into this runner. In a method of operating a pump-turbine, in which the closing pattern of the water volume regulating means is set differently for pump operation and water turbine operation, and the closing pattern of the water volume regulating means is switched depending on the operation mode, the pump rotates in reverse during operation of the pump, thereby effectively turning the water turbine When the water turbine operation is started, a means is provided to detect the transition to the water turbine operation, and a signal output from this detection means automatically changes the closing pattern of the water flow control means that was set to the pump operation mode to the water turbine operation mode. There is a pump-turbine that is designed to switch over.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the plunger 2 of the secondary pressure distribution valve 1 distributes pressure oil to the opening and closing sides of a guide vane servo motor (not shown), and operates the guide vane with hydraulic pressure. It is moved up and down by.

This valve servo motor 3 is a pilot plunger 4
It is moved up and down according to the up and down movement of.

That is, since pressure oil is constantly acting on the lower chamber of the valve servo motor 3, when the pilot plunger 4 moves upward and the oil in the upper chamber of the valve servo motor 3 is discharged through the passage 37, the valve servo motor Motor 3 moves upward.

When the pilot plunger 4 moves downward and the pressure oil also communicates with the upper chamber of the valve servo motor 3 through the passage 37, the valve servo motor 3 moves downward.

The reason for this is that the upper chamber of the valve servo motor 3 has a larger pressure receiving area than the lower chamber.

6 and 7 are lever mechanisms, which feed back the movement of the valve servo motor 3 to a bushing 5 paired with the pilot plunger 4 and located on the outer periphery of the pilot plunger 4.

The lever mechanisms 6 and 7 are provided so that the displacement of the valve servo motor 3 and the pilot plunger 4 are in a constant proportional relationship.

8 is an oil motor that is constantly rotated by pressure oil.

9 is an eccentric cam that transmits minute vibrations to a dedicated lever 10 as the oil motor 8 rotates.

This slight vibration is transmitted to the bushing 5 via the lever mechanisms 6 and 7, and is useful for reducing the frictional force and hydraulic force between the pilot plunger 4 and the bushing 5.

The pilot plunger 4 can be moved up and down in accordance with the difference between the displacement of an auxiliary servo motor of a speed governor (not shown) and the displacement of a guide vane servo motor.

In other words, the guide vane servo motor is controlled according to the positional displacement of the auxiliary servo motor on the command side, but its speed is determined depending on the displacement of the plunger 2.

That is, when there is a large downward displacement, the closing speed is fast, and when the downward displacement is small, the closing speed is slow.

In addition, in the case of upward movement, it becomes an opening movement.

Numeral 11 is a nut for setting the maximum allowable closing speed of the guide vane servo motor, and 12 is a nut for setting the maximum allowable closing speed.

By the way, the closing speed of the guide vanes needs to be switched depending on the operating condition, and simply setting the maximum closing speed using the nut 12 is not enough.

To achieve this, stop pistons 13 to 15 of the guide vane closing speed selection device are provided.

These stop pistons 13 to 15 are arranged around the valve servo motor 3 and operate to limit the downward movement of a stop plate 16 mounted on the top of the valve servo motor 3.

First, the stop piston 13 is used to determine the closing speed of the guide vane before buckling in the water turbine operation mode.In the pump operation mode, the lower chamber is drained of oil and remains in an invalid state, but in the water turbine operation mode, the lower chamber remains in the disabled state. Pressure oil is guided through the solenoid valve 17 to provide a predetermined restriction.

The degree of restriction is determined by adjusting the position of a nut 18 mounted on the rod of the stop piston 13.

Similarly, the stop piston 14 is for determining the guide vane closing speed after buckling in the water turbine operation mode, and the stop piston 15 is for determining the guide vane closing speed after buckling in the pump operating mode. .

19 and 20 are electromagnetic valves that operate the stop pistons 14 and 15, respectively; 21 and 22 are the stop pistons 14;
and a stop piston 1 mounted on a rod of 15
This is a nut that adjusts the positions of numbers 4 and 15.

23 is an operation mode selection solenoid valve for distinguishing between the water turbine operation mode and the pump operation mode.

24 and 25 are coils of the solenoid valve 23;
When turned on, the pressure oil is passed to the solenoid valve 19 and utilized.
When the coil 25 is turned on, pressure oil is passed to the solenoid valve 20 to utilize it.

That is, the solenoid valve 19 allows pressurized oil to flow to the stop piston 14 only when the coil 26 is turned on, thereby activating the bend in the water turbine operation mode.

Further, the solenoid valve 20 allows pressurized oil to flow to the stop piston 15 while the coil 27 is turned on, thereby activating the pump operation mode.

In addition, 28 is a coil of the solenoid valve 17, 29 is a body of a guide vane closing speed selection device, and each stop piston 13 to 15 is incorporated in this body 29.

The main engine is selected to the pump operation mode by operating the "pump-water turbine" operation mode switching switch 30 in FIG. 2, and
The case where the pump is in operation will be explained.

A maintenance device (not shown) for immediately giving a guide vane closing command to the main engine in the above operating state when the main engine loses input for some reason, for example, to the pump drive motor.
Due to reasons such as non-operation of the guide vanes, the guide blades remain open and reverse, effectively turning into a water turbine operation, and the rotation increases further.
When the rotational speed of the water wheel reaches a specified rotational speed or higher in the rotating direction of the water wheel, the overspeed switch 31 shown in FIG. 2 is closed.

When the overspeed switch 31 of FIG. 2 closes, the auxiliary relay 32 of the same diagram is energized.

That is, by closing the a contact (a contact that is closed when the relay coil is energized) of the auxiliary relay 32 in FIG. 2, the coil 28 in the figure is energized even though the pump is in the pump operation mode.

Coil 24 is also energized at the same time, while coil 25 is de-energized, essentially readying the closed pattern of the turbine operation mode.

Thus, the coil 26 is deenergized below the guide vane opening detected by the guide vane opening position switch 33.

Therefore, in FIG. 1, the solenoid valve 17 for the guide vane closing speed selection device is switched to the water turbine operation mode, and the operation mode selection solenoid valve 23 is switched to the water turbine operation mode.

Furthermore, the solenoid valve 19 for the guide vane closing speed selection device is a second
When the guide vane opening is less than or equal to the guide vane opening detected by the guide vane opening position switch 33 shown in the figure, it is switched to the oil passing side, and the stop piston 14 of the guide vane closing speed selection device shown in FIG. 1 is moved upward.

In this way, the guide vanes close exactly according to the turbine operating mode guide vane closing speed curve 36 of FIG.

In the above description, the overspeed switch 31 detects that the rotation is reversed and the mode is substantially shifted to the water turbine operation mode, and the reason for this will be explained.

While operating at the rated rotation in the water turbine operation mode, the guide vane opening at which the turbine output becomes exactly zero is called the no-load opening.If the above-mentioned reversal occurs exactly at this no-load opening, then even after the reversal, the rotation will be exactly at the rated rotation. It will not cause overspeed just by reaching the maximum speed.

However, in reality, when the pump is operated, it is operated at an appropriate opening that provides the highest efficiency, and this opening is much higher than the no-load opening.

That is, if a reverse rotation occurs at this high opening degree, it is inevitable that the rated rotation will be exceeded and an overspeed state will occur.

Conversely, if the rotation is reversed to the extent that it does not result in an overspeed condition, it means that the guide vane opening is already quite closed.

With such a small opening degree, even if the pump is closed in the closed pattern of the pump operation mode, a large increase in water pressure will not occur and it is not dangerous.

Incidentally, in the case of a pump-turbine, there is a method of intentionally reversing the operation mode from the pump operation mode to the turbine operation mode without stopping the main engine, and directly transitioning, but in this case, it is not a malfunction, so the guide vane closing pattern switching command is used. is also properly provided, so there is no need to rely on the protection device of the invention.

By operating the "pump-water turbine" operation mode switching switch 30 in FIG. 2, the main engine is selected to the water turbine operation mode, and
It goes without saying that when the water turbine is in operation, the main engine is stopped in accordance with the water turbine operation mode guide vane closing speed curve 36 in FIG. 3 at any time and in any state.

In the case where the main engine is selected to be in the pump operation mode and stopped in the pump operation state, that is, in the pump rotation direction, it goes without saying that the main engine will be in the pump operation mode as shown in Fig. 3 at any time and in any state. It is stopped according to the guide vane closing speed curve 35.

That is, the main engine is always stopped at the guide vane closing speed of the operating mode that matches the rotation direction.

Note that the guide vane position switch 34 is turned ON when the opening is below a predetermined small opening.
.

It turns OFF when the opening is greater than that.

In the above, the guide vane closing signal accompanying the loss of input to the pump drive electric motor is generally given to an auxiliary servo motor (not shown in FIG. 1), which immediately lowers the plunger 2 of the secondary pressure regulating valve 1 and It is designed to stop.

According to the present invention, the drawbacks of the prior art as described above are completely compensated for, in addition to the method of manually selecting each mode of pump operation mode and water turbine operation mode and automatic operation of sequence progression. By enabling a so-called closed-loop mode selection method in which the operating state of the main engine itself is detected and fed back to the mode selection device, it is possible to always select the operating mode of the main engine that matches the rotational direction. , it is possible to avoid accidents such as the rupture of penstocks.

In the embodiment of the present invention, an overspeed switch is used to detect reverse rotation during pump operation, but it is also possible to detect the pressure inside the penstock or the flow rate instead of using the overspeed switch. It is possible to detect the reverse rotation indirectly, and it is also possible to detect the reverse rotation simply by using a tachometer or a general speed switch by partially changing the control circuit.

[Brief explanation of drawings]

FIG. 1 shows an embodiment in which the present invention is applied to a pump water turbine having a plurality of guide vane closing patterns in each of the pump operation mode and the water turbine operation mode, and having an electric guide vane closing speed selection device. 2 is a diagram of the hydraulic operation system, FIG. 2 is a control circuit diagram of FIG. 1, and FIG. 3 is a diagram showing the closing speed curves of the guide vanes of the pump, water turbine, and each other. 1...Secondary pressure distribution valve, 2...Plunger, 13-15...Plunger piston, 1
7,19゜20.23... Solenoid valve, 35...
... Pump operation mode guide vane closing speed curve, 36.
...Hydraulic turbine operation mode guide vane closing speed curve.

Claims (1)

[Claims] 1. It has a reversible runner that performs pump operation in forward rotation and water turbine operation in reverse rotation, and a water volume adjustment means that adjusts the amount of water flowing into this runner, and the closing pattern of this water volume adjustment means is used for pump operation. In a method of operating a pump-turbine in which the closing pattern of the water volume regulating means is set differently from that of a water-turbine operation and the closing pattern of the water volume regulating means is switched according to the operating mode, if the pump rotates in reverse during operation and the mode essentially shifts to a water-turbine operation, Provide a means to detect the transition to water turbine operation,
A method for protecting a pump-turbine, characterized in that the closing pattern of the water volume regulating means, which has been set to a pump operating mode, is automatically switched to a water-turbine operating mode using a signal output from the detecting means.