JPH08242539A - Self-exciting converter controller - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent a shock when switching the converter 2 which is operating in cooperation with the system 5 through the circuit breakers 4A and 4B to the isolated operation by breaking the circuit breaker 4B. [Structure] The power control circuit 2 is formed by closing the circuit breakers 4A and 4B.
0 and the added value 20c of the output of the voltage calculation circuit 11 are used to open the circuit breaker 4B from the state in which the converter 2 is interconnected, and the active / reactive voltage reference circuit 40A. When the operation is switched to the isolated operation through 40B and the voltage control circuit 31, the output 20d of the voltage control circuit 31 is gradually increased from the added value 20c immediately before the switching to reach the effective / reactive voltage command. Minute / reactive voltage reference circuit 40A. 40B
A control device for a self-excited converter characterized by having a soft start function in the.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a self-excited converter which is connected to an AC system to control active power and reactive power.

[0002]

2. Description of the Related Art In recent years, a new energy power converter has been used which uses a storage battery or the like as a DC power supply and converts this DC power into AC power by a self-exciting converter and supplies the AC power to a grid. FIG. 5 shows this power converter.

In FIG. 5, 1 is a DC power source, 2 is a self-exciting converter (hereinafter referred to as a converter) composed of a self-arc-extinguishing type semiconductor device, and 3A is a desired value for the output voltage of the converter 2. Output transformers 3B for stepping down or stepping up are transformers for stepping down or stepping up the voltage of the AC power system 5 to a predetermined value, 4A, 4
B and 4C are circuit breakers to connect the converter 2 to the AC system 5 by closing the circuit breakers 4A and 4B, and to open the circuit breaker 4C to load 50 from either the AC system 5 or the converter 2. It is cut off.

The output current of the converter 2 is detected by the current detector 6, and the system voltage is detected by the voltage detector 7. Further, even if the circuit breaker 4B is open, the signal such as the phase of the system voltage necessary for controlling the converter is detected by the synchronization detecting circuit 9 via the phase detecting transformer 8.

The power calculation circuit 10 receives the output signals (AC signal) of the current detector 6 and the voltage detector 7, and the active power (DC signal) and reactive power (DC signal) output by the converter 2. Is calculated and output.

Although not shown in detail, the power operation circuit 10 converts the three-phase signal (AC signal) from the current detector 6 and the voltage detector 7 into a two-phase signal (AC signal), and further
A circuit having a function of converting a phase signal into a d-axis signal and a q-axis signal (DC signal), and a circuit having such a function is well known, and therefore the details thereof will be omitted here.

Further, the voltage calculation circuit 10, the power control circuit 20 and the like, which will be described later, also have similar functions. In addition, the voltage command calculation circuit 21, which will be described later, outputs the d, q-axis signals (DC signals) to 2
It is provided with a function of converting into a phase signal (AC signal) and further converting a two-phase signal (AC signal) back into a three-phase signal (AC signal).

The active power and the reactive power calculated by the power calculation circuit 10 are respectively supplied to the power control circuit 20.
Compensation voltage command 20a, which is amplified and compared with the active power reactive command and reactive active power command given externally by the active voltage compensating component (DC signal) and reactive voltage corresponding to the voltage drop between the converter 2 and the AC system 5. Compensation (DC signal)].

Switches 30A, 3 which are interlocked with the circuit breaker 4B
0B is (1) when the circuit breaker 4B is closed,
Further, when the circuit breaker 4B is switched to the open circuit state, it becomes the (2) side. Therefore, when the circuit breaker 4B is closed, the effective component voltage (DC signal) and the reactive component voltage (DC signal) of the voltage 20b of the AC system 5 detected by the voltage detector 7 are output from the synchronization detection circuit 9. Voltage calculation circuit 11 based on the phase signal 9a of
Is calculated and output.

When the switch 30A is on the (1) side,
A signal 20C (DC signal) obtained by adding the compensation voltage command 20a and the signal 20b corresponding to the voltage Vs of the AC system 5 by an adder is given to the voltage command calculation circuit 21 as a voltage reference, and further, from the synchronization detection circuit 9 The three-phase AC output voltage command 21a (AC signal) of the converter 2 is output based on the signal synchronized with the voltage of the AC system 5.

In the pulse width modulation control circuit 22, the three-phase AC output voltage command 21a is compared with the carrier wave, and the gate signal of the power semiconductor element forming the converter 2 is output and given to the converter 2. In the converter 2, a voltage is output according to the active power command and the reactive power command externally given by this gate signal, and power is supplied to the AC system 5. In this way, the control system that controls the converter 2 when the switches 30A and 30B are on the (1) side is the first control system.

Next, if the breaker 4B is opened, the converter 2
Is in a state of being disconnected from the AC system 5, and the converter 2 is not in an interconnected operation (power control) but in a CVCF operation with a constant output voltage / output frequency (or described as an independent operation). The constant frequency (for example, 50 Hz) of the CVCF operation is determined by the phase signal 9b having a predetermined frequency, and 9b is a sine wave having a constant frequency. Since this 9b is synchronized with the signal 9a synchronized with the voltage of the AC system 5, the changeover switch 30
Even if A and 30B are switched to the (2) side, the voltage calculation circuit 1
The output 20b of 1 does not change. Changeover switch 30A, 3
In the state where 0B is switched to the (2) side, the converter 2 uses the voltage reference 20d provided from the voltage control circuit 31 for the second reference.
Will be controlled by the control system.

As the voltage command, a valid voltage command and a reactive voltage command are externally given to the voltage control circuit 31.
Further, since the changeover switch 30B is connected to the (2) side, the phase signal 9b having a predetermined frequency is transmitted to the voltage calculation circuit 1
1. Voltage command calculation circuit 21 and pulse modulation control circuit 22
Will be given to.

With respect to the voltage detected by the voltage detector 7, an effective component voltage and a reactive component voltage 20b are calculated by the voltage calculation circuit 11 based on the phase signal 9b. These signals 20b are compared and amplified by the voltage control circuit 31 with an active component voltage command and a reactive component voltage command given from the outside, and a voltage reference 20d.
(Effective voltage reference and reactive voltage reference).

The voltage reference 20d is input to the voltage command calculation circuit 21 through the (2) side of the changeover switch 30A, and in this voltage command calculation circuit 21, the phase signal 9b becomes the three-phase AC output voltage command 21a of the converter 2, It is given to the pulse width modulation control circuit 22. In the pulse width modulation control circuit 22, the three-phase AC output voltage command 21a is compared with the carrier wave, and the gate signal of the power semiconductor element forming the converter 2 is output and given to the converter 2.

In the converter 2, a voltage is output according to the voltage command by the gate signal, and power is supplied to the load 50. As described above, the operation by the first control system in which the circuit breaker 4B is closed and the converter 2 is connected to the AC power system 5 to perform the interconnected operation, and the circuit breaker 4B is opened to connect the converter 2 to the load 50. Then, the operation by the second control system that performs the independent operation can be performed.

[0017]

FIG. 6 is a vector diagram showing a state in which the converter 2 is in power control operation by being connected to the AC system 5 at a forward power factor, where Vs is the system voltage and VI is the converter. 2 is the output voltage of I, I is the output current of the converter 2, Vx is the voltage drop between the converter 2 and the AC system 5, where the inductance drop of the transformer 30A is shown, and the output of the converter 2 during interconnection operation The voltage depends on the driving power factor θ, the current I, the inductance of the transformer 30A, and the like.

The output 20b of the voltage calculation circuit 11 of FIG.
s, the output 20a of the power control circuit 20 corresponds to Vx, and 20c corresponds to VI. When the converter 2 is switched from the state in which it is connected to the system in the state of FIG. 6 to the independent operation, in order to maintain the voltage of the system of P at Vs, the effective component voltage command of the voltage control circuit 31 and A voltage control circuit 3 is supplied with a signal corresponding to Vs as a reactive voltage command.
The output 20d of 1 outputs a signal corresponding to Vs and stands by.

Therefore, the circuit breaker 4B is opened from the power control operation connected to the AC system 5, and the changeover switches 30A and 30B are opened.
Is switched to the (2) side to switch to the independent operation of supplying electric power to the load 50, the output of the converter 2 may be an overcurrent or an overvoltage depending on the interconnected operation state immediately before the switching and the independent operation state immediately after the switching. In other words, there is a problem that the converter 2 is not protected and the CVCF operation for supplying electric power to the load 50 cannot be performed.

Therefore, an object of the present invention is to solve the above-mentioned problems, and when disconnecting the converter 2 from the AC system 5 and switching to the independent operation for supplying electric power to the in-house load 50, an excessive operation is required. An object of the present invention is to provide a control device for a self-excited converter that can continue operation stably without stopping due to electric current or the like.

[0021]

In order to achieve the above object, the invention according to claim 1 is a self-exciting converter for converting a direct current supplied from a direct current power source into an alternating current, and the self-exciting converter. A current detector and a voltage detector for detecting a voltage of an AC system to which the self-excited converter is connected via an output current and a circuit breaker for interconnection, and the output signal of the voltage detector and the current detector from the self-exciting converter. A power calculation circuit for calculating active power and reactive power output by the excitation converter, an output signal of the power calculation circuit, and an active power command and a reactive power command to be output from the self-excitation converter given from the outside. And a power control circuit for calculating the effective component and the reactive component of the voltage drop between the self-excited converter and the AC system, and the effective voltage and the reactive voltage of the AC system voltage from the output signal of the voltage detector. And a voltage calculation circuit that calculates An adder for obtaining an added value of the output of the power control circuit and the output of the voltage calculation circuit when the circuit breaker for interconnection is closed, and controlling an output voltage of the self-excited converter according to the added value When the control system of No. 1 and the circuit breaker for interconnection are opened, command values of an effective voltage and a reactive voltage and an output signal of the voltage calculation circuit are applied so that the self-excited converter provided from the outside outputs. In a control device for a self-excited converter including a second control system that controls an output voltage of the self-excited converter by a voltage control circuit, when switching from the first control system to the second control system. , An effective voltage reference circuit and a reactive voltage reference circuit which set the added value immediately before switching as an initial value and give a voltage reference to the voltage control circuit so as to reach command values of an effective voltage and a reactive voltage given from the outside after a predetermined time. Specially To.

In the invention according to claim 2, the self-exciting converter for converting direct current supplied from the direct current power source into alternating current, and the output current of the self-exciting converter and the circuit breaker for interconnection are provided. A current detector and a voltage detector that detect the voltage of the AC system to which the self-excited converter is connected, and active power and reactive power that the self-excited converter outputs from the output signals of the voltage detector and the current detector. An output of the self-exciting converter, a power calculating circuit for calculating the power, an output signal of the power calculating circuit, and an active power command and a reactive power command to be output from the self-exciting converter that are externally applied A power control circuit for calculating command values of active and reactive components of current, a current operation circuit for calculating active and reactive components of output current of the self-excited converter from the output of the current detector, and the power control Circuit and the output signal of the current calculation circuit Is applied, a current control circuit for calculating the effective component and the reactive component of the voltage drop between the self-excited converter and the AC system, and the effective voltage and the reactive voltage of the AC system voltage from the output signal of the voltage detector. A voltage operation circuit for calculating, an adder for obtaining an added value of the output of the current control circuit and the output of the voltage operation circuit when the circuit breaker for interconnection is closed, and the self-excited conversion according to the added value. Control system for controlling the output voltage of the transformer and the command value of the effective voltage and the reactive voltage to be output by the self-excited converter given from the outside when the circuit breaker for interconnection is opened, and the voltage calculation And a second control system for controlling the output voltage of the self-excited converter by a voltage control circuit to which an output signal of the circuit is applied. Two
When switching to the control system, the effective voltage that gives the voltage reference to the voltage control circuit is set so that the added value immediately before switching is the initial value, and the command value of the effective voltage and the reactive voltage given from the outside is reached after a predetermined time. A reference circuit and a reactive voltage reference circuit are provided.

Further, the invention described in claim 3 is the same as claim 1.
Alternatively, the active voltage reference circuit (or the reactive voltage reference circuit) according to the invention of claim 2 is an integrator that stores the added value from the adder, and the self-excited type that is given from the output of the integrator and the outside. A comparator that compares the command value of the effective voltage (or the command value of the reactive voltage) to be output by the converter and outputs the deviation thereof; and the comparator at the time of switching from the first control system to the second control system. A switch for applying the output signal of the comparator to the integrator, and a switch for separating the added value from the adder applied to the integrator, and the output of the integrator is the effective voltage reference circuit ( Alternatively, the output signal of the reactive voltage reference circuit) is used.

[0024]

According to the first aspect of the present invention, the sum of the output of the power control circuit and the output of the voltage calculation circuit immediately before switching to the preceding stage of the voltage control circuit, that is, the converter outputs it during the interconnection operation. By setting an active voltage reference circuit and a reactive voltage reference circuit that give a voltage reference that reaches the system voltage command value after a predetermined time by using the break command value as an initial value, from the interconnection operation by the first control system, Immediately after switching to CVCF operation by the second control system, the output voltage of the converter outputs the voltage immediately before switching and is controlled so as to reach the system voltage after a predetermined time. There is no difference immediately after switching to the output voltage during CVCF operation, and since the system voltage is raised in a predetermined time, the voltage can be stably output.

According to a second aspect of the present invention, in addition to the first aspect of the invention, a current calculation circuit for calculating the active component and the reactive component of the output current of the self-excited converter from the output of the current detector, and the current. A current control circuit is added to which output signals of the control circuit and the power control circuit are applied and which calculates an effective component and a reactive component of the voltage drop between the self-exciting converter and the AC system. That is, the current control circuit is provided at the subsequent stage of the power control circuit. Therefore, in addition to the effect of the invention described in claim 1, current control can be performed while power control is performed, so that it is possible to prevent an overcurrent due to disturbance or the like.

Furthermore, the invention described in claim 3 is the same as claim 1.
Alternatively, an active voltage reference circuit (or a reactive voltage reference circuit) according to the invention of claim 2 is provided with an integrator storing the added value from the adder, and the output of the integrator and the self-applied externally. At the time of switching from the first control system to the second control system, a comparator that compares the command value of the active voltage (or the command value of the reactive voltage) to be output by the excitation converter and outputs the deviation thereof. A switch for applying the output signal of the comparator to the integrator, and a switch for disconnecting the added value from the adder applied to the integrator, and the output of the integrator is the effective voltage reference circuit. By using the output signal of (or the reactive voltage reference circuit), the output voltage of the converter immediately after the switching from the interconnected operation by the first control system to the CVCF operation by the second control system is the voltage immediately before the switching. Output, and after a predetermined time the grid It can perform stable switching operation to reach the pressure.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claims 1 and 3 will be described below with reference to FIGS. The same parts as those in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, reference numerals 40A and 40B denote an effective component voltage reference circuit and a reactive component voltage reference circuit, respectively, and the effective component voltage reference circuit 40A and the reactive component voltage reference circuit 40B are the same. Collectively referred to as an active / reactive voltage reference circuit 40. An active / reactive voltage command is externally applied to one input of the circuit 40 and the adder output signal 20c is applied to the other input. Given.

The effective / reactive voltage reference circuit 40 is
A function of outputting the output signal 20c of the adder to the output signal 40a immediately after the converter 2 is switched from the interconnected operation to the isolated operation, and outputting the effective / reactive voltage command given from the outside after a predetermined time. It is a circuit equipped with.

FIG. 4 is a block diagram showing a specific embodiment of the effective / reactive voltage reference circuit 40 according to the third aspect. In FIG. 4, the switch S1 is opened and the switches S2 and S3 are closed by the switching signal during the interconnected operation, and the switch S1 is opened by the switching signal during the isolated operation.
1 is closed and switches S2 and S3 are opened.

R1 is a resistor, ZD is a Zener diode,
Reference numeral 41 denotes an inverting amplifier, which constitutes a comparison circuit for detecting a difference between two signals input to each R1. Further, R2 is a resistor, C is a capacitor, and 42 is an inverting amplifier, which constitutes an integrating circuit.

On the other hand, the series circuit of the resistor R4 and the switches S2 and S3 is an initial value setting circuit for setting an initial value in the capacitor C of the integrating circuit. The resistor R3 and the inverting amplifier 43 form an inverting circuit.

The effective / reactive voltage command is a signal given from the outside. In fact, the active voltage reference circuit 40A is supplied with the active voltage command and the reactive voltage reference circuit 40B is supplied with the reactive voltage command. Given.

Further, the active / reactive voltage 20c is the output 20b of the voltage calculation circuit 11 and the output 2 of the power control circuit 20.
It becomes a signal obtained by adding 0a by the adder. Voltage reference 40a
Becomes an input signal to the voltage control circuit 31.

In FIG. 4, the active / reactive component voltage command indicates that the voltage Vs (6.6 kv) of the AC system 5 is substantially constant when the converter 2 is connected to the AC system 5 of 6.6 kv. Therefore, this effective / reactive voltage command is V
The signal is equivalent to s (6.6 kv).

On the other hand, the effective / reactive voltage 20c is a signal obtained by adding the output 20b of the voltage calculation circuit 11 and the output 20a of the power control circuit 20 by an adder, and this signal has already been described in the prior art. Thus, this is a signal corresponding to the output voltage VI of the converter 2 when the converter 2 is in the interconnected operation.

Therefore, when the converter 2 is connected, the effective / reactive voltage 20 is applied to the capacitor C of the integrating circuit.
Because c is stored. The converter 2 is used as the voltage reference 40a.
A signal corresponding to the output voltage VI of the converter 2 during the interconnected operation is output and stands by.

When the converter 2 is in the interconnected operation, the changeover switches 30A and 30B are connected to the (1) side, and the output 20a of the power control circuit 20 outputs a signal corresponding to Vx in FIG. The output 20b of the voltage calculation circuit 11 outputs a signal corresponding to Vs, and a signal 20c obtained by adding these signals becomes a signal corresponding to the output voltage VI of the converter 2. Therefore, the converter 2 uses the signal 20c to generate the voltage command calculation circuit 2 in the subsequent stage.
1. The output voltage is controlled to be VI through the pulse width modulation circuit 22.

Next, when the circuit breaker 4B is cut off to switch from the interconnected operation to the independent operation, the changeover switches 30A and 30B.
Is connected to the (2) side, and 9b is a signal from an oscillator (not shown). Since this signal is synchronized with the signal 9a synchronized with the system voltage Vs, the output of the changeover switch 30 does not change.

The output 40a of the effective voltage reference circuit 40A and the reactive voltage reference circuit 40B is an initial value as shown in FIG. 3, and this initial value is external after a predetermined time from the signal corresponding to VI as described above. Since the voltage command and the external voltage command also change so as to reach the signal corresponding to Vs as described above, the switching from the interconnected operation to the isolated operation is stably performed.

Next, the invention described in claim 2 will be described with reference to FIG. FIG. 2 is a diagram in which an active / reactive current calculation circuit 34 and a current control circuit 35 are added to the device of FIG.

The active / reactive current calculation circuit 34 calculates the active and reactive currents of the output current of the converter 2 based on the current detected by the current detector 6 and the phase signal 9a. It is added to one input of the control circuit 35. The other input of the current control circuit 35 is given the output from the power control circuit 20, that is, the active current command and reactive current command of the current output by the converter 2, and the output 20a of the current control circuit 35 is supplied.
, The effective and ineffective components of the voltage drop Vx between the converter 2 and the AC system 5 are obtained.

The effective voltage reference circuit 40A and the reactive voltage reference circuit 40B are the same, and are configured as shown in FIG. A signal 20 obtained by adding the output of the current control circuit 35 and the output of the voltage calculation circuit 11 with an adder.
c corresponds to the output voltage VI of the converter 2 during the interconnection operation,
The effective / reactive voltage command is a signal corresponding to the system voltage Vs. Therefore, the switching from the interconnected operation to the isolated operation can be stably performed as described above.

As described above, the invention of claim 2 is the same as the invention of claim 1, wherein the active / reactive current calculation circuit 34 is used.
And a current control circuit 35 is added. As a result, current control can be performed while power control is performed, so that the response of the system of the converter 2 to disturbance or the like can be improved, and an effect of preventing overcurrent due to disturbance or the like can be obtained. .

As described above, the voltage reference of the converter 2 is always used at the time of switching from the interconnected operation to the independent operation, and the output voltage during the interconnected operation is used as the initial value to start the voltage control from this value. A large change in the voltage reference at the time of switching is eliminated, and the converter 2 can be stably shifted to the independent operation without being overloaded by the overcurrent and overvoltage.

In the above description, the DC power supply is used as an example of the DC power supply, but the same effect can be obtained with a rechargeable battery, fuel cell, solar cell, or the like. Also, the output of the converter can be applied in the same manner in either single phase or three phase.

Further, an example of the effective voltage reference circuit 40A and the reactive voltage reference circuit 40B is shown in FIG. 4, but a combination of a comparison circuit, an integration circuit, and a setting circuit for setting an initial value in the integration circuit. So long as it has other configurations,
The same effect can be obtained even if a similar circuit configuration is made by software instead of a drive circuit.

[0048]

As described above, according to the invention described in claim 1, from the interconnected operation in which the converter is connected to the AC system, to the isolated operation in which the converter is disconnected from the AC system and electric power is supplied to the in-house load. Can be stably switched regardless of the operating state of the interconnection operation.

According to the second aspect of the present invention, the interconnection operation in which the converter is connected to the AC system is switched to the islanding operation in which the converter is disconnected from the AC system and the electric power is supplied to the in-house load. It is possible to switch stably regardless of the operating state of the operation.In addition, during interconnection operation with the converter connected to the AC system, current control is performed while power control is performed, so it is not easily affected by external disturbances. A control device for the excitable converter can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the invention according to claim 1;

FIG. 2 is a configuration diagram showing an embodiment of the invention according to claim 2;

FIG. 3 is a configuration diagram showing an embodiment of the invention described in claim 3.

FIG. 4 is a characteristic diagram for explaining the operation of the invention described in claim 3.

FIG. 5 is a configuration diagram of a control device for a conventional self-excited converter.

FIG. 6 is a vector diagram when the self-excited converter is interconnected.

[Explanation of symbols]

1 ... DC power supply 2 ... Self-exciting converter 3 ... Output transformer 4A-4C ... Circuit breaker 5 ... AC power system 6 ... Current detector 7 ... Voltage detection transformer 8 ... System voltage phase detection transformer 9 ... Synchronization detection circuit 10 ... Electric power Arithmetic circuit 11 ... Effective / ineffective component voltage arithmetic circuit 20 ... Power control circuit 21 ... Voltage command arithmetic circuit 22 ... Pulse width modulation circuit 30A ... Changeover switch 30B ... Changeover switch 31 ... Voltage control circuits 41 to 43 ... Inverting amplifier 40A ... Effectiveness Divided voltage reference circuit 40B ... Reactive divided voltage reference circuit 50 ... Load R1 to R4 ... Resistor ZD ... Zener diode C ... Capacitor

Claims (3)

[Claims] 1. A self-exciting converter for converting direct current supplied from a direct current power source into alternating current, and an alternating current to which the self-exciting converter is connected via an output current of the self-exciting converter and a circuit breaker for interconnection. A current detector and a voltage detector that detect the voltage of the grid, and a power calculation circuit that calculates the active power and the reactive power output by the self-exciting converter from the output signals of the voltage detector and the current detector, The output signal of the power calculation circuit and the active power command and the reactive power command to be output from the self-excited converter that are externally applied are applied, and the voltage drop between the self-excited converter and the AC system is effective. Power control circuit for calculating the active and reactive voltage of the AC system voltage from the output signal of the voltage detector, the power control circuit when the interconnection breaker is closed. The output of the circuit and the An adder for obtaining an added value of the output of the arithmetic circuit, a first control system for controlling the output voltage of the self-excited converter according to the added value, and an externally applied signal when the circuit breaker for interconnection is opened. Second control for controlling the output voltage of the self-excited converter by a voltage control circuit to which the effective voltage and reactive voltage command values to be output by the self-excited converter and the output signal of the voltage calculation circuit are applied In a controller of a self-excited converter including a system, when the first control system is switched to the second control system, the added value immediately before the switching is set as an initial value, and the external value is given from the outside after a predetermined time. 2. A control device for a self-excited converter, comprising: an active voltage reference circuit and a reactive voltage reference circuit that provide a voltage reference to the voltage control circuit so as to reach the command values of the effective voltage and the reactive voltage. 2. A self-exciting converter for converting direct current supplied from a direct current power source into alternating current, and an alternating current to which the self-exciting converter is connected via an output current of the self-exciting converter and a circuit breaker for interconnection. A current detector and a voltage detector that detect the voltage of the grid, and a power calculation circuit that calculates the active power and the reactive power output by the self-exciting converter from the output signals of the voltage detector and the current detector, An output signal of the power calculation circuit, an active power command and a reactive power command to be output from the self-excited converter that are externally applied, are applied, and a command for the active and reactive components of the output current of the self-excited converter is applied. A power control circuit that calculates a value, a current operation circuit that calculates an active component and a reactive component of the output current of the self-exciting converter from the output of the current detector, the power control circuit, and the output of the current operation circuit A signal is applied and the self-excited A current control circuit for calculating an effective component and a reactive component of a voltage drop between the converter and the AC system, and a voltage calculation circuit for calculating an effective voltage and a reactive voltage of the AC system voltage from an output signal of the voltage detector, An adder for obtaining an added value of the output of the current control circuit and the output of the voltage calculation circuit when the circuit breaker for interconnection is closed; and controlling an output voltage of the self-excited converter according to the added value. When the first control system and the circuit breaker for interconnection are opened, the command values of the effective voltage and the reactive voltage and the output signal of the voltage calculation circuit are applied so that the self-excited converter given from the outside outputs. And a second control system for controlling the output voltage of the self-excited converter by means of a voltage control circuit for switching from the first control system to the second control system. The current control circuit immediately before switching Of the output of the voltage calculation circuit as an initial value, and an effective voltage reference for giving a voltage reference to the voltage control circuit so as to reach the command value of the effective voltage and the reactive voltage given from the outside after a predetermined time. A control device for a self-excited converter, comprising a circuit and a reactive voltage reference circuit. 3. The active voltage reference circuit (or reactive voltage reference circuit) includes an integrator storing the added value from the adder, and the self-excited converter provided from the output of the integrator and the outside. And a comparator for comparing the effective voltage command value (or the reactive voltage command value) to output the deviation thereof, and the comparator at the time of switching from the first control system to the second control system. A switch for applying the output signal from the integrator to the integrator,
A switch for disconnecting the added value from the adder applied to the integrator, wherein the output of the integrator is the output signal of the active voltage reference circuit (or reactive voltage reference circuit). The control device for the self-excited converter according to claim 1 or 2.