JPH01130070A - Driving method for variable speed hydraulic machine - Google Patents

Abstract

PURPOSE:To obtain an output of good following characteristic and stability by correcting a rotational speed with a value obtained through multiplication of the changed rate of a guide vane opening by a gain. CONSTITUTION:The opening of a guide vane is detected by a guide vane opening detector 20 so as to be inputted in a rotational speed correction control circuit 21. A change rate of a guide vane opening (a) or its differential value is calculated, and multiplied by a negative gain to obtain a speed correction value Nc, and a value obtained by adding this value Nc to a rotational target value N* is transmitted to a rotational speed controller 18. The rotational speed controller 18 controls a real rotational number at a rotational speed higher than the rotational speed target value N* by the speed correction values Nc. When the rotational speed is raised, one part of the hydraulic turbine shaft output is absorbed as the inertia energy of the rotational part.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method for controlling the operation of a hydraulic machine such as a pump having a guide vane or a pump water turbine, and particularly relates to a method for controlling the operation of a hydraulic machine such as a pump having a guide vane or a pump water turbine. This invention relates to a method for controlling the operation of a machine during power generation.

(Prior art) In hydraulic machines such as water turbines or pump-turbines installed in hydroelectric power plants, the shaft output when the water turbine is in operation is determined by the opening degree of the guide vane when the head is constant. When changing the output in hydroelectric power generation equipment equipped with a generator or generator-motor, it is customary to control the opening and closing of the guide vanes so that the guide vane opening degree corresponds to the output target value of the generator or generator-motor. It is.

FIG. 5 shows a schematic configuration of a hydroelectric power generation facility to which the present invention is applied, in which the energy of water led from an upper reservoir 10 through a penstock 11 is converted into mechanical energy by a water wheel or a pump water wheel 12, and is then converted into mechanical energy to generate a generator. Alternatively, the generator motor 13 is driven, and the generated energy is supplied as electric power to an electric power system (not shown). After energy has been absorbed by the water wheel or pump water wheel 12, the water is drained to the lower pond 14 as waste water.

The water wheel or pump water wheel 12 is provided with a guide vane (not shown), and by changing the opening degree of the guide vane, the flow ff1Q of water supplied to the water wheel or pump water rt112 via the penstock 11 is adjusted.

FIG. 6 shows an example of a conventionally used output control method, in which the output target value P* and the generator output PG are manually input to the output control device 15, and a number of guide vane opening target values are output. . The guide vane control device 16 sets the guide vane opening degree a in accordance with the guide vane opening degree target value a*. The opening degree of the guide vane 17 is controlled by this guide vane opening degree a, thereby adjusting the flow rate flowing into the water wheel or pump water wheel 12, and adjusting the shaft output Pt thereof.

On the other hand, a variable speed control device 18 such as a cycloconverter that controls the rotational speed is connected to the generator or generator motor 13, and the rotational speed is set according to the output target value P* by the optimum rotational speed setting device 19. The speed is controlled to the target speed value N*.

The generator output PG is the shaft output p of the water turbine or pump water turbine 12.
The value is determined by the sum of the release and absorption of inertial energy of the rotating part due to changes in t and rotational speed N.

FIG. 7 shows an example of output control when the output is changed in this way. In this figure, the horizontal axis shows time T, and the vertical axis shows generator output PC, guide vane opening a1, and effective head H of the water turbine.
e, shows how the turbine flow rate Q1 rotational speed N1 rotational speed target value N* changes, the solid line in the diagram of generator output PG indicates the actual generator output PG, and the broken line indicates the output target value P* It shows. As can be seen from Figure 7, immediately after point A, where the generator output begins to change, the actual output PG deviates significantly from the output target value P*, and even though the goal is to lower the output. Despite this, there is a phenomenon in which it rises for -10 seconds and then falls. This phenomenon is caused by water hammer in the penstock 11 connected to the water wheel or pump water wheel.

That is, in the hydroelectric power generation equipment having the above-mentioned configuration, when the flow rate of water is changed by changing the opening degree of the guide vane, the water hammer installed at the end of the penstock 11 or The water pressure at the inlet of the pump turbine 12 fluctuates.

Assuming that the inlet pressure of the water wheel or pump water wheel 12 at this time is H, this population pressure H can be expressed as follows from the basic equation of water hammer.

H-C-dQ/dt+Ho...(1)
Here, the flow mQ is the flow rate of water flowing through the penstock 1], Ho
represents the inlet water pressure of the water turbine or pump water turbine 12 before the flow HQ changes, and C is a negative constant determined by the length, cross-sectional area, and water density of the penstock 11.

That is, the water pressure H is determined according to the rate of change dQ/dt of the water flow HQ, and when the flow rate Q decreases, the water pressure H becomes higher than the water pressure HO before the change.

Therefore, considering the characteristics shown in Fig. 7, when the guide vane opening degree a starts to be closed in an attempt to decrease the generator output PG,
The flow ff1Q decreases, and as a result, the above-mentioned water hammer phenomenon occurs in the penstock, and the inlet pressure of the water turbine increases, so that the effective head He of the water turbine also increases.

Since the shaft output pt of a water turbine is approximately proportional to the product of the water flow rate Q and the effective head He of the water turbine, if the increase in the effective head He of the water turbine platform due to the above-mentioned water hammer effect is large, the shaft output of the water turbine will increase. −q rises. That is, if the absolute value l dQ/d t/ 1 of the time rate of change of the water flow mQ is large, the above-mentioned problem will occur.

As described above, the water flow ff1Q is adjusted by the guide vane opening a. In other words, the rate of change in flow rate dQ/dt
changes depending on the rate of change da/dt of the guide vane.

Therefore, when the rate of change da/dt of the guide vane opening degree a is large, dQ/dt becomes large, and the increase in inlet water pressure due to the water hammer phenomenon becomes large. As a result, the shaft output Pt of the water turbine
A phenomenon occurs in which the output value temporarily changes in the opposite direction to the output target value P*.

On the other hand, with one optimum rotation speed setting device (Fig. 6), in order to achieve the highest efficiency operation of the water turbine based on the output target value P*,
The rotational speed target value N* is output. There is a relationship between this optimum rotational speed N* and the output target value P* as shown in FIG. That is, where the output target value P* is large, the rotational speed target value N* is also large, and where the two outputs are small, N* is also small.

As shown in FIG. 7, when a command is issued to lower the output target value P*, the rotational speed target value N* is also commanded to lower. The rotational speed N is controlled to approach the rotational speed target value N* by the rotational speed control device 18 to which the rotational speed target value N* is input. As a result, the rotational speed N is reduced as shown in FIG.

As mentioned above, when the output target value P* decreases, the water wheel shaft output pt increases once due to the water hammer of the penstock, and the rotational speed N is controlled in the decreasing direction, so the inertia of the rotating part increases. Energy will be released. Therefore, even though the output target value P* is in the decreasing direction, a phenomenon occurs in which the generator output PC increases once.

(Problem to be solved by the invention) In this way, in the conventional output control method, the output of the generator or generator motor responds in the opposite direction to the request from the power grid, so This was a problem in terms of operation.

(Objective of the Invention) The present invention was made to solve the above-mentioned drawbacks of the conventional technology, and provides a method for operating a hydraulic machine that can easily follow the output request from the system and can stably control the output. The purpose is to provide

[Structure of the invention]

(Means for Solving the Problems) A method for operating a variable speed hydraulic machine according to the present invention includes a hydraulic machine such as a water turbine or a pump water turbine having guide vanes for adjusting the amount of water, and a winding guide directly connected to the hydraulic machine. A method for operating a variable speed control hydraulic machine comprising a variable speed generator/motor such as a generator or a wound induction generator/motor, and a rotation speed control device for controlling the rotational speed of the variable speed generator/motor, etc., wherein the guide vane It is characterized in that the rate of change or differential value of the opening degree or its target value is detected, and the rotational speed of the variable speed generator motor etc. is controlled using a value obtained by multiplying the rate of change or differential value by a negative gain.

(Function) According to the method of the present invention configured as described above, the output [:
The guide vane opening changes according to a change in one mark, and the rotation speed is corrected by the value obtained by multiplying the rate of change by a negative gain, so opening and closing of the guide vane reduces head fluctuations caused by water hammer action on the penstock. By absorbing or discharging the fluctuations in the output caused by this as rotational energy of the rotating part, it is possible to suppress a transient phenomenon in which the generator output swings once in the opposite direction to the output target.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a configuration example of an output control system to which the control method according to the present invention is applied. Water guided by a penstock 11 passes through a guide vane 17 and rotates a water wheel or a pump water wheel 12. The shaft output pt of the water turbine or pump water turbine thus generated is converted into an electrical output PG by the variable speed generator 13.

When the output target value P* is given, the output control device 15 compares it with the actual generator output PG and derives the guide vane opening (vote value a*).This value is sent to the guide vane control device 16. The guide vane opening degree a is output manually.

On the other hand, the optimum rotational speed setter 19 outputs a rotational speed target value N* corresponding to the output target value P* to the rotational speed control device 18. The opening degree of the guide vane is detected by a guide vane opening degree detection device 20 and input to a rotation speed correction control circuit 21 .

Here, if a command is given to lower the output target value P*, the output control device 15 controls the guide vane opening degree target value a
Issue a command to reduce *. This causes the guide vane to close.

As a result, the amount of water in the penstock 11 decreases, a water hammer phenomenon occurs, and the effective head applied to the water turbine or pump turbine increases, so that the shaft output Pt of the water turbine or pump turbine increases.

At this time, the guide vane opening degree detection device 20 detects the guide vane opening degree a and sends it to the rotational speed correction control circuit 21 . This rotational speed correction control circuit calculates the rate of change or differential value of the guide vane opening degree a.

Next, the operation of the embodiment of the present invention described above will be explained with reference to FIGS. 1 and 2. Note that the definitions of lines and symbols are the same as in the previous figures.

FIG. 2 shows a case where the output target value P* is in the downward direction, but in this case, the guide vane is closed, so the rate of change or differential value takes a negative value. Therefore, in the rotational speed correction control circuit 21, this rate of change or differential value is multiplied by a negative gain to obtain a speed correction value Nc. In this case, a value obtained by adding the speed correction value Nc to the rotational speed target value N* is sent to the rotational speed control device 18.

The rotational speed control device 18 controls the actual rotational speed to be higher than the rotational speed target value N* by the speed correction value Nc. When the rotational speed is increased, a part of the water wheel shaft output Pt is absorbed as inertial energy of the rotating part. Therefore, as shown in Fig. 7, the rotation speed is increased so that the excess energy (water wheel shaft output) that increases contrary to the generator output PG or output target value P* is absorbed as inertia energy of the rotating part. If the output target value P* is lowered, the generator output P
C will no longer rise once, and as shown in FIG. 2, the followability of the generator output PC to the output target value P* will improve, making stable output control possible.

FIG. 3 shows another embodiment of the invention. This embodiment differs from the previously described embodiments in that instead of detecting the guide vane opening a*, the guide vane opening a* is sent to the rotational speed correction control circuit 21, and the change rate or differential of the guide vane opening a* is A speed correction value Nc obtained by multiplying this value by a negative gain is added to the rotational speed target value N* and sent to the rotational speed control device 18 to control the rotational speed N.

In this control method, when the output target value P* decreases,
Since the guide vane opening degree a* is decreased, the rate of change or differential value of a* becomes negative. On the other hand, the guide vane opening a also closes as a* decreases, so the penstock 1
The effective head rises due to the water hammer phenomenon caused by the decrease in the flow rate within 1, and the shaft output pt of the water turbine or pump water turbine increases. By correcting the rotational speed target value N* using the speed correction value Nc obtained by increasing the rotational speed and increasing the rotational speed, the increase in the shaft output pt of the water turbine or pump turbine described above is absorbed as rotational energy (inertial energy) of the rotating part. .

According to this method, the phenomenon in which the generator output PC swings by one row in the opposite direction when the command to lower the output target value P* shown in FIG. 7 is eliminated, and the followability of the generator output PG to the output target value P* is improved. Get better.

Incidentally, in all of the above-mentioned embodiments, the case where the output target value P* decreases has been described, but the output control can be performed in the same manner even when a command to increase the output target value P* is received. That is, when the output target value P* increases, the output control device 15 commands the target value a* in the direction of opening the guide vane.

When this opening command a* is input, the guide vane 17 is opened by the guide vane control device 16.

At this time, the flow rate increases in the penstock, causing a water hammer phenomenon and reducing the effective head. Due to this reduction in effective head, the shaft output of the submersible or pump turbine decreases even though a command to increase output is issued.

On the other hand, the value Nc (in this case, negative) that produces a negative gain in the rate of change or differential value (in this case, positive) of the guide vane opening a or the guide vane opening target value a* is the rotation speed. In addition to the target value N*, by performing control to reduce the rotation speed N, a decrease in the shaft output of the water turbine or pump water turbine is compensated for in the form of releasing inertial energy of the rotating part. This improves the followability of the generator output PG to the output target value P* and allows stable output control.

In addition, as shown in FIG. 8, when the above control method is applied to a power plant where a plurality of water conductive pipes branch from one penstock 11 and a plurality of water turbines or pump water turbines 12a and 12b are operated. , when there are many units in operation that are simultaneously controlled to the output target value P*, the flow rate change dQ/dt is large, so the change in the effective head due to the water hammer phenomenon of the penstock described above is large, and the target output P* When the number of operating units to be controlled at the same time is small, the flow rate change dQ/dt is small, so the rotation speed correction control device 21 adjusts the rate of change of the guide vane opening, taking into account that the change in effective head due to the water hammer phenomenon is small. The absolute value of the multiplied negative gain is increased when there are many vehicles in operation,
If the number of units in operation is small, the generator output P for the target output value P* can be reduced even if the number of units in operation changes.
Output control can be performed to optimize G followability.

〔Effect of the invention〕

As described above, according to the present invention, output control during power generation operation is extremely stable, and hydroelectric power generation equipment can be controlled with good followability.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram for realizing the method of operating a variable speed hydraulic machine of the present invention, FIG. 2 is a graph showing its operation, and FIG. 3 is a control block diagram showing another embodiment of the present invention.
Fig. 4 is a system diagram of a power plant with a branch waterway showing still another embodiment of the present invention, Fig. 5 is a schematic diagram of a conventional hydroelectric power plant, and Fig. 6 is a control block of a conventional hydroelectric power plant. figure,
FIGS. 7 and 8 are graphs showing the operation. 10... Upper pond, 11... Penstock, 12... Water wheel or pump water wheel, 13... Variable speed generator motor, 14
...Lower pond, ]5... Output control device, 16... Guide vane control device, ]7... Guide vane, 18...
・Rotation speed control device, 19...optimum rotation speed setting device,
20... Guide vane opening detection device, 21... Rotation speed control circuit. Applicant's agent Mr. Sato - Figure 2

Claims (1)

[Scope of Claims] 1. A hydraulic machine such as a water wheel or a pump water turbine having a guide vane for adjusting the amount of water, and a variable speed generator or a variable speed generator motor (hereinafter referred to as a variable speed generator motor etc.) directly connected to this hydraulic machine. ) and a rotation speed control device for controlling the rotation speed of the variable speed generator-motor, etc., in a power generation operation method of a variable speed control hydroelectric power generation facility having a rotation speed control device for controlling the rotation speed of the variable speed generator motor, etc. A method for operating a variable speed hydraulic machine, comprising: detecting the change rate or differential value, and correcting and controlling the rotational speed of the variable speed generator motor, etc. using a value obtained by multiplying the rate of change or the differential value by a negative gain. 2. In a hydroelectric power plant where the waterway consists of a single pipe section connected to the upper pond and multiple branch pipes branching from it, and a variable speed control hydraulic machine is connected to each branch pipe, the guide vane or its When the rate of change or differential value of the target value is detected and the rotational speed of a variable speed generator motor is corrected and controlled using a value obtained by multiplying this rate of change or differential value by a negative gain, the gain is used as the hydraulic power that moves the guide vane. 2. The method of operating a variable speed hydraulic machine according to claim 1, wherein the speed is changed depending on the number of machines in operation.