JP2002359928A - Voltage variation compensator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost and the size of a voltage variation compensator, which is fitted with a detection control unit for monitoring voltage lowering in a power system, and for controlling power supply on the basis of that, and suppresses variations in the voltage supplied to a load, and to realize high- precision voltage compensation. SOLUTION: By connecting in series to the power system a plurality of voltage compensating circuits P, N which convert DC voltages stored in capacitors 11 having charged voltages different respectively (approximately 2K times a minimum voltage (K=0, 1, 2, and so on)) into ACs and output them, and collating the quantity of voltage lowering of the power system with reference values, using detected voltage values V1-V3 of capacitors 11 in each compensating circuit P, N as the reference values for individual bit signals, the quantity is analog-to-digital converted into a binary signal. Using this signal, compensating circuits P, N of a desired combination are selected, and voltage lowering of the power system is compensated for by the sum of their output voltages.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage fluctuation compensator for detecting when a voltage of a power system supplied to a load drops instantaneously and compensating for the voltage drop.

[0002]

2. Description of the Related Art Lightning or the like instantaneously lowers the voltage of an electric power system, and erroneous operation or temporary stoppage of precision equipment in factories or the like may cause serious damage to production lines. In order to prevent such damage, a voltage fluctuation compensating device that monitors a voltage fluctuation such as an instantaneous voltage drop of a power system and compensates for the voltage drop has been used. FIG. 18 shows a schematic configuration diagram of a conventional voltage fluctuation compensation device. As shown in the figure,
The power from the transmission line 1 is stepped down by the transformer 2 and connected to the customer 3 (load) via the voltage fluctuation compensator,
Power is supplied. The voltage fluctuation compensator is a DC power supply 4,
Inverter 5, smoothing filter 6, and large capacity transformer 7
It consists of. The voltage compensation operation in such a conventional voltage fluctuation compensating device when the system voltage instantaneously drops (hereinafter, referred to as an instantaneous sag) will be described below. FIG. 19 shows the system voltage, the output of the voltage fluctuation compensation circuit, and the voltage supplied to the customer 3 when the system voltage is momentarily dropped. As shown in the figure, when an instantaneous voltage drop occurs in the system voltage, a detection unit (not shown) that monitors voltage fluctuations
Detects a voltage drop at
In the voltage fluctuation compensating device, an AC voltage is generated by the DC power supply 4 and the inverter 5 and connected in series to the power system via the smoothing filter 6 and the large-capacity transformer 7.
Compensate for voltage drops in the power system. Thereby, the customer 3
, The output voltage from the voltage fluctuation compensator is added to the reduced system voltage, and power is supplied at a substantially normal voltage.

[0003]

Since the conventional voltage fluctuation compensating apparatus is configured as described above, even when the system voltage is normal, a load current equivalent to the load current flows to the inverter 5 via the transformer 7. As a result, a loss between the transformer 7 and the inverter 5 occurs during normal operation, and a large-sized cooling device is required. In addition, when the system voltage is dropped, a voltage is supplied to the power system via the smoothing filter 6 and the transformer 7, so that the capacities of the smoothing filter 6 and the transformer 7 are increased, and there is a problem that the size of the apparatus is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to perform highly accurate voltage compensation at the time of an instantaneous drop of system voltage, and to make the whole apparatus inexpensive and compact. It is an object of the present invention to obtain a voltage fluctuation compensator that can be used.

[0005]

Means for Solving the Problems Claim 1 according to the present invention.
The voltage fluctuation compensator described above includes a detection control unit that monitors a voltage drop in a power system and controls power supply based on the voltage fluctuation. In the voltage fluctuation compensator that suppresses voltage fluctuation supplied to a load, different voltages are accumulated. A plurality of voltage compensating circuits that convert the DC voltage stored in the energy storing means into an alternating current and output the AC voltage, and connect the voltage compensating circuits in series with the power system, The voltage value of the voltage stored in the energy storage means in each voltage compensating circuit is set as a reference value of each bit signal, and is compared with the reference value to convert the binary signal into an A / A signal.
D conversion is performed, and a desired combination is selected from the plurality of voltage compensating circuits according to the signal, and a voltage drop of the power system is compensated by the sum of the output voltages.

According to a second aspect of the present invention, there is provided a voltage fluctuation compensating apparatus according to the first aspect, wherein the absolute value of each of the different voltages stored in the energy storage means in the plurality of voltage compensating circuits is set to the smallest voltage. the output voltage of the compensation circuit generally ^{2 K} times the (absolute value) (K = 0,1,2, ···)
It was made.

According to a third aspect of the present invention, there is provided a voltage fluctuation compensating apparatus according to the first or second aspect, wherein the energy storage means is a capacitor.

According to a fourth aspect of the present invention, in the voltage fluctuation compensating apparatus according to the third aspect, the A / A
The charge voltage value of the capacitor, which is a reference value for D conversion, is a voltage detection value obtained by detecting the voltage of each capacitor as needed.

According to a fifth aspect of the present invention, in the voltage fluctuation compensating apparatus according to the third aspect, the A / A
The charging voltage value of the capacitor, which is a reference value for D conversion, is a voltage calculation value that is calculated as needed by monitoring the system current of the power system and predicting the voltage drop amount of each capacitor based on the current value. is there.

According to a sixth aspect of the present invention, there is provided a voltage fluctuation compensating apparatus according to any one of the third to fifth aspects, wherein the maximum possible output voltage of all the compensating circuits including all the voltage compensating circuits connected in series is: The charging voltage of the capacitor in each voltage compensation circuit is set so as to exceed the maximum voltage drop amount in the power system.

According to a seventh aspect of the present invention, there is provided a voltage fluctuation compensating apparatus according to any one of the third to sixth aspects, wherein the capacitance of the capacitor in each voltage compensating circuit increases as the charging voltage of the capacitor increases. It is set to be small.

[0012] voltage fluctuation compensation device according to claim 8, wherein according to the present invention, in claim 7, the capacitance of the capacitor in each voltage compensation circuit, approximate 2 ^K times the smallest capacitance value (K = 0, 1, 2,...) Or more, and is set smaller as the charging voltage of the capacitor becomes higher.

According to a ninth aspect of the present invention, in the voltage variation compensating apparatus according to any one of the third to eighth aspects, when the A / D conversion is performed from a voltage drop amount to a binary signal, the signal is determined by the signal. When the sum of the output voltages of the voltage compensating circuits is equal to or less than a voltage value obtained by subtracting a predetermined voltage amount from the voltage drop amount, the minimum charging voltage value of the capacitor is added to the sum of the output voltages. One is added to a binary signal.

According to a tenth aspect of the present invention, there is provided a voltage fluctuation compensating apparatus according to the third aspect, which is connected in series to a power system together with a voltage compensating circuit, converts a DC voltage charged in a capacitor into an AC, and outputs the AC. A sag voltage compensating circuit, and when the voltage of the capacitor in the voltage compensating circuit falls below a predetermined value, the sag voltage compensating circuit is detected and operated in accordance with the operation of the voltage compensating circuit. The voltage drop of the power system is compensated by the sum of the output voltages of the voltage compensation circuit and the sag voltage compensation circuit.

In the voltage fluctuation compensating apparatus according to the present invention, the voltage compensating circuit selected by the binary signal may have an output voltage whose polarity is opposite to the voltage polarity of the power system. And the capacitor in the voltage compensation circuit whose output voltage has the same polarity as the power system is discharged during operation, and the capacitor in the voltage compensation circuit having the opposite polarity is charged during operation.

According to a twelfth aspect of the present invention, in the voltage fluctuation compensating apparatus according to the eleventh aspect, each bit value is converted from a binary signal to 1 when the capacitor is discharged and to 1 when the capacitor is charged. Converted to a binary value of 1
A logic table for selecting a combination of the voltage compensating circuits is created, a voltage drop of a capacitor in each voltage compensating circuit is detected, and a binary value of a mode in which the capacitor can be charged is determined according to the state. A capacitor in the voltage compensation circuit selected from the logic table and selected according to each bit value of the binary value is discharged when the bit value is 1, and charged when the bit value is -1.

According to a thirteenth aspect of the present invention, in the eleventh aspect, the output voltage of one of the voltage compensating circuits has the first polarity and the output voltages of all the other voltage compensating circuits are the same. The second polarity opposite to the first polarity, and the charging voltage of the capacitor in the voltage compensation circuit of the first polarity is:
When the sum and absolute value of the charging voltages of the capacitors in all the other second polarity voltage compensating circuits are substantially the same and the voltage of the power system is the first polarity, the desired voltage of the second polarity voltage compensating circuit And the voltage compensating circuit of the first polarity is selected and operated, and when the voltage of the power system has the second polarity, a combination of only the voltage compensating circuit of the second polarity is selected and operated. .

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described in detail. FIG. 1 is a configuration diagram of a voltage fluctuation compensating apparatus according to Embodiment 1 of the present invention. The power from the transmission line 1 is stepped down by the transformer 2 and is passed through the voltage fluctuation compensating device 100 to the customer 3 (load).
And power is supplied. Voltage fluctuation compensator 10
At 0, as shown in the figure, a plurality of compensation units 110 each composed of two voltage compensation circuits P and N selected according to the polarity of the voltage are connected in series to the power system. The all-compensation circuit 120 composed of a plurality of (in this case, six) voltage-compensation circuits N1, P1, N2, P2, N3, and P3 connected in series has an output terminal connected in parallel with the all-compensation circuit 120. A high-speed mechanical steady short-circuit switch 8 is provided. Each of the voltage compensating circuits P1 to P3 and N1 to N3 has a voltage sag switch 9 and a voltage sag compensating switch 1 provided in parallel at the output terminals.
0, a charging capacitor 11 as an energy storage means, a charging diode 12 for charging the charging capacitor 11, and a secondary winding 14 of a charging transformer 200. The charging voltage of the charging capacitor 11 is Are connected to the power system by the sag compensation switch 10 connected in series. In addition, the sag switch 9
The instantaneous sag compensation switch 10 is configured by a semiconductor switching element in which a diode is connected in anti-parallel, for example, an IGBT. The semiconductor switching element is I
A self-extinguishing element other than the GBT may be used.

The charging capacitor 11 includes a charging diode 12
The voltage is charged by the secondary winding 14 of the charging transformer 200 and the charging primary winding 13 is connected to the power system. Reference numeral 15 denotes a core of the charging transformer 200. Two voltage compensation circuits P and N in one compensation unit 110 are responsible for generating positive and negative voltages, respectively. That is, by the action of the two charging diodes 12p and 12n, the charging capacitor 11p and the charging capacitor 11p
The n and n are charged with the same magnitude by using the common secondary winding 14 with voltages of opposite polarities. Each compensation unit 1
Charging capacitor 11 in (10 (11p1, 11n1)
The ratio of the voltage charged to (11p2, 11n2) (11p3, 11n3)) is set to a power ratio of about 2. That is, the following relationship is satisfied. Vn3 = 2 × Vn2 = 2 × 2 × Vn1 (same for p)

The steady short-circuit switch 8, the instantaneous sag switch 9, and the sag compensation switch 10 are connected to a voltage sag control circuit 16 as a detection control unit. The system voltage is also input to the voltage sag control circuit 16. The configuration and operation of the voltage sag control circuit 16 will be described below. FIG.
3 is a circuit diagram showing details of the voltage sag control circuit 16. FIG.
FIG. 3 is a waveform diagram showing the relationship between the operation of voltage compensation by voltage fluctuation compensating apparatus 100 shown in FIG. 1 and the control operation of voltage sag control circuit 16. As shown in FIG. 2, the system voltage is input to the voltage sag control circuit 16 and the target voltage 25
Is compared to At this time, the target voltage 25 is a normal system voltage. The difference between the two signals is amplified by the error amplifier 26 and further subjected to absolute value conversion, and then converted to a 3-bit digital signal (D1 to D3) by the A / D converter 27. The difference between the system voltage and the target voltage 25 is the charging capacitor 11p
The gain of the error amplifier 26 is adjusted in advance so that when the charging voltage Vp1 becomes equal to 1, only the least significant bit in the output signal from the A / D converter 27 becomes 1, ie, {001}.

When any one of the signals D1 to D3 becomes 1, the steady short-circuit switch 8 is turned off by the signal Z (= 0) through the NOR circuit 28. On the other hand, the system voltage input to the voltage sag control circuit 16 is also input to the polarity determination circuit 29 to determine the polarity. Then, depending on whether the polarity of the system voltage is positive or negative, the signals Yp or Yn, Xp or X that are activated by the digital signals D1 to D3.
n is selected via the AND circuit 30 and the inverter 31.
Xp and Xn are drive signals for the instantaneous sag compensation switch 10,
p and Yn are drive signals for the instantaneous voltage drop changeover switch 9, and the inverter 31 is configured so that the instantaneous voltage changeover switch 9 and the voltage sag compensation switch 10 always operate with opposite polarities. When the system voltage is normal, that is, when the digital signals D1 to D3 are all 0, the steady short-circuit switch 8 is turned on (the signal Z is 1), the voltage sag switch 9 is turned on (the signal Y is 1), and the voltage sag compensation switch. 10 is in the off state (signal X is 0), and the current flows through the steady short-circuit switch 8. At this time, the charging capacitor 11 is charged to a constant voltage by the charging transformer 200. Since the charging transformer 200 only has to work to charge the charging capacitor 11, it is sufficient to use a small-capacity transformer.

Next, a compensating operation at the time of a sag will be described with reference to FIG. At time t0, it is assumed that a voltage drop occurs instantaneously in the system voltage. After time t0, the error amplification circuit 2
An error voltage is generated at the output of No. 6. A /
Digital signals D1 to D3 are generated at the output of the D converter 27 according to the error voltage. At the same time, the signal Z becomes 0, and the steady short-circuit switch 8 is turned off. Time t0
At t1, since the polarity of the system voltage is positive, the digital signal D
1 to D3 are transmitted to the p-side elements, respectively. When the least significant bit signal D1 is 1, in the voltage compensating circuit P1, Xp1 becomes 1 and Yp1 becomes 0, the sag compensation switch 10p1 is turned on, and the sag switch 9p1 is turned off.
The voltage Vp1 of the charging capacitor 11p1 is output by the instantaneous sag compensation switch 10p1. When the signal D2 is 1,
In the voltage compensation circuit P2, Xp2 becomes 1 and Yp2 becomes 0, the sag compensation switch 10p2 is turned on, the sag switch 9p2 is turned off, and the voltage Vp2 of the charging capacitor 11p2 is output by the sag compensation switch 10p2.
Similarly, when the signal D3 of the most significant bit is 1, the voltage Vp3 of the charging capacitor 11p3 in the voltage compensation circuit P3.
Is output. Note that, among the digital signals D1 to D3, a signal which becomes 0 is, for example, a signal D of the least significant bit.
When 1 is 0, since Xp1 is 0 and Yp1 is 1 in the voltage compensating circuit P1, the output terminal is short-circuited by the instantaneous voltage drop switch 9p1, and the output from the voltage compensating circuit P1 becomes almost zero. These outputs are combined in a system to generate voltage outputs of eight gradations of {000} to {111}, and the maximum compensation voltage is 7 × Vp1. From time t1 to t2, since the polarity of the system voltage is negative, the digital signals D1 to D3 are transmitted to the n-side elements, respectively, and similarly output compensation voltages in the voltage compensation circuits N1 to N3. The compensation voltage is 7 × Vn1.

In the above description, the operation in an ideal state is described without considering the voltage change of the charging capacitor 11. However, since the capacitance of the capacitor is limited, the sag (voltage) is not applied to the charging capacitor 11. Decrease).
For example, when a sag occurs in the charging voltage Vp3 of the charging capacitor 11p3, the above-described binary signals (D1 to D3) are formed using the voltage sag control circuit 16 shown in FIG. Then, as shown in FIG. 4, the sag of the charging voltage Vp3 causes distortion in the generated compensation voltage. For this reason, the A / D converter for outputting a binary signal by the A / D converter 27 shown in FIG. 2 is preferably performed in consideration of the sag of the charging capacitor 11, which will be described below.

FIG. 5 is a block diagram showing the details of the A / D converter 27 for performing A / D conversion in consideration of the voltage drop of the charging capacitor 11. In the figure, 50 (50-1, 50)
-2, 50-3) are comparators, and 51-1 and 51-2 are arithmetic circuits using an arithmetic processor or the like. The charge capacitors 11 in each of the voltage compensation circuits P1 to P3 and N1 to N3
Is provided with a voltage detector to monitor the voltage, and inputs the detected voltage values V3, V2, V1 to the A / D converter 27. In this case, V3, V2, and V1 are the detected voltages of the charging capacitors 11p3, 11p2, and 11p3 of the p-side elements, respectively (see FIG. 1). As shown in FIG. 5, first, the output V3in of the error amplifier 26 and the voltage of V3 are compared by a comparator 50-3, and when V3in ≧ V3, 1 and V3
When in <V3, D3 is formed as 0. Next, in the arithmetic circuit 51-2, if D3 is 1, V2in = V3in-V
3, and when D3 is 0, V2in = V3in. Here, V2in represents a voltage that has not been compensated when a compensation voltage is output in the signal state of D3. Next, V2in
And V2 are compared by the comparator 50-2 to output D2. Next, V1in is calculated by the arithmetic circuit 51-1 in the same manner as described above. V1in represents a voltage at which compensation is insufficient when a compensation voltage is output in the signal states of D3 and D2. Finally, V1in and V1 are compared by the comparator 50-1.
1 is determined.

As described above, using the A / D converter 27 as shown in FIG. 5, the output of the error amplifier 26 that amplifies the amount of voltage drop in the power system is converted to binary signals (D1 to D3) by the A / D converter. At the time of conversion, each bit signal of a binary signal is determined by checking the voltage of each charging capacitor 11 with voltage detection values V3, V2, and V1 detected as needed. Therefore, according to the voltage state of the charging capacitor 11, the voltage compensation circuits P1 to P
3. Since a signal to be operated by selecting N1 to N3 is determined, accurate compensation can be realized. Thereby, even when sag occurs in the charging capacitor 11, distortion does not occur in the compensation voltage, so that the capacitance value of the charging capacitor 11 can be reduced.

In the first embodiment, a plurality of voltage compensating circuits N1, P1, N2, P2, N connected in series are connected.
3. Since the entire compensation circuit 120 composed of P3 is directly connected in series to the power system, a large transformer as in the related art is not required. Also, in parallel with the entire compensation circuit 120,
A high-speed mechanical steady short-circuit switch 8 is provided to
When the switch 10 is normal, the steady short-circuit switch 8 conducts and bypasses the current, so that the device loss during normal operation is almost zero, the cooling device can have a small capacity, and the entire device can be inexpensive and downsized. When the system voltage drops instantaneously, a plurality of voltage compensating circuits N1, P1, N2, P2, N each having a charging capacitor 11 charged with a different voltage.
3, a combination of P3 is selected by digital gradation control, and the voltage is compensated by the sum of the output voltages. Therefore, fine voltage compensation becomes possible, and an output filter is unnecessary or small. In addition, in contrast to a case where a response delay corresponding to the bandwidth of the output filter occurs in the case of generally used PWM control or the like, since the control method is digital gradation control,
The voltage can be compensated in real time, and the voltage can be compensated more accurately.

Each of the voltage compensating circuits P1 to P3, N1 to
The voltage charged in the charging capacitor 11 of N3 is Vn3
= 2 × Vn2 = 2 × 2 × Vn1 (p is also the same), so that the compensation voltage can be controlled at equal intervals with high precision. Furthermore, since the charging capacitor 11 can be slowly charged when the system voltage is normal via the charging transformer 200 connected to the power system, the charging transformer 200 has a small capacity and is sufficient, and the charging circuit is small and inexpensive. . In addition, since the charging is performed automatically, the device is simplified.

In the above embodiment, V3, V2 and V1 used in the A / D converter 27 are the voltage detection values of the charge capacitors 11p3, 11p2 and 11p1, respectively, of the p-side element. Is substantially constant irrespective of the polarity of the system voltage, the voltage state of each charging capacitor 11n of the n-side element changes in substantially the same manner as the p-side element. The voltage may be detected and its absolute value may be used. Further, two A / D converters 27 for the p-side and the n-side may be provided, and the voltage detection values of the corresponding charging capacitors 11 may be input to generate binary signals (D1 to D3). Well, in that case,
One of the output signals of the two A / D converters 27 is selected and used in accordance with the output of the polarity determination circuit 29 (see FIG. 2). Thereby, more accurate compensation can be realized. Furthermore, voltage detectors are provided for both the p-side and the n-side, and in accordance with the output of the polarity determination circuit 29,
One of the n-side voltage detectors may be selected and the detected voltage value may be used.

Further, in the first embodiment, one steady short-circuit switch 8 is provided at the output end of all compensation circuits 120 in parallel with all compensation circuits 120. However, as shown in FIG. The output terminals of P1 to P3 and N1 to N3 may be provided in parallel. Further, a steady short-circuit switch 8 may be provided for each output terminal of each compensation unit 110 composed of a pair of voltage compensation circuits P and N. Even if a plurality of stationary short-circuit switches 8 are provided, the control method is the same as that of a single short-circuit switch 8. Normally, all stationary short-circuit switches 8 are closed and all the voltage compensation circuits P1 to P3, N1 to N3 are closed. Bypass
When the voltage of the power system drops, all the steady short-circuit switches 8 are opened to compensate for the voltage drop of the power system by the voltage output from the voltage compensation circuits P1 to P3 and N1 to N3.

Further, in the first embodiment, the compensation unit 110 is constituted by the pair of voltage compensation circuits P and N. However, as shown in FIG. 7, one voltage compensation circuit PN outputs positive and negative voltages. Each compensation unit 110 may be configured. In the example shown in FIG. 7A, the voltage compensation circuit PN1
A full-bridge inverter including four semiconductor switching elements 17a to 17d in which diodes are connected in anti-parallel, and a charging capacitor 1 as energy storage means
8 and the charging voltage Vpn1 of the charging capacitor 18 is
The semiconductor switching elements 17a to 17d are connected to the power system with either positive or negative polarity by on / off control.
In the example shown in FIG. 7B, the voltage compensation circuit PN1
A half-bridge inverter composed of two semiconductor switching elements 19p1 and 19n1 connected in anti-parallel diodes, and two semiconductor switching elements 20p1 and 20n1 connected in anti-parallel diodes connected in series in the reverse direction to generate a voltage. An instantaneous voltage drop switch connected in parallel to the output terminal of the compensation circuit PN1 and charging capacitors 21p1 and 21n1 as energy storage means are provided. Compensation of either positive or negative polarity is performed by on / off control of the semiconductor switching elements 19 and 20. A voltage is output.

Embodiment 2 Next, a second embodiment of the present invention will be described. FIG. 8 is a configuration diagram showing details of the A / D converter 27 according to the second embodiment of the present invention. As shown in the figure, the A / D converter 27 has a prediction operation circuit 52 that predicts and calculates the voltage of each charging capacitor 11.
(52-1, 52-2, 52-3). Further, the system current of the power system is monitored, and each prediction operation circuit 52
The current value of the system current and the A / D converter 27
, And corresponding signals in the digital signals (D1 to D3). In each prediction operation circuit 52,
The voltage value of each charging capacitor 11 is predicted and calculated based on the current value of the system current and each digital signal (D1 to D3). The calculation result is a voltage prediction calculation value V as a voltage calculation value.
1x to V3x, and is output as shown in FIG.
Are input to the comparators 50 (50-1, 50-2, 50-3) instead of the voltage detection values V1 to V3 shown in FIG. 5, and the other components are the A / D converters shown in FIG. It operates similarly to 27 and outputs each digital signal (D1 to D3).

FIG. 9 shows an example of each prediction operation circuit 52. Here, a prediction calculation circuit 52 that predicts and calculates the voltage of the charging capacitor 11p3 (or 11n3).
-3 is shown as a representative. While the digital signal D3 is 1, the voltage compensation circuit P3 outputs the compensation voltage from the charging capacitor 11p3, and the current value of the system current is input to the integration circuit 54 and integrated. As a result, the amount of voltage drop of the charging capacitor 11p3 is calculated and output to the output of the integration circuit 54. In the subtractor 55, the integration circuit 5 is calculated from the initial charging voltage set value Vp3 of the charging capacitor 11p3.
4 by subtracting the output of the charging capacitor 1
A voltage prediction calculation value V3x of 1p3 is obtained.

As described above, by using the A / D converter 27 as shown in FIG. 8, the output of the error amplifier 26 that amplifies the amount of voltage drop of the power system is converted to binary signals (D1 to D3) by A / D conversion. At the time of conversion, the voltage of each charging capacitor 11 is calculated at any time by a prediction calculation, and the voltage prediction calculation values V3x, V2
x, V1x, and each bit signal of the binary signal is determined. Therefore, as in the first embodiment, the voltage compensating circuits P1 to P1 depend on the voltage state of the charging capacitor 11.
A signal to be operated by selecting P3 and N1 to N3 can be determined, and accurate compensation can be realized. Thereby, even when sag occurs in the charging capacitor 11, no distortion occurs in the compensation voltage.
Can be reduced. Also, the charging capacitor 11
Since the voltage calculation value obtained by predicting and calculating the voltage is used, it is not necessary to provide a voltage detector in each capacitor 11, and the above-described effects can be obtained with an inexpensive device configuration.

Embodiment 3 Next, a third embodiment of the present invention will be described. FIG. 10 is a configuration diagram of a voltage fluctuation compensation device according to Embodiment 3 of the present invention. As shown in the figure,
A sag compensation unit 110S is provided in addition to the three compensation units 110 shown in FIG. 1 of the first embodiment. The configuration of the sag compensating unit 110S is the same as that of the other compensating units 110. The sag compensating unit 110S includes two sag voltage compensating circuits PS and NS that respectively control positive and negative voltage generation. An instantaneous sag switch 9, an sag compensation switch 10, a charging capacitor 11 as an energy storage means,
A charging diode 12 for charging the charging capacitor 11; and a secondary winding 14 of the charging transformer 200. The charging voltage of the charging capacitor 11 is set to a voltage sag compensating switch 10 connected in series to the charging capacitor 11. Connected to the power system.

The voltage fluctuation compensator 1 configured as described above
The voltage compensation operation at 00 will be described with reference to FIG. In the figure, Xps is a drive signal for the instantaneous sag compensation switch 10ps in the sag voltage compensation circuit PS. When sag occurs in the charging voltage Vp3 of the charging capacitor 11p3, waveform distortion occurs in the compensation voltage as described above. The waveform distortion due to such sag is corrected by operating the sag voltage compensation circuit PS. That is, in FIG. 11, when the voltage of Vp3 drops below the preset sag compensation switching voltage, it is detected and the drive signal X
Whenever p3 becomes 1, the drive signal Xps is set to 1 so that the sag voltage compensation circuit PS also outputs the compensation voltage. The sag compensation switching voltage is, for example, a point at which the voltage drop amount of Vp3 matches the initial charging voltage value of the charging capacitor voltage Vps of the sag voltage compensating circuit PS. As a result, the sag of Vp3 is corrected by the sag voltage compensating circuit PS, and the compensation voltage has a waveform with little distortion.

FIG. 12 illustrates the voltage sag control circuit 16 according to the third embodiment, and corrects sag of Vp3, for example. When Vp3 falls below the sag compensation switching voltage, the comparator 56 and the AND circuit 57
Thus, the sag voltage compensating circuit PS is configured to perform the voltage compensating operation. Thereby, the charging capacitor 1
Even if sag occurs in the voltage of 1, the waveform distortion does not occur, and the capacitance value of the charging capacitor 11 can be greatly reduced. Thereby, an inexpensive device can be configured.

In the above embodiment, the p-side element has been described, but the same applies to the n-side element.
The sag of Vn3 is corrected by the sag voltage compensating circuit NS. Further, the case where the sag of the voltage of the charging capacitors 11p3 and 11n3 is corrected has been described, but a sag voltage compensating circuit that corrects the sag of another charging capacitor 11 may be provided.

Embodiment 4 FIG. Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, a method for setting the voltage of the charging capacitor 11 in each compensation unit 100 will be described. Since the charging capacitor 11 has only a finite capacitance, sag always occurs. As the sag increases, the compensable voltage decreases. For this reason, a large charging voltage is set in advance in the charging capacitor 11 so that the voltage drop of the system voltage can be completely compensated even when sag occurs. For example, assuming that the maximum voltage drop amount during an instantaneous drop of the system voltage (within a predetermined duration) is ΔVmax, each voltage is set as follows. Vp3, Vn3> (. DELTA.Vmax / 7) .times.4 Vp2, Vn2> (. DELTA.Vmax / 7) .times.2 Vp1, Vn1> (. DELTA.Vmax / 7) .times.1 Depending on the setting method, the relationship between the respective voltages is 2 as described above. there may deviate slightly from the relationship ^K times (K = 0, 1, 2), if in the approximate ^{2 K} multiple of,
The accuracy of the compensation voltage does not decrease. By setting such a voltage, even if sag occurs in the charging capacitor 11, although the voltage is reduced, a sufficient compensation voltage can be secured. Thereby, the capacitance value of the charging capacitor can be designed to be small, and an inexpensive device can be realized.

Embodiment 5 Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, a method of setting the capacitance value of the charging capacitor 11 in each compensation unit 100 will be described. As described above, since the charging capacitor 11 has only a finite capacitance, a sag always occurs. Therefore, for example, any of the charging capacitor 11 is also left to choose the same capacitance value, although the magnitude of the sag is generally the same, the ratio of sag to the initial charging voltages are different, the voltage approximate 2 ^K times the relationship Will collapse. For this reason, the capacitance value is selected as follows. Note that, for example, the capacitance value of the charging capacitor 11p1 is Cp
Expressed as 1. Cp1 (Cn1) ≒ 2 × Cp2 (Cn2) Cp2 (Cn2) ≒ 2 × Cp3 (Cn3)

[0040] Thus, by the electrostatic capacitance of the charging capacitor 11 is set higher the charging voltage decreases, resulting in even approximate 2 ^K multiple of the electrostatic capacitance value, when the same current flows, the since the ratio of sag to the initial charging voltage are the same, when the sag occurs, also approximate 2 ^K multiple of voltage relationship for each charging capacitor 11 is maintained. Therefore, even when voltage sag occurs, accurate voltage compensation can be realized.

The capacitance value of each charging capacitor 11 may be selected as follows. Cp1 (Cn1) ≧ 2 × Cp2 (Cn2) Cp2 (Cn2) ≧ 2 × Cp3 (Cn3) By setting in this way, even when the same current flows, the voltage of the charging capacitor 11 having a low charging voltage decreases. Nikuku becomes hardly approximate 2 ^K times the relationship impaired, even when the voltage sag occurs, allowing accurate voltage compensation.

Embodiment 6 FIG. Next, a sixth embodiment of the present invention will be described. In general, when determining the device specifications, it is necessary to consider the maximum guaranteed voltage drop at the customer 3 during an instantaneous sag. For example, assuming that the voltage drop guarantee value is Vz, it is necessary to compensate the voltage so that the voltage drop amount of the supply voltage to the customer 3 is equal to or less than Vz. The minimum voltages Vp1 and Vn1 of the charging capacitor 11 are calculated from the guaranteed voltage drop Vz.
Is set to be large, in the above-mentioned A / D conversion by the A / D converter 27 shown in FIG.
3 is determined to be Vz
Even if the above is not more than V1, D1 does not become 1. Therefore, although the voltage fluctuation compensating apparatus 100 has the ability to output a voltage, the voltage supplied to the customer decreases by Vz or more from the normal state. Therefore, when the minimum voltages Vp1 and Vn1 of the charging capacitor 11 are set to be higher than the guaranteed voltage drop Vz,
The D conversion will be described below.

FIG. 13 is a configuration diagram showing details of the A / D converter 27 according to the sixth embodiment. As shown in the figure, the output V3in of the error amplifier 26 and the voltage of V3 are compared by a comparator 50-3, and when V3in ≧ V3, 1 and V3
When in <V3, D3a is formed as 0. Next, in the arithmetic circuit 51-1, if D3a is 1, V2in = V3in
−V3, and when D3a is 0, V2in = V3in. Here, V2in represents a voltage that has not been compensated when a compensation voltage is output in the signal state of D3a. Next, V2in and V2 are compared by the comparator 50-2, and D2
2a is output. Next, in the same manner as above, the arithmetic circuit 51-2
Calculate V1in. V1in represents a voltage at which compensation is insufficient when a compensation voltage is output in the signal state of D3a and D2a. Next, V1in and V1 are compared with the comparator 50-1.
And D1a is determined. Next, the uncompensated voltage ΔV when each of the voltage compensation circuits P and N operates and outputs a compensation voltage is obtained by the arithmetic circuit 58 by the digital signals (D1a to D3a) determined in this way. In the arithmetic operation circuit 59, when ΔV ≧ Vz, add = 1 is set, and in the logical operation circuit 60, the digital signals (D1a to D3
is added to the binary number according to a). For example, D1a = 1,
Assuming that D2a = 0 and D3a = 0, the following logical operation is performed when add = 1. 001 + 1 = 010 As a result, signals of D1 = 0, D2 = 1, and D3 = 0 are output.

As described above, when ΔV ≧ Vz in the arithmetic circuit 59, the compensation power obtained by adding the voltage corresponding to the minimum voltage Vp1 (Vn1) of the charging capacitor 11 is obtained.
To determine the digital signals (D1 to D3), the customer 3
The amount of voltage decrease of the supply voltage to Vz is equal to or less than Vz. In the present embodiment, even when the minimum voltage of the charging voltage of the capacitor 11 is set to be larger than the guaranteed voltage drop Vz, the function of supplying the customer 3 with a voltage equal to or lower than the normal voltage minus Vz is given priority. Work. Thereby, the voltage of the charging capacitor 11 in each of the voltage compensating circuits P and N can be set high, and the capacitance of the charging capacitor 11 can be reduced. When such control is performed, the customer 3
The supply voltage to the power supply may increase from a normal value, but there is no problem if the amount of increase in the voltage is small.

Embodiment 7 Next, a seventh embodiment of the present invention will be described. When the amount of voltage drop in the power system is relatively small, only the voltage compensating circuits (for example, P1 and N1) having the charging capacitors 11 having a small charging voltage operate, and voltage sag is generated only in those charging capacitors 11 so that electric charges are generated. Disappears quickly. In the seventh embodiment, when the amount of voltage drop is small as described above, the charge of the charging capacitor 11 having a high charging voltage is used to suppress the voltage sag of the charging capacitor 11 having a low charging voltage. 1
4 will be described below. When the voltage compensating circuits P and N are selected by the 3-bit digital signals (D1 to D3) to perform the voltage compensating operation, the voltage gradation S is 1, 2, 3,
There are seven types, 4, 5, 6, and 7. To realize this voltage gradation command, a digital signal (D1, D2,
A logic table 62 as shown in the figure is created by making the value of D3) both -1 and +1 possible. In the logic table 62, +1 indicates a discharging operation and -1 indicates a charging operation. For example, in the voltage fluctuation compensating apparatus 100 as shown in FIG. 1, when the phase of the system current is the same as the phase of the system voltage, the required compensation voltage is positive, and the logic is +1, the P-side charging capacitor. The voltage compensating circuits P and N are selected and operated so that the charging capacitor 11n on the N side is charged when 11p is discharging and -1. That is, the operation of the voltage compensating circuit P whose output voltage is the same polarity as the system voltage is a discharging operation (+1), the operation of the voltage compensating circuit N whose output voltage is the opposite polarity is a charging operation (-1), and the discharging voltage is Then, the voltage obtained by subtracting the charging voltage from is output from all the compensation circuits 120 as a compensation voltage.

That is, as can be seen from the logic table 62, when 1 is output as the voltage gradation S value, there are three types of 2
Hexadecimal signal can be selected. For example, the voltage of the compensation unit 110 (voltage compensation circuits P1, N1) corresponding to D1 can be charged or discharged. For example, D
1 and the compensation unit 110 operating with the unit 1 and D2 (the voltage compensation circuits P2 and N
2) is the unit 2 and the compensation unit 1 which operates in D3
10 (voltage compensation circuit P3, N3) is called unit 3.
To increase only the charging capacitor voltage 11 of the unit 1, select 1-. When you want to increase the voltage of the charging capacitor 11 of both the unit 1 and the unit 2,
Select 1-. To reduce the voltage of the charging capacitor 11 of the unit 1, select 1-. Here, the units for increasing the voltage are V1Δ (unit 1), V2Δ
(Unit 2). That is, when V1Δ is 1, the voltage of the unit 1 is increased. That is, according to each S value and the unit to be increased / decreased, the digital signal (D
By selecting (1, D2, D3), the voltages of the unit 1, the unit 2, and the unit 3 can be adjusted. Since the voltage to be compensated is always generated by alternating current, the voltage of both the P-side and N-side charging capacitors 11 can be adjusted in one cycle of alternating current.

When the compensating unit 110 outputs both positive and negative voltages from one charging capacitor 18pn as shown in FIG. 7 (a), when the phase of the system current and the phase of the system voltage are the same, For example, when the necessary compensation voltage is positive and the logic is +1 the charging capacitor 18p
In the case where n is discharging and −1, charging capacitor 18pn operates to charge.

Next, A / D conversion from a voltage drop amount of the system voltage to a binary signal composed of (D1, D2, D3) in the logic table 62 as described above will be described. FIG.
In the A / D converter shown in FIG. 4, the A / D converter 27a performs the same operation as the A / D converter shown in FIG. 5, and outputs D1a, D2a, and D3a. D1
a, D2a and D3a calculate the voltage gradation S value by the arithmetic circuit 61.
And input to the logic table 62. Arithmetic circuit 61
Is the voltage gradation command calculation in S = D3a × 4 + D2a
× 2 + D1a. In the arithmetic circuit 63,
From the voltage obtained by dividing the monitored voltage V3 by 4, V1
Is smaller, the voltage increase signal V1Δ is set to 1. If the voltage V2 is smaller than the voltage obtained by dividing the monitored voltage V3 by 2, the voltage increase signal V2Δ is set to 1
Set as That is, when V1Δ is 1, the voltage of the charging capacitor 11 of the unit 1 is lower than the binary condition based on the voltage of the charging capacitor 11 of the unit 3, and the voltage of the charging capacitor 11 of the unit 1 is lower. Need to be increased. When V2Δ is 1, the same applies to the charging capacitor 11 of the unit 1. V1Δ
And V2Δ are input to the logic table 62.
In the logic table 62, the binary signals (D1, D2, D3) in the columns corresponding to the S value and the values of V1Δ, V2Δ are selected.

[0049] In this manner, the voltage of the charging capacitor 11 is not deviated from the approximate ^{2 K} multiple of, (D1, D2,
The signal of D3) can be set. Therefore, accurate compensation can always be performed. Also, regardless of the voltage level of the compensation voltage, only the charges of the charge capacitors 11 of some of the voltage compensation circuits P and N are not used, and the charges of the charge capacitors 11 of all the voltage compensation circuits P and N are effective. Available to Therefore, even when a low compensation voltage continues for a long time, voltage compensation can be reliably continued for a long time.
As a result, the capacitance value of the charging capacitor 11 can be set small, and an inexpensive device can be configured.

Embodiment 8 FIG. Next, an eighth embodiment of the present invention will be described. FIG. 15 is a configuration diagram of the voltage fluctuation compensating apparatus according to the eighth embodiment. As shown in the figure,
Three voltage compensating circuits P1, P2, P3 for outputting a positive voltage
And one voltage compensating circuit N0 that outputs a negative voltage are connected in series to the power system. Voltage compensating circuit P1, P2, P3 has a voltage approximate 2 ^K times the relation of the charging capacitor 11 similar to that shown in the first embodiment. The voltage compensating circuit N0 outputs a voltage having a magnitude substantially equal to the sum of the output voltages of the three voltage compensating circuits P1, P2, and P3 and having the opposite polarity. That is, the voltage of each charging capacitor 22 has the following relationship in absolute value. Vp3 = Vp2 × 2 = Vp1 × 4 Vn0 = (Vp1 + Vp2 + Vp3) By the way, when the system voltage drops, it is almost always the case that a short circuit or ground fault due to lightning or the like occurs somewhere in the original part of the system. The voltage to be applied is AC. Accordingly, each of the voltage compensating circuits P1 to P
3. Output a compensation voltage from N0. By the combination of these voltage compensation circuits P1 to P3 and N0, an alternating current can be generated as follows. Assuming that Vp1 = 1V, when setting the compensation output from -7 to 7V, a signal as shown in the table of FIG. 16 may be used. Here, D1 is a control signal for operating the voltage compensating circuit P1, and 1 indicates a compensation voltage output state. Similarly, D2
Is a control signal for operating the voltage compensation circuit P2, D3 is a control signal for operating the voltage compensation circuit P3, and D0 is a control signal for operating the voltage compensation circuit N0.

The voltage compensating operation by such a voltage fluctuation compensating device will be described below with reference to FIG. The system voltage and the system current are assumed to be in the same phase. As shown in the drawing, the voltage Vn0 of the charging capacitor 11n0 decreases during the negative voltage compensation operation. However, while the voltage Vp3 of the charging capacitor 11p3 decreases during the voltage compensation operation of the positive voltage, the charge is conversely charged by operating the voltage compensation circuit P3 during the voltage compensation operation of the negative voltage, and the voltage recovers. I do. Charge capacitors 11p1, 11p
The same applies to the two voltages Vp1 and Vp2. As described above, the voltages of the charging capacitors 11 other than the charging capacitor 11n0 in the voltage compensating circuit N0 do not change during one AC cycle.

In this embodiment, a positive voltage 3 is output.
One of the voltage compensating circuits P1, P2, P3 and one of the voltage compensating circuits N0 for outputting a negative voltage, the compensation voltage output is -7 to -7.
It is possible to achieve high-precision voltage compensation with an inexpensive device configuration that can perform gradation control up to and is significantly simplified. The sag of the charging capacitors 11 in the voltage compensating circuits P1, P2, P3 does not cause distortion of the compensation voltage, and their capacitance values are compared with those of the charging capacitor 11n in the voltage compensating circuit N0 having the maximum voltage. Can be selected sufficiently small, and the whole apparatus becomes inexpensive.

In each of the above embodiments, the ratio of the voltage charged to the charging capacitor in each compensation unit is approximately 2
Is set to the power ratio, but other combinations of voltage ratios may be used. By setting the voltage ratio to approximately a power of 2, the voltage values that can be supplied are not duplicated by the combination, so that the voltage value can be optimized.

In each of the above embodiments, a capacitor is used as the energy storage means. However, for example, a battery may be used as the energy storage means.

[0055]

As described above, the voltage fluctuation compensator according to the first aspect of the present invention includes a detection control unit that monitors a voltage drop in a power system and controls power supply based on the voltage drop. A voltage fluctuation compensating device for suppressing voltage fluctuations, comprising a plurality of voltage compensating circuits each of which has energy storing means for storing a different voltage and converts a DC voltage stored in the energy storing means into an alternating current and outputs the alternating current. The voltage drop amount of the power system is compared with the reference value by using the voltage value of the voltage stored in the energy storage means in each of the voltage compensation circuits as a reference value of each bit signal. Gives A / to the binary signal
D-converting, selecting a desired combination from the plurality of voltage compensating circuits based on the signal, and compensating for the voltage drop of the power system by the sum of the output voltages. In addition to the configuration, fine and highly accurate voltage compensation can be performed.

According to a second aspect of the present invention, in the voltage fluctuation compensating apparatus according to the first aspect, the absolute value of each of the different voltages stored in the energy storage means in the plurality of voltage compensating circuits is set to the smallest voltage. the output voltage of the compensation circuit generally ^{2 K} times the (absolute value) (K = 0,1,2, ···)
In this case, the apparatus can be configured inexpensively and reduced in size, and the compensation voltage can be gradation-controlled at regular intervals, so that fine and highly accurate voltage compensation can be performed.

According to a third aspect of the present invention, there is provided a voltage fluctuation compensating apparatus according to the first or second aspect, wherein the energy storage means is a capacitor. An effect similar to that of the voltage compensating device is obtained.

According to a fourth aspect of the present invention, in the voltage fluctuation compensating apparatus according to the third aspect, A / A
Since the charge voltage value of the capacitor, which is the reference value for D conversion, is a voltage detection value obtained by detecting the voltage of each capacitor as needed, the A / D conversion into a binary signal is performed according to the voltage state of the charge capacitor. And accurate compensation can be realized. Thereby, the distortion of the compensation voltage can be suppressed, and the capacitance of the charging capacitor can be reduced.

According to a fifth aspect of the present invention, in the voltage fluctuation compensating apparatus according to the third aspect, the A / A
The charging voltage value of the capacitor, which is a reference value for D conversion, is a voltage calculation value that is calculated as needed by monitoring the system current of the power system and predicting the voltage drop amount of each capacitor based on the current value. Therefore, with an inexpensive device configuration, A / D conversion can be performed to a binary signal according to the voltage state of the charging capacitor, and accurate compensation can be realized. Thereby, the distortion of the compensation voltage can be suppressed, and the capacitance of the charging capacitor can be reduced.

According to a sixth aspect of the present invention, there is provided a voltage fluctuation compensating apparatus according to any one of the third to fifth aspects, wherein the maximum possible output voltage of all compensating circuits comprising all the voltage compensating circuits connected in series is: Since the charging voltage of the capacitors in each voltage compensation circuit is set so as to exceed the maximum voltage drop amount in the power system, even if a voltage drop occurs in the charging capacitor, the compensation voltage can be secured, and the electrostatic charge of the charging capacitor can be secured. The capacity can be reduced.

According to a seventh aspect of the present invention, there is provided a voltage fluctuation compensating apparatus according to any one of the third to sixth aspects, wherein the capacitance of the capacitor in each voltage compensating circuit increases as the charging voltage of the capacitor increases. Since the voltage is set small, accurate voltage compensation can be realized even if a voltage drop occurs in the charging capacitor.

[0062] The voltage fluctuation compensation device according to claim 8, wherein according to the present invention, in claim 7, the capacitance of the capacitor in each voltage compensation circuit, approximate 2 ^K times the smallest capacitance value (K = 0, 1, 2,...) Or more, and the higher the charging voltage of the capacitor is, the smaller the voltage is set. Therefore, even if a voltage drop occurs in the charging capacitor, more accurate voltage compensation is performed. Can be realized.

According to a ninth aspect of the present invention, in the voltage variation compensating apparatus according to any one of the third to eighth aspects, when the A / D conversion is performed from a voltage drop amount to a binary signal, the signal is determined by the signal. When the sum of the output voltages of the voltage compensating circuits is equal to or less than a voltage value obtained by subtracting a predetermined voltage amount from the voltage drop amount, the minimum charging voltage value of the capacitor is added to the sum of the output voltages. Since 1 is added to the binary signal, the supply voltage to the load can be ensured to be equal to or higher than the voltage value obtained by subtracting the above-mentioned predetermined amount of voltage, and the voltage of the charging capacitor can be set to a high value. Capacitance can be reduced.

According to a tenth aspect of the present invention, in the voltage fluctuation compensating apparatus according to the third aspect, a DC voltage charged in a capacitor is connected to a power system in series with a voltage compensating circuit, and the DC voltage is converted to an AC and output. A sag voltage compensating circuit, and when the voltage of the capacitor in the voltage compensating circuit falls below a predetermined value, the sag voltage compensating circuit is detected and operated in accordance with the operation of the voltage compensating circuit. Since the voltage drop of the power system is compensated by the sum of the output voltages of the voltage compensation circuit and the sag voltage compensation circuit, even if a voltage drop occurs in the charging capacitor, distortion of the compensation voltage can be suppressed, and the static charge of the charging capacitor can be suppressed. The capacitance can be greatly reduced.

In the voltage fluctuation compensating apparatus according to the present invention, the voltage compensating circuit selected by the binary signal has an output voltage having a polarity opposite to the voltage polarity of the power system. Since the capacitor in the voltage compensation circuit having the same output voltage as the power system is discharged during operation and the capacitor in the voltage compensation circuit having the opposite polarity is charged during operation, the charge of the charging capacitor Can be used effectively, and the voltage compensation period can be extended.

According to a twelfth aspect of the present invention, in the voltage variation compensating apparatus according to the eleventh aspect, each bit value is converted from a binary signal to 1 when the capacitor is discharged and to 1 when the capacitor is charged. Converted to a binary value of 1
A logic table for selecting a combination of the voltage compensating circuits is created, a voltage drop of a capacitor in each voltage compensating circuit is detected, and a binary value of a mode in which the capacitor can be charged is determined according to the state. Since the capacitor in the voltage compensation circuit selected from the logic table and selected according to each bit value of the binary value is discharged when the bit value is 1, and charged when the bit value is -1, the accuracy is always high. The voltage compensation can be performed, and the charge of the charging capacitor can be effectively used, so that the voltage compensation can be reliably continued for a long time. In addition, the capacitance of the charging capacitor can be reduced.

According to a thirteenth aspect of the present invention, in the eleventh aspect, the output voltage of one of the voltage compensating circuits has the first polarity and the output voltages of all the other voltage compensating circuits are the same. The second polarity opposite to the first polarity, and the charging voltage of the capacitor in the voltage compensation circuit of the first polarity is:
When the sum and absolute value of the charging voltages of the capacitors in all the other second polarity voltage compensating circuits are substantially the same and the voltage of the power system is the first polarity, the desired voltage of the second polarity voltage compensating circuit And the voltage compensating circuit of the first polarity is selected and operated, and when the voltage of the power system is the second polarity, a combination of only the voltage compensating circuit of the second polarity is selected and operated. In addition, a highly accurate voltage compensation can be realized with a simplified and inexpensive device configuration, and the capacitance of the capacitor in the first polarity voltage compensation circuit can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a voltage fluctuation compensation device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing details of a voltage sag control circuit according to Embodiment 1 of the present invention;

FIG. 3 is a waveform chart illustrating an operation of the voltage fluctuation compensating device according to the first embodiment of the present invention.

FIG. 4 is a waveform diagram illustrating an operation when the voltage of the charging capacitor drops according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram illustrating details of an A / D converter according to the first embodiment of the present invention;

FIG. 6 is a configuration diagram of a voltage fluctuation compensation device according to another example of the first embodiment of the present invention.

FIG. 7 is a configuration diagram of a voltage compensation circuit according to another example of the first embodiment of the present invention.

FIG. 8 is a configuration diagram showing details of an A / D converter according to a second embodiment of the present invention.

FIG. 9 is a configuration diagram showing details of a prediction operation circuit according to a second embodiment of the present invention.

FIG. 10 is a configuration diagram of a voltage fluctuation compensation device according to a third embodiment of the present invention.

FIG. 11 is a waveform diagram illustrating an operation of the voltage fluctuation compensating device according to the third embodiment of the present invention.

FIG. 12 is a circuit diagram showing details of a voltage sag control circuit according to Embodiment 3 of the present invention;

FIG. 13 is a configuration diagram showing details of an A / D converter according to a sixth embodiment of the present invention.

FIG. 14 is a configuration diagram showing details of an A / D converter according to a seventh embodiment of the present invention.

FIG. 15 is a configuration diagram of a voltage fluctuation compensation device according to an eighth embodiment of the present invention.

FIG. 16 is a diagram showing an A / D converted binary signal according to an eighth embodiment of the present invention.

FIG. 17 is a waveform chart illustrating an operation of the voltage fluctuation compensator according to the eighth embodiment of the present invention.

FIG. 18 is a schematic configuration diagram of a conventional voltage fluctuation compensation device.

FIG. 19 is a diagram illustrating a voltage compensation operation of a conventional voltage fluctuation compensation device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 transmission line, 3 load (consumer), 11 charging capacitor as energy storage means, 16 voltage sag control circuit as detection control unit, 18 charging capacitor as energy storage means, 21 (21p1, 21n1) energy storage means Charging capacitor, 62 logic table, 100 voltage fluctuation compensator, 120 total compensation circuit,
P1 to P3, N1 to N3, PN, N0 voltage compensation circuit,
PS, NS sag voltage compensation circuit, V1, V2, V3 voltage detection value, V1x, V2x, V3x voltage prediction calculation value as voltage calculation value, Vz voltage drop guarantee value as predetermined voltage amount.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Sasao 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Kenichi Koyama 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Rishi Electric Co., Ltd. (72) Inventor Toshiyuki Kikunaga 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Sanbishi Electric Co., Ltd. (72) Inventor Mitsugu Takahashi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) in Denki Co., Ltd. 5G066 DA07

Claims (13)

[Claims] 1. A voltage fluctuation compensator comprising a detection control unit for monitoring a voltage drop in a power system and performing a power supply control based on the voltage drop, and in which a voltage fluctuation compensating device for suppressing a voltage fluctuation supplied to a load has different voltages stored therein. A plurality of voltage compensating circuits, each of which includes a storage unit and converts a DC voltage stored in the energy storage unit into an AC and outputs the AC voltage, are connected in series to the power system. The voltage value of the voltage stored in the energy storage means in the circuit is set as a reference value of each bit signal, and is compared with the reference value to perform A / D conversion into a binary signal. A voltage fluctuation compensating device, wherein a desired combination is selected from a voltage compensating circuit, and a voltage drop of the power system is compensated by a sum of the output voltages. 2. The absolute value of a different voltage stored in the energy storage means in each of the plurality of voltage compensating circuits is approximately ^2K times (K = ^K ) of the smallest output voltage (absolute value) of the voltage compensating circuit. 0, 1, 2,...). 3. The voltage fluctuation compensator according to claim 1, wherein the energy storage means is a capacitor. 4. The voltage according to claim 3, wherein the charging voltage value of the capacitor, which is a reference value for A / D conversion from the voltage drop amount, is a voltage detection value obtained by detecting the voltage of each capacitor as needed. Fluctuation compensator. 5. A charging voltage value of a capacitor, which is a reference value for A / D conversion from a voltage drop amount, is obtained by monitoring a system current of a power system and calculating a voltage drop amount of each capacitor based on the current value. The voltage fluctuation compensating apparatus according to claim 3, wherein the voltage fluctuation value is calculated as needed. 6. The charging voltage of a capacitor in each voltage compensation circuit is set such that the maximum possible output voltage of all compensation circuits composed of all voltage compensation circuits connected in series exceeds the maximum voltage drop in the power system. The voltage fluctuation compensator according to any one of claims 3 to 5, wherein 7. The voltage fluctuation compensating device according to claim 3, wherein the capacitance of the capacitor in each voltage compensating circuit is set smaller as the charging voltage of the capacitor increases. . 8. The capacitance of a capacitor in each voltage compensation circuit is approximately 2K times (K = ^{K) of} the smallest capacitance value.
8. The voltage fluctuation compensator according to claim 7, wherein the voltage is set to 0, 1, 2,... 9. When performing A / D conversion from a voltage drop amount to a binary signal, a sum of output voltages of a voltage compensation circuit determined by the signal is a voltage obtained by subtracting a predetermined voltage amount from the voltage drop amount. When the value is equal to or less than the value, the minimum charge voltage value of the capacitor is added to the sum of the output voltages so that
4. The method according to claim 3, wherein 1 is added to the signal of the base number.
9. The voltage fluctuation compensator according to any one of 8. 10. A sag voltage compensating circuit, which is connected in series to a power system together with a voltage compensating circuit and converts a DC voltage charged in a capacitor into AC and outputs the AC voltage, wherein a voltage of the capacitor in the voltage compensating circuit is a predetermined voltage. If the voltage drops below the value, it is detected and the sag voltage compensating circuit is operated in accordance with the operation of the voltage compensating circuit, and the power system is calculated by the sum of the output voltages of the voltage compensating circuit and the sag voltage compensating circuit. The voltage fluctuation compensating device according to claim 3, wherein the voltage drop is compensated. 11. A voltage compensation circuit selected by a binary signal enables an output voltage to include a polarity opposite to a voltage polarity of a power system, and a voltage compensation circuit in which the output voltage has the same polarity as the power system. 4. The voltage fluctuation compensator according to claim 3, wherein a capacitor in the circuit is discharged during operation, and a capacitor in the voltage compensation circuit of the opposite polarity is charged during operation. 12. From a binary signal, each bit value is
1 if the capacitor is discharged,-if the capacitor is charged
It is converted to a binary value of 1 to create a logic table for selecting a combination of voltage compensation circuits, detects a voltage drop of a capacitor in each voltage compensation circuit, and applies a voltage to the capacitor according to the state. The binary value of the chargeable mode is selected from the logic table, and the capacitor in the voltage compensation circuit selected according to each bit value of the binary value is discharged when the bit value is 1, -1. The voltage fluctuation compensating device according to claim 11, wherein the voltage fluctuation compensating device is charged when: 13. An output voltage of one voltage compensation circuit is a first voltage.
Polarity, and the output voltages of all the other voltage compensating circuits
The charge polarity of the capacitor in the voltage compensation circuit of the first polarity is substantially equal to the second polarity opposite to the polarity, and the sum and absolute value of the charge voltages of the capacitors in all the other voltage compensation circuits of the second polarity are approximately equal to each other. The same, when the voltage of the power system is the first polarity, the desired combination of the voltage compensation circuit of the second polarity and the voltage compensation circuit of the first polarity are selected and operated, and the voltage of the power system is 12. The voltage fluctuation compensating apparatus according to claim 11, wherein a combination of only the voltage compensating circuit of the second polarity is selected and operated at the time of the second polarity.