JPS61149582A - Stopping method for variable speed reversible pump-turbine or pump - Google Patents

Abstract

PURPOSE:To reduce the input from an electric power system at the time of parallel-off stopping the operation of pump by reducing the number of revolutions of a generator-motor and further reducing the opening of guide vanes when a pump is stopped. CONSTITUTION:When the command to stop the operation of pump is received, the performance of pump changes in accordance with the thick solid line C-D. The opening of guide vanes is gradually throttled, and at the same time the number of revolutions is gradually decreased via speed controller being a means to regulate the number of revolutions. The motor is brought into parallel-off from an electric power system at the point D where the number of revolutions is not less than the lowest number of revolutions and the opening of guide vanes is the parallel-off opening GVOd. Thus, as compared with that the pump input at the time of parallel-off was the parallel-off input Pd1 in the case of a constant speed machine, it can be reduced to the parallel-off input Pd2 in the time of parallel-off notwithstanding the same guide vane parallel-off opening GVOd.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for stopping the operation of a Kaga-speed pump-turbine or a pump. This relates to a method for stopping a pump-turbine or a pump.

[Background of the invention]

Regarding the conventional spear device, Japanese Patent Application Laid-Open No. 56-12667
As described in Publication No. 5, it has been shown that the efficiency of a hydroelectric power generation device can be improved by adjusting the rotational speed. The axis shows the rotational speed of the runner, and the vertical axis shows the pump input and the opening degree of the guide vane, and the tendency is as shown in FIG. 1 of the embodiment of the present invention, which shows the case where the lift is constant. . Figure 1 shows how the pump input changes depending on the rotation speed using the guide vane opening degree as a parameter. No - ΔN = N
o+ΔN is the variable speed machine rotation speed range. In a conventional pump-turbine or pump, the rotational speed is the rated rotational speed No. of the constant-speed machine, and it does not change when electric motors are connected in parallel in the power system, so only the center line La in the figure is the conventional constant speed. This is the operating area for speed pump turbines or constant speed pumps.

The normal pump operating condition corresponds to point A in the llil diagram, and the opening degree of the nine guide vanes arranged around the runner's outer circumference is the optimum opening degree GVO, which makes the pump pumping amount most efficient.
It is in. In this case, when a pump operation stop command is received, the guide vane opening degree is narrowed down to reduce the amount of water pumped and the pump input, and then the electric motor is disconnected from the power system. However, although it is true that reducing the guide vane opening will reduce the pump input, the limit to this reduction is the input during shut-off operation, which is equivalent to several tens of rated input64), and the input during disconnection beyond this limit. It is difficult to reduce. That is, this is because the runner only rotates underwater after the constant speed machine enters the shut-off operation. Figure 4 shows the normal pump input white line when the horizontal axis shows the guide vane opening and the vertical axis shows the pump input when the head is constant and the rotational speed is constant. This is an example showing how much the pump input is reduced.

As is clear from FIG. 4, even if the guide vane opening is reduced to an appropriate opening, it will not be reduced unless the kana is narrowed down.

Reducing the pump input during disconnection has the effect of reducing the load on the circuit breaker and extending its life, and in order to reduce the shock during disconnection without affecting the power system, especially for large-capacity pump-turbines. Alternatively, in the case of a pump, it is desired to reduce pump input as much as possible. On the other hand, if the opening degree of the guide vane is excessively reduced in order to reduce the input at the time of decoupling, the operating condition of the pump-turbine or the pump will deteriorate. At the optimum guide vane opening degree G V Oo, the flow condition inside the pump is very good and the magnitude of the water pressure pulsation is small. As the pump approaches its shut-off operation (fully closed opening), the flow inside the pump deteriorates significantly, the water pressure pulsation increases, and the vibration and noise of the equipment also increases. An increase in water pressure pulsation causes an increase in the stress amplitude of the pump turbine or various parts of the pump body.
This is unfavorable in terms of the fatigue strength of the equipment.

Therefore, the opening degree of the guide vane when disconnecting the motor from the power grid must be such that the pump input during disconnection is as small as possible, the vibration noise and stress amplitude of the equipment during disconnection are the maximum allowable, It is generally determined by two conditions. 15th! J.

Point B in Figure 4 corresponds to the operating point at the time of disconnection. In this case, due to the vibration noise and strength limitations of the equipment, the input is about 1/2 of the rated pump input, well before the shut-off operation state is reached. Corresponding pumps are disassembled using human power. Harmful shock t-
1it power will be given to the system.

Fig. 2 shows an embodiment of the present invention in which the horizontal axis shows the time when the operation of the pump-turbine or the pump is stopped, and the vertical axis shows the guide vane opening degree GvO1 rotational speed N and pump manual power P. The case is shown by broken line E. After receiving the pump operation stop command at the pump operation stop command (stop operation start) time TsK, the guide vane opening degree G
At the disconnection time Td when Oa is reached, the motor is disconnected from the grid.

Since it is a constant speed machine, it rotates at the rated rotational speed N@ as shown by the broken line E until it is disassembled, and the pump input during this period is reduced as shown by the broken line E by narrowing the guide vane opening degree GvO. Therefore, as can be seen from the pump input characteristics shown in Fig. 4, the input does not change much at the beginning of the guide vane opening, so the pump input will not decrease unless the pinion is tightened, and if the guide vane opening is not tightened too much, the pump input will not decrease. If it is too high, the noise from the equipment will increase. In other words, when a fixed-speed pump turbine or pump is stopped, the pump input before disconnection is large, which has a negative impact on the power system, and the vibration and noise are also large, which inevitably worsens the equipment environment. was.

In the above description, conventional pump operation stoppage has been described for a pump or pump-turbine having a movable guide vane, but the same applies to a pump or pump-turbine having a discharge valve instead of a movable guide vane.

[Purpose of the invention]

The present invention was made in view of the above situation, and an object of the present invention is to provide a variable speed pump-turbine or a method for stopping a pump, which can reduce the input from the electric power system when disconnecting the pump to stop operation. It is something.

[Summary of the invention]

The variable speed pump turbine or pump stopping method of the present invention includes:
When stopping a pump water turbine or pump equipped with a discharge valve or a guide vane disposed on the outer periphery of the runner and a variable speed magnetic motor or variable speed generator motor connected in parallel to the power system, 1. Before disconnecting the electric motor or the generator motor, 1. Decrease the rotation speed of the electric motor or generator motor and reduce the opening degree of the guide vane or the discharge valve to reduce the pump input compared to when the motor is driven at the rated rotation speed. This is the way to do it. By reducing the rotational speed of the motor and reducing the opening of the guide bay/or discharge valve to reduce pump input, it is possible to reduce the impact of impact on the circuit breaker load and power system. .

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The variable speed pump turbine or the method for stopping a pump according to the present invention will be explained below using an embodiment with reference to FIGS. 1 and 2. 1st
In the figure, the process from steady pump operation to disconnection of the pump in this embodiment is shown by thick Ln% line C-D, and the diagonally shaded range shows the variable speed operation range. Since this embodiment deals with a pump turbine or a pump whose rotational speed is variable, the rotational speed in a steady operating state is not necessarily at the rated rotational speed No. For this reason, for example, if the pump is operated steadily at a rotation speed point C, which is larger than the rated rotation speed number, with the appropriate (optimum) guide vane opening G V Oo,
When a pump operation stop command is received, the process progresses as shown by the thick solid line C-D. Therefore, after receiving an order to stop pump operation,
The opening of the guide vane is gradually squeezed in, and the rotational speed is gradually lowered through a speed control device which is a means for adjusting the rotational speed.

At the point DK when the rotational speed is the lowest rotational speed in the variable speed range and higher than the minimum rotational speed unique to the motor [(N o - ΔN) and the guide vane opening becomes the alignment opening GVOa, the motor is powered up. Disassociate from the system.

By doing this, the pump input at the time of unalignment is the unaligned input Pdl in the case of a constant speed machine, but even though the guide vane unaligned opening degree G V Oa is the same, the unaligned pump input at the time of unaligned The input power can be reduced to Pd2. On the other hand, it can be seen that the vibration noise and strength severity of the pump-turbine near the point of decoupling are alleviated as the rotation speed approaches the lowest rotational speed (N(1-ΔN)K) of the variable speed range.In other words, the guide vane In operating conditions that are much smaller than the optimum opening degree G V Oo and almost close to the shut-off operating condition, the water pressure inside the pump-turbine runner chamber, and therefore the stress amplitude of each part of the pump-turbine, decreases as the rotational speed decreases. This is because it is smaller than when it is thick.

In this way, the variable speed pump-turbine or pump stopping method of this embodiment is such that before the motor is disconnected from the magnetic system, the rotational speed of the motor is reduced and the RKt of the guide vane is reduced. Since the pump input during operation can be reduced, the impact on the circuit breaker load and the power system can be reduced, and the strength environment of the equipment, such as fatigue strength, can be alleviated. Numerically, according to an estimate based on pump characteristics, the input at the time of decoupling can be reduced to about 601 by simply reducing the rotational speed to 90% of the rated rotational speed. Furthermore, the amplitude of water pressure pulsation near the time of disconnection can be reduced to about 80 degrees. In the above embodiment, the guide vane opening I
Although the case where the discharge valve is narrowed down has been described, the same effect can be obtained when the opening degree of the discharge valve is narrowed down.

FIG. 3 shows another embodiment, in which the rotational speed is changed immediately after receiving a command to stop pump operation,
Control is performed so that the lowest value of the variable speed range is achieved at the lower-level train-disconnecting input Pd2.

However, in order to achieve the object of the present invention, it is not necessarily necessary to control only as described above.

In addition, the rotation speed during steady operation before the stop command is not necessarily at the rated rotation speed No. (
It is also possible that the vehicle is being operated under the condition (No+ΔN). In Figure 3, the variable speed minimum rotational speed (No.
-ΔN) is controlled at a rotational speed change gradient. Therefore, according to this embodiment, no matter which rotational speed within the variable speed range is being operated, when disconnecting, the rotational speed is set to the minimum possible rotational speed (No - ΔN) of the pump input of the speed control device. Pump input during disconnection can be reliably reduced. This example also has the same effects as the above example.

〔Effect of the invention〕

As described above, the variable speed pump-turbine or pump stopping method of the present invention can reduce the pump input when the train is disconnected, so it has the effect of reducing the impact on the circuit breaker load and the power system. .

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the relationship between rotational speed and pump input when the variable speed pump-turbine or pump stopping method of the present invention is implemented, and Figures 2 and 3 are respectively diagrams when the stopping method of Figure 1 is implemented. FIG. 4 is an explanatory diagram of the relationship between guide vane opening degree 2 rotational speed and pump input with respect to the time from the start of pump stop operation to disassembly. FIG. 4 is an explanatory diagram of the relationship between guide vane opening degree and pump input during normal operation. G V Oo...Optimum opening [, GVO-...Disconnection opening degree, No...Rated rotation speed, No-ΔN...Variable speed minimum rotation speed, Pd2...Disconnection input, Td・...At the time of disassembly, (1 other person) - 1 rotation speed N time T

Claims (1)

[Claims] 1. A method for stopping a pump water turbine or pump provided with a discharge valve or a guide vane disposed on the outer periphery of a runner, and a variable speed electric motor or variable speed generator motor connected in parallel to an electric power system. Before disconnecting the electric motor or generator motor from the power system, reduce the rotational speed of the electric motor or generator motor, reduce the opening degree of the guide vane or the discharge valve, and drive the motor to the rated rotational speed. A method for stopping a variable speed pump-turbine or pump, characterized by reducing the pump input compared to the current time. 2. The rotational speed of the motor or generator-motor at the time of disconnecting the motor or generator-motor from the power system is at least the lowest rotational speed unique to the motor or generator-motor, and the speed control device A method for stopping a variable speed pump-turbine or a pump according to claim 1, wherein the controllable minimum rotational speed is set.