JPH05252798A - Speed controller for variable-speed power generating system - Google Patents

Abstract

PURPOSE:To immediately suppress a speed rise of an induction motor during parallel off. CONSTITUTION:In parallel state, a velocity deviation (h) between the velocity signal (a) of an induction motor and the velocity command (e) of a vector velocity controller 8 is added to a guide vane opening command b2 and a predetermined allowance (d) as a guide vane opening command b1 which is input together with a guide vane opening command b2 to a low value priority circuit 7, and a guide vane opening command b3 is output and controls a guide vane 1. At the time of parallel off, the guide vane opening command b1 decreases due to a rise of the velocity signal (a), the guide vane opening command b1 is output as the guide vane opening command b3 from the low value priority circuit 7 and controls the guide vane 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotational speed control of an induction generator in a variable speed power generation system of a hydraulic pumped storage power plant, and particularly to a speed control of a variable speed power generation system for suppressing an increase in the rotational speed when a load is cut off. Regarding the device.

[0002]

2. Description of the Related Art As control means at the time of power generation operation of a variable speed power generation system in a hydraulic pumped-storage power plant, there are guide vane opening control and rotation speed control of an induction generator by a cycloconverter. In the variable speed power generation system, the speed control of the induction generator before or after the induction generator is connected in parallel to the system is controlled by the opening degree control of the guide vanes that control the water intake to the turbine directly connected to the induction generator. To do.

On the other hand, the speed control after the induction generator is paralleled to the system is performed by vector-controlling the secondary alternating current of the induction generator by using a cycloconverter capable of converting the frequency using a thyristor. .. That is, by controlling the effective current of the secondary alternating-current excitation current of the induction generator, the electric output can be varied by controlling the speed of the induction generator, regardless of the mechanical input of the water turbine controlled by the guide vanes.

Therefore, when the mechanical input of the hydraulic turbine is constant, the speed of the induction generator can be changed by increasing or decreasing the effective current of the secondary AC exciting current, and thus the speed control by vector control becomes possible. In this way, generally, the rotation speed control is performed by controlling the secondary alternating current of the induction generator so as to prevent unnecessary operation of the guide vanes and increase the stability of control while the induction generator is parallel to the system. Vector speed control means is employed.

FIG. 6 is a block diagram of a speed control device of this type of variable speed power generation system.

In the figure, a guide vane 1 is opened and closed to control the amount of water taken into the turbine 2. The water turbine 2 is driven by the amount of water controlled by the guide vanes 1, and the induction generator 3 directly connected to the water turbine 2 is driven. Before the induction generator 3 is connected in parallel to the system (not shown) by the parallel circuit breaker 4, the guide vane speed is determined based on the speed signal a of the induction generator 3 detected by the speed detector 5 in the guide vane command mode. The control device 6 calculates the guide vane opening degree command b1, and the opening degree command b1 controls the opening degree of the guide vane 1 via the low value priority circuit 7.

On the other hand, after the induction generator 3 is connected in parallel to the system by the parallel circuit breaker 4, the gate of the thyristor calculated by the vector speed controller 8 based on the speed signal a as the vector command mode. The pulse signal c is transmitted to the cycloconverter 10 via the parallel condition contact 9a. In the cycloconverter 10, the power source from the transformer 11 is the gate pulse signal c from the vector speed control device 8.
Is vector-converted and the secondary AC exciting current of the induction generator 3 is frequency-controlled to control the electric output and speed of the induction generator 3.

By the way, the induction generator 3 has the parallel circuit breaker 4
, And the parallel condition contact 9a is in the closing operation, the vector speed controller 8 and the cycloconverter 10 control the induction generator 3 as a vector command. The opening command b1 is no longer necessary, and the guide vanes 1 are allowed to escape to the fully open position (100%) as shown in FIG.

Therefore, the guide vane opening command b2 from the load control device 12 via the parallel condition contact 9a as shown in FIG.
As a priority, the opening of the guide vane 1 is controlled.

[0010]

However, the conventional device has a problem that the increase in the rotation speed of the induction generator 3 cannot be suppressed when the load is cut off.

That is, as shown in FIG. 7, while the induction generator 3 is in parallel with the system by the parallel circuit breaker 4 from time t1 to time t2, the guide vane opening control command b1 from the guide vane speed control device 6 causes the guide vane to move. 1 Escape to a high value equivalent to full opening. When the load of the induction generator 3 is cut off in this state, for example, at time t2, the rotation speed of the induction generator 3 rapidly increases. At this time, the guide vane opening control command b1 from the guide vane speed control device 6 is a signal corresponding to the guide vane 1 fully opened (100%), and the switching of the control device of the variable speed power generation system to the guide vane command mode is a delay circuit. The operation is performed at time t3. After that, since the rotation speed of the induction generator 3 decreases based on the guide vane opening command signal of the guide vane speed control device 6, it takes a wasteful time to reach the normal speed control state, and the induction generator 3 due to the load shedding. There was a problem that it was not possible to sufficiently suppress the increase in speed.

Therefore, an object of the present invention is to provide a speed control device for a variable speed power generation system capable of enhancing the effect of suppressing the speed increase of the induction generator when the load is cut off.

[0013]

According to the present invention, a guide vane speed control device controls a rotation speed of an induction generator by opening / closing a guide vane based on a guide vane command signal to control a water intake amount in a guide vane command mode. On the other hand, in the speed controller of the variable speed power generation system in which the vector speed controller controls the rotation speed of the induction generator based on the vector command signal as the vector command mode when the parallel breaker is turned on in the system, the vector command Means for calculating a speed deviation signal between the speed signal of the induction generator and the speed command signal of the vector speed control device in the mode, and a guide vane opening command signal from the guide vane speed control device in the vector command mode is predetermined. Of the predetermined margin value signal in order to keep the margin value of Means for the margin value setting means, a guide vane opening command signal from said margin value signal and the load command signal and the speed deviation signal is added to the vector command mode the guide vane speed controller provided,
A low value priority circuit is provided which inputs the load command signal and the guide vane opening command signal and outputs a low value signal among these signals as a guide vane opening command signal for controlling the guide vane. It was done like this.

[0014]

With the above structure, in the vector command mode, the speed deviation signal generated by the speed signal of the induction generator and the speed command signal of the vector speed control device, the load command signal of the load control device, and the predetermined margin value are added, and the guide vanes are added. As a guide vane command signal for the speed control device, this signal and the load command signal are input to the low value priority circuit. In this case, since the speed deviation signal is substantially zero during normal parallel operation, the guide vane command signal of the guide vane speed control device in which a predetermined margin value is added to the load command signal follows the load command signal and has a low value. A load command signal is output from the priority circuit, and this signal controls the guide vanes. After the parallel circuit breaker is disconnected, the speed signal of the induction generator rises and the speed deviation signal decreases until the guide vane command mode is switched. As a result, when the speed deviation signal corresponding to the predetermined margin value decreases, the low value priority circuit outputs the guide vane command signal of the guide vane speed control device, and the guide vane is controlled by this signal. Therefore, there is no dead time for narrowing down the guide vanes until the parallel circuit breaker switches the guide vane command mode after disconnection, and thus it is possible to suppress the speed increase of the induction generator.

[0015]

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

FIG. 1 is a system diagram of a speed control device of a variable speed power generation system showing an embodiment of the present invention, and FIG. 2 is a configuration diagram of FIG. 1 is different from FIG. 6 in that the margin value setting means 1
3 and addition means 14 and addition means 15 are additionally provided. Then, the margin value d of the margin value setting means 13 and the guide vane opening command b2 of the load control device 12 are added to the addition means 14
Are added, and the added value and the speed command e of the vector speed control device 8 are added by the addition means 15 and input to the guide vane speed control device 6.

In this embodiment, when the induction generator 3 is in the vector command mode, the guide vane opening command b2 of the load control device 12 is output from the low value priority circuit 7, and the guide vane opening command b2 has a predetermined margin. The guide vane opening command b1 added with the value d, that is, the speed deviation signal h by the speed signal a of the induction generator 3 and the speed command signal e of the vector speed control device 8, the margin value d, and the guide vane opening command b2. And the guide vane opening command b1 follows, and the guide vane 1 is controlled by the guide vane opening command b1 from the low value priority circuit 7 until the parallel circuit breaker 4 is disconnected and switched to the guide vane command mode. I am trying.

The structure of the present embodiment will be specifically described with reference to FIG. 2. First, in the guide vane speed control device 6,
When the parallel condition contact 9a is closed, the speed command e of the vector speed control device 8 and the bias signal g are added by the adding means 15, and this is set as the speed command f. Further, a value obtained by dividing the added value obtained by adding the guide vane opening degree command b2 of the load control device 12 and the margin value d by the constant K1 by the dividing means 16 is used as the bias signal g. Further, in the guide vane speed control device 6, the speed command f and the speed signal a are added by the adding means 6a.
And the speed deviation h, and this speed deviation h
Is multiplied by a constant K1 in the multiplication means 6b to perform proportional control.

In the vector speed control device 8, the speed command e
And the speed signal a are added together by the adding means 8a to obtain the speed deviation i, and the output obtained by multiplying the speed deviation i by the constant K2 by the multiplying means 8b and the output integrated by 1 / TS by the integrator 8c are added by the adding means 8d. Is added to perform proportional + integral control.

With the above construction, the parallel condition contact 9a of the vector speed control device 8 is closed in parallel, the speed command e is output to the adding means 8a as the vector command mode, and the speed deviation from the speed signal a of the speed detector 5 is generated. i is input to the multiplication means 8b and the integrator 8c, added by the addition means 8d, and the addition signal j is output to the cycloconverter 10.

In the steady state, the vector speed control device 8
The velocity deviation i is integrated by the integrator 9c and becomes zero,
It is controlled so that the speed signal a matches the speed command e. At this time, in the guide vane speed control device 6, the speed command e and the bias signal g are added by the adding means 15,
The added signal is input as a speed command f, the speed command f is added by the adding means 6a to the speed signal a by the symbol shown in the figure, and the speed deviation h is multiplied by K1 by the multiplying means 6b. Is output as a guide vane opening degree command b1.

In this case, the speed signal a and the speed command e are
Since they substantially match, the velocity deviation h substantially matches the bias signal g, and the value obtained by multiplying the bias signal g by the constant K1 is the guide vane opening command b1. By the way, the bias signal g is obtained by adding the guide vane opening command b2 of the load control device 12 and the allowance value d of the allowance value setting means 13 by the adding means 14, and dividing this value by the constant K1 by the dividing means 16. There is. Therefore, the guide vane opening degree command b1 is maintained at a value obtained by adding the margin value d to the guide vane opening degree command b2.

Therefore, in the low value priority circuit 7, time t
From 1 to time t2, as shown in FIG. 3, the guide vane opening command b1 is always larger than the guide vane opening command b2 by the margin value d, and the guide vane opening command b2 of the load control device 12 is selected. Guide vane opening command b
3 is output to the guide vane 1. Thereby, the opening control of the guide vane 1 is performed by the guide vane opening command b2 by the load control, and is not interfered with by the guide vane opening command b1 from the guide vane speed control device 6.
Since the guide vane opening command b1 from the guide vane speed control device 6 is increased by the margin value d, the guide vane opening command b2 follows the speed conversion value of the margin value d even in speed control.

When the load is cut off at time t2 as shown in FIG. 3, the parallel breaker 4 is first opened (OFF). Along with this, the speed signal a of the induction generator 3 increases, and the increased speed signal a is input to the adding means 6a. In the adding means 6a, the increased speed signal a is subtracted from the speed command f, and the speed deviation h is output from the multiplying means 6b as the guide vane opening command b1 so as to lower the guide vane 1. As a result, the guide vane opening degree command b1 having a low value is output from the low value priority circuit 7 and the opening degree of the guide vane 1 is controlled as the guide vane opening degree command b3. Therefore, as shown in FIG. 3, the guide vane opening command b1 starts narrowing down immediately as the speed of the induction generator 3 increases, and at time t3 when the vector command mode is switched to the guide vane command mode, the guide vane opening command b3.
Is almost 0%.

Then, the guide vane command mode is set by the operation of the parallel condition contacts 9a and 9b, and the speed command of the vector speed control device 8 is switched to the speed command of the guide vane speed control device 6, and the speed of the guide vane speed control device 6 is changed. The opening of the guide vane 1 is controlled based on the command.

In this way, the guide vane opening command of the guide vane speed control device has a margin value so as not to interfere with the guide vane opening command of the load control device,
Moreover, the margin value follows a change in the speed command of the vector speed control device at a constant value. Therefore, when the speed control is switched from the vector speed control device to the speed command of the guide vane speed control device for load shedding, the dead time when narrowing down the guide vane 1 due to the speed increase of the induction generator 3 is a margin value. Is equivalent to the opening degree of. By properly adjusting this margin value, it is possible to reduce the dead time that occurs at the time of solution and suppress the increase in speed of the induction generator.

4 and 5 show another embodiment of the present invention.

In another embodiment of FIG. 4, the dividing means 16 is provided on the input side of the adding means 14, and the added value of the margin value d and the output of the dividing means 16 is used as the bias signal g. Also, FIG.
In another embodiment, the guide vane speed control device 6 is provided with an integrator 8c and an adding means 6d, and the integrated output of the guide vane opening command b2 and the margin value d becomes the guide vane opening command b1 in a steady state. I am trying to. In both cases of FIG. 4 and FIG. 5, it can be carried out in the same manner as the embodiment of FIG.

[0029]

As described above, according to the present invention, there is provided a means for making the guide vane opening command by the guide vane speed control always follow the speed command of the speed control of the vector speed control with a certain margin value. Therefore, when the speed of the induction generator increases due to load shedding, the guide vanes can be swiftly narrowed down and unnecessary speed increase can be suppressed.

[Brief description of drawings]

FIG. 1 is a system diagram of a speed control device of a variable speed power generation system showing an embodiment of the present invention.

FIG. 2 is a specific configuration diagram of FIG.

FIG. 3 is an explanatory view showing the operation of FIG.

FIG. 4 is a configuration diagram showing another embodiment of FIG.

5 is a configuration diagram showing another embodiment of FIG.

FIG. 6 is a system diagram of a speed control device of a variable speed power generation system showing a conventional example.

FIG. 7 is an explanatory diagram showing the operation of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 guide vane 2 water turbine 3 induction generator 6 guide vane speed control device 7 low value priority circuit 8 vector speed control device 10 cycloconverter 12 load control device 13 margin value setting means 15 adding means

Claims (1)

[Claims] 1. A guide vane speed control device controls a rotational speed of an induction generator by controlling a water intake amount by opening and closing a guide vane based on a guide vane command signal in a guide vane command mode, while a parallel breaker is a system. In the speed control device of the variable speed power generation system in which the vector speed control device controls the rotation speed of the induction generator based on the vector command signal as the vector command mode when the switch is turned on, the speed of the induction generator in the vector command mode. Means for calculating the speed deviation signal between the signal and the speed command signal of the vector speed control device, and the guide vane opening command signal from the guide vane speed control device in the vector command mode holds a predetermined margin value and loads the load. Margin value setting means for providing the predetermined margin value signal in order to follow the load command signal of the control device, Means for adding the margin value signal, the load command signal, and the speed deviation signal in the vector command mode to obtain a guide vane opening command signal from the guide vane speed control device; the load command signal and the guide vane A variable speed characterized by comprising a low value priority circuit for inputting an opening command signal and outputting a low value signal of these signals as a guide vane opening command signal for controlling the guide vane. Power generation system speed controller.