JP2001016781A - Power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a power converter which can always be controlled appropriately and stably, even when a fault or fluctuation occurs in an AC power system and the power system is restored from an abnormal phenomenon. SOLUTION: When a fault detecting means 13 detects occurrence of a fault in an AC power system 1, a switch means 11 outputs I2Qref2 from a voltage control means 10 to a power converter circuit 4 as I2Qref instead of I2Qref1 from a reactive power control means 8. When the detecting means 13 detects the restoration of the system 1 from the fault, the switch means 11 outputs the I2Qref1 from the reactive power control means 8 to the power converter circuit 4 as the I2Qref, in place of the I2Qref2 from the voltage control means 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a generator motor having a primary side connected to an AC power system, and a power converter having an AC side connected to a secondary side of the generator motor. The present invention relates to a power converter that controls input and output of power.

[0002]

2. Description of the Related Art An AC excitation generator motor has a primary side connected to an AC power system via a transformer, and a secondary side connected to a power converter for supplying variable frequency power to the generator motor. By supplying variable frequency power to the generator motor, the rotor can be operated at a frequency different from that of the AC power system. For this reason, power can be supplied and absorbed at high speed, which can contribute to frequency adjustment and stabilization of the AC power system.

FIG. 23 is a configuration diagram showing an example of the configuration of a conventional control device for a generator motor. In the figure, 1 is an AC power system, 2 is a transformer, 3 is a generator motor, 4 is a current control type power conversion circuit, 5 is a current detector, 6 is a voltage detector, 7 is power detection means, and 8 is power control. Means. The configuration shown in FIG. 23 is disclosed, for example, in Yamamoto and Motoyoshi, "Active / Reactive Power Control Method for Wire-Wound Induction Machines", Proceedings of the 1991 IEEJ Industrial Application Division, pp. 443-446, 1989.

First, the power control means 8 will be described.
First, the active power and the reactive power of the AC power system are calculated by the power detection means 7 from the current voltage of the AC power system 1 detected by the current detector 5 and the voltage detector 6.
For a three-phase AC power system, the currents are Isa, Isb,
If Issc and the voltages are Vsa, Vsb and Vsc, the active power P and the reactive power Q are calculated as follows, for example. P = Vsa * Isa + Vsb * Isb + Vsc * Isc (1) Q = {(Vsb-Vsc) * Isa + (Vsc-Vsa) * Isb + (Vsa-Vsb) * Isc} / {3}

The power control means 8 detects the detected powers P, Q
And the power command value Pre of the power command setting means 807 and 808.
The deviations of f and Qref are obtained by subtraction means 801 and 803,
The deviations are amplified by the compensators 802 and 804 to output secondary current command values I2Pref and I2Qref, and operate so that the electric powers P and Q and the command values Pref and Qref match. When a secondary current flows through the generator motor 3, an induced voltage is generated on the primary side, and as a result, a primary current flows. At this time, when the magnitude and phase of the secondary current are adjusted, the magnitude and phase of the voltage induced on the primary side change. If the secondary current is adjusted so as to change the magnitude of the induced voltage, the reactive current on the primary side changes and the reactive power can be adjusted. If the secondary current is adjusted so as to change the phase of the induced voltage, the active current on the primary side changes and the active power can be adjusted. Assuming that the magnitude of the primary voltage is V1, P1 ≒ V1 * I2P (3) Q2 ≒ V1 * (I2Q−I2m) (4) The orthogonal secondary current components I2P and I2Q that satisfy the relationship of (4)
It is known that can be selected.

Here, I2m is a secondary current component when the induced voltage matches the system voltage in a state where no current flows on the primary side of the generator motor 3. Changing the secondary current component I2Q changes the magnitude of the induced voltage, and changing the secondary current component I2P is orthogonal to I2Q, so changing the I2P changes the phase of the induced voltage, adjusting the reactive power and active power, respectively. can do. Since the changes of the electric powers P1, Q1 of the generator motor 3 and the electric powers P, Q of the AC power system 1 with respect to the secondary current are the same, the secondary current is controlled according to the secondary current command output by the power control means 8. Then, the system operates so that the system power matches the command value.

Next, the operation of the current control type power conversion circuit 4 will be described. The current control type power conversion circuit 4 is a power conversion circuit that converts AC power into AC power having different frequencies, such as a cycloconverter or a combination of an inverter and a converter, and a control circuit that operates so that the current matches a current command. The voltage applied to the generator motor 3 is adjusted so that the secondary current of the generator motor 3 matches the command value. The detailed description of the operation of the current control type power conversion circuit can be found in the above-mentioned known example or by BKBose (Sinsenji,
Translated by Naito), "Power Electronics & AC Drive"
Since it is disclosed on September 15, 1987, it is omitted here.

As described above, in the conventional control apparatus for a generator motor, the secondary current of the generator motor 3 is adjusted by the power control means 8 to operate so that the power matches the command value. The operation continues even if the error occurs. Lines with ground faults are cut off in tens to 100 milliseconds after the accident occurs, but if an accident occurs on multiple lines,
There is a case where the generator motor 3 is separated from the AC power system 1 and operates alone. During this time, although the command values Pref and Qref maintain constant values, the current cannot flow to the AC power system side and the powers P and Q become almost zero, so that the power control means 8 reduces the secondary current. Operate in the direction of increasing.
If the current does not flow to the AC power system, the magnitude of the primary voltage of the generator motor is proportional to the magnitude of the secondary current. It may be damaged.

[0009]

Since the conventional control device of the power conversion circuit for controlling the current of the generator motor is constructed as described above, when an accident such as a ground fault occurs in the AC power system, the output is controlled. There is a problem that the voltage becomes overvoltage. The present invention has been made to solve the above-described problems, and has as its object to obtain a power conversion device that can always perform appropriate and stable control according to the state of an AC power system. It is another object of the present invention to provide a power conversion device that can always perform appropriate and stable control even when an accident or fluctuation occurs in the AC power system and when the AC power system recovers from the abnormal phenomenon. Still another object of the present invention is to provide a power converter that can always perform appropriate and stable control even when an accident or a disturbance occurs in the AC power system and the AC power system is subsequently shut down.

[0010]

A power converter according to the present invention comprises a power converter having an AC side connected to an AC power system, a reactive power detecting means for detecting reactive power on the AC side of the power converter, and In a power converter including a reactive power control unit that controls the power converter so that the reactive power detection value matches a reactive power command value, a voltage detection unit that detects a voltage on an AC side of the power converter. An accident occurrence / recovery detecting means for detecting occurrence and return of an accident in the AC power system; and voltage control means for controlling the power converter so that the detected voltage value matches a voltage command value. The control means is switched so as to enable either the reactive power control means or the voltage control means in accordance with the output of the means.

Further, the power converter according to the present invention includes a generator motor having a primary side connected to an AC power system, a power converter having an AC side connected to a secondary side of the generator motor, and a primary converter connected to a primary side of the generator motor. A power conversion device comprising: a reactive power detection unit configured to detect a reactive power; and a reactive power control unit configured to control the power converter so that the reactive power detection value matches the reactive power command value. And voltage control means for controlling the power converter so that the voltage detection value matches the voltage command value, and one of the reactive power control means and the voltage control means is effective. The control means is switched so that

Further, the power converter according to the present invention includes an accident occurrence detecting means for detecting the occurrence of an accident in the AC power system, and a reactive means for making the control means effective when the occurrence of the accident is detected. To voltage control means.

Further, the power conversion device according to the present invention includes a fluctuation detecting means for detecting the presence or absence of fluctuation in the AC power system, and when the fluctuation is detected, the control means for validating the voltage from the reactive power control means is supplied from the reactive power control means. It switches to the control means.

Further, the power converter according to the present invention includes an accident recovery detecting means for detecting the recovery of an accident in the AC power system. Switching to the reactive power means.

Further, the power converter according to the present invention includes a fluctuation detecting means for detecting the presence or absence of fluctuation in the AC power system, and, after detecting the absence of the fluctuation, the control means for validating the voltage from the voltage control means. It switches to the control means.

The power converter according to the present invention further comprises means for inputting a reclosing signal after the occurrence of an accident in the AC power system. Means to the reactive power control means.

Further, the power conversion device according to the present invention is characterized in that the control means is enabled after a predetermined time has elapsed after detecting recovery from the accident, after detecting no shaking, or after inputting the reclosing signal. Is switched from the voltage control means to the reactive power control means.

In the power converter according to the present invention, after the control means to be enabled is switched from the reactive power control means to the voltage control means, the normality of the AC power system is detected and then the original reactive power control means is returned to. In the period before switching,
The output upper limit value of the voltage control means is set to a suppression upper limit value lower by a predetermined amount than the allowable maximum upper limit value.

Further, the power converter according to the present invention includes active power fluctuation detection means for detecting the presence or absence of fluctuation of the active power in the AC power system, and the control means to be enabled is changed from the reactive power control means to the voltage control means. After the switching, the output upper limit value of the voltage control means is set to a suppression upper limit value lower than the allowable maximum upper limit by a predetermined amount before the active power fluctuation detecting means detects the absence of fluctuation.

Further, in the power converter according to the present invention, the suppression upper limit value is the output value of the reactive power control means immediately before switching the control means to be effective from the reactive power control means to the voltage control means. is there.

Further, the power converter according to the present invention includes a system cutoff detecting means for detecting whether or not the AC power system is cut off on the primary side of the generator motor, and the control means to be enabled is changed from the reactive power control means to the voltage. After switching to the control means, the valid control means is switched from the voltage control means to the reactive power control means under the condition that the system interruption detection means detects no interruption.

The power converter according to the present invention determines the occurrence or return of an accident in the AC power system from the magnitude of the current on the primary or secondary side of the generator motor.

The power converter according to the present invention determines the occurrence or return of an accident in the AC power system from the magnitude of the voltage on the primary side or the secondary side of the generator motor.

Further, the power converter according to the present invention determines whether or not there is fluctuation in the AC power system from the time change rate of the voltage amplitude value on the primary side of the generator motor.

Further, the power converter according to the present invention determines whether or not there is fluctuation in the AC power system from the time change rate of the power value on the primary side of the generator motor.

In the power converter according to the present invention, when the control means to be enabled is switched from the reactive power control means to the voltage control means, the output of the reactive power control means immediately before the switching is initialized by the voltage control means. When the control means to be validated is switched from the voltage control means to the reactive power control means, the output of the voltage control means immediately before the switching is used as the initial value of the reactive power control means.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a configuration diagram showing a power conversion device according to Embodiment 1 of the present invention. In the figure, 1 is a three-phase AC power system, 3 is a generator motor whose primary side is connected to the AC power system 1 via a transformer 2, and 4 is an AC side connected to the secondary side of the generator motor 3 In a power conversion circuit which is a current control type power converter, the magnitude of the output voltage on the AC side is set so that the current on the primary side of the generator motor 3 detected by the current detector 5 matches a command value described later, Control the phase. Reference numeral 6 denotes a voltage detector for detecting the voltage on the primary side of the generator motor 3, and reference numeral 7 denotes an active power detection value P and a reactive power detection value based on the current detection value from the current detector 5 and the voltage detection value from the voltage detector 6. Q is a power detection means for obtaining the voltage amplitude value V from the voltage detection value from the voltage detector 6.

Numeral 8 denotes power control means, which is a subtraction means 801 for calculating a deviation between the active power detection value P and the active power command value Pref, and outputs a secondary current valid command value I2Pref based on the deviation output. A compensator 802 for calculating the reactive power command value Qref and a subtractor 803 for calculating a difference between the two, and a compensator for outputting a secondary current reactive component command value I2Qref1 based on the output of the difference. 804. 10 is a voltage control means,
A subtraction means 1001 for calculating the difference between the two so that the voltage detection value V matches the voltage command value Vref, and a compensator 1002 for outputting a secondary current invalid component command value I2Qref2 based on the difference output.

Numeral 11 denotes switching means, which is based on a selection signal C from a control selecting means 12 which will be described later, and which has a command value I2Qref1 from a compensator 804 as reactive power control means or a command value I2Qref2 from a compensator 1002 as voltage control means. Of the secondary current ineffective command value I2Qre
Output to the power conversion circuit 4 as f. Reference numeral 12 denotes a control selection unit that outputs a selection signal C based on the current detection value is and the voltage detection value vs.

Next, the operation will be described. Voltage detector 6
Are Vsa, Vsb, and Vsc.
In the voltage amplitude detecting means 9, for example, when V = √ (Vsa * Vsa + Vsb * Vsb + Vsc * Vsc) (5) is calculated as the amplitude V of the AC voltage, a voltage value equivalent to the effective value of the line voltage is obtained. When removing the effects of harmonics and unbalance, a filter is configured in the voltage amplitude detecting means 9 to remove harmonic components contained in the calculated voltage V. The difference between the obtained voltage V and the voltage command value Vref of the voltage command setting means 1005 is obtained by the subtraction means 1001, and the difference is calculated by the compensator 1002.
And outputs I2Qref2. By changing I2Qref, the magnitude of the voltage induced on the primary side changes. Therefore, when the power conversion circuit 4 controls the secondary current with I2Qref = I2Qref2, the power conversion circuit 4 operates so that the voltage command Vref matches the voltage V. Current command value I2Qref of power conversion circuit 4
Is the output I2Qr of the compensator 804 among the outputs of the power control means 8.
If it is equal to ef1, it is the same as before, and the power conversion circuit 4
The operation is performed so that the reactive power detection value Q and the reactive power command value Qref of the power command setting means 808 match.

The switching means 11 includes current command values I2Qref1 and I2Qre
f2 is output.
In response to the selection signal C from Normally, the switching means 11 selects and outputs the current command value I2Qref1 (C = 0), and when the control selection means 12 determines that the control to be operated from the current, voltage, etc. of the AC power system 1 is voltage control, a selection signal is output. C changes to 1 and switches to the current command value I2Qref2. As a result, the voltage control means 10 operates to make the voltage constant. For example, when an accident occurs and the control selecting means 12 detects it, the switching means 11 switches the current command value to I2Qref2, and thereafter, even if the fault line is removed and the generator motor 3 is disconnected from the AC power system 1, ,
Since the voltage control means 10 operates so as to make the voltage constant, an overvoltage does not occur and the device is not damaged. Further, when the AC power system 1 is in a normal state, the selection signal C from the control selection unit 12 becomes 0, and the switching unit 11 switches to the current command value I2Qref1 to control the power of the generator motor 3 to be constant. As a result, the power of the AC power system 1 can be maintained at a desired command value. That is, the power conversion device shown in FIG. 1 is a configuration that is positioned at a higher level than each of the embodiments described later, and a user related to power control performs control in consideration of individual and specific system operation conditions and the like. Selection means 1
By setting the output determination criterion of the selection signal C in 2, the generator motor 3 can always be appropriately operated by switching between the reactive power control and the voltage control according to the state of the AC power system 1.

Embodiment 2 FIG. FIG. 2 is a configuration diagram showing a power conversion device according to Embodiment 2 of the present invention, and FIG. 3 is a detailed configuration diagram of the accident detection means 13. In the figure,
The description of the same reference numerals as in the first embodiment is omitted. Reference numeral 13 denotes an accident detecting means for detecting the occurrence of an accident in the AC power system 1 from the voltage amplitude value V from the voltage amplitude detecting means 9.
1301 is a subtraction means, 1302 is an edge detection means, 13
03 is a flip-flop and 1314 is a setting means.

Next, the operation will be described. Switching means 11
Outputs one of the current command values I2Qref1 and I2Qref2, and switches according to the output of the accident detection means 13. Normally, the switching means 11 selects and outputs the current command value I2Qref1, and when the fault detecting means 13 detects an AC power system fault from the voltage of the AC power system 1, the selection signal C changes to 1 and the current command I2Qref2 Switch to. As a result, the voltage control means 10 operates to make the voltage constant. As a result, the primary voltage of the generator motor 3 does not become overvoltage, and the device is not damaged.

Next, the operation of the accident detecting means 13 will be described.
V is subtracted from the set value Vsw set by the setting unit 1314 by the subtracting unit 1301. Since Vsw is set to a value smaller than the normal V (for example, about 30% of the rated value), the subtraction means 1301 outputs a negative value. Voltage V
Decreases to a value smaller than Vsw, the subtracting means 13
The output of 01 changes positively. In order to detect the rise of the deviation signal, the edge detecting means 1302 generates a pulse when the output of the subtracting means 1301 changes from negative to positive. In the flip-flop 1303, the output Q (selection signal C) changes from 0 to 1 by the pulse output from the edge detection means 1302. As a result, the switching means 11 switches the current command value from I2Qref1 to I2Qref2, and operates the voltage control means 10.

Embodiment 3 FIG. FIG. 4 is a configuration diagram showing a power converter according to Embodiment 3 of the present invention. FIG. 5 is a configuration diagram showing a detailed configuration of the accident detection means 13. Here, the accident detecting means 13 detects the occurrence of an accident and its return. In the figure, the description of the same reference numerals as in the first embodiment is omitted. 1308 is an absolute value calculating means, 1
309 is an OR gate, 1310 is current amplitude detection means, 1
311 is a level determination means, 1312 is a delay means, 131
Reference numeral 3 denotes an AND gate, and reference numeral 1315 denotes a setting unit.

Next, the operation will be described. Current detector 5
The phase currents Ia, Ib, and Ic detected in step (1) are input to absolute value calculation means 1308a to 1308c, respectively, and their absolute values are obtained. From these values, Isw preset by the setting unit 1315 is subtracted by the subtracting units 1301a to 1301c.
Since Isw is set to a value larger than the peak value of the normal alternating current, the subtraction means 1301a to 1301c always output negative values. When an accident occurs and the alternating currents Ia to Ic increase and the value exceeds the set value Isw, the subtraction means 1301a
~ C output positive values. Edge detecting means 1302a-
c, a pulse is generated when the input changes from negative to positive, so that the magnitude of the alternating currents Ia to Ic is equal to the set value Isw.
A pulse is generated when it exceeds. The outputs of the three-phase edge detection means 1302a to 1302c are sent to a flip-flop 1303 via an OR gate 1309, and the three-phase AC current Ia
When the magnitude of any of .about.Ic exceeds the set value Isw, the output (selection signal C) of the flip-flop 1303 changes from 0 to 1. Next, the switching means 11 is the accident detecting means 1
3 is I2Qref1 when the selection signal C is 0, I
When the magnitude of the AC current exceeds Isw, I2Qref2 is output and the voltage control means 10 is activated. As a result, the voltage control means 10 operates so as to make the voltage constant, so that the primary voltage of the generator motor 3 does not become overvoltage, and the equipment is not damaged.

Next, the operation in the case where the accident is recovered without the generator motor 3 being disconnected from the AC power system will be described. FIG. 6 shows a schematic waveform example of the operation. FIG. 6A shows a case where the accident is removed (recovered from the accident) with the AC power system 1 connected, and FIG. 6B shows a case where the AC power system 1 is cut off and the accident is removed. In the accident detecting means 13 of FIG. 5, the magnitude of the alternating current is detected by the current amplitude detecting means 1310. The detection of the magnitude of the alternating current is realized by, for example, a method similar to the equation (5). The magnitude of the alternating current increases when the voltage drops due to the occurrence of an accident.
When the accident is eliminated with the terminal connected, the current returns to the normal value. Further, if the accident is eliminated in a state where the AC power system 1 is shut off, the current stops flowing and the current amplitude becomes zero. The subtractor 1301d subtracts the AC current amplitude I from the set value Isw. The output of the edge detecting means 1302d generates a pulse when the alternating current amplitude I falls from a value larger than the set value Isw to below it. Therefore, a pulse is generated when the accident is eliminated and the AC current returns to the normal current value, or when the AC power system 1 is cut off and the current becomes zero (FIGS. 6 (1) c and (2) c). Then, delay means 1312
Then, the generated pulse is supplied for a predetermined time (0.5 to 1.0 sec.).
(Degree) (FIG. 6 (1) d, (2) d) At this point, it is determined whether the AC power system 1 is connected or disconnected as described later.

The subtracting means 1301e subtracts a predetermined value Imin from the AC current amplitude I, and the signal is sent to the level determining means 1311. Level determination means 1311
Outputs 1 when the input signal is 0 or more, and outputs 0 when the input signal is other than 0.
If it is larger than 1, 1 is output, otherwise 0 is output. The output of the delay means 1312 and the level determination means 1311
Is sent to the Clear input of the flip-flop 1303 via the AND gate 1313. When a pulse is input to the Clear input, the flip-flop 1303 performs an operation of returning its output Q (selection signal C) to 0. When the accident is eliminated in a state where the AC power system 1 is connected, the current returns to a state close to the normal state.
Outputs 1 (FIG. 6 (1) e). Accordingly, the output of the AND gate 1313 becomes the output of the delay means 1312 (FIG. 6 (1) f), the flip-flop 1303 is cleared, the selection signal C becomes 0, and the switching means 11 switches from I2Qref2 to I2Q.
Switch to 2Qref1 to return to normal operation. When the AC power system 1 is cut off, the output of the level determination means 1311 is 0 (FIG. 6 (2) e), and the AND gate 1313
(0) (FIG. 6 (2) f), the flip-flop 1303 is not cleared, the selection signal C holds 1, the switching means 11 holds I2Qref2, and the voltage control means 10 By continuing, overvoltage will not occur.

As described above, in the third embodiment, when an accident occurs in the AC power system 1, this is immediately detected from the overcurrent of any phase, and the reactive power control means 8 Switching to the control means 10, the generator motor 3
To prevent overvoltage from occurring. Then, when the fault is eliminated, that is, when the recovery from the fault is detected, the voltage control unit 1 passes through the time for system stabilization set by the delay unit 1312 and passes.
By switching from 0 to the reactive power control means 8 again, the original control operation is returned.

When the accident elimination is performed together with the interruption of the AC power system 1, the control is returned to the reactive power control means 8.
Since there is a possibility that a large voltage rise occurs, the operation of the voltage control means 10 is continued without switching to the reactive power control means 8 to reliably prevent the occurrence of overvoltage.

In this embodiment, an accident is detected by the primary current. However, when an accident occurs, the secondary current increases with an increase in the primary current. effective. However, in this case, the set value Imin for detecting the cutoff state of the AC power system 1
Needs to be set in consideration of the exciting current of the generator motor 3.

Embodiment 4 FIG. 7 is a configuration diagram showing a power conversion device according to Embodiment 4 of the present invention. Here, the occurrence of an accident in the AC power system 1 is detected from the voltage amplitude value V. In the drawings, the description of the same reference numerals as those in the above embodiment is omitted.

Next, the operation will be described. Switching means 11
Outputs one of the current command values I2Qref1 and I2Qref2 according to the selection signal C output from the accident detection means 13. FIG. 8 shows an example of a detailed configuration of the accident detection means 13. In the figure, 1301 is a subtraction means, 1302 is an edge detection means, and 1303 is a flip-flop. The voltage amplitude detecting means 9 from the set value Vsw by the subtracting means 1301
The detected V is subtracted. Since the set value Vsw is set to a value smaller than the normal voltage amplitude value V, the subtraction means 130
1 outputs a negative value. When the voltage V decreases to a value smaller than the set value Vsw, the output of the subtractor 1301 changes to a positive value. In order to detect the rise of the deviation signal, the edge detecting means 1302 generates a pulse when the output of the subtracting means 1301 changes from negative to positive.
In the flip-flop 1303, the edge detecting means 1302
Changes the output Q (selection signal C) from 0 to 1. The switching means 11 switches so as to output I2Qref1 when the selection signal C from the accident detection means 13 is 0, and outputs I2Qref2 when it is 1, respectively. Normally switching means 1
1 selects and outputs the current command value I2Qref1, and switches to the current command I2Qref2 when the detected voltage falls below a predetermined value. As a result, the voltage control means 10 operates to make the voltage constant. For example, when an accident occurs and the voltage drops, the switching means 11 switches the current command from I2Qref1 to I2Qref2, and the voltage control means 10 operates to keep the voltage constant, so that overvoltage does not occur and the equipment is not damaged. .

The operation of the return is the same as that of the third embodiment, and the description is omitted. In the present embodiment, the accident is detected by the primary voltage, but the same effect can be obtained by detecting the accident by increasing the secondary voltage.

Embodiment 5 FIG. FIG. 9 is a configuration diagram showing a power conversion device according to Embodiment 5 of the present invention. Here, the return of the accident in the AC power system 1 is detected from the reactive power deviation. In the drawings, the description of the same reference numerals as those in the above embodiment is omitted.

Next, the operation will be described. The voltage V and the reactive power deviation Qerr are input to the accident detection means 13 to switch the current command I2Qref. The configuration for the occurrence of an accident is the same as that of the second embodiment. However, when the reactive power deviation becomes smaller, the recovery of the accident is detected, and switching from I2Qref2 to I2Qref1 is performed. As a result, since the voltage control means 10 operating after the voltage drop is switched to the reactive power control means 8, it is possible to return to the operation before the accident.

FIG. 10 shows a detailed configuration of the accident detecting means 13 of the present embodiment. Depending on the voltage V, I2Qref1 to I2Q
The configuration and operation for switching to ref2 are the same as those in the second embodiment, and thus description thereof will be omitted. 1303 is a flip-flop,
Reference numeral 1304 denotes a fluctuation detection means, and reference numeral 1305 denotes a logic inversion means.

Next, the operation, particularly the operation at the time of recovery from an accident, will be described. The reactive power deviation Qerr is calculated by the
4, the fluctuation detecting means 1304 calculates the time change rate of the input signal, and outputs 1 if the value exceeds a predetermined set value and the system is fluctuating, and outputs 0 if not. Therefore, when the fluctuation of the AC power system 1 has subsided and the fluctuation of the reactive power has converged, the output of the fluctuation detecting means 1304 changes from 1 to 0. The logic of this signal is inverted by the logic inversion means 1305, and when the fluctuation of the AC power system 1 stops, 1 is input to the Clear input of the flip-flop 1303.
The flip-flop 1303 resets the output Q to 0 when the Clear input goes to 1. When the output Q (selection signal C) of the flip-flop 1303 becomes 0, the switching means 11 outputs I2
It operates to output I2Qref1 as Qref, and the secondary current is controlled in accordance with the output of the reactive power control means 8 to return to normal operation. For this reason, when the system fault is eliminated and the AC power system 1 no longer fluctuates, the operation is switched to the normal reactive power control operation.

Embodiment 6 FIG. FIG. 11 is a configuration diagram showing a power conversion device according to Embodiment 6 of the present invention. Here, occurrence and return of an accident in the AC power system 1 are detected from fluctuations in the voltage amplitude V. In the drawings, the description of the same reference numerals as those in the above embodiment is omitted. Reference numeral 19 denotes a fluctuation detecting means for detecting the presence or absence of fluctuation from the time change rate of the input signal.

Next, the operation will be described. Switching means 11
Outputs one of the current command values I2Qref1 and I2Qref2 according to the selection signal C output from the fluctuation detecting means 19. The fluctuation detecting means 19 detects the presence or absence of fluctuation from the magnitude of the time change rate of the voltage amplitude V detected by the voltage amplitude detecting means 9, and outputs 1 when the voltage amplitude fluctuates. If it converges and is in a steady state, it outputs 0. The switching means 11 receives the selection signal C from the motion detection means 19.
Is switched to output I2Qref1 when I is 0 and I2Qref2 when I is 1. Normally, the switching means 11 selects and outputs the current command value I2Qref1, and the detected voltage V
Swings, the current command is switched from I2Qref1 to I2Qref2. As a result, the voltage control means 10 operates to make the voltage constant. For example, when the load changes abruptly and the voltage fluctuates, the switching means 11 switches the current command to I2Qref2, so that the generator motor 3 operates to maintain the voltage and contributes to stabilization of the AC power system 1. be able to.

As described above, in the sixth embodiment, the presence or absence of fluctuation of the voltage amplitude V is detected and the switching between the reactive power control means 8 and the voltage control means 10 is performed based on the result. As compared with the case where both control means are switched on the basis of the magnitude of the above, in particular, the state of return of the AC power system 1 can be determined with more accurate and more realistic judgment, and the transition to the reactive power control means 8 can be made more easily. Smooth and stable.

Embodiment 7 FIG. FIG. 12 is a configuration diagram showing a power conversion device according to Embodiment 7 of the present invention. Here, the control operation at the time of switching of the control means is facilitated. In the drawings, the description of the same reference numerals as those in the above embodiment is omitted. 14 is a logic inversion means, 805,
1003 is a compensator.

Next, the operation will be described. The switching operation of the control unit by the accident detection unit 13 and the switching unit 11 is the same as that of the fourth embodiment, and the description is omitted. When the accident detecting means 13 detects an accident and the output of the selection signal C changes from 0 to 1, the switching means 11 switches from reactive power control to voltage control. At this time, the output of the logic inversion means 14 changes from 1 to 0, but the compensator 805 is in the operating state when the output of the logic inversion means 14 is 1 and in the stopped state when the output is 0, so that the compensator 805 is in the stopped state. Becomes
On the other hand, the compensator 1003 shifts from the stopped state to the operating state at this time in order to control the operation and the stop according to the output of the accident detecting means 13. That is, only the compensator that outputs the signal selected by the switching means 11 is in the operating state, and the other is in the stopped state. By the way, compensators 805, 1
003 sets the output values of the respective compensators to the outputs of the compensators 1003 and 805 in the stop state. Then, when the state shifts to the operation state, normal operation is performed with the value as an initial value. The current command value
The I2Qref changes continuously even if it is switched by the switching means 11, so that the control means can be switched without impact.

Embodiment 8 FIG. FIG. 13 is a configuration diagram showing a power conversion device according to Embodiment 8 of the present invention. In the drawings, the description of the same reference numerals as those in the above embodiment is omitted. Reference numeral 15 denotes an upper limit value setting unit, and 1004 denotes a compensator.

Next, the operation will be described. The switching operation of the control unit by the accident detection unit 13 and the switching unit 11 is the same as that of the fourth embodiment, and the description is omitted. The upper limit setting means 15 changes the output according to the output of the accident detection means 13. In response, the voltage control means 10
Is set as the upper limit of the compensation output. When an accident occurs in the AC power system 1 and the voltage drops, the voltage control means 10
Increases the current command I2Qref to maintain the voltage. When the accident is eliminated, the AC voltage returns, so the voltage increases sharply under the influence of the increased I2Qref, and overshoot occurs. Further, the active power also has an adverse effect such as fluctuating the frequency of the AC power system 1 with overshoot. In the upper limit value setting means 15, a predetermined time has elapsed since the output of the accident detection means 13 changed from 0 to 1
The output upper limit of the compensator 1004 is set to a suppression upper limit lower by a predetermined amount than the normal allowable maximum upper limit so as not to increase Qref. As a result, overshoot of the voltage after the elimination of the accident can be reduced, and the AC power system 1 operates without being adversely affected. By limiting the upper limit of the output of compensator 1004, the generation of the divided advanced reactive power is limited, but the output of the delayed reactive power generated by reducing the output value is not limited. .

FIG. 14 is a configuration diagram showing an example of the configuration of the upper limit value setting means 15. In the figure, 1501 is a switching means,
Reference numeral 1502 denotes timer means. When the selection signal C from the accident detection means 13 changes from 0 to 1, the timer means 1
502 operates and outputs 1 for a predetermined period. Switching means 1
At 501, the output is switched so that the AVRMAX1 set by the setting means 1503 is output when the output of the timer means 1502 is 0, and the AVRMAX2 set by the setting means 1504 is output when the output of the timer means 1502 is 1. Here, AVRMAX1 is a normal allowable maximum upper limit, and AVRMAX2 is a suppression upper limit used when an AC system accident occurs. Therefore, AVRMAX1> AVRMAX
There are two relationships.

The time set by the timer means 1502 is determined by the timing at which the upper limit value is returned from AVRMAX2 to the normal AVRMAX1 by the delay means 1312 shown in FIG.
Is set in the middle of the delay time. That is, after the elimination and recovery of the accident is detected, the voltage control operation by the voltage control means 10 becomes stable,
The upper limit value of 04 is returned to the normal value AVRMAX1, and thereafter the switching means 11 switches the control means from the voltage control means 10 to the reactive power control means 8. Of course, when the AC power system 1 is cut off, the voltage control means 10 with the upper limit value set to AVRMAX1 continues its operation. Considering the detection point of the elimination and return of the accident as a reference, the suppression of the upper limit value is executed before this detection point and for a certain period after the detection point elapses, thereby preventing the voltage overshoot accompanying the accident elimination. Therefore, the voltage suppression effect by the suppression of the upper limit value of the compensator described above is surely exhibited.
Since the operation is performed as described above, the voltage overshoot after the accident is eliminated can be reduced, and the overvoltage can be suppressed when the AC power system 1 is disconnected.

Embodiment 9 FIG. FIG. 15 is a configuration diagram showing a power conversion device according to Embodiment 9 of the present invention. In the drawings, the description of the same reference numerals as those in the above embodiment is omitted. 16 is an upper limit value setting means.

Next, the operation will be described. The operation in which the compensator 1004 of the voltage control means 10 has its output upper limit limited in accordance with the accident detection means 13 and reduces overshoot after the elimination of the accident is the same as in the eighth embodiment, and a description thereof will be omitted. . The upper limit value setting means 16 outputs a predetermined suppression upper limit value when the selection signal C from the accident detection means 13 changes from 0 to 1. Then, when the fluctuation of the active power deviation falls below a predetermined level, the operation is performed so that the upper limit value is returned to a normal value. FIG. 16 is a configuration diagram illustrating an example of the configuration of the upper limit value setting unit 16. In the figure, 1601 is switching means, 1602 is edge detecting means, 1603 is flip-flop with reset, 1604 is fluctuation detecting means, 1
605 is a logic inversion unit, and 1606 and 1607 are setting units. In the edge detecting means 1602, the accident detecting means 13
When the selection C changes from 0 to 1, a pulse is generated. Since the output of the flip-flop 1603 changes from 0 to 1 in response to this pulse, the switching unit 1601 switches from AVRMAX1 set by the setting unit 1606 to the setting unit 160.
Switch to AVRMAX2 set in 7. Active power deviation P
The operation of clearing the flip-flop 1603 from the err is the same as the operation of clearing the flip-flop 1303 from the reactive power deviation Qerr shown in the fifth embodiment, and a detailed description thereof will be omitted. If the flip-flop 1603 is cleared,
The operation of the output of the switching means 1601 changes from AVRMAX2 to the original AVRMAX1 and returns to the normal set value.

The upper limit of the compensator 1004 is set to the suppression upper limit AV
The timing to return from RMAX2 to the original normal upper limit value AVRMAX1,
In the eighth embodiment, the timer 150 shown in FIG.
In the ninth embodiment, since the active power deviation Perr is determined by the convergence of the fluctuation, an appropriate operating characteristic is always obtained. With the configuration as described above, the active power control means mainly operates after the AC system fault is eliminated, so that the active power is quickly restored.

Embodiment 10 FIG. FIG. 17 is a configuration diagram showing a power conversion device according to Embodiment 10 of the present invention.
In the drawings, the description of the same reference numerals as those in the above embodiment is omitted. 17 is an upper limit setting means. FIG. 18 shows an example of a detailed configuration of the upper limit value setting means 17. 1 in the figure
701 is a switching unit, 1702 is a timer unit, 1703
Denotes a sample holding unit, and 1704 denotes a setting unit.

Next, the operation will be described. The operation of the compensator 1004 of the voltage control means 10 for limiting the output upper limit according to the accident detection means 13 and reducing the overshoot after the elimination of the accident is the same as in the eighth embodiment, and therefore the description is omitted. Also, the timing of the upper limit value switching operation is the same as that in the eighth embodiment, and the description is omitted. In FIG. 18, the selection signal C from the accident detection means 13 is 0.
The switching means 1701 switches the upper limit from AVRMAX1 set by the setting means 1704 to the output of the sample and hold means 1703. The input of the sample and hold unit 1703 is the output of the compensator 804 of the reactive power control unit 8, and when the selection signal C from the accident detection unit 13 changes from 0 to 1, the input is sampled, and the output is changed to that value. Will be retained. For this reason, even if the voltage control means 10 is limited to the suppression upper limit value, it is possible to generate reactive power to be output by the generator motor 3, and when the voltage of the generator motor 3 increases, the voltage control means 10 becomes effective and the voltage becomes higher. Work to maintain.

Embodiment 11 FIG. FIG. 19 is a configuration diagram showing a power conversion device according to Embodiment 11 of the present invention.
In the drawings, the description of the same reference numerals as those in the configuration diagram of the above embodiment is omitted. 18 is an upper limit setting means. FIG.
3 shows an example of a detailed configuration of the upper limit value setting means 18. In the figure, reference numeral 1801 denotes switching means, 1802 denotes edge detecting means, 1803 denotes a flip-flop with reset,
4 is a motion detection means, 1805 is a logic inversion means, 1806
Denotes sample holding means, and 1807 denotes setting means.

Next, the operation will be described. The operation of the compensator 1004 of the voltage control means 10 for limiting the output upper limit according to the accident detection means 13 and reducing the overshoot after the elimination of the accident is the same as that of the ninth embodiment, and therefore the description is omitted. Also, the timing of the upper limit value switching operation is the same as that in the ninth embodiment, and the description is omitted. In FIG. 20, the selection signal C from the accident detection means 13 is 0.
From 1 to 1 and the switching means 1801 switches the upper limit value from AVRMAX1 set by the setting means 1807 to the output of the sample and hold means 1806. The input of the sample-and-hold unit 1806 is the output of the compensator 804 of the reactive power control unit 8, and when the selection signal C from the accident detection unit 13 changes from 0 to 1, the input is sampled, and the output is changed to that value. Will be retained. For this reason, even if the voltage control means 10 is limited to the suppression upper limit value, it is possible to generate reactive power to be output by the generator motor 3, and when the voltage of the generator motor 3 increases, the voltage control means 10 becomes effective and the voltage becomes higher. Work to maintain.

Embodiment 12 FIG. FIG. 21 is a configuration diagram showing a power conversion device according to Embodiment 12 of the present invention, and FIG. 22 is a configuration diagram showing a detailed configuration of the accident detection means 13. In the drawings, the description of the same reference numerals as those in the above embodiment is omitted. Reference numeral 20 denotes a system control unit that controls a circuit breaker or the like of the line of the AC power system 1, and 21 denotes a circuit breaker.

Next, the operation will be described. When an accident occurs, the output of the flip-flop 1303 is set to 1 and the operation of switching the switching means 11 is the same as in the third embodiment. The system control means 20 shuts off the circuit breaker 21 due to an accident.
For example, a time limit is provided, and a re-closing signal is sent to the circuit breaker to return the line again. This allows the AC power system 1 to return to the normal state. Then, this re-closing signal is sent to the clear signal of the flip-flop 1303 of the accident detecting means 13 and the output of the flip-flop 1303 is set to 0, so that the switching means 11 operates again to select the current command I2Qref1 and becomes invalid. The power control means 8 operates.

As described above, according to the present embodiment, the suppression operation of generator motor 3 can be switched after AC power system 1 has completely returned to the normal state. In particular, even when only one of the three phases is interrupted and power is transmitted and received only by the two phases, the voltage control means 10 is operating during that time, so that the voltage of the generator motor 3 is maintained to prevent occurrence of overvoltage. can do.

In each of the above embodiments, the power conversion circuit 4 controls the generator motor 3 connected to the AC power system 1 to control power with the AC power system 1. Although the power converter has been described, the reactive power control means and the voltage control means are appropriately switched, and the
The present invention of keeping the output voltage to the AC power stable is similarly applied to a power converter or the like that directly connects a power conversion circuit to the AC power system 1 and mainly controls the reactive power with the AC power system 1. Can achieve the same effect.

[0069]

As described above, the power converter according to the present invention comprises a power converter having an AC side connected to an AC power system, a reactive power detecting means for detecting reactive power on the AC side of the power converter, And in a power converter including a reactive power control means for controlling the power converter so that the reactive power detection value matches the reactive power command value, voltage detection means for detecting a voltage on the AC side of the power converter, An accident occurrence / recovery detecting means for detecting occurrence and return of an accident in the AC power system, and voltage control means for controlling the power converter so that the detected voltage value matches a voltage command value; Since the control means is switched so as to enable either the reactive power control means or the voltage control means in accordance with the output of the detection means, Control operating characteristics to maintain the output voltage to the system always stable can be obtained.

Further, the power converter according to the present invention includes a generator motor having a primary side connected to an AC power system, a power converter having an AC side connected to a secondary side of the generator motor, and a power converter having a primary side connected to the secondary side of the generator motor. A power conversion device comprising: a reactive power detection unit configured to detect a reactive power; and a reactive power control unit configured to control the power converter so that the reactive power detection value matches the reactive power command value. And voltage control means for controlling the power converter so that the voltage detection value matches the voltage command value, and one of the reactive power control means and the voltage control means is effective. Since the control means is switched so as to satisfy the following condition, a control operation characteristic that always keeps the primary voltage of the generator motor stable can be obtained.

Further, the power converter according to the present invention includes an accident detection means for detecting the occurrence of an accident in the AC power system. Is switched to the voltage control means, so that even if the generator motor is cut off from the AC power system due to an AC power system accident, there is no overvoltage and no damage to the equipment.

Further, the power converter according to the present invention includes a fluctuation detecting means for detecting the presence or absence of fluctuation in the AC power system, and when the fluctuation is detected, the control means which is enabled is supplied from the reactive power control means to the voltage control section. Since the control unit is switched to the control unit, even if the generator motor is disconnected from the AC power system due to the fluctuation of the AC power system, an overvoltage does not occur and the device is not damaged.

Further, the power converter according to the present invention is provided with an accident recovery detecting means for detecting the recovery of an accident in the AC power system. Since switching to the reactive power means is performed, when the AC power system recovers from the accident, it is possible to return to the original reactive power control operation.

Further, the power converter according to the present invention includes a fluctuation detecting means for detecting the presence or absence of fluctuation in the AC power system, and after detecting the absence of the fluctuation, the control means for making the power valid becomes the reactive power from the voltage control means. Since the control is switched to the control means, when the fluctuation of the AC power system stops, the original reactive power control operation can be returned.

The power converter according to the present invention further comprises means for inputting a reclosing signal after the occurrence of an accident in the AC power system. Since the means is switched to the reactive power control means, even if the open phase state continues for a predetermined time due to an accident or fluctuation of the AC power system, the voltage control is maintained during the continuation, so that the voltage of the generator motor can be safely reduced. Value can be kept.

Further, the power conversion device according to the present invention is characterized in that the control means is enabled after a predetermined time has passed after detecting recovery from an accident, detecting no shaking, or inputting a reclosing signal. Is switched from the voltage control means to the reactive power control means, and the AC power system is returned to the reactive power control means in a sufficiently stabilized state, so that the switching operation of the control means is performed more smoothly.

Further, the power conversion device according to the present invention switches the control means to be enabled from the reactive power control means to the voltage control means, and then detects normality of the AC power system and then returns to the original reactive power control means. In the period before switching,
Since the output upper limit value of the voltage control means is set to the suppression upper limit value which is lower than the allowable maximum upper limit by a predetermined amount, the voltage overshoot after the elimination of the accident can be reliably suppressed.

Further, the power converter according to the present invention includes active power fluctuation detecting means for detecting the presence or absence of fluctuation of the active power in the AC power system, and the control means to be enabled is changed from the reactive power control means to the voltage control means. After the switching, the output upper limit value of the voltage control means is set to a suppression upper limit value which is lower than the allowable maximum upper limit by a predetermined amount before the active power fluctuation detecting means detects the absence of fluctuation. The timing of the cancellation of the upper limit suppression of the means is more reliably determined.

Further, in the power converter according to the present invention, the suppression upper limit value is set to the output value of the reactive power control means immediately before switching the control means to be effective from the reactive power control means to the voltage control means. Even if the upper limit of the voltage control means is suppressed, the output of the original reactive power amount is secured.

Further, the power converter according to the present invention includes a system cutoff detecting means for detecting whether or not the AC power system is cut off on the primary side of the generator motor. After switching to the control means, the control means to be enabled is switched from the voltage control means to the reactive power control means under the condition that the system cutoff detecting means detects no interruption, so that when the AC power system is cut off, Since the voltage control is maintained without switching to the control, occurrence of an overvoltage due to disconnection and opening is prevented.

Further, the power converter according to the present invention determines the occurrence or return of an accident in the AC power system from the magnitude of the current on the primary side or the secondary side of the generator motor. Occurrence and return can be easily detected.

Further, the power converter according to the present invention determines occurrence or return of an accident in the AC power system from the magnitude of the voltage on the primary side or the secondary side of the generator motor. Occurrence and return can be easily detected.

Further, the power converter according to the present invention determines the presence or absence of fluctuations in the AC power system from the time change rate of the voltage amplitude value on the primary side of the generator motor, so that the timing at which the control means should be switched can be more reliably determined. Can be detected.

Further, since the power converter according to the present invention determines the presence or absence of fluctuation in the AC power system from the time change rate of the power value on the primary side of the generator motor, the timing at which the control means should be switched is more reliably determined. Can be detected.

In the power converter according to the present invention, when the control means to be enabled is switched from the reactive power control means to the voltage control means, the output of the reactive power control means immediately before the switching is changed to the initial value of the voltage control means. When the control means to be enabled is switched from the voltage control means to the reactive power control means, the output of the voltage control means immediately before the switching is used as the initial value of the reactive power control means. The control operation is performed smoothly.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a power conversion device according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram showing a power conversion device according to Embodiment 2 of the present invention.

FIG. 3 is a configuration diagram showing details of an accident detection unit 13 of FIG. 2;

FIG. 4 is a configuration diagram showing a power conversion device according to Embodiment 3 of the present invention.

FIG. 5 is a configuration diagram showing details of the accident detection means 13 of FIG. 4;

FIG. 6 is a timing chart showing the operation of the third embodiment of the present invention.

FIG. 7 is a configuration diagram showing a power conversion device according to Embodiment 4 of the present invention.

FIG. 8 is a configuration diagram showing details of the accident detection means 13 of FIG. 7;

FIG. 9 is a configuration diagram illustrating a power conversion device according to a fifth embodiment of the present invention.

FIG. 10 is a configuration diagram showing details of the accident detection means 13 of FIG. 9;

FIG. 11 is a configuration diagram showing a power conversion device according to Embodiment 6 of the present invention.

FIG. 12 is a configuration diagram showing a power conversion device according to Embodiment 7 of the present invention.

FIG. 13 is a configuration diagram illustrating a power conversion device according to an eighth embodiment of the present invention.

FIG. 14 is a configuration diagram illustrating details of an upper limit value setting unit 15 of FIG. 13;

FIG. 15 is a configuration diagram showing a power conversion device according to Embodiment 9 of the present invention.

FIG. 16 is a configuration diagram showing details of an upper limit value setting unit 16 of FIG. 15;

FIG. 17 is a configuration diagram showing a power conversion device according to Embodiment 10 of the present invention.

18 is a configuration diagram illustrating details of an upper limit value setting unit 17 of FIG. 17;

FIG. 19 is a configuration diagram showing a power conversion device according to Embodiment 11 of the present invention.

FIG. 20 is a configuration diagram showing details of the motion detection means 18 of FIG. 19;

FIG. 21 is a configuration diagram showing a power conversion device according to Embodiment 12 of the present invention.

FIG. 22 is a configuration diagram showing details of the accident detection means 12 of FIG.

FIG. 23 is a configuration diagram showing a conventional power converter.

[Explanation of symbols]

1 AC power system, 2 transformers, 3 generator motors, 4
Current control type power conversion circuit, 5 current detector, 6 voltage detector, 7 power detection means, 8 power control means, 9 AC voltage amplitude detection means, 10 voltage control means, 11 switching means, 12 control selection means, 13 accident Detection means, 14
Logic inversion means, 15 to 18 upper limit value setting means, 19 fluctuation detection means, 20 system control means, 21 circuit breaker, C
Selection signal, Qref reactive power command, Vref voltage command, I
2Qref1, I2Qref2 Secondary current command, P, Q power detection value, V voltage amplitude value.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaru Shimomura 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Kotaro Higashi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F term in Ryo Denki Co., Ltd. (reference) 5G066 CA03 DA04 FA01 FB11 FB17 FC11 5H420 BB03 BB12 BB14 BB15 BB16 CC04 DD04 FF03 FF04 FF05 FF24 FF25 KK01 KK04 LL01 LL04

Claims (17)

[Claims] 1. A power converter having an AC side connected to an AC power system, a reactive power detecting means for detecting reactive power on the AC side of the power converter, and the reactive power detection value coincides with a reactive power command value. A power conversion apparatus having reactive power control means for controlling the power converter as described above, comprising: voltage detection means for detecting a voltage on the AC side of the power converter; and detecting occurrence and return of an accident in the AC power system. Fault recovery detection means, and voltage control means for controlling the power converter so that the detected voltage value matches the voltage command value, the reactive power control means or the voltage according to the output of the fault recovery detection means A power converter characterized in that the control means is switched so as to enable one of the control means. 2. A generator motor having a primary side connected to an AC power system, a power converter having an AC side connected to a secondary side of the generator motor, and a reactive power detecting means for detecting reactive power on a primary side of the generator motor. And a reactive power control unit including a reactive power control unit that controls the power converter so that the reactive power detection value matches the reactive power command value, wherein a voltage detection unit that detects a voltage on a primary side of the generator motor; And voltage control means for controlling the power converter so that the detected voltage value matches the voltage command value, and the control means is switched so that one of the reactive power control means and the voltage control means becomes effective. A power converter characterized by the following. 3. An accident detection means for detecting occurrence of an accident in an AC power system, wherein when the occurrence of the accident is detected, the control means to be enabled is switched from the reactive power control means to the voltage control means. The power converter according to claim 2, wherein 4. A vibration detecting means for detecting the presence or absence of a fluctuation in an AC power system, wherein when the fluctuation is detected, the control means to be enabled is switched from the reactive power control means to the voltage control means. The power converter according to claim 2. 5. An accident recovery detecting means for detecting recovery of an accident in an AC power system, wherein after detecting the recovery of the accident, the control means to be enabled is switched from the voltage control means to the reactive power means. The power converter according to claim 3 or 4, wherein 6. A vibration detecting means for detecting the presence or absence of vibration in the AC power system, and after detecting no vibration,
5. The power converter according to claim 3, wherein the control means to be enabled is switched from the voltage control means to the reactive power control means. 7. A means for inputting a reclosing signal after the occurrence of an accident in an AC power system, wherein after the reclosing signal is inputted, the control means to be enabled is switched from the voltage control means to the reactive power control means. The power converter according to claim 3 or 4, wherein: 8. After a predetermined time elapses after detecting recovery from the accident in claim 5, after detecting no shaking in claim 6, or after inputting a reclosing signal in claim 7, the validity is determined. A power conversion device, wherein the control means for performing the switching is switched from the voltage control means to the reactive power control means. 9. An output upper limit value of said voltage control means is allowed within a period up to halfway of a predetermined time after switching the control means to be enabled from the reactive power control means to the voltage control means. A power conversion device characterized in that the suppression upper limit is set to a predetermined lower limit than the maximum upper limit. 10. An active power fluctuation detecting means for detecting presence or absence of fluctuation of active power in an AC power system, wherein the control means to be enabled is switched from the reactive power control means to the voltage control means, and then the active power fluctuation detection is performed. 9. The apparatus according to claim 5, wherein the output upper limit value of the voltage control means is set to a suppression upper limit value lower by a predetermined amount than the allowable maximum upper limit value within a period until the means detects no fluctuation. 3. The power converter according to claim 1. 11. The method according to claim 9, wherein the suppression upper limit value is an output value of the reactive power control means immediately before switching the control means to be effective from the reactive power control means to the voltage control means. Power converter. 12. A system according to claim 1, further comprising: a system cutoff detecting means for detecting whether or not the AC power system has been cut off on the primary side of the generator motor, wherein the control means to be enabled is switched from the reactive power control means to the voltage control means. The power converter according to any one of claims 5 to 11, wherein the control unit that is enabled is switched from the voltage control unit to the reactive power control unit under a condition that the cutoff detection unit detects that there is no cutoff. 13. The method according to claim 3, wherein the occurrence or return of an accident in the AC power system is determined from the magnitude of the current on the primary side or the secondary side of the generator motor.
13. The power converter according to any one of claims 12 to 12. 14. The method according to claim 3, wherein the occurrence or return of an accident in the AC power system is determined from the magnitude of the voltage on the primary side or the secondary side of the generator motor.
13. The power converter according to any one of claims 12 to 12. 15. The presence or absence of fluctuation in the AC power system
The power converter according to any one of claims 4 to 12, wherein the determination is made based on a time change rate of a voltage amplitude value on a primary side of the generator motor. 16. The presence or absence of fluctuation in the AC power system
The power converter according to any one of claims 4 to 12, wherein the determination is performed based on a temporal change rate of the power value on the primary side of the generator motor. 17. When the control means to be enabled is switched from the reactive power control means to the voltage control means, an output of the reactive power control means immediately before the switching is set as an initial value of the voltage control means, 17. The electric power according to claim 1, wherein when switching from the voltage control means to the reactive power control means, an output of the voltage control means immediately before the switching is used as an initial value of the reactive power control means. Conversion device.