JPH11178397A - Controller for generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent overvoltage of a transmission line by detecting single operation of a generator accurately. SOLUTION: A power plant 1 is provided with a voltage transformer 21 as the exciter for a generator motor 41, a current transformer 22, an automatic voltage regulator 23, an excitation thyristor 24, and a phase switching disconnector 44 for operating the generator motor 41 as a generator or a motor. A controller for generator comprises a single operation detector 43 connected with the high voltage side of a main transformer 13 via a voltage transformer 15 and a current transformer 16 and detecting the valid power (or effective current) and reactive invalid (or reactive current) of the generator motor 41, and an operation limiter 42 for altering the limit line of the operating range of the generator motor 41 by acting on the automatic voltage regulator 23 with a single operation detection signal from the detector 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a generator for detecting the isolated operation of a power plant and for safely operating a generator (including a generator motor), a main transformer connected to the generator, and equipment of a power system. It relates to a control device.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram of an apparatus for detecting an isolated operation of a synchronous generator disclosed in Japanese Patent Publication No. 4-68874. In this figure, a synchronous generator 11 of a power plant 1 is connected to a main transformer 13 via a circuit breaker 12 for parallel connection, and further connected to a transmission line 2 leading to a power system via a high voltage side circuit breaker 14. . In the power plant 1, an instrumentation transformer 21, an instrumentation current transformer 22, an automatic voltage regulator 23,
A thyristor 24 for excitation is provided, and a reactive power regulator 25 for outputting a command for generating a reactive power of a fixed value or more from the synchronous generator 11 to the automatic voltage regulator 23.
Is added. A reactive power relay (or current relay) 26 that is connected to the high voltage side of the main transformer 13 via the instrument transformer 15 and the instrument current transformer 16 and detects reactive power is provided.

In this configuration, the breaker 12 for parallel connection and the high-voltage side breaker 14 enter, and the synchronous generator 11
During parallel operation with a power system (not shown) via the other end circuit breaker 31, the reactive power regulator 25 is activated, and the excitation of the synchronous generator 11 is controlled by the automatic voltage regulator 23, so that the synchronous generator 11 Reactive power exceeding a certain value is generated.

In this state, when the other end circuit breaker 31 of the other end electric station 3 is cut off, the high voltage side reactive power of the main transformer 13 becomes substantially zero. By detecting this by the reactive power relay (or current relay) 26, the reactive power (or reactive current) becomes zero even though the isolated operation detection circuit (the synchronous generator 11 is in parallel with the system). ), An independent operation signal is output from the circuit, and control such as damping switching of a governor (not shown) is performed by this signal.

[0005]

However, in the above-mentioned conventional method, the reactive power becomes substantially zero when the opposite electric station 3 is short in distance or when the high-voltage side circuit breaker 14 of the power plant 1 is cut off. Detection is possible, but when the power station and the power station are connected by the overhead power transmission line 2 and the power station and the power station are connected to each other as in the case of a hydroelectric power station, the power station and the power station are disconnected at the power station 3 When the power supply 31 is shut off, the synchronous generator 11 supplies a leading current to the overhead power transmission line 2 due to the capacitance between the overhead power transmission line 2 and the ground, so that the ground potential of the overhead transmission line 2 increases. become. Synchronous generator 11 has automatic voltage regulator 23
In order to maintain the terminal voltage of the generator 11 at a constant value, the operation is further performed in the advanced phase region. However, generally, although not described in the related art, the automatic voltage regulator 23 is provided with an operation range limiting device for stable operation of the synchronous generator 11, and the phase advance operation of the generator is performed. On the other hand, an underexcitation limiting function is provided to limit the decrease in the exciting current so that the exciting current is reduced and the synchronous operation with the power system is not deviated.

Therefore, in the conventional system, the synchronous generator 11 is operated in the early-phase region, so that the reactive power does not become substantially zero and it is impossible to detect the isolated operation. Since the synchronous generator 11 cannot be operated in a sufficient phase advance region due to the underexcitation limiting function of the 23 operation range limiting device, the ground potential of the overhead transmission line cannot be suppressed, resulting in an overvoltage and power supply for the transmission line. There was concern that equipment could be damaged.

FIG. 9 is a view showing the ground potential of the overhead transmission line 2 when the charging current is supplied to the overhead transmission line 2 by the synchronous generator 11 in the isolated operation. If the operating point of the synchronous generator 11 does not sufficiently enter the phase advance region due to the function of the underexcitation limiting function of the operation limiting device 27, the terminal voltage of the synchronous generator 11 cannot be reduced to a constant value. As shown by the dashed line, the ground potential of the overhead transmission line rises.

According to the present invention, when such a generator enters an operation in the early-phase operation region, the operation state is accurately detected to prevent overvoltage of the transmission line and allow the generator to operate independently. It is intended to supply equipment.

[0009]

That is, the invention according to claim 1 is an invention of a power plant in which a generator is connected to a main transformer via a parallel circuit breaker and further connected to a power system via a high voltage side circuit breaker. In the generator control device for controlling the generator, an isolated operation detection device that detects the isolated operation of the generator based on the output of the generator, and an operation limiting device that limits the operation range of the generator, An operation limiter that changes the limit line of the operation range according to an isolated operation detection signal from the operation detector, and an excitation that detects the terminal voltage of the generator and controls the voltage of the generator within the operation range limited by the operation limiter. And an apparatus.

According to the first aspect of the present invention, since the terminal voltage of the generator is not limited, the power equipment of the transmission line is not exposed to an abnormal voltage due to a charging current flowing into the overhead transmission line.

According to a second aspect of the present invention, in the generator control device according to the first aspect, the isolated operation detecting device generates power by causing the active power of the generator to rapidly change to zero and the reactive power to rapidly increase to the early phase region. Detecting the isolated operation of the machine.

According to a third aspect of the present invention, in the generator control device according to the first aspect, the isolated operation detecting device is such that the active current of the generator suddenly changes to zero and the reactive current suddenly changes from the late region to the early region. Thus, the isolated operation of the generator is detected.

According to a fourth aspect of the present invention, the operation limiting device includes:
An underexcitation limit line that limits the operation range of the early phase region of the generator's performance curve based on the isolated operation detection signal from the isolated operation detection device is excluded.

According to a fifth aspect of the present invention, the operation limiting device includes:
It is characterized in that the underexcitation limit line for limiting the operation range of the early phase region of the generator's performance curve is changed in the direction to enlarge in accordance with the isolated operation detection signal from the isolated operation detection device.

According to the fourth and fifth aspects of the present invention, even when the generator changes from the slow operation region of the steady operation to the early operation region in the single operation when the generator is in the independent operation, the operating point is maintained. Since there is no limitation, an increase in the ground potential of the power system can be suppressed.

According to a sixth aspect of the present invention, there is provided a generator control for connecting a generator to a main transformer via a parallel circuit breaker and controlling a generator of a power plant connected to a power system via a high voltage side circuit breaker. In the device, an operation limiting device that limits an operation range of the excitation device, an excitation device that detects a terminal voltage of the generator and controls a voltage of the generator within an operation range limited by the operation restriction device, and an output of the generator And a control circuit that shuts off the high-voltage circuit breaker of the power plant based on the isolated operation detection signal from the isolated operation detection device. It is characterized by.

According to a seventh aspect of the present invention, there is provided an apparatus for controlling a generator of a power plant, wherein the generator is connected to a main transformer via a parallel circuit breaker and further connected to a power system via a high voltage side circuit breaker. An operation limiting device that limits the operating range of the generator, an exciter that detects a terminal voltage of the generator and controls the voltage of the generator within an operating range limited by the operating limiting device, and an output of the generator. And a control circuit for shutting off the parallel-circuit breaker based on the isolated operation detection signal from the isolated operation detection device.

According to the sixth and seventh aspects of the present invention, the generator shifts to the terminal voltage constant operation and enters the standby operation (no-load excitation operation) state. Therefore, since the overhead power transmission line is disconnected from the power supply, it is not exposed to an abnormal voltage.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. The same parts as those in the conventional example are denoted by the same reference numerals, and duplicate description will be omitted.

FIG. 1 shows a generator motor control device according to a first embodiment of the present invention. Compared with the conventional configuration shown in FIG. 8, the generator 11 has a generator motor 41 and a reactive power regulator. 25 is replaced by an operation limiting device 42 that limits the operating range of the generator motor 41 that is voltage-controlled by the automatic voltage regulator 23, and the reactive power relay (or current relay) 26 detects the occurrence of isolated operation and restricts operation. Device 4
2 is converted to the islanding operation detection device 43 that notifies the second operation.

Normally, the (hydraulic) power plant 1 is provided with an instrument transformer 21, an instrument current transformer 22, an automatic voltage regulator 23, and an exciting thyristor 24 as an exciting device of the generator motor 41. In addition, a phase switching disconnector 44 is provided to set the generator motor 41 in the generator operation or the motor operation. In the present embodiment, in addition to these, an operation limiting device 42 of the generator motor 41 acting on the automatic voltage regulator 23 is installed, and an isolated operation detection device 43 provided at an output end of the generator motor 41, That is, the main transformer 13 is connected via the instrument transformer 15 and the instrument current transformer 16.
And an isolated operation detection device 43 that detects the active power (or active current) and the reactive power (or reactive current) of the generator motor 41 is installed.

Next, the operation of the present embodiment will be described. The generator motor 41 and the power system (not shown) in which the parallel circuit breaker 12 and the high-voltage circuit breaker 14 enter are operated in parallel via the overhead transmission line 2. In this state, when the other end circuit breaker 31 of the other end power station 3 is cut off, the generator motor 41 is operated independently of the power system, but the isolated operation detection device 43 is provided.
Detects islanding based on the active power (or active current) and reactive power (or reactive current) of the generator motor 41. When the islanding detection device 43 detects islanding,
The operation limiting device 42 of the generator motor 41 receives the isolated operation detection signal from the isolated operation detection device 43 and
Voltage regulator 2 of the exciter to change the operating range of
3 is controlled.

Further, when the generator motor 41 is operating in the generator mode, control such as damping switching of a governor (not shown) is performed based on the isolated operation detection signal from the isolated operation detection device 43. When the generator motor 41 is operating in the motor mode, the supply of electric power required for the motor operation from the power system is cut off, and the stop of the generator motor 41 is controlled by a protection device (not shown).

Next, an islanding detection method of the islanding detection device 43 will be described with reference to FIGS.

FIG. 2 shows the transition of the operating point of the generator motor 41 with the active power P and the reactive power Q. The generator motor 41 operating in parallel with the power system converts rotational energy from a water turbine (not shown) into active power P1 and supplies the power to the power system. In addition, a reactive power Q1 delayed at the request of the power system (to compensate for a decrease in system voltage due to an inductive load such as an electric motor) is supplied.

When the power system and the generator motor 41 are operating in parallel, and the counter circuit breaker 31 of the counter power station 3 is cut off, when the distance of the overhead transmission line 2 is long, the power is generated to the ground capacitance. Active power P1 to supply charging current from the
Suddenly changes to zero (0), the reactive power Q1 suddenly increases to the leading phase region, and Q
It becomes 2.

Therefore, the islanding operation detecting device 43 can detect the islanding operation of the generator motor 41 by detecting the shift of the active power to zero and the shift of the reactive power to the phase advance region.

FIG. 3 shows the transition of the operating point of the generator motor 41 by the active current Ip and the reactive current Iq. The generator motor 41 operating in parallel with the power system converts rotational energy from a water turbine (not shown) into an effective current (a component having the same phase as the terminal voltage of the synchronous generator) Ip1 and supplies the current to the power system. In addition, at the request of the power system (to compensate for a decrease in the system voltage due to an inductive load such as a motor), a delayed reactive current (a component delayed by 90 ° from the terminal voltage of the synchronous generator) Iq1
Has been supplied.

When the counterpart circuit breaker 31 of the counterpart power station 3 is cut off while the power system and the generator motor 41 are operating in parallel, when the distance of the overhead transmission line 2 is long, the power is generated to the ground capacitance. Since the charging current is supplied from the machine, the effective current Ip1
Suddenly changes to zero (0), the delayed reactive current Iq1 advances, and becomes a reactive current (a component advanced 90 ° from the terminal voltage of the synchronous generator) Iq2.

Therefore, the islanding operation detecting device 43 can detect the islanding operation of the generator motor 41 by detecting the shift of the active current to zero and the shift of the delayed reactive current to the advanced reactive current.

Next, a method for changing the operation range of the generator motor 41 by the operation limiting device 42 based on the isolated operation detection signal from the isolated operation detection device 43 will be described with reference to FIGS.

FIG. 4 shows an example of changing the operation range of the generator motor 41 by the operation restricting device 42 when the operation is shifted from the parallel operation (a) to the single operation (b). During parallel operation, as shown in FIG. 4A, the operation limiting device 42 includes an overexcitation limiting function 42a that limits the upper limit side (field overcurrent of the generator motor) of the generator's performance curve. Underexcitation limiting function 42c for limiting the lower limit of the performance curve (field undercurrent of the generator motor)
In addition, the operation of the exciter is controlled by an operation limiting function of an overcurrent limiting function 42b for limiting the excess of the effective current on the exciter side in the performance curve.

When the islanding operation detecting device 43 detects the islanding operation of the generator motor 41, the islanding operation detection signal from the islanding operation detecting device 43 is transmitted to the operation limiting device 42. As shown in FIG. 4B, the operation limiting device 42 invalidates the underexcitation limiting function 42c in the operation limiting function of the generator motor 41 while the isolated operation detection signal continues.

At the time of the transition from the parallel operation to the isolated operation, the potential rises to charge the ground capacitance of the transmission line 2,
Since the terminal voltage of the generator motor 41 is controlled to be a constant value by the automatic voltage regulator 23 from which the underexcitation restriction has been released, the operating point of the generator motor 41 is advanced from the state of reactive power supply with a delay in normal operation and invalid. The state shifts to a state in which power is supplied, and an increase in the ground potential at the power receiving end of the transmission line 2 can be suppressed.

FIG. 5 shows another example of changing the operation range of the generator motor 41 by the operation restricting device 42 when the operation is shifted from the parallel operation (a) to the independent operation (b). During the parallel operation of the generator motor 41 and the power system, the operation limiting device 42, as shown in FIG. 5A, controls the overexcitation limiting function 42a that limits the upper limit side of the generator's performance curve. The operation of the exciting device is controlled by an underexcitation limiting function 42c for limiting the lower limit and an overcurrent limiting function 42b for limiting the excess of the effective current in the performance curve on the exciting device side.

When the islanding operation detecting device 43 detects the islanding operation of the generator motor 41, the islanding operation detecting signal from the islanding operation detecting device 43 is transmitted to the operation limiting device 42. While the isolated operation detection signal continues, the operation restriction device 42 changes the restriction line of the underexcitation restriction function 42c to a direction in which the restriction line expands to the early phase operation region as shown in FIG. As a result, the potential increases to charge the ground capacitance of the overhead power transmission line 2 during the transition from the parallel operation to the isolated operation, but the terminal voltage of the generator motor 41 is reduced by the automatic voltage adjustment in which the underexcitation limit is relaxed. The operating point of the generator motor 41 is advanced from the state of the reactive power supply with a delay in the normal operation to the state of supplying the reactive power, and the operating point of the power receiving end of the overhead transmission line 2 is controlled. The rise of the ground potential can be suppressed.

Although the generator operation of the generator motor has been described with reference to FIGS. 2 to 5, the same applies to the motor operation of the generator motor, except that the operating point of the generator motor in the steady state is reversed left and right. It is.

As described above, according to the present embodiment,
By eliminating the underexcitation limiting function 42c of the operation limiting device 42 or expanding the underexcitation limiting line to a more advanced phase region, the reactive power is not restricted by the exciter, so that the terminal voltage of the generator motor 41 is kept at a constant value. Thus, it is possible to suppress an increase in the ground voltage of the overhead power transmission line 2, and to prevent damage to power equipment of the overhead power transmission line 2.

FIG. 6 shows a generator motor control device according to a second embodiment of the present invention. Compared with the first embodiment shown in FIG. Instead of changing the operation restriction function of the operation restriction device 42 by a signal, a plant control device 51 that shuts off the high-pressure side circuit breaker 14 by an isolated operation detection signal of the isolated operation detection device 43 is provided.

Normally, the (hydraulic) power plant 1 has a generator motor 4
As the excitation device 1, an instrumentation transformer 21 and an instrumentation current transformer 2
2. An automatic voltage regulator 23 and an excitation thyristor 24 are provided. In addition, a phase switching disconnector 44 is provided to set the generator motor 41 in the generator operation or the motor operation. In the present embodiment, in addition to these, the operation limiting device 42 acting on the automatic voltage regulator 23 is provided, while the isolated operation detection device 43 provided at the output end of the generator motor, that is, the instrument transformer 15 , Instrument current transformer 1
6 is connected to the high-voltage side of the main transformer 13 via an independent operation detection device 43 for detecting the active power (or active current) and the reactive power (or reactive current) of the generator motor 41. A plant control device 51 that opens the high-pressure circuit breaker 14 in response to an isolated operation detection signal from the device 43 is provided.

Next, the operation of the present embodiment operates. The generator motor 41 in which the parallel-circuit breaker 12 and the high-voltage
And a power system (not shown) are operated in parallel via the overhead transmission line 2. In this state, when the other end circuit breaker 31 of the other end power station 3 shuts off, the generator motor 41 is operated in an isolated state separated from the electric power system. Based on the current and the reactive power (or the reactive current), the isolated operation is detected in the same manner as in the first embodiment. Plant control device 51
Performs opening control of the high-voltage side circuit breaker 14 of the main transformer 13 in accordance with the isolated operation detection signal from the isolated operation detection device 43. Further, the isolated operation detection signal is used for switching the control gain of the governor control device (not shown), and changes the load gain to the no-load gain.

Thus, when the generator motor 41 is in the generator operation, the operation shifts to the terminal voltage constant operation of the generator motor, the generator motor 41 continues to operate in the standby operation (no-load excitation operation), and the overhead transmission line 2 Since the power supply is disconnected from the power supply, the power potential of the transmission line is not exposed to abnormal overvoltage because the ground potential does not rise.

When the generator motor 41 operates in the motor mode, power is not supplied from the power system for the motor operation, so that the protective relay stops the operation. However, the overhead transmission line 2 is disconnected from the power source as in the generator operation. Since the power is released, the power potential of the transmission line is not exposed to abnormal overvoltage because the ground potential does not rise.

FIG. 7 shows a generator motor control device according to a third embodiment of the present invention. Compared with the second embodiment shown in FIG. 6, the plant control device 51 'detects an isolated operation. The circuit breaker 12 for parallel
Output an open signal to shut off.

Next, the operation of the present embodiment operates. The generator motor 41 in which the parallel-circuit breaker 12 and the high-voltage
And a power system (not shown) are operated in parallel via the overhead transmission line 2. In this state, when the other end circuit breaker 31 of the other end power station 3 shuts off, the islanding operation detection device 43 detects the islanding operation based on the active power (or active current) and the reactive power (or reactive current) of the generator motor 41. I do. The plant control device 51 ′ responds to the isolated operation detection signal from the isolated operation detection device 43 by using the parallel circuit breaker 1 of the generator motor 41.
2 is performed. Further, the isolated operation detection signal is used for switching the control gain of the governor control device (not shown), and changes the load gain to the no-load gain.

As a result, when the generator motor 41 is in the generator operation, the operation shifts to the terminal voltage constant operation of the generator motor, the generator motor 41 continues to operate in the standby operation (non-load excitation operation), and the main transformer 13 Since the overhead transmission line 2 is disconnected from the power supply, the ground potential does not rise, and the power equipment of the transmission line is not exposed to an abnormal overvoltage.

When the generator motor 41 is in motor operation, power is not supplied from the power system for motor operation, so that the protection relay stops the operation. However, as in the generator operation, the main transformer 13 and the overhead transmission line 2 are stopped. Since the power supply is disconnected from the power supply, the power potential of the transmission line is not exposed to abnormal overvoltage because the ground potential does not rise.

In the above embodiment, a generator motor capable of generator operation and motor operation has been described as an example. However, a generator can be controlled in the same manner.

[0049]

As described above, according to the present invention, when the generator is operated independently during the cooperative operation with the power system,
By accurately detecting this isolated operation and using the generator operation limiting device to change the operating range of the excitation device,
It is possible to suppress an increase in the ground voltage of the overhead power transmission line and prevent a situation in which the main transformer of the power plant and the power equipment of the transmission line are exposed to an abnormal overvoltage.

According to the present invention, in a power plant in which a generator is connected to a main transformer via a parallel circuit breaker and further connected to a power system via a high voltage side circuit breaker, the power generator is connected to the power system. In the event of an islanding operation during the cooperative operation with the power station, the islanding operation is accurately detected, and the overhead power transmission line is cut off by separating the generator and the power system using a parallel circuit breaker or high-voltage circuit breaker. Since the ground potential does not rise, it is possible to prevent a situation in which the main transformer and power equipment of the transmission line are exposed to abnormal overvoltage.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a generator motor control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a change in an operation state of a generator from a parallel operation state to an independent operation state in a relationship between active power and reactive power.

FIG. 3 is a diagram showing a change in an operation state of the generator from a parallel operation state to an independent operation state by an output current state of the generator.

FIG. 4 is a diagram illustrating an example of a change in a generator operation restriction function during a parallel operation (a) and an independent operation (b) of the operation restriction device illustrated in FIG. 1;

FIG. 5 is a diagram showing another example of a change in the generator operation restriction function during the parallel operation (a) and the single operation (b) of the operation restriction device shown in FIG.

FIG. 6 is a block diagram illustrating a generator motor control device according to a second embodiment of the present invention.

FIG. 7 is a block diagram showing a generator motor control device according to a third embodiment of the present invention.

FIG. 8 is a block diagram showing a conventional synchronous generator independent operation detection device.

FIG. 9 is a diagram showing the ground potential of the overhead power transmission line in the unloading operation in which the power plant is operated independently.

[Explanation of symbols]

 1 ... power station 2 ... (overhead) transmission line 3 ... partner electric station 12 ... parallel-circuit breaker 13 ... Main transformer 14 ·············································································· / ····· Current transformer for instrument 23 ········································································ End circuit breaker 41: Generator motor 42: Operation limiting device 43: Single operation detection device 44: Phase switching disconnector 51, 51 '... .... Plant control equipment

Claims (7)

[Claims] An apparatus for controlling a generator of a power plant connected to a main transformer via a parallel circuit breaker and further connected to a power system via a high voltage side circuit breaker, wherein the generator comprises: An islanding operation detecting device that detects an islanding operation of the generator based on the output, and an operation limiting device that limits an operating range of the generator, wherein the operating range is determined by an islanding operation detection signal from the islanding operation detecting device. An operation limiting device that changes the limit line of the generator, and an excitation device that detects a terminal voltage of the generator and controls a voltage of the generator within an operating range limited by the operation limiting device. Generator control device. 2. The isolated operation detecting device detects the isolated operation of the generator by abruptly changing the active power of the generator to zero and rapidly increasing the reactive power to an early phase region. Item 2. The generator control device according to Item 1. 3. The islanding operation detection device detects that the generator's active current suddenly changes to zero, and that the reactive current suddenly changes from a lag region to a leading region, thereby detecting the islanding operation of the generator. The generator control device according to claim 1, characterized in that: 4. The apparatus according to claim 1, wherein the operation limiting device excludes an underexcitation limiting line that limits an operation range in a fast-phase region of a performance curve of the generator based on an isolated operation detection signal from the isolated operation detection device. The generator control device according to claim 1, wherein 5. The operation limiting device changes a setting in a direction to expand an underexcitation limiting line for limiting an operation range of an advance region of a performance curve of the generator according to an isolated operation detection signal from the isolated operation detection device. The generator control device according to claim 1, wherein 6. An apparatus for controlling a generator of a power plant connected to a main transformer via a parallel circuit breaker and further connected to an electric power system via a high voltage side circuit breaker, wherein: An operation limiting device that limits an operation range, an excitation device that detects a terminal voltage of the generator and controls a voltage of the generator within an operation range limited by the operation restriction device, based on an output of the generator. And a control circuit for shutting off the high-voltage circuit breaker of the power plant according to an isolated operation detection signal from the isolated operation detection device. Generator control device. 7. An apparatus for controlling a generator of a power plant connected to a main transformer via a parallel circuit breaker and further connected to a power system via a high voltage side circuit breaker, wherein the generator comprises: An operation limiting device that limits an operation range, an excitation device that detects a terminal voltage of the generator and controls a voltage of the generator within an operation range limited by the operation restriction device, based on an output of the generator. A generator control, comprising: an islanding operation detection device that detects the islanding operation of the generator; and a control circuit that shuts off the parallel breaker based on the islanding operation detection signal from the islanding operation detection device. apparatus.