JPH0610464B2 - Variable speed hydraulic machine control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pumping operation control method for a variable speed hydraulic machine, and more particularly to a vibration noise caused by a transition path of an operating point accompanying a change in input passing through a pump reverse flow region. The present invention relates to a method for controlling a hydraulic machine, which prevents an increase in power consumption and makes an operating state suitable when an input is increased or decreased.

[Conventional technology]

As described in Japanese Patent Laid-Open No. 56-107748, the conventional device obtains the most efficient operation from the pump head determined by the water level difference of the power plant and the motor input request value determined by the power system requirement. It was to adjust the motor rotation speed and the guide vane opening. However, the conventional device has not been able to improve the transient operating state that occurs when the most efficient operating point, which is a certain motor input, shifts to the optimum operating point, which is a certain different motor input.

[Problems to be Solved by the Invention]

The above-mentioned conventional technology has a risk of plunging into rough operation in the pump reverse flow region when shifting to an operating point where different electric motor inputs are applied, deteriorating the fatigue strength environment of the machine, and generating vibration after vibration. There was a problem.

An object of the present invention is to avoid this danger and provide a control method that always maintains a quiet operating state even when the electric motor input is increased or decreased.

[Means for solving problems]

The purpose of the above is to increase the input of the motor by holding the opening of the guide vane for a certain period of time after the input increase command and detecting that the rotation speed has reached the target rotation speed before the guide vane is detected. It is achieved by increasing the opening degree.

[Action]

FIG. 2 shows a general characteristic diagram of the pump. The horizontal axis shows the amount of pumped water at the standard rotational speed, and the vertical axis shows the head at the standard rotational speed. When the pump characteristics are expressed using each guide vane opening as a parameter, the backflow region is located higher as the guide vane opening is smaller, as shown in FIG. Also,
When the rotational speed of the pump increases, the operating point moves downward in FIG. Ideally, it is desirable that the operating point moves on the envelope lined up with the maximum efficiency points that each guide vane opening can take. That is, if the operating point moves on the envelope shown by the broken line in FIG. 2 in response to any input change command, high efficiency operation can be performed without entering the reverse flow region, which is ideal. In fact, if this input change request is extremely gradual, it is possible to move the operating point by following this envelope, but if the input change request is rapid, the inertia of the rotating body is large and However, there is a risk that the operating point may deviate from the envelope, rush into the reverse flow region, and pass through rough operation with large vibration and noise due to an increase in head fluctuation due to rapid changes in flow rate. For example, it is assumed that there is a rapid input increase request to the place where the vehicle was operating at point A in FIG. The guide vane opening with relatively small inertia and quick response moves from opening Y ₁ to Y ₂ , while
The rotation speed, which has a large inertia and a slow response, has a small increment and passes through the reverse flow region while shifting to point B (A-D-E-B in FIG. 2).

After the input increase command is issued as in the present invention, if the initial guide vane opening degree Y ₁ is held for a certain period of time, that is, only while the rotation speed is increasing, and then the opening degree is increased to Y ₂ , It does not pass through the backflow area (A in Fig. 2).
-CB). If this control method is adopted, the efficiency deviates from the ideal envelope and causes a transient decrease in efficiency, but there is an advantage that it can respond immediately to input change demands and does not pass severe operation in the reverse flow region.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. Reference numeral 1 is a function generator, and based on the water level difference H of the power plant and the required electric motor input P from the electric power system, the rotational speed No of the electric motor 5 and the initial guide vane opening Y of the pump turbine 3 for the most efficient operation. ₁ and the target value Y ₂ of the guide vane opening are output. Reference numeral 2 denotes a speed governor, which adjusts the motor rotation speed N and the guide vane opening GVO to the target values output by the function generator. Reference numeral 4 is a determiner until the difference (No-N) between the target rotation speed No and the motor actual rotation speed N becomes equal to or less than the allowable rotation speed ε (positive), that is, to a position sufficiently close to the target rotation speed. The initial guide vane opening Y ₁ is output while the speed is being increased, and after (No−N) is equal to or less than ε, the target guide vane opening Y ₂ generated by the function generator is output.

Now, it is assumed that the electric motor input request P has increased during operation at point A in FIG. The function generator calculates the target rotation speed No and the target guide vane opening Y ₂ corresponding to the point B in FIG. 2 from the water level difference H and the required input P at that time. The governor first increases the rotation speed N. During this period N ₂ -N
Since> ε, the output from the determiner 4 is the initial guide vane opening degree Y ₁ , and the guide vane opening degree of the pump turbine 6 is maintained. In FIG. 2, the operating point moves from A to C. The actual rotation speed of the electric motor 5 increases, approaches No, and N
_{When 2-} N> ε, the output of the determiner 4 changes from Y ₁ to Y ₂ , the guide vane opening of the pump turbine 6 increases, and the operating point shifts to C → B in FIG.

According to the present embodiment, when the electric motor input is increased, the operating point does not pass through the pump reverse flow region and enter the rough operation.

On the contrary, there is no risk that the operating point will pass through the pump backflow region even if a command to reduce the input is input. FIG. 3 shows the movement of the rotational speed, the guide vane opening, and the input (flow rate) when the input is increased or decreased. The solid line shows when the input increases, and the broken line shows when the input decreases.

〔The invention's effect〕

According to the present invention, it is possible to always reach a target input through an operating point with a margin for pump backflow in response to a request for increasing or decreasing an input for pump operation of a variable speed hydraulic machine.

[Brief description of drawings]

FIG. 1 is a control block diagram of an embodiment of the present invention, FIG. 2 is a general pump characteristic diagram, and FIG. 3 is a rotational speed, a guide vane opening degree and an input (flow rate) when the input is increased or decreased according to the present invention. It is a figure which shows the movement of. 1 ... Function generator.

Claims (1)

[Claims] 1. An electric motor capable of changing speed, and a pump having a guide vane which is connected to a shaft of the electric motor and whose opening can be changed.
In a hydraulic machine consisting of a rotation speed of the electric motor and a controller for adjusting the opening of the guide vane, after the input increase command of the electric motor, the opening of the guide vane is held for a certain period of time, and then the rotation A control method for a variable speed hydraulic machine, comprising: increasing the opening of the guide vane after detecting that the speed has reached a target rotation speed.