JP2695813B2 - Operation control device of variable speed hydraulic machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an operation control method of a variable speed hydraulic machine such as a water turbine or a pump water turbine having a guide vane.

(Prior art) In a hydraulic machine such as a turbine or a pump turbine installed in a hydroelectric power plant, the shaft output during the operation of the turbine is determined by the opening of the guide vanes under a constant head. When the output is changed in a hydroelectric power plant equipped with a generator or a generator motor, it is customary to control the opening and closing of the guide vanes so that the guide vane opens in accordance with the output target value of the generator or the generator motor. is there.

FIG. 3 shows a schematic configuration of a hydroelectric power plant to which the present invention is applied. The energy of water guided by a penstock 11 from the upper pond 10 is converted into mechanical energy by a water turbine or a pump water turbine 12 and is wound. Induction generator or induction generator motor
13 is driven, and the generated energy is supplied to a power system (not shown) as electric power. The water after the energy is absorbed by the turbine or pump turbine 12 is treated as waste water in the lower pond.
Drained to 14.

A guide vane (not shown) is provided on the water wheel or the pump water wheel 12, and by changing its opening degree,
The flow rate Q of water supplied to the water turbine or the pump water turbine 12 via the penstock 11 is adjusted.

FIG. 4 shows an example of an output control device of a conventionally used variable speed control hydraulic machine, and an output target value P * is shown.
And the generator output PG are input to the output control device 15 to output a guide vane opening target value a * according to their deviation. The guide vane controller 16 sets the guide vane opening a in accordance with the guide vane opening target value a *. The guide vane 17 is controlled in its opening by the guide vane opening a to regulate the flow rate flowing into the water turbine or the pump water turbine 12,
By adjusting the shaft output Pt, the output PG of the generator or the generator motor 13 is changed.

On the other hand, a rotation speed control device 18 such as a cycloconverter for controlling the rotation speed is connected to the generator or the generator motor 13, and the rotation speed of the generator or the generator motor 13 is output by an optimum rotation speed setter 19. Target value P * and still head
Maximum efficiency operation rotational speed target value N calculated by Hst
Controlled by *. Therefore, the generator output PG is a value determined by the shaft output Pt of the water turbine or the pump water turbine 12 and the sum of the release and absorption of the inertial energy of the rotating part due to the change in the rotation speed N.

FIG. 5 shows an example of output control when the output is changed in this manner. In this figure, the horizontal axis represents time T, and the vertical axis represents generator output PG, guide vane opening a, and effective head H of the turbine.
e, the state of changes in the water turbine flow rate Q and the rotation speed N. In the figure of the generator output PG, the solid line PG indicates the actual generator output, and the broken line indicates the target output value P *.

As can be seen from FIG. 5, immediately after the point A at which the generator output starts to change, the actual output PG greatly deviates from the output target value P *. However, there is a phenomenon of rising and then falling. This phenomenon is caused by the penstock connected to the turbine or pump turbine.
It is caused by a water hammer inside.

That is, in the hydroelectric power plant having the above-described configuration, when the flow rate of water is changed by changing the opening degree of the guide vane, the water hammer of the penstock 11 causes a water turbine or a pump installed at the end thereof. The water pressure at the inlet of the water wheel 12 fluctuates. Assuming that the inlet water pressure of the water turbine or the pump water wheel 12 at this time is H, the inlet water pressure H can be expressed as follows from the basic formula of water hammer.

H = C · dQ / dt + Ho (1) where Q is the flow rate of the water flowing through the penstock 11, Ho is the inlet water pressure of the turbine or the pump turbine 12 before the flow rate Q changes, and C is the penstock 11. Is a negative constant determined by the flow, cross-sectional area, and density of water.

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

Therefore, in consideration of the characteristics shown in FIG. 5, when the guide vane opening a starts to be reduced in order to reduce the generator output PG,
The flow rate Q decreases, and as a result, a water hammer phenomenon occurs in the penstock described above, and the hydraulic pressure at the inlet of the turbine increases, so that the effective head He of the turbine also increases.

Since the shaft output Pt of the turbine is substantially proportional to the product of the flow rate Q of water and the effective head He of the turbine, when the effective head He of the turbine due to the above-mentioned water hammer has a large increase, the shaft output of the turbine becomes large. As a result, the above-described phenomenon occurs as a result of the increase once and the generator output PG also increasing.

Here, as shown in FIG. 5, when a lowering direction command is issued as the output target value P *, if the output target value P * decreases, the optimum rotational speed setting unit is obtained according to the efficiency characteristics of a general hydraulic machine. Since the maximum efficiency operation rotation speed target value N * set in 19 decreases, the rotation speed N is controlled in a decreasing direction, and the increase in the generator output PG due to the increase in the effective head He due to the inertia energy of the rotating part. The rotation speed N is controlled so that the power cannot be absorbed and the generator output PG increases.

(Problems to be Solved by the Invention) As described above, in the conventional output control method, the output of the generator or the generator motor once responds in reverse to the request from the power system. There were problems in the operation of the power system, such as power fluctuations and frequency fluctuations.

Accordingly, it is an object of the present invention to provide an operation control device for a variable-speed hydraulic machine that has a good ability to follow an output request from a system and can stably control the output.

[Configuration of the invention]

(Means for Solving the Problems) The present invention relates to a hydraulic machine such as a water turbine or a pump turbine having a guide vane for adjusting the amount of water, a variable speed generator or a generator motor coupled to the hydraulic machine, And a rotation speed control device for controlling the rotation speed of the generator or generator motor, the operation control device of the variable speed hydraulic machine,
An inlet water pressure or an effective head detector for detecting an inlet water pressure or an effective head acting on the hydraulic machine, and a fluctuation value of the inlet water pressure or the effective head inputted from the inlet water pressure or the effective head detector at every fixed time are calculated. A fall fluctuation detector for obtaining a time integral value of the fluctuation value, and a rotation / rotation input to the rotation speed control device as a speed correction value using a signal proportional to the time integral value of the fluctuation value output from the fall fluctuation detector. And a speed correction control device.

(Operation) As described above, according to the present invention, when opening and closing the guide vanes of the hydraulic machine according to the change of the output target value P * from the power system, the inlet hydraulic pressure or the effective head He acting on the hydraulic machine is adjusted. Is detected, and a signal proportional to the time integral of the variation is used as a speed correction value to correct the rotation speed of the generator or the generator motor. The fluctuation of the output of the generator or generator-motor caused by the fluctuation of the head due to the fluctuation can be absorbed or released as the rotational energy of the rotating part, so that the power generation output temporarily swings in the opposite direction to the output target. It is possible to suppress the decrease, and it is possible to stably follow the output request from the power system.

(Example) Hereinafter, an example of the present invention is described with reference to drawings.

FIG. 1 shows an example of the configuration of an output control system to which the present invention is applied. Water guided by a penstock 11 passes through guide vanes 17 to rotate a water wheel or a pump water wheel 12.
The shaft output Pt of the turbine or pump turbine generated by this
Is converted into an electrical output PG by the variable generator 13,
It is supplied to a power system (not shown) as electric energy.

When the output target value P * is given based on the power demand from the grid, the actual power output P
The value is compared with G, and the target opening degree value a * of the guide vane is calculated. This value is input to the guide vane control device 16 to set the guide vane opening a. As a result, the flow rate Q of the water flowing into the turbine or the pump turbine 12 is adjusted, and the shaft output Pt of the turbine or the pump turbine 12 is controlled to a value corresponding to the output target value P *.

On the other hand, the optimum rotation speed setter 19 outputs a target rotation speed target value N * calculated based on the output target value P * and the static fall difference Hst.

In addition, the inlet water pressure H acting on the turbine or the pump turbine 12
Alternatively, the effective head He is detected by the inlet water pressure detector or the effective head detector 21 and input to the head fluctuation detector 22. This head variation detector calculates a variation value ΔH of the inlet water pressure H or the effective head He at regular intervals before the guide vane 17 starts to close, and outputs the time integral value ΣΔH to the rotation speed correction control device 20. doing.

The rotation speed correction control device 20 outputs a signal proportional to the time integral value ΣΔH of the variation value ΔH of the inlet water pressure H or the effective head He as the speed correction value Nc.

Therefore, the rotation speed control device 18 is an optimum rotation speed setting device.
The speed correction value Nc is added to the 19 rotation speed target value N *, and the rotation speed is controlled by the corrected optimum rotation speed (N * + Nc).

That is, for example, assuming that the output target value P * is given as the output reduction command, the output control device 15 compares the output target value P * with the actual output PG of the generator or the generator motor 13 and outputs the guide vane. Is output to the guide vane control device 16 as a closing control command. This causes the guide vanes 17 to start closing.

When the guide vane 17 starts to close, the flow rate Q decreases, and as a result, a water hammer phenomenon occurs in the penstock 11 and the effective head He acting on the water turbine or the pump turbine increases.

As shown in FIG. 2, the fall fluctuation detector 22 is set to a predetermined time interval T1 to before the guide vane 17 starts to close.
Inlet water pressure H generated in each time section of T2, T2 to T3, T3 to T4 ...
Alternatively, a variation value ΔH of the effective head He is calculated, and a time integration value ΣΔH of these variation values is output to the rotation speed correction control circuit 20.

When the guide vane 17 is in the closing direction, the time integration value ΣΔH of the head variation ΔH takes a positive value, as shown in FIG.
Positive speed correction value proportional to the time integral ΣΔH
Output Nc.

Since a signal obtained by adding a positive speed correction value Nc to the rotation speed target value N * from the optimum rotation speed setting device 19 is input to the rotation speed control device 18, the rotation speed control device 18 The rotation speed N of the electric motor 13 is increased. Therefore,
Since the inertia energy of the rotating part is absorbed by the shaft output Pt of the water turbine or the pump turbine 12 which rises due to the water hammer action, the generator output P in response to the command to decrease the output target value P *
G does not temporarily increase so much that it follows the output target value P * well, enabling stable output control.

Although the above-described embodiment has described the case where the output target value P * decreases, the output control can be performed in the same manner when the output increase value comes to the output table value P *.

That is, when the output target value P * increases, the output control device 15 compares the output target value P * with the actual generator output PG.
And a target value a in the direction in which the guide vane 17 is opened.
* Is commanded. When the opening command a * is input, the guide vane 17 is opened by the guide vane control device 16.

In this example, since the flow rate Q in the penstock 11 increases, a water hammer phenomenon occurs, and the effective head He acting on the turbine or the pump turbine decreases.

Also in this case, the inlet water pressure H or the effective head He of the water turbine or the pump water turbine 12 is detected by the inlet water pressure detector or the effective head detector 21 before the guide vanes start to open.
Further, the head change detector 22 is provided with a preset section T1.
TT2, T2〜T3,..., The fluctuation value ΔH of the inlet water pressure H or the effective head He generated in each of the time sections is calculated. Output.

Further, since the guide vane 12 is in the opening direction, the integral value ΣΔH of the head variation value ΔH takes a negative value, and the rotational speed correction control device 20 outputs the negative rotational speed correction value, contrary to the case of FIG. Set Nc.

Therefore, the rotation speed control device 18 has the rotation speed target value N *
And the corrected signal obtained by adding the negative speed correction value Nc to the motor, the generator or the generator motor 13
Is controlled to decrease the As a result, the inertia energy emitted from the rotating part is added to the shaft output Pt of the water turbine or the pump water turbine that is reduced by the water hammer phenomenon, and the generator output PG temporarily decreases in response to the command to decrease the output target value P *. Without this, it is possible to perform stable output control with good followability.

〔The invention's effect〕

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

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a control device for carrying out the present invention, FIG. 2 is a graph showing its operation, and FIG. 3 is a schematic diagram of a hydroelectric power plant to which the present invention is applied. FIG. 4 is a block diagram of a conventional operation control device for a variable speed hydraulic machine, and FIG. 5 is a graph showing its operation. 10 ... Upper pond, 11 ... Penstock, 12 ... Turbine or pump turbine, 13 ... Variable speed generator motor, 14 ... Lower pond, 15 ... Output control device, 16 ... Guide vane control device, 17 ... … Guide vane, 18… Rotation speed control device, 19 …… Optimal rotation speed setting device, 20 …… Rotation speed correction control device, 21 …… Inlet water pressure detector or effective head detector, 22 …… Head fluctuation detector .

Claims (1)

(57) [Claims] 1. A hydraulic machine such as a water turbine or a pump turbine having a guide vane for adjusting a water amount, a variable speed generator or a generator motor coupled to the hydraulic machine, and a rotational speed of the generator or the generator motor. An operation control device for a variable speed hydraulic machine having a rotation speed control device for controlling, an inlet water pressure or an effective head detector for detecting an inlet water pressure or an effective head acting on the hydraulic machine, and the inlet water pressure or an effective head detector Calculate the fluctuation value of the inlet water pressure or effective head input from
A drop variation detector for calculating a time integral value of the variation value; and a rotation speed correction which inputs a signal proportional to the time integration value of the variation value output from the fall variation detector to the rotation speed control device as a speed correction value. An operation control device for a variable speed hydraulic machine, comprising: a control device.