JPH01300068A - Method for starting variable speed type water power generation facility - Google Patents

Abstract

PURPOSE:To smoothly start a facility by starting a hydraulic machine, interposing a generator in an electric system, thereafter changing a time constant of speed control circuit at the point where the matching at the time of interposing is cleared over a second value, and moving operation to the normal while delaying the response. CONSTITUTION:When an aimed output is input to an output controller 1 based on a power generation command, the controller 1 computes the aimed rotary speed corresponding to the aimed output to generate a command to an opening controller 2, thereby a guide vane 3 is operated and a runner 4 is rotated. The rotary speed of an induction generator 5 directly coupled to the runner 4 is detected by a speed detector 6. A speed control circuit 7 outputs a control signal to a speed controller 8 in response to the difference between the actual rotation speed of detector 6 and the aimed rotary speed of controller 1. In this case, after the induction generator 5 is interposed in an electric system, the time constant of speed control circuit 7 is changed over a second value at the point where the shock at the time of interposition so as to speed up the response.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a method of controlling hydroelectric power generation equipment, and is particularly applicable to hydraulic machines such as water turbines and pump water turbines capable of variable speed operation. This invention relates to a control method for smoothly starting a generator or generator motor directly connected to this hydraulic machine.

(Conventional technology) In the past, synchronous generators and synchronous generator motors were often used as main engines in water horn power generation equipment, but recently induction generators and induction generator motors have been used in their place. It's here.

FIG. 2 shows a control system of a variable speed hydroelectric power generation facility equipped with an induction generator or an induction generator motor as the main engine.

When starting this variable speed hydroelectric power generation equipment, first, the target output P* is set to the output control device fl! based on the power generation command. It is input to tl. This output control device calculates the target rotational speed N* corresponding to the two target outputs, issues a command to the opening controller 2, and operates the guide vane 3 of the water turbine or pump water turbine (hereinafter referred to as "ill"). to rotate runner 4. An induction generator or an induction generator motor (hereinafter simply referred to as an induction generator) directly connected to this runner 4
5 is detected by a speed detector 6. The speed control circuit 7 detects the difference between the actual rotation speed N detected by the speed detector 6 and the target rotation speed N* output from the output #J control device 1, and applies a control signal according to this difference to the speed control. Output to device 8.

The speed control circuit 7 has a built-in control time constant circuit (not shown) in order to improve followability of the rotational speed of the main engine during variable speed control, and the control time constant circuit (not shown) is used to control the target rotational speed of the induction generator 5. It operates in such a way that it does not fall away.

Note that controlling the induction generator 5 in parallel with the electric power system from the time of startup increases the required capacity of the speed control device 8 and is not practical. Therefore, the rotation speed range in which variable speed control is possible is not determined. There is. Therefore, at the time of starting, the induction generator 5 is connected in parallel to the electric system only after reaching the lower limit rotational speed at which variable speed control is possible, and from that point on, the above-mentioned speed control circuit 7
Speed control is started.

(Problems to be Solved by the Invention) When starting a variable speed water turbine using the above-described control method, the following problems occur.

That is, when the rotational speed of the induction generator 5 increases and reaches the lower limit rotational speed at which variable speed control is possible, if the induction generator 5 is connected in parallel to the power system, the control by the speed control circuit 7 is simultaneously performed. Since the rotational speed is started, the speed control device 8 rapidly suppresses the increase in the rotational speed. As a result, a large braking torque is instantaneously generated in the induction generator 5, and a large output is generated in the induction generator 5.

The details will be explained with reference to FIG. The figure shows the output P, guide vane opening A, rotational speed N, and speed control time constant T at the time of startup of variable speed hydroelectric power generation equipment using the conventional method.
This figure shows how G changes over time. The guide vane is first opened to the starting guide vane opening A2, and the rotational speed N of the main engine increases to the lower limit rotational speed N1 at which variable speed control is possible.
When it approaches , the opening degree will be adjusted to the no-load opening At. Rotational speed N
At time 11 when the induction generator 5 reaches the lower limit rotational speed Nl, the induction generator 5 is paralleled to the power system, and at the same time, the target rotational speed N for paralleling is set to the lower limit rotational speed Nl.

At this time, the speed control circuit 7 is activated, and the speed control device 8 rapidly suppresses the increase in the rotational speed N. the result,
At time tl, the output P of the induction generator 5 changes instantaneously in a stepwise manner, and an output ΔP is generated.

Such large and transient power fluctuations may not only adversely affect system operation, but also apply a mechanical impact force to the induction generator 5, which is undesirable.

In addition, in order to eliminate the output ΔP that occurs stepwise as described above, it is possible to set the starting guide vane opening degree A2 to the no-load opening degree A1, but in that case, the rotation speed N will be lower than the lower limit rotation speed N1. This has the disadvantage that it takes a long time to reach this point, which impedes the functional operation of the hydroelectric power generation equipment.

An object of the present invention is to provide a control method that eliminates the large power fluctuations that occur when the main engine is connected in parallel to the power system as described above, and can start variable speed hydroelectric power generation equipment smoothly in a short time. It is something.

[Means to solve the problem]

The method for starting variable speed hydroelectric power generation equipment of the present invention is that when the generator or generator motor is disconnected from the power system and a hydraulic machine such as an athlete's foot or a pump athlete is started or accelerated from a stopped state, the speed control circuit The rotational speed of the main engine is controlled by setting the control time constant to a relatively large first value so that the response of After confirming that the electrical and mechanical fluctuations during parallel entry have subsided under predetermined conditions, the control constant of the speed control circuit is changed to a second value smaller than the first value. This speeds up the response and shifts to steady operation.

(Function) The method for starting the variable speed hydroelectric power generation equipment of the present invention is that, as mentioned above, when the main engine is connected in parallel to the power grid, the response of the speed control circuit is slow. After gradually increasing, the target rotation speed is reached. As a result, a generator or a generator! ! The torque required to suppress the increase in rotational speed of the electric motor, that is, the large output ΔP as shown in FIG. 3 is not generated.

On the other hand, since the control time constant of the speed control circuit is switched to a second value smaller than the initial value when a predetermined time has elapsed after paralleling, the response of the speed control circuit during steady operation becomes faster, and the rotation speed increases. Followability is not impaired either.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. Note that the hardware configuration of the control system used in the embodiment of the present invention is such that the speed control circuit 7 has a control time constant T.
It is the same as FIG. 2 except that it includes a built-in mechanism for switching G between the first value and the second value. Further, FIG. 1 shows temporal changes in the output P, the guide vane opening degree A1, the rotation speed N, and the control gain TG of the speed control circuit 7.

1 and 2, when a power generation command is issued, two target outputs are manually supplied to the output control device 1 based on the power generation command. This output control device instructs the opening regulator 2 to open the guide vane 3 to the starting guide vane opening A2, and starts the induction generator 5 directly connected to the runner 4.

When the rotational speed N increases and approaches the lower limit rotational speed Nl at which variable speed control is possible, the guide vane 3 is adjusted to the no-load opening degree A1. At this time, the control time constant TG of the speed control circuit 7 is set to a large value TGI, and it is no longer possible to control the rotation speed N to suddenly bring it to the target rotation speed N* (in this case, the lower limit rotation speed Nl). ing.

Next, at time 11 when the rotational speed N increases and reaches the lower limit rotational speed Nl at which variable speed control is possible, the induction generator 5 is connected in parallel to the power grid, and at time t2 when a predetermined period of time has passed after paralleling, the induction generator 5 is The control time constant TG of the control circuit 7 is switched to a small value TG2.

In this way, when the induction generator 5 is connected in parallel to the power system at time t1, the target rotational speed N is set to the upper limit rotational speed Nl, but the control time constant TG of the speed control circuit 7 is set to a large value TGI. Therefore, the increase in the rotational speed N is not suppressed rapidly, but the rotational speed N gradually increases and then reaches the target rotational speed N*. Therefore, the induction generator 5 has the torque necessary to suppress the sudden increase in the rotational speed N.
In other words, a large output ΔP as shown in FIG. 3 is not generated.

Furthermore, since the value of the control time constant TG of the speed control circuit 7 is adjusted so that the rotational speed N does not exceed the upper limit rotational speed N2, there is no possibility of loss of control due to an excessive increase in the rotational speed N. .

On the other hand, if the control time constant TG remains at a large value TGI, the followability of the rotational speed N to the target rotational speed N becomes poor when the operation shifts to steady state. , the control time constant TG of the speed control circuit 7 is switched to a small value TG2, and the rotation speed N during steady operation is changed.
It has good followability.

As described above, in this embodiment, when the variable speed hydroelectric power generation device is started and connected in parallel to the power grid, a large power fluctuation does not occur, and therefore, an adverse effect on the power grid is eliminated.

In the above-mentioned embodiment, after the main engine is brought in parallel, the control time constant for speed control is set to the second value TG2, which is smaller than the first value TGI.
We used the time from system parallelization as a condition for switching to
The present invention is not limited to this, and other conditions may be used depending on individual conditions.

That is, the main object of the present invention is to control the speed control device at the moment when the power system is connected to the power system, and immediately thereafter, during periods when various fluctuations (for example, fluctuations in rotational speed, fluctuations in generator output) are occurring. This is achieved by increasing the control time constant of the speed control device. Therefore, after the main engine is connected to the power grid, if it is confirmed that the vibration at the time of parallel connection has subsided, the control time constant of the speed control device can be changed to You may switch to a value of 2.

In this case, as a condition for confirming that the tremor has subsided, in addition to using the elapsed time since the parallel entry as described above, the generator output is detected after the parallel entry, and it is set to a predetermined value (see Figure 1). Although omitted in the explanation, even when the present invention is applied, when the grid is paralleled, a very slight fluctuation in the generator output [reduced output fluctuation ΔP in Fig. 3] occurs. The condition may be that it is inside.

Further, as shown in FIG. 1, since the rotational speed overshoots to some extent, the switching condition may be that the lower limit rotational speed is reached when the rotational speed N becomes parallel again. Of course,
In this case, the rotation speed may undershoot, so in practice it is necessary to simultaneously monitor the rotation speed fluctuation rate so that the value of the rotation speed N falls within the allowable range from the lower limit rotation speed. Yes, and its rate of change over time (IdN/
The switching condition may be that del) is within a predetermined range.

〔Effect of the invention〕

As described above, according to the present invention, when variable speed hydroelectric power generation equipment is started and connected in parallel to the power grid, it is possible to smoothly increase the output without generating a large output instantaneously. Significant power fluctuations are not generated, and the variable speed hydroelectric power plant can therefore be started smoothly.

[Brief explanation of the drawing]

Fig. 1 is a graph showing changes over time in generator output, guide vane opening, rotation speed, and control gain in the method of the present invention, Fig. 2 is a block diagram showing the control method for variable speed hydroelectric power generation equipment, and Fig. 3 is It is a graph showing an example of operation of a conventional method. 1... Output control device, 2... Opening degree regulator, 3...
Guide vane, 4...Runner, 5...Induction generator or induction generator motor, 6...Speed detector, 7...Speed control circuit, 8...Speed control device. ! bl figure

Claims (1)

[Claims] A hydraulic machine such as a water turbine or pump water turbine equipped with guide vanes, a variable speed generator or variable speed generator motor connected to this hydraulic machine, and a speed control device that controls the speed of the generator or generator motor to a target speed. In a variable speed hydropower generation facility equipped with a variable speed hydropower generation facility, the generator or generator motor is disconnected from the electrical system, the hydraulic machine is started and accelerated from a stopped state, and the generator or generator motor is connected to the electrical system. The time constant of the speed control device is set to the first value to slow down the response until it is confirmed that the disturbance at the time of parallel entry has subsided according to predetermined judgment conditions. However, after it is confirmed that the vibration at the time of parallel entry has subsided under the above-mentioned judgment conditions, the time constant of the speed control device is switched to a second value to speed up the response and shift to steady operation. Features: How to start variable speed hydroelectric power generation equipment.