JP2011125189A - Voltage control device of power plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage control device of a power plant for mutual cooperation control between generator voltage control and tap switching control. <P>SOLUTION: The voltage control device of the power plant includes a voltage converter 5 in which a generator voltage is input through a transformer 4, a reactive power converter 8 in which the generator voltage is input through the transformer 4 and a generator current is input through a current transformer 7 and which detects a generator reactive power from the input generator voltage and generator current, and a sequencer 6 in which the reactive power output from the reactive power converter 8 and the generator voltage output from the voltage converter 5 are input. The sequencer 6 includes a reactive power comparison unit 6b which outputs a voltage increase/decrease signal to an automatic voltage controlling device 10 when a difference occurs in the comparison results between the reactive power output from the reactive power converter 8 and a preset reactive power target value, and a voltage comparison unit 6c which confirms whether the generator voltage detected by the voltage converter 5 is within an operation range of a generator 1, and outputs a tap increase/decrease signal to a main transformer 1 if it is outside the operation range. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a voltage control device for a power plant in which a generator is linked to a power transmission system via a main transformer having tap switching means.

  The electric power system is configured so that electric devices and the like can function normally due to the stable operation of the system. For this reason, stable voltage control without voltage fluctuation is required. It has been known that voltage fluctuations in such a power system are due to the effect of active power and that due to the effect of reactive power, and various countermeasures have been taken.

  For example, in Patent Document 1, since reactive power is uniquely correlated with voltage, a measure to be dealt with by power generation control is taken as control for suppressing fluctuations in reactive power to a low level. There is disclosed a technique capable of performing voltage control on the main transformer power transmission system side by tap switching of the main transformer in conjunction with generator voltage control. That is, in a power plant where the generator is linked to the power transmission system via a main transformer having a load tap switching means, a generator voltage within a predetermined allowable variation range is calculated according to a control command, and the generator voltage is supported. Calculating and controlling means for determining the tap position of the main transformer, detecting the transmission system side voltage of the main transformer, selecting the generator voltage so that the contents of the control command are equal, and selecting the generator voltage There is disclosed a power plant voltage control apparatus comprising execution control means for giving a tap switching command to the on-load tap switching means so that the generator voltage falls within a predetermined allowable range.

Japanese Laid-Open Patent Publication No. 1-148026 (Structure of Invention, FIG. 3)

  According to the technique disclosed in Patent Document 1, voltage control on the main transformer transmission system side by tap switching of the main transformer can be performed in conjunction with generator voltage control, so that the operability of voltage control is improved. In addition, it is possible to ensure the responsiveness and reliability of voltage control and to expect stable operation of the power system.

  However, in the technique disclosed in Patent Document 1, the tap switching operation of the main transformer is generally an operation by an operator, and the generator voltage control is also performed by a generator excitation device, a constant voltage control means, a generator When the power factor constant control means (or power factor limiting means) and the generator reactive power constant control means are individually equipped and the generator is linked to the grid, fluctuations in the grid voltage will cause the generator reactive power to vary. As a result, the following problems have been encountered due to the restrictions imposed by the generator's operation restriction range.

  When the system voltage rises during the generator reactive power constant control, the generator reactive power temporarily decreases as the system voltage increases, and the generator reactive power constant control means is set with the reduced reactive power. The generator voltage is increased to return to the reactive power set value. At that time, depending on how the system voltage rises, the generator voltage operating range (± 5% of the rated voltage) exceeds + 5%, and it is impossible to return the generator reactive power to the set reactive power. For this reason, the generator reactive power control is locked, and the generator operator can control the generator reactive power to the target reactive power value by operating the tap switching means of the main transformer by the power plant operator. It was necessary to be within the range (in the direction of decreasing the generator side voltage). On the other hand, when the system voltage drops, it will be lower than the generator voltage operating range of -5%, and the power factor may not be improved. Similarly, voltage adjustment by the operator's tap switching operation is necessary. It was.

  In addition, if the system voltage rises during generator power factor constant control (assuming it is set to a delay of 0.85 pf), the generator reactive power decreases as the system voltage rises, and the generator power factor is temporarily , Will go in the direction of advance. The generator power factor constant control means raises the generator voltage to return the advanced power factor to the set 0.85 pf delay. At that time, depending on how the system voltage increases, the generator voltage operating range exceeds + 5%, and the generator power factor cannot be returned to 0.85 pf. For this reason, the generator power factor constant control is locked, and the power plant operator operates the tap switching means of the main transformer, and the generator power factor constant means can be controlled to a delay with a set power factor of 0.85 pf. It was necessary to be within the machine voltage operating range (in the direction of decreasing the generator side voltage). Conversely, if the system voltage drops, it will be lower than the generator voltage operating range of -5%, and the power factor may not be improved. Similarly, voltage adjustment by the operator's tap switching operation is required. Yes.

  The present invention has been made to solve the above-described problems, and is a main transformer so that generator reactive power control and fluctuations in generator reactive power due to system voltage fluctuations can be controlled within the generator voltage fluctuation range. It is an object of the present invention to obtain a power plant voltage control device that automatically changes the tap switching.

  A voltage control device for a power plant according to the present invention is configured such that a generator whose generator voltage is adjusted by an automatic voltage regulator is linked to a power transmission system via a main transformer having tap switching means, and the generator voltage control is performed. And a voltage control device for a power plant that performs mutual cooperative control of tap switching control of the tap switching means, the voltage converting means for transforming and inputting the generator voltage by a transformer, and the generator voltage to be transformed. A power conversion means for transforming and inputting a generator current by a current transformer and inputting a generator reactive power by the input generator voltage and generator current, and the power conversion means A control device that inputs the reactive power output by the power converter and the generator voltage output by the voltage conversion means, and the control device is preset with the generator reactive power output by the power conversion means. The reactive power comparison unit that compares the electric machine reactive power target value and outputs a voltage increase / decrease signal to the automatic voltage regulator when there is a difference in the comparison result, and the generator voltage detected by the voltage conversion means, A voltage comparison unit that checks whether or not the generator is within the operating range, and outputs the tap increase / decrease signal of the tap switching means to the main transformer if the generator is out of the operating range. is there.

  According to the present invention, the generator reactive power control and the voltage of the power plant that automatically changes the tap switching of the main transformer so that the fluctuation of the generator reactive power due to the system voltage fluctuation can be controlled in the generator voltage fluctuation range. A control device can be obtained.

It is a block diagram explaining the generator reactive power constant control in the voltage control apparatus of the power plant by Embodiment 1 of this invention. It is an operation | movement flowchart of the generator reactive power constant control in the voltage control apparatus of the power plant by Embodiment 1 of this invention, and the tap cooperative control of the main transformer. It is a block diagram explaining the generator power factor fixed control in the voltage control apparatus of the power plant by Embodiment 2 of this invention. It is an operation | movement flowchart of the generator power factor fixed control in the voltage control apparatus of the power plant by Embodiment 2 of this invention, and the tap cooperative control of the main transformer. It is a block diagram of the power transmission end reactive power constant control in the voltage control apparatus of the power plant by Embodiment 3 of this invention. It is an operation | movement flowchart of the power transmission end reactive power fixed control in the voltage control apparatus of the power plant by Embodiment 3 of this invention, and tap cooperative control of the main transformer. It is a block diagram of the power transmission terminal power factor constant control in the voltage control apparatus of the power plant by Embodiment 4 of this invention. It is an operation | movement flowchart of the power transmission terminal power factor fixed control in the voltage control apparatus of the power plant by Embodiment 4 of this invention, and the tap cooperative control of a main transformer.

  Preferred embodiments of a voltage control apparatus for a power plant according to the present invention will be described below with reference to the accompanying drawings. It should be noted that the present invention is not limited to this embodiment, and includes various design changes.

Embodiment 1 FIG.
1 is a configuration diagram illustrating constant generator reactive power control and cooperative tap control of a main transformer in a power plant voltage control apparatus according to Embodiment 1 of the present invention.
FIG. 1 shows that in a main circuit configuration in which a generator 1 to be controlled is linked to a power system via a main transformer 3 having a tap switching means 2 that boosts the system voltage of the power system. An operation mode in which a target value is set and the generator reactive power is controlled to a predetermined target value will be described.

  The generator voltage generated by the generator is detected by a transformer (hereinafter referred to as VT) 4 that transforms the generator voltage to a low voltage level, and the detected generator voltage is passed through a voltage converter 5 as voltage conversion means. To the control device (hereinafter referred to as sequencer) 6. The generator current is detected by a current transformer (hereinafter referred to as CT) 7 that transforms the generator current to a 5A level. The generator voltage detected by VT4 and the generator current detected by CT7 are input to the reactive power converter 8 which is power conversion means, and the generator reactive power is detected. The generator reactive power detected by the reactive power converter 8 is converted into a sequencer input signal level and input to the sequencer 6.

  The sequencer 6 includes a difference between the MW / VAR reading unit 6a that reads the generator reactive power output from the reactive power converter 8 and the generator reactive power and the reactive power target value read by the MW / VAR reading unit 6a. Check whether the generator voltage input from the reactive power comparison unit (hereinafter referred to as VAR control unit) 6b and the voltage converter 5 is within the generator operating range (± 5% of the rated voltage). The voltage comparison part 6c which has the function to perform is provided.

  The output of the VAR control unit 6b of the sequencer 6 is input to the automatic voltage adjustment device 10 as a voltage increase / decrease signal via the control circuit 9, and the generator voltage output from the voltage comparison unit 6c of the sequencer 6 is the generator operation. The confirmation signal as to whether or not it is within the range is input to the tap switching means 2 of the main transformer 3 by the main transformer tap increase / decrease signal output circuit 11.

The power plant voltage control apparatus according to the first embodiment is configured as described above. Next, the operation thereof will be described.
FIG. 2 is an operation flowchart of the generator reactive power constant control and the tap cooperative control of the main transformer 3. In FIG. 2, first, the generator reactive power target value Gsv is set in the VAR control unit 6b of the sequencer 6 (step S10). When changing the generator reactive power target value Gsw, the target value is changed and set (step S11).

  Next, in the MW / VAR reading unit 6a of the sequencer 6, the reactive power converter 8 detects the generator reactive power Gmw detected by the generator voltage from VT4 and the generator current from CT7, and the generator voltage Vg from VT4. Is read (step S12).

  Next, the VAR control unit 6b of the sequencer 6 compares the generator reactive power Gmw read by the MW / VAR reading unit 6a with the generator reactive power target value Gsw (step S13), and the generator reactive power Gmw is If it is larger than the generator reactive power target value Gsw, it is necessary to lower the generator reactive power Gmw, so a generator voltage lowering command is output to the automatic voltage regulator 10 (step S14).

  When the generator reactive power Gmw is smaller than the generator reactive power target value Gsw (step S15), it is necessary to increase the generator reactive power Gmw. Output (step S16).

  And control of said step S13-step S16 is continued until generator reactive power Gmw becomes equal to generator reactive power target value Gsw (step S17).

  The reactive power control is generator voltage control and needs to be executed within the generator voltage operation range. Therefore, if the generator voltage is outside the operation range, the automatic voltage regulator 10 is outside the control range, and the reactive power constant control cannot be continued. For this reason, in parallel with the reactive power control, in order to prevent the reactive power constant control due to the fluctuation of the system voltage from being restricted, the main transformer 3 is controlled so that the generator voltage is within the generator operating range. Tap control is controlled in parallel.

  Next, this tap switching control will be described. In step S12, the generator reactive power Gmw and the generator voltage Vg are read by the MW / VAR reading unit 6a of the sequencer 6, and then the generator voltage Vg and the generator voltage upper limit value (rated voltage Vgr + 5%) are compared. (Step S18) When the generator voltage Vg is higher than the generator voltage upper limit value, it is necessary to lower the generator voltage Vg, so that a tap voltage increase command is output to the tap switching means 2 of the main transformer 3. (Step S19).

  When the generator voltage Vg is lower than the generator voltage lower limit (rated voltage Vgr−5%) (step S20), it is necessary to increase the generator voltage Vg, so that the tap switching means 2 of the main transformer 3 is used. In response, a tap voltage lowering command is output (step S21).

  The tap voltage control in steps S18 to S21 is continued until the generator voltage Vg is within ± 5% of the generator rated voltage Vgr (step S22).

  As described above, since the voltage control device for the power plant according to the first embodiment simultaneously controls the generator reactive power and the tap voltage of the main transformer 3, the restriction of the constant reactive power control with respect to the system voltage fluctuation can be lifted and requested. It is possible to automatically perform tap selection of the generator reactive power output and the appropriate main transformer 3. Therefore, the complicated operation that the operator has dealt with can be simplified, and the power plant can be operated with high accuracy.

Embodiment 2. FIG.
Next, a power plant voltage control apparatus according to Embodiment 2 will be described. In the first embodiment, the case where the generator reactive power constant control and the tap cooperative control of the main transformer are implemented has been described, but the embodiment 2 performs the generator power factor constant control and the main transformer tap cooperative control. To implement.

FIG. 3 is a block diagram illustrating generator power factor constant control and main transformer tap cooperative control in the power plant voltage control apparatus according to Embodiment 2 of the present invention. In the second embodiment, as shown in FIG. 3, the power converter 30 which is the second power conversion means for obtaining the generator active power from the generator current detected by the CT 7 is the invalidity in which the first power conversion means is used. The MW / VAR reading unit 6a of the sequencer 6 provided with the power converter 8 reads the generator reactive power output from the reactive power converter 8 and the generator active power output from the power converter 30. It is configured to read.

  The sequencer 6 includes a power factor control unit 6d that detects the generator power factor based on the generator reactive power and the generator active power read by the MW / VAR reading unit 6a. The VAR control unit 6b according to the first embodiment. It is provided on behalf of. In addition, about another structure, it is the same as that of Embodiment 1, or is equivalent, The description is abbreviate | omitted by attaching | subjecting the same code | symbol.

The power plant voltage control apparatus according to the second embodiment is configured as described above. Next, the operation thereof will be described.
FIG. 4 is an operation flowchart of the generator power factor constant control and the tap cooperative control of the main transformer 3. In FIG. 4, first, the generator power factor target value Gsf is set in the power factor controller 6d of the sequencer 6 (step S30). When changing the generator power factor target value Gsf, the target value is changed and set (step S31).

  Next, the power factor control unit 6d obtains the generator active power Gw, the generator reactive power Gmw, and the generator voltage Vg read by the MW / VAR reading unit 6a (step S32), and the generator operating power factor. Gpf is calculated (step S33).

  Next, the generator operating power factor Gpf calculated in step S33 is compared with the generator power factor target value Gsf (step S34). If the generator operating power factor Gpf is larger than the generator power factor target value Gsf, Since it is necessary to lower the machine voltage Vg, a generator voltage lowering command is output to the automatic voltage regulator 10 (step S35).

  When the generator operating power factor Gpf is smaller than the generator power factor target value Gsf (step S36), it is necessary to increase the generator voltage Vg. Output (step S37).

  And control of said step S34-step S37 is continued until generator operating power factor Gpf becomes equal to generator power factor target value Gsf (step S38).

  Note that the step of performing parallel control of tap switching of the main transformer 3 so that the generator voltage Vg is within the generator operating range is the same as that described in the first embodiment, and the same step number is assigned. Therefore, the description is omitted.

  As described above, the voltage control device for the power plant according to the second embodiment allows the MW / VAR reading unit 6a of the sequencer 6 to have the function of reading the generator active power Gw output from the power converter 30, and By performing the driving power factor calculation in the rate control unit 6d, the generator power factor constant control and the main variable tap control are simultaneously controlled, so that the required generator power factor constant operation and the appropriate tap selection of the main transformer 3 are selected. Can be performed automatically. Therefore, the complicated operation that the operator has dealt with can be simplified, and the power plant can be operated with high accuracy.

Embodiment 3 FIG.
Next, a power plant voltage control apparatus according to Embodiment 3 will be described. In the first embodiment, the case where the generator reactive power constant control and the tap cooperative control of the main transformer are performed has been described, but the third embodiment measures the generator reactive power at the high-voltage power transmission end of the main transformer. The measurement point is changed so that it can be done.

FIG. 5 is a configuration diagram illustrating constant power transmission reactive power constant control and main transformer tap cooperative control in the power plant voltage control apparatus according to the third embodiment. In the third embodiment, as shown in FIG. 5, the CT7 for converting the generator current to the 5A level is provided at the high-voltage side power transmission end of the main transformer 3, and the second method for transforming the generator voltage to the low voltage level. VT50 is provided. The generator voltage detected by the second VT 50 and the generator current detected by CT7 are input to the reactive power converter 8 to detect the generator reactive power. The generator reactive power detected by the reactive power converter 8 is converted into a sequencer input signal level and input to the sequencer 6. In other words, the generator reactive power can be measured at the high-voltage side power transmission end of the main transformer 3. In addition, about another structure, it is the same as that of Embodiment 1, or is equivalent, The description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  The power plant voltage control apparatus according to the third embodiment is configured as described above, and the power transmission end reactive power constant control and the main transformer tap cooperative control are configured such that the generator reactive power is transmitted to the high-voltage side power transmission of the main transformer 3. The only difference is that the measurement is performed at the end, which is the same as in the first embodiment as shown in the operation flowchart of FIG. In the flowchart of FIG. 6, the generator reactive power target value at the transmission end is displayed as GTsw, and the generator reactive power at the transmission end is displayed as GTmw.

  As described above, the power plant voltage control apparatus according to the third embodiment can automatically perform the required power transmission end reactive power constant control and appropriate tap selection of the main transformer 3 with respect to the system voltage fluctuation. . Therefore, the complicated operation that the operator has dealt with can be simplified, and the power plant can be operated with high accuracy.

Embodiment 4 FIG.
Next, a power plant voltage control apparatus according to Embodiment 4 will be described. In the second embodiment, the case where the generator power factor constant control and the main transformer tap cooperative control are performed has been described. However, the fourth embodiment measures the power factor of the high-voltage power transmission end of the main transformer. Thus, the measurement points are changed so that the power and reactive power at the power transmission end can be measured.

  FIG. 7 is a configuration diagram for explaining power transmission end power factor constant control and main transformer tap cooperative control in the power plant voltage control apparatus according to the fourth embodiment. In the fourth embodiment, as shown in FIG. 7, the CT7 for converting the generator current to the 5A level is provided at the high-voltage side power transmission end of the main transformer 3 and the second method for transforming the generator voltage to the low-voltage level. VT50 is provided. Further, a power converter 30 that obtains a generator active power from the generator voltage detected by the second VT 50 and the generator current detected by CT7 is provided together with the reactive power converter 8 that obtains a generator reactive power. The MW / VAR reading unit 6 a of the sequencer 6 reads the generator reactive power output from the reactive power converter 8 and also reads the generator active power output from the power converter 30. Yes. In other words, the generator active power and reactive power can be measured at the high voltage side power transmission end of the main transformer 3. In addition, about another structure, it is the same as that of Embodiment 2, or is equivalent, and description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  The power plant voltage control apparatus according to the fourth embodiment is configured as described above, and the power transmission constant power factor control is performed by using the generator active power and the generator reactive power at the high voltage side power transmission end of the main transformer 3. The measurement is only different from the second embodiment, and the control is performed in the same manner as the second embodiment as shown in the operation flowchart of FIG. In the flowchart of FIG. 8, the generator reactive power target value at the transmission end is represented by GTsw, the generator reactive power at the transmission end is represented by GTmw, the generator active power at the transmission end is represented by GTw, and the generator power factor target value is represented by GTsf and the generator operating power factor are displayed as GTpf.

  As described above, the power plant voltage control apparatus according to the fourth embodiment can automatically perform the requested constant operation of the power transmission / reception power factor and the appropriate tap selection of the main transformer 3 with respect to the system voltage fluctuation. Become. Therefore, the complicated operation that the operator has dealt with can be simplified, and the power plant can be operated with high accuracy.

  In each of the above embodiments, for convenience of explanation, an example in which the VAR control unit 6b and the power factor control unit 6d are separately provided in the sequencer 6 is illustrated and described. However, in the implementation, the VAR control unit 6b And the power factor control unit 6d are provided in the sequencer 6.

DESCRIPTION OF SYMBOLS 1 Generator 2 Tap switching means 3 Main transformer 4 Transformer (VT)
5 Voltage Converter 6 Sequencer 6a MW / VAR Reading Unit 6b VAR Control Unit 6c Voltage Comparison Unit 6d Power Factor Control Unit 7 Current Transformer (CT)
8 Reactive power converter 9 Control circuit 10 Automatic voltage regulator 11 Main transformer tap increase / decrease signal output circuit 30 Power converter 50 Second transformer (VT)

Claims (4)

A generator whose generator voltage is adjusted by an automatic voltage regulator is linked to a power transmission system via a main transformer having a tap switching means, and the control of the generator voltage and the tap switching control of the tap switching means. A voltage control device for a power plant that performs mutual cooperative control,
Voltage conversion means for transforming and inputting the generator voltage by a transformer;
The power conversion means for inputting the generator voltage by transforming the generator voltage with a transformer, and inputting the generator current by transforming the current with a current transformer, and outputting the generator reactive power with the input generator voltage and generator current. When,
A control device for inputting the reactive power output by the power conversion means and the generator voltage output by the voltage conversion means;
The controller is
The generator reactive power output from the power conversion means is compared with a preset generator reactive power target value, and if a difference occurs in the comparison result, a voltage increase / decrease signal is output to the automatic voltage regulator. Reactive power comparator,
It is confirmed whether or not the generator voltage detected by the voltage conversion means is within the operating range of the generator. If the generator voltage is outside the operating range, the tap increase / decrease signal of the tap switching means is sent to the main transformer. A voltage control device for a power plant, comprising: a voltage comparison unit for outputting. A generator whose generator voltage is adjusted by an automatic voltage regulator is linked to a power transmission system via a main transformer having a tap switching means, and the control of the generator voltage and the tap switching control of the tap switching means. A voltage control device for a power plant that performs mutual cooperative control,
Voltage conversion means for transforming and inputting the generator voltage by a transformer;
The generator voltage is transformed and inputted by a transformer, the generator current is transformed and inputted by a current transformer, and the generator reactive power is outputted by the inputted generator voltage and the generator current. Power conversion means;
A second power conversion means for inputting the generator current by a current transformer and outputting the generator active power;
A controller for inputting the generator voltage output from the voltage converter, the generator reactive power output from the first power converter, and the generator active power output from the second power converter; And
The controller is
A generator power factor calculated from the generator reactive power output from the first power converter and the generator active power output from the second power converter, and a preset power factor target value set in advance. A power factor control unit that outputs a voltage increase / decrease signal to the automatic voltage regulator when the comparison results in a difference, and
It is confirmed whether or not the generator voltage output from the voltage converting means is within the operating range of the generator. If the generator voltage is outside the operating range, the tap increase / decrease signal of the tap switching means is sent to the main transformer. And a voltage comparison unit for outputting to the power plant. A generator whose generator voltage is adjusted by an automatic voltage regulator is linked to a power transmission system via a main transformer having a tap switching means, and the control of the generator voltage and the tap switching control of the tap switching means. A voltage control device for a power plant that performs mutual cooperative control,
Voltage conversion means for transforming and inputting the generator voltage by a first transformer;
At the high-voltage side power transmission end of the main transformer, the generator voltage is transformed and inputted by a second transformer, and at the high-voltage side power transmission end of the main transformer, the generator current is transformed and inputted by a current transformer. And
Power conversion means for outputting the generator reactive power by the input generator voltage and generator current;
A control device for inputting the generator reactive power output by the power conversion means and the generator voltage output by the voltage conversion means,
The controller is
The generator reactive power output from the power conversion means is compared with a preset generator reactive power target value, and if a difference occurs in the comparison result, a voltage increase / decrease signal is output to the automatic voltage regulator. Reactive power comparator,
It is confirmed whether or not the generator voltage output from the voltage converting means is within the operating range of the generator. If the generator voltage is outside the operating range, the tap increase / decrease signal of the tap switching means is sent to the main transformer. A voltage control device for a power plant, comprising: a voltage comparison unit for outputting. A generator whose generator voltage is adjusted by an automatic voltage regulator is linked to a power transmission system via a main transformer having a tap switching means, and the control of the generator voltage and the tap switching control of the tap switching means. A voltage control device for a power plant that performs mutual cooperative control,
Voltage conversion means for transforming and inputting the generator voltage by a first transformer;
The generator voltage is transformed and inputted by a second transformer at the high-voltage power transmission end of the main transformer, and the generator current is transformed and detected by a current transformer at the high-voltage power transmission end of the main transformer. And first power conversion means for outputting a generator reactive power based on the input generator voltage and generator current,
A second power conversion means for inputting the generator current by a current transformer and outputting the generator active power;
A controller for inputting the generator voltage output from the voltage converter, the generator reactive power output from the first power converter, and the generator active power output from the second power converter; And
The controller is
The generator power factor calculated from the generator reactive power output from the first power converter and the active power output from the second power converter is compared with a preset power factor target value set in advance. A power factor control unit that outputs a voltage increase / decrease signal to the automatic voltage regulator when a difference occurs in the comparison result;
It is confirmed whether or not the generator voltage output from the voltage converting means is within the operating range of the generator. If the generator voltage is outside the operating range, the tap increase / decrease signal of the tap switching means is sent to the main transformer. And a voltage comparator for outputting to the power plant.

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