JPH0768937B2 - How to stop pumping operation of variable speed pump turbine - Google Patents

Description

The present invention relates to a method for stopping pumping operation of a variable speed pump turbine,
In particular, the present invention relates to a pumping stopping method for stopping a variable speed pump turbine whose operation speed can be arbitrarily controlled from the pumping operation.

(Prior Art) FIG. 9 shows a configuration of a conventional pumping machine of a pumped storage power plant, in which reference numeral 1 is a penstock, 2 is a pump turbine, and 3 is a pump turbine.
Is a movable guide vane for adjusting the amount of flowing water or blocking the flowing water, 4 is a runner, 5 is a draft tube, and the guide vane 3 is designed so that the governor device 6 controls the water outlet opening. Further, reference numeral 7 is a synchronous generator motor, which is driven at a constant synchronous speed determined by the number of poles of the motor and the system frequency of the transmission line during the pumping operation to drive the runner 4 to flow running water from the draft tube 5 to the hydraulic iron pipe. Pump to.

When stopping the pumping operation in such a conventional pumping machine, the guide vane 3 is closed and the motor 7 is disconnected from the power transmission line when the opening degree reaches about 15 to 10%, and the guide vane 3 is fully closed. It was

(Problems to be solved by the invention) In such a case, the motor input at the time of disconnection is about 30 to 50% of that at the time of steady pumping operation, for example, 300 to 100M to 150M.
It became W and the power fluctuation of the transmission system was large at the same time as the disconnection, which had a great influence on the system operation.

Therefore, an object of the present invention is to provide a method for stopping the pumping operation of a variable speed pump turbine to minimize such power fluctuations.

[Structure of Invention]

(Means for Solving Problems) In order to achieve the above object, the present invention provides a cycloconverter for variably controlling the rotation speed of an AC excitation induction generator motor directly connected to a pump or a pump turbine to the induction generator motor. In a method of stopping pumping operation of a variable speed control pumped-storage power generation system, the guide vanes are first controlled to be closed when the pumping operation is stopped, and after the guide vane opening reaches the pumping operation allowable minimum opening. While continuing to control the closing of the guide vanes, control the cycloconverter to reduce the speed of the pump turbine, detect that the rotation speed has reached the minimum speed allowed by the cycloconverter, and disconnect the main engine from the power transmission system. After that, the guide vanes are fully closed.

(Operation) When the pumping operation is stopped, the guide vanes are first controlled to be closed while keeping the speed of the pump turbine constant. After the guide vane opening reaches the pumping operation allowable minimum opening a ₁ , the cycloconverter is controlled and the speed of the pump turbine is reduced while continuing the closing control of the guide vane. Detecting that the rotation speed has reached the minimum speed N = N _-1 allowed by the cycloconverter, the main engine is disconnected from the power transmission system, and then the guide vanes are fully closed. As a result, it is possible to avoid the region where the vibration is excessive even when the region moves to the reverse flow region, and to operate.

(Embodiment) An embodiment of the method for stopping pumping operation of a variable speed pump turbine according to the present invention will be described below with reference to the drawings.

Before explaining the method of stopping the pumping operation of the variable speed pump turbine according to the present invention, the apparatus used for carrying out the method of the present invention will be described with reference to FIG. In FIG. 8, reference numeral 2 indicates a pump turbine, to which an AC excitation induction generator motor 8 is directly connected. This electric motor includes an AC exciter 9, a cycloconverter 10 for converting a constant frequency of the power transmission system into a required frequency of the generator motor 8, a detector 11 for detecting each of the electric motor input, rotation speed and guide vane opening, and a control unit. The necessary data input / calculation / output device 12, the excitation amount detector necessary for controlling the rotation speed of the generator motor, and the required excitation amount calculation device 13 are electrically connected in advance.

When pumping such a variable speed pump turbine, the performance of the pump or pump turbine is as shown in FIGS. 6 and 7.

In Fig. 6, the horizontal axis shows the pumping volume and the vertical axis shows the pump head. In the figure, H _MIN shows the minimum pump head, H _MAX shows the maximum pump head, and the pump turbine can rotate from N _-1 to N _+1. When operating in variable speed H
From the _MIN in N _-1 it is operated at a speed of between N _a H _MAX in N _b
Driven at speeds between N ₊₁ . In this figure, the line connecting points B and D is the maximum input line controlled by the capacity of the electric motor, and the line connecting points A and C is the limiting line given by the pump or pump turbine. Generally, the secondary flow in the runner ( It is the limit point at which noise and vibration become excessive) and the minimum allowable input point for steady operation at each head. Further, the line connecting the points A ′ and C shows the operating state at the variable minimum speed allowed by the cycloconverter 10.

On the other hand, FIG. 7 shows the motor input on the horizontal axis, and the vertical axis shows the head in a shaking manner with FIG. In this figure, points A, B,
C and D indicate the same points as points A, B, C and D in FIG. 6 described above. Therefore, it is understood that, for example, the rotation speed can be selected from N ₋₁ to N _a in the lowest head operation, but the motor input can be reduced by controlling the rotation speed from N _a to N ₋₁ . The opening of the guide vane at the points ▲ and ▼ is constant even if the head changes, and can be said to be the minimum opening during normal pumping operation. Further, the line connecting the points A ′ and C shows the performance at the minimum speed N ₋₁ that the cycloconverter allows.

Next, the control of the guide vanes for reducing the amount of pumped water will be described with reference to FIG. FIG. 5 shows the characteristics of the guide vane opening degrees a ₀ and a ₁ at the rotational speeds N = N _a and N = N _{−1, where the} horizontal axis is the flow rate and the vertical axis is the head. Assuming now operating head H _MIN , maximum flow rate (maximum shaft input) in Fig. 6 mentioned above
If the guide vane opening at points D and D is a _D or the guide vane opening at point C to obtain the allowable minimum speed N _Mi is a _1, and if the stop operation is executed from point D now, the rotation speed is advanced. Then, when N _{a is changed} to N ₋₁ (N _Mi ), point D does not move to D ′ on the guide vane opening a ₀ characteristic of N = N _{−1 and} the pump discharge head and upper
It will move to point F, which balances the water level of the lower pond. F
The point is on the smaller flow rate side than the point C in the figure, that is, in the excessive vibration region, which is not preferable. On the other hand, if the guide vane opening degree a ₀ to a ₁ is changed from point D to N = N _{a, the} point moves to point G. If the rotational speed is reduced to N _{−1, the} point moves from point G to point C and vibrates. Never enter an oversized area. In the case of _HMAX operation, if the guide vane is closed to point A and then the rotation speed is controlled to decrease, the rotation speed is low but the vibration does not become excessive because the rotation speed is low. Therefore, it is preferable to precede the guide vane closing operation with the stop command.

Next, an embodiment of the method for stopping pumping operation according to the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a control block diagram showing one mode of the pumping stop operation, and FIG. 2 is a diagram showing the operating conditions of the guide vanes, the motor input and the changing conditions of the rotational speed according to the present invention with the passage of time.

In FIG. 1, the guide vane opening detector 11c indicates that the guide vane is closed in response to the pumping stop command 14 and the guide vane opening a is closed to the pumping operation allowable minimum opening a ₁ which is allowed in advance. To detect.

On the other hand, the required excitation amount calculation device 13 determines that the minimum allowable rotation speed N
_-1 calculates the amount of excitation required, and based on this calculated value, the AC excitation device 9 is controlled to decrease and the guide vanes 3 continue to be closed, and the cycloconverter 10 has an allowable minimum rotation speed.
Controlled to N _-1 . When the rotation speed detector 11c detects that the rotation speed of the main engine reaches N _-1 , the main engine is disconnected and stopped, and the guide vanes are fully closed.

According to such an embodiment of the present invention, there is no abnormal vibration, it is possible to suppress the system sway that occurs when the main engine is disengaged, and enable a smooth stop.

Next, another embodiment of the present invention will be described with reference to FIGS.

Whereas in the above-mentioned embodiment, the allowable minimum rotation speed N _-1 was detected and the main engine was disconnected from the system, in this embodiment, as is apparent from FIG. It is characterized in that the generator input value P _M is detected as reaching the set value as the disconnection condition, and the generator motor is disconnected from the system, and the contents of the other methods are the same.

〔The invention's effect〕

As is clear from the above description, according to the present invention, it is possible to suppress the fluctuation given to the power transmission system by controlling the reduction of the rotation speed and the motor input, and to shorten the excessive vibration region passing time. The life of the device can be extended. Further, since the breaking input at the time of disconnection is small, the life of the breaker can be extended and it can contribute to the stabilization of the power transmission system.

[Brief description of drawings]

FIG. 1 is a control block diagram showing an embodiment of a method for stopping pumping operation of a variable speed pump according to the present invention, and FIG. 2 is a time of guide vane opening, electric motor input, rotational speed according to the control method of FIG. 3 is a time chart showing a temporal change state, FIG. 3 is a control block diagram according to another embodiment of the present invention, FIG. 4 is a time chart showing a temporal change by the control method of FIG. 3, and FIG. A diagram showing the relationship between the pumping volume and the pump head when the speed changes, Fig. 6 is a diagram showing the pumping capacity performance to pumping head, Fig. 7 is a diagram showing the input curve to pumping head, Fig. 8 Is a diagram showing a variable speed pump turbine that constitutes the present invention, and FIG. 9 is a diagram showing a conventional constant pump turbine. 2 ... Pump turbine, 7 ... Synchronous generator motor, 8 ... AC excitation induction generator motor, 9 ... AC exciter, 10 ... Cycloconverter, 11a ... Input detector, 11b ... Rotation speed detector, 11c: Guide vane opening detector, 11d: Head (head) detector, 12: Data calculation device, 13 ... Excitation amount detector and excitation amount calculation device.

Claims (1)

[Claims] 1. A method of stopping pumping operation of a variable speed pump turbine, wherein a cycloconverter for variably controlling the rotation speed of an AC excitation induction generator motor directly connected to the pump turbine is electrically connected to the induction generator motor. ; When stopping the pumping operation, first control the guide vanes to be closed, and after the guide vane opening reaches the pumping operation allowable minimum opening a ₁ , the cycloconverter is controlled while continuing the guide vane closing control. The speed of the pump turbine is reduced by detecting that the rotational speed has reached the minimum speed N = N _-1 allowed by the cycloconverter, the main engine is disconnected from the power transmission system, and then the guide vanes are fully closed. A method for stopping the pumping operation of a variable speed pump turbine, which is characterized in that