JPH0984394A - Control method of control device for hydroelectric power plant - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To control voltage establishment and rated voltage retention without causing overshoot or undershoot. SOLUTION: Detected generator voltage V indicating generator output voltage
_{The difference} between _G and the set voltage V ₀ is calculated by PI to obtain the set field current I _f0 . Further, the deviation between the detected field current I _f indicating the generator field current and the set field current I _f0 is PI-calculated to obtain a field current command I _D , and based on this I _D , the thyristor controller Th The exciting current value is determined. The value of voltage V ₀ is
The initial excitation voltage value is gradually increased stepwise by a fixed value,
Eventually the rated value is reached.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for a control device for a hydraulic power plant, and is devised so that stable voltage control can be performed without causing overshoot or undershoot.

[0002]

2. Description of the Related Art A controller for a hydroelectric power plant controls speed control, excitation control, voltage control, power factor control, etc. of the hydroelectric power plant.

The hydroelectric power plant and its control system will now be described with reference to FIG. Regarding the control device, only the field control system is shown.

As shown in FIG. 1, the generator AG is a water turbine W.
It is rotated by T to generate electric power, while the transformer T
The exciting current extracted by r and obtained by the thyristor control unit Th is supplied to the exciter EX to excite the generator AG. In addition, the guide vane mechanism G operates to adjust the guide vane opening degree of the water turbine WT.

In the control device 100, the set voltage V ₀ is set by the voltage setter 90R. The value of the set voltage V ₀ is
It is set as a percentage value with the rated value being 100%. Further, the generator voltage detector 101 is a transformer P for instrument.
Generator voltage is detected via T and detected generator voltage V
Outputs _G [%]. The lead / lag compensator 102 compensates the lead / lag of the detected generator voltage V _G and outputs the compensated detected generator voltage V _GC . The lead / lag compensation is performed using the following equation (1).

[0006]

[Equation 1]

The field current detector 103 detects the field current output from the thyristor controller Th and outputs the detected field current _If . The field breakers 41-1 and 41-2 are turned on when generating power.

The subtractor 104 subtracts the detected generator voltage V _GC from the set voltage V ₀ and outputs the deviation voltage ΔV. A proportional-plus-integral calculator 105 with a limiter calculates the set field current I _f0 by proportional-plus-integral calculation of the deviation voltage ΔV. The value of the set field current I _f0 is limited so as not to exceed a preset upper limit value.

The subtractor 106 has a set field current I_f0From
Field current I_fTo subtract the deviation field current ΔI_fSeeking
You. The proportional-plus-integral calculator 107 with a limiter
Flow ΔI _fTo calculate the field current command I_DSeeking
You. The field current command I_DThe value of is preset
It is restricted not to exceed the upper limit. This field current
Command I_DIs converted into an analog signal by the D / A converter 108.
It is converted and sent to the thyristor control unit Th.

The thyristor control unit Th uses the field current command I
_The field current is controlled according to _D. By thus controlling the field current, the voltage value of the generator AG (detected generator voltage V _G ) becomes equal to the set voltage V ₀ .

There are the following two modes for the generator voltage control by the above-mentioned control device. (1) A voltage establishment control mode that raises the voltage from no voltage to the rated voltage. (2) Rated voltage holding mode in which the output voltage is controlled to be held at the rated value after the rated voltage is reached.

In the voltage establishment control mode, the difference between the set voltage V ₀ and the detected generator voltage V _G (V _GC ) is large, and the value of the deviation voltage ΔV is large. On the other hand, in the rated voltage holding mode, the set voltage V ₀ and the detected generator voltage V _G (V _GC )
Is large and the value of the deviation voltage ΔV is small.

[0013]

In the control device 100, the time constant and the gain of each control block are tuned so that optimum speed response and stability can be obtained in the voltage establishment control mode ( Time constant 1 and gain 1
As described above, the control response overshoots or undershoots when shifting to the rated voltage holding mode. On the contrary, if the time constant and gain of each control block are tuned (time constant is 1 and gain is 1) so that optimum quick response and stability can be obtained in the rated voltage holding mode, the voltage is established. The control response overshoots or undershoots in the control mode. Note that conventionally, tuning is performed so that optimum control can be performed in the voltage establishment control mode.

At present, if the overshoot amount at the time of voltage establishment is 10% or less, it is judged that the tuning at that time is good.

In view of the above-mentioned conventional technique, the present invention is such that even in the voltage establishment control mode in which the generated voltage is increased from no voltage to the rated voltage, the generated voltage is set to the rated voltage after being established. It is an object of the present invention to provide a control method for a control device for a hydroelectric power plant, which can perform voltage control without overshooting or undershooting even in a rated voltage holding mode in which it is controlled to hold.

[0016]

SUMMARY OF THE INVENTION The present invention which solves the above-mentioned problems includes a voltage setter for setting a set voltage, a generator voltage detector for obtaining a detected generator voltage indicating a generator output voltage,
A field current detector for obtaining a detected field current indicating a field current of the generator; first computing means for obtaining a set field current based on a difference between the set voltage and the detected generator voltage; In a controller for a hydraulic power plant having a second calculation means for obtaining a field current command based on a difference between a detected field current and the set field current, a value of the set voltage is first set to an initial excitation voltage value. It is characterized in that the value of the set voltage is gradually increased by a constant value until the rated value is reached.

In the present invention, the value of the set voltage is sequentially increased by a constant value from the initial excitation voltage value to the rated value, so that voltage control can be performed without overshoot or undershoot.

[0018]

Embodiments of the present invention will be described below. The configuration of the control device 100 of the present embodiment is the same as the conventional one as shown in FIG. 1, but in the present embodiment, the value of the set voltage V ₀ set by the voltage setter 90R is set as shown in the flowchart of FIG. Have control. Also, tuning is performed so that the gain is 1 and the time constant is 1.

That is, when the control is started, the field breaker 41-
It is determined whether or not 1 and 41-2 are input (step S1). In the field circuit breakers 41-1 and 41-2, the rotation speed of the main engine (generator AG or turbine WT) is about 8 times the rated speed.
It is thrown in when it becomes 0% or more.

When the field breakers 41-1 and 41-2 are turned on, it is next determined whether or not the value of the detected generator voltage V _G is stable (step S2). The stable voltage means that the voltage of the detected generator voltage V _G is about 80% of the rated voltage.

When the value of the detected generator voltage V _G is stable, the process proceeds to step S3, and the value of the set voltage V ₀ set by the voltage setter 90R is set as the initial excitation voltage value α. Although this initial excitation voltage value is slightly different depending on the size of the initial excitation resistance, it is usually a value corresponding to 80% of the rated voltage. This initial excitation voltage value is preset in the voltage setter 90R by a dedicated tool.

After the value of the set voltage V ₀ is set to the initial excitation voltage value α, the value of the set voltage V ₀ is gradually increased from the initial excitation voltage value α by the increment value β, and finally, When the value of the set voltage V ₀ reaches the rated value [100%], the value of the set voltage V ₀ is held at the rated value (steps S4, S).
5). The increase value β can be set by the voltage setting device 90 with a special tool.
It is preset to R.

The increase value β is obtained by the following equation (2). In the equation (2), T is the field breaker 4
Τ is the calculation cycle, which is the time from the input of 1-1 and 41-2 to the rated voltage.

[0024]

[Equation 2]

As described above, in this embodiment, since the value of the set voltage V ₀ is increased stepwise, the deviation voltage ΔV becomes constant, and the control does not change greatly depending on the value of the time constant for lead / lag compensation. The voltage can be established in a short time without overshoot or undershoot, and stable control can be performed.

Moreover, by changing the time T, the time until the voltage is established can be made variable.

Of course, stable control can be performed even after the rated voltage is reached.

FIG. 3 shows the characteristics of the voltage establishment control in this embodiment, and FIG. 4 shows the set voltage V ₀ of 10 in this embodiment.
The indicial response when 0% → 90% → 100% is shown. As can be seen from FIGS. 3 and 4, according to this embodiment, stable voltage control can be performed in both the voltage establishing control mode and the rated voltage holding mode.

[0029]

According to the present invention as described in detail with reference to the above embodiments, the value of the set voltage is gradually increased from the value of the initial excitation voltage by an increasing value, and finally the rated value is reached. As a result, the voltage can be established in a short time without causing undershoot or overshoot, and stable voltage control can be performed even after the rated voltage is reached.

[Brief description of drawings]

FIG. 1 is a block diagram showing a controller for a hydroelectric power plant.

FIG. 2 is a flowchart showing a control procedure according to the present invention.

FIG. 3 is a characteristic diagram showing voltage establishment control according to the present invention.

FIG. 4 is a characteristic diagram showing an indicial response according to the present invention.

[Explanation of symbols]

41-1, 41-2 field breaker 90R voltage setting device 100 control device 101 generator voltage detector 102 lead / lag compensator 103 field current detector 104, 106 subtractor 105, 107 proportional-plus-integral calculator 108 D / A converter V ₀ setting voltage V _G detection generator voltage ΔV deviation voltage I _f detection field current I _f0 setting field current ΔI _f deviation field current I _D field current command AG generator WT water turbine Tr transformer Th thyristor Controller EX Exciter G Guide vane mechanism PT Instrument transformer

Claims (1)

[Claims] 1. A voltage setter for setting a set voltage, a generator voltage detector for determining a detected generator voltage indicating a generator output voltage, and a field for determining a detected field current indicating a field current of the generator. A current detector; first computing means for obtaining a set field current based on a difference between the set voltage and the detected generator voltage;
In a controller for a hydroelectric power station having a second calculation means for obtaining a field current command on the basis of a difference between the detected field current and the set field current, a value of the set voltage is first set to an initial excitation voltage value. The control method for the hydraulic power plant controller is characterized in that the value of the set voltage is gradually increased by a constant value until the rated value is reached.