JPS61152969A - Operation controlling method of reversible pump-turbine - Google Patents

Abstract

PURPOSE:To perform a stop from pumping operation so speedily as well as to perform the transition from the pumping operation to generating operation speedily and stably, by carrying out the closure of a guide vane and an inlet valve and the parallel-off of a main machine with a method of proper timing. CONSTITUTION:Closure in an inlet valve 6 is started with the first specified opening a1 in the closure of a guide vane 8. And, at that point that the guide vane 8 closes up to the second specified opening a2, a main machine is paralleled off from an electronic power system. In addition, at that point that the inlet valve 6 reaches within the range of full-close from its small opening after the guide vane fully closes, the main machine is made to be stopped. With this constitution, the closure of the guide vane 8 and the inlet valve 6 and the parallel-off of the main machine are all performable with a method of proper timing. Thus, a stop from pumping operation is speedily performed, and the transition from the pumping operation to generating operation is performable speedily and stably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of controlling the operation of a pump-turbine, and particularly to a method of controlling the operation of a pump-turbine to stop pumping operation and to shift the pump-turbine to power generation.

[Technical background of the invention and its problems]

With the construction of thermal power plants and nuclear power plants in recent years, pumped storage power plants that can handle peak loads are also becoming larger in capacity. It is desirable to start and stop in time.

Conventionally, in such a pumped-storage power plant, stopping a pump-turbine during pumping operation has been carried out in an operation control mode as shown in FIG. In this figure, time T is plotted on the horizontal axis, and guide vane opening degree a, inlet valve opening degree 11, and rotational speed N of the pump turbine are plotted on the vertical axis. According to this method, the time T. The guide vane starts to close due to the stop command, and the generator motor is disconnected from the power system at a predetermined opening degree a2 in the middle of closing, while the guide vane continues to close and closes. The inlet valve starts closing at a quiet time to bring the total I+. According to this method, the rotational speed of the pump-turbine (19N) gradually decreases after the main engine is disengaged due to loss torque in various parts, but this loss torque decreases rapidly as the rotational speed decreases, so it takes a long time to stop. I was using it. For this reason, mechanical brakes were activated when the rotational speed decreased to a few percent, but even so, it was customary to take 7 to 8 minutes from the time the main engine disengaged to the stop. . This is because mechanical brakes cannot be used at high speeds due to heat dissipation problems, and can only be activated when the rotational speed has sufficiently decreased.

Other methods for shortening the stop time include reusing the Nyristor for pumped water start-up to perform regenerative braking of the generator-motor, and using electric braking with three-phase short termination of the generator-motor. However, the former method can only be applied to pumped storage power plants that use a thyristor system for pumped storage startup, and the latter method does not provide sufficient braking force unless the speed is reduced to about 10 to 20% of the rated speed. The drawback was that it could not be done.

In addition, recently there has been a demand for rapid switching of the operation mode from pumping operation to power generation operation. The control method for this purpose is to start closing the guide vanes of the pump-turbine during pumping operation, disconnect the main engine such as the N/R generator from the power system at a predetermined opening degree in the middle of closure, and then stop closing the guide vanes. This method maintains the guide vane opening at an intermediate opening. By holding this guide vane at an intermediate opening, the water that was flowing in the pumping direction is reversed and flows in the power generation direction, and a large braking torque is applied to the pump turbine launcher to stop its rotation, and then the water flows in the power generation direction. The circulating water starts the rotation in the direction of power generation and shifts to power generation operation. However, in this method, even though the runner is rotating in the direction of the pump, the water does not have to pass through the operating state under the so-called pump brake region, where the water overcomes the rotating centrifugal force of the runner and flows in the direction of the water turbine. Must not be.

In addition, this control method cannot avoid the collision of the inflow water from the guide vanes with the runner blades of the pump-turbine at a large relative angle of incidence and at high speed, resulting in large water pressure pulsations and the runner and guide vanes. There was a problem in that severe vibrations were generated near the vanes. Frequent use of such methods shortens the life of the equipment and is not desirable.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned disadvantages of the prior art, to be able to quickly stop pumping operation, and to switch from pumping operation to power generation operation quickly, quietly and stably. An object of the present invention is to provide a method for controlling the operation of a pump water turbine.

[All essentials of the invention]

To achieve the above object, the present invention initiates the closing of the inlet valve at a first predetermined opening a1 in the closing of the guide vane, and furthermore the guide vane starts closing the inlet valve at a second predetermined opening a1 which is smaller.
When the main engine is closed to 2, disconnect the main engine from the power system, and when the guide vane is fully closed ff1s'r and the population valve has reached the predetermined small opening to fully closed range, the guide vane is disconnected from the power system. ], and the main engine is stopped with the guide vane opening wide. Furthermore, when transitioning from this state to power generation operation, the first
When the main engine reaches a second predetermined speed, the guide vanes are closed again and maintained at a small opening equivalent to the no-load opening. When the main engine reaches a second predetermined speed, the fully closed speed is maintained. The inlet valve is opened.

[Embodiments of the invention]

Hereinafter, an embodiment of the method of operating a pump-turbine IIJ i11 according to the present invention will be described with reference to FIGS. 1 to 4.

FIG. 3 shows the structure of a pump-turbine to which the present invention is applied, in which a runner 1 is connected to a generator-equipment 4 via a water-turbine main lNl2 and a generator-motor shaft 3.

In addition, the inlet valve 6 is installed between the penstock 5 and the casing 7, and guide vanes 8 for adjusting the flow ω are provided outside the runner 1 in the form of a circular blade cascade.
A suction pipe 9 is provided below.

FIG. 1 shows a diagram of the operation control according to the present invention. In the figure, when a stop command is received at time To,
When the guide vane 8 starts to close and reaches a first predetermined opening degree a1 in the middle of closing, the inlet valve 6 starts to close, and the guide vane 8 continues to close until it reaches a second predetermined opening degree a2 of 1 m. The main engine is disconnected from the power system, and the guide vane 8 is completely closed. On the other hand, the inlet valve 6 also continues to close, and when the inlet valve 6 reaches a predetermined opening FI11, the fully closed guide vane 8 begins to open, and when the predetermined opening degree a3 is reached, the opening degree a3 is increased. After the pump turbine stops rotating, the guide vane 8 is fully closed again.

Through such operation control, a large braking torque can be obtained and the stopping time can be shortened. Figure 2 shows the relationship between the pump cut-off torque of the pump-turbine, that is, the shaft torque when the inlet valve 6 is fully closed and the constant-speed pump is cut-off, and the guide vane opening at that time. On the other hand, the vertical axis shows the ratio T/T0 of the cut-off torque T to the cut-off torque for fully closing the guide vane - [. As is clear from FIG. 2, the pump shutoff torque when the inlet valve 6 is fully closed increases by opening the guide vane 8, and when the guide vane 8 is fully closed.
In this case, the value is more than twice that when the guide vane is fully closed. Although this ratio varies depending on the specific speed of the pump, it is usually about 1.5 to 2.5 times the specific speed range of a pump-turbine. Therefore, when the guide vane 8 is once fully closed and then wide open again, it is possible to obtain a braking torque approximately 1.5 to 2.5 times as much as when the guide vane 8 is fully closed, resulting in a stoppage. It can significantly shorten the time.

Furthermore, the reason why the inlet valve 6 starts closing at the first predetermined opening degree a1 before the guide vane 8 is fully closed is that if the guide vane 8 and the inlet valve 6 are closed at the same time, the main engine will disengage. This is to avoid the situation where the inlet valve 6 reaches a small opening and the casing water pressure increases, resulting in a dangerous water pressure state. The timing at which the inlet valve 6 begins to close can be controlled by a timer or the like. The reason why the once-closed guide vane 8 is re-opened is at a predetermined small opening degree I immediately before the artificial valve 6 is fully closed. Even if the guide vane 8 is opened, the flow rate of the water flowing in from the guide vane 8 by 1° is small.
This is because vibrations near the launch and guide vanes due to collision between the runner and the water flow will not be severe. For this reason, the guide vane 8 may begin to open after the inlet valve 6 is fully closed, and this is easier to control as long as there is no time loss.

Figure 4 shows an operation mode diagram for switching the pump-turbine from water pumping operation to power generation operation. This is the same control mode as shown in the figure.

In this embodiment, in which the pumping operation is switched to the power generation operation, the rotational speed of the main engine is decreased while the opening degree a3 of the guide vane 8 is maintained, and when the main engine reaches the first predetermined speed N1, the guide vane is turned off. When the guide vane opening degree A4, which is equivalent to the no-load opening of the water turbine, is reached, the opening degree is maintained, and when the rotational speed N reaches the second predetermined speed N2, the inlet valve 6 starts to close. Start opening. By leaving the runner 1 in this state, after reaching the speed O, the runner 1 is rotated and accelerated in the direction of the water turbine, and the same speed as the system frequency is achieved from time T1 using the same procedure as the normal water turbine starting method. After performing the control, at time T2, the power is paralleled to the grid power and the power generation operation is shifted. In order to shift to power generation operation using this method, the guide vane 8 is not completely closed and then the power generation is started, but the guide vane 8 is held at an indication a4 corresponding to no-load l7i1 degree in the middle of closing, Since the inlet valve 6 is opened and the transition to power generation operation is made after the rotation speed has decreased to N2 at which vibrations due to passage through the pump brake area do not occur, the transition from pumping operation to power generation operation can be performed smoothly and quietly. I can do it.

Note that the rotational braking method described above can be performed only by controlling the pump-turbine side, so if in addition to these methods, mechanical braking, regenerative braking, or electric braking using three-phase short termination on the generator motor side is used in combination, Furthermore, braking time can be reduced.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, the closing of the guide vane, the closing of the inlet valve, and the disconnection of the main engine are performed at the same time. This can be done within a reasonable amount of time, and the transition from pumping operation to power generation operation can also be done quickly and quietly.

[Brief Description of the Drawings] Fig. 1 is an operation mode diagram from pumping operation to stoppage according to the present invention, Fig. 2 is a characteristic diagram showing the relationship between pump cut-off torque and guide vane opening in a pump-turbine, and Fig. Figure 3 is a sectional view showing the structure of a pump-turbine to which the present invention is applied;
FIG. 4 is an operation mode diagram showing the transition from the stop of pumping operation to power generation operation, and FIG. 5 is an operation mode diagram of the conventional method. 1...Runner, 6...Inlet valve, 8...Guide vane.

Claims (1)

[Claims] 1. Close the guide vanes of the pump-turbine during pumping operation at a predetermined closing speed, start closing the inlet valve when closed to the first predetermined opening a_1, and then close the guide vanes at a predetermined closing speed. is smaller than the first predetermined opening a_1
When it is closed to __2, the main engine will be disconnected from the power grid,
After the guide vane is fully closed and the inlet valve reaches a predetermined range from small opening to fully closed, the guide vane is opened again, and the main engine is started while the guide vane is kept wide open. A method for controlling the operation of a pump-turbine, characterized in that the pump-turbine is stopped. 2. The method for controlling the operation of a pump-turbine according to claim 1, characterized in that the start of closing of the inlet valve is performed by a timer. 3. Close the guide vane of the pump-turbine during pumping operation at a predetermined closing speed, and when it closes to the first predetermined opening a_1, start closing the inlet valve, and furthermore, the guide vane closes at the first predetermined opening a_1. A second predetermined opening degree a smaller than the opening degree a_1
When it is closed to __2, the main engine will be disconnected from the power grid,
After the guide vane is fully closed and the inlet valve reaches a predetermined range from small opening to fully closed, the guide vane is opened again, and the main engine is started while the guide vane is kept wide open. When the main engine has descended to the first predetermined speed N_1, the guide vane is closed again and the guide vane opening is reduced to a small opening a_4 equivalent to the no-load opening.
When the main engine reaches a second predetermined speed N_2, which is smaller than the first predetermined speed, the main engine is operated in the power generation direction by opening the fully closed inlet valve. A method for controlling the operation of a pump-turbine, characterized in that the operation of a pump-turbine is caused to shift to .