JP6065396B2 - Generator voltage control method - Google Patents

Description

  The present invention relates to a voltage control device for a generator, and more particularly to a voltage control method at the time of voltage establishment of an automatic voltage control device.

  FIG. 3 shows a control device for a turbine generator described in Patent Document 1, and a digital automatic voltage control device (hereinafter referred to as AVR) is provided in a field winding of a generator 2 driven by the turbine 1. ) A field current is supplied from 4. The generated voltage detected by the transformer PT is input to the AVR 4, analog is converted to digital by the A / D converter 5, and then converted to an effective value by the effective value conversion unit 6. The effective value conversion unit 6 has a power fluctuation stabilization function together with an effective value conversion function, adjusts the phase advance / delay, and outputs a signal to the subtraction unit 8. The subtraction unit 8 obtains a deviation between the input converted value and the set value of the rated voltage by the voltage setting unit 7 and inputs the deviation to the voltage control calculation unit 9 with a limiter to perform PI (proportional integration) calculation to perform field calculation. Get current command.

The changeover switch 10 switches between the field current command from the voltage control calculation unit 9 and the field current command set by the field current setter 11. The switched field current command is received by the subtraction unit 13. Difference calculation with the magnetic current detection value If is performed, and PI calculation is performed on the difference by the field current control calculation unit 14 for the minor loop with a limiter. The field current control value is converted from a digital signal to an analog signal by the D / A converter 15 and is input to the field current control unit 3 as a field current control value, and power is generated via the field current control unit 3. Supply to the field winding of the machine. The field current is detected by a current transformer CT, an analog signal is converted into a digital signal by an A / D converter (field current detection unit) 12, and a field current detection value If is supplied to a subtraction unit 13. Is output.

JP2009-189195A

  When the generator 2 is started, the changeover switch 10 of the AVR 4 is switched to the field current setter 11 side and is initially excited based on the set value set in the field current setter 11. That is, the AVR 4 at the time of starting the generator 2 turns on the initial excitation on the condition that the field circuit breaker (# 41) is turned on by an input command from the outside, and the field current setter A current is supplied to the field winding based on the value set in 11. Thereafter, it is determined whether or not the voltage generated by the generator 2 has reached a preset voltage (e.g., equivalent to 80% of the rating), and when the generated voltage exceeds the set value, the changeover switch 10 The setting device 11 side is switched to the voltage control calculation unit 9 side.

The AVR4 control loop becomes an open loop at the time of switching from the field current setting device 11 side to the voltage control calculation unit 9 side, so that the integration term of the voltage control calculation unit 9 becomes unstable due to an uncontrolled state. It becomes a state. For this reason, when switching to the automatic control side, overshoot / undershoot is caused and the control becomes unstable.
In particular, when the field winding excitation method is self-excited, the power source of the exciter is a self-electromotive force, so that the excitation current at the start is small and the deviation calculated by the subtractor 13 is large, and the minor loop is increased. The upper limit value of the field current control calculation unit 14 is quickly reached, and an excessive control command is output to the control unit 3 to increase the degree of unstable control.

  An object of the present invention is to provide a voltage control method for a generator in which control is stabilized by switching a limiter upper limit value of a field current control calculation unit.

A voltage control calculation unit that obtains a field current command by proportional integral calculation of the deviation between the detected voltage of the generator and the set value by the rated voltage setter;
A changeover switch that switches the field current command from the field current setter side to the voltage control calculation unit when the power generation voltage by the generator is equal to or higher than a preset set voltage ;
Field current control calculation unit with a limiter that obtains a field current command by proportional integral calculation of the deviation between the output from the changeover switch and the field current detection value flowing through the field winding detected by the field current detection unit When,
In the D / A conversion of the output of the field current control calculation unit, the field current supplied to the field winding of the generator via the field current control unit is controlled.
In the field current control calculation unit, a first limiter upper limit value in which the limiter value is variably set to a voltage value with a ratio smaller than the rated voltage of the generator voltage, and a ratio voltage corresponding to the rated voltage when the rated voltage is established. While setting a fixed second limiter upper limit value,
Limiter switching means for performing switching control of each limiter upper limit value of the field current control calculation unit based on voltage detection of the generator is provided,
The limiter switching means is
When the field breaker # 41 is turned on, the field current setting device sets the field current I ₃₀ value corresponding to the initial value to the field current setter, and sets the limiter upper limit value of the field current control calculation unit. Set to the first limiter upper limit value, fix the second limiter upper limit value after the rated voltage is established,
The voltage control calculation unit is
Those until the field magnetizing breaker # 41 set rated voltage established from being turned on that and calculates the integral term in the detected field current value detected by the field current detector It is.

  As described above, according to the present invention, the control until the generator voltage is established is stable, it is possible to prevent overshoot / undershoot, and the control after the voltage is established is also stable control. . Further, by changing the set value and the limit value, it becomes possible to perform stable control regardless of the type of generator, and to shorten the adjustment time.

The block diagram which shows embodiment of this invention. The flowchart at the time of starting. The block diagram of the conventional generator AVR.

  FIG. 1 is a block diagram showing an embodiment of the present invention. The difference from the prior art shown in FIG. 3 is that a voltage detector 20 and a limiter switching means 21 are provided. Further, instead of the field current control calculation unit 14, a field current control calculation unit 14a whose upper limit value can be changed is used. As the voltage detection unit 20, a voltage relay 84G for a generator that has been conventionally used for voltage establishment detection is used.

The limiter switching means 21 performs switching control of the limiter upper limit value of the field current control calculation unit 14a. When the generated voltage does not reach a predetermined value relative to the rated voltage, for example, about 80% of the rated voltage, the field limiter switching means 21 A switching signal a for setting the upper limit value of the limiter of the current control calculation unit 14a to, for example, 70% of the rated voltage is output. When the generated voltage reaches about 80% of the rated voltage (when the voltage is established), the limiter upper limit value is set to, for example, a fixed upper limit value equivalent to 130% of the rated voltage for the field current control calculation unit 14a. A switching signal b for setting is output. When the generated voltage is equal to or lower than the set value, the switching signal c is output to fix the calculation result of the field current setter 11 to a standard value of, for example, 40%. That is, when the field circuit breaker # 41 is turned on, the internal automatic mode of the set voltage of the field current setter 11 is not gradually increased from 0, but the field breaker # 41 is turned on. At the same time, the initial value is set to 40%. At the same time, the field current voltage control calculation unit 9 is based on the field current value detected by the A / D converter (field current detection value) 12 from 0 to the voltage setting voltage establishment voltage. Perform integral term calculation. Others are the same as FIG.

FIG. 2 is a flowchart for switching the limiter upper limit value of the field current control calculation unit 14a.
In step S1, it is determined whether or not a field breaker # 41 (not shown) has been turned on. If it is turned on, initial excitation is executed and control for voltage establishment is performed. At that time, whether the generated voltage has reached the set value (initial value 40%) by the field current setter 11 in step S2 It is determined whether or not. If not, the process proceeds to step S3, where the calculation result by the field current setter 11 is equivalent to, for example, 65% of the field current output range 0 to 130% output by the A / D converter 12. The field current I30 value is fixed. In step S4, the integral term of the voltage control calculation unit 9 is fixed to the field current value. Further, in step S2, when the voltage has reached the set value, the normal PI operation corresponding to the deviations from the subtracting unit 8 to definitive to the voltage control calculation unit 9 goes to step S5 is performed.

  In step S6, the limiter switching means 21 determines whether or not the relay 84G (voltage detector 20) has been operated. If the relay 84G has not been operated, the process proceeds to step S8, where the limiter switching means 21 outputs the rated voltage of 70. % Is output to the field current control calculation unit 14a, and the limiter upper limit value is set to 70% of the rated voltage. In step S6, the limiter switching means 21 determines that the relay 84G has been operated, and sends a switching signal b to the limiter upper limit value corresponding to the upper limit value 130% at the rated voltage to the field current control calculation unit 14a. Output, and set the limiter upper limit value to 130% of the rated voltage.

  As described above, according to the present invention, when the generated voltage in a certain time after the field breaker # 41 is turned on is less than the set value, the integral term of the voltage control calculation unit 9 that performs the PI calculation is used as the field current. The detection value is fixed, and each integral term of the field current control calculation unit 14a is fixed to about 70% of the rated voltage, and the integral term when the voltage becomes equal to or higher than the set equivalent voltage of the field current setter 11. Is released and returned to normal PI calculation equivalent to the rated voltage of 80%. Further, before the 84G voltage is established, the limiter upper limit value of the field current control calculation unit 14a is set to be lower than the rated voltage equivalent to 80%, for example, 70%, and after the voltage is established, the limiter upper limit value is set to the normal 130%. Switching control to return to% is performed.

  Therefore, according to the present invention, the control at the time of establishing the voltage and the control after the establishment of the voltage are stabilized, and overshoot / undershoot can be prevented. In addition, by making the set value of the integral term of the voltage control calculation unit and the field current control calculation unit variable, stable control is possible regardless of the type of generator, and further, the adjustment time for AVR can be shortened. It will be.

DESCRIPTION OF SYMBOLS 1 ... Turbine 2 ... Generator 3 ... Field current control part 4 ... Automatic voltage control apparatus (AVR)
5, 12 ... A / D converter 6 ... RMS conversion unit 7 ... Voltage setting unit 8, 13 ... Subtraction unit 9 ... Voltage control calculation unit 10 ... Changeover switch 11 ... Field current setting unit 14, 14a ... Field current Control calculation unit 15 D / A converter (field current detection unit)
20 ... Voltage detector (84G)
21 ... Limiter switching means

Claims (1)

A voltage control calculation unit that obtains a field current command by proportional integral calculation of the deviation between the detected voltage of the generator and the set value by the rated voltage setter;
A changeover switch that switches the field current command from the field current setter side to the voltage control calculation unit when the power generation voltage by the generator is equal to or higher than a preset set voltage ;
Field current control calculation unit with a limiter that obtains a field current command by proportional integral calculation of the deviation between the output from the changeover switch and the field current detection value flowing through the field winding detected by the field current detection unit When,
In the D / A conversion of the output of the field current control calculation unit, the field current supplied to the field winding of the generator via the field current control unit is controlled.
In the field current control calculation unit, a first limiter upper limit value in which the limiter value is variably set to a voltage value with a ratio smaller than the rated voltage of the generator voltage, and a ratio voltage corresponding to the rated voltage when the rated voltage is established. While setting a fixed second limiter upper limit value,
Limiter switching means for performing switching control of each limiter upper limit value of the field current control calculation unit based on voltage detection of the generator is provided,
The limiter switching means is
When the field breaker # 41 is turned on, the field current setting device sets the field current I ₃₀ value corresponding to the initial value to the field current setter, and sets the limiter upper limit value of the field current control calculation unit. Set to the first limiter upper limit value, fix the second limiter upper limit value after the rated voltage is established,
The voltage control calculation unit is
Power until the field magnetizing breaker # 41 set rated voltage established from being turned on, characterized in that for calculating the integral term in the detected field current value detected by the field current detector Voltage control method.

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