JP4677242B2 - Instantaneous voltage drop compensation device - Google Patents

Description

  The present invention relates to an instantaneous voltage drop compensator that compensates for a voltage supplied to a load when the voltage on the power system side instantaneously drops.

Generally, an instantaneous voltage drop compensator is provided between the power system and the load device in preparation for a case where the voltage on the power system side instantaneously decreases due to lightning or the like. This instantaneous voltage drop compensator includes, for example, a capacitor, an inverter, and a control device that controls them. When the voltage on the power system side instantaneously drops, the power charged in the capacitor is passed through the inverter. By controlling to supply to the load device, the voltage supplied to the load device is maintained at a predetermined voltage (see, for example, Patent Document 1).
JP 2002-10528 A

  By the way, the control device that performs control for maintaining the voltage supplied to the load device at a predetermined voltage must function while the voltage on the power system side is decreasing. Therefore, the instantaneous voltage drop compensator includes a UPS (Uninterrupted Power Supply) for supplying power of a predetermined voltage to the control device even while the voltage on the power system side is dropping.

  However, since the UPS has a battery inside, maintenance such as periodic replacement of the battery is necessary. In addition, the battery is troublesome to handle, such as requiring special processing when discarded. Furthermore, in order to reliably supply a predetermined voltage to the control device even during an instantaneous voltage drop, it is necessary to mount a UPS having a battery with a corresponding capacity. For this reason, it is difficult to use a small UPS for the instantaneous voltage drop compensator provided between the power system and the load device in preparation for an instantaneous voltage drop on the power system side. It was one of the factors that hindered the transformation.

  The present invention has been made in view of the above problems, and a main object of the present invention is to provide an instantaneous voltage drop compensator that is small and lightweight and has a small maintenance burden.

In order to solve the above problems, the present invention is interposed between an electric power system and a load device, and compensates for the reduced voltage when the voltage of AC power supplied from the electric power system is instantaneously reduced, and An instantaneous voltage drop compensation device for supplying to a load device, comprising: an AC / DC converter for converting a part of AC power supplied from the power system into DC power; and DC power supplied from the AC / DC converter. A capacitor to be stored; an inverter that converts DC power supplied from the capacitor into AC power; a control unit that controls the inverter according to a voltage of AC power supplied to the load device; that the AC power, and a compensation voltage supply unit for supplying to the load device to compensate for the voltage of the AC power supplied from the electric power system, the control unit Function by DC power supplied from the capacitor, wherein the control unit includes a voltage detecting unit for sequentially detecting a voltage of the AC power supplied to the load device, and stores a voltage detected by the voltage detecting section A voltage storage unit; an average value calculation unit for calculating an average value of a predetermined number of past voltages stored in the voltage storage unit; and a voltage newly detected by the voltage detection unit for calculating the average value A voltage comparison unit that compares the average value calculated by the unit with a determination value obtained by multiplying a predetermined ratio; and when the newly detected voltage is equal to or less than the determination value, the load device And an inverter control unit that starts control of the inverter so that the voltage of the alternating-current power supplied to the average value becomes the average value .
In this way, by supplying power for causing the control unit to function from the capacitor, a stable voltage is supplied to the control unit even when an instantaneous voltage drop of the power system occurs. It becomes possible. As a result, there is no need to install a UPS in the instantaneous voltage drop compensator, so that the instantaneous voltage drop compensator can be reduced in size and weight. In addition, maintenance such as UPS battery replacement can be eliminated.
According to such an aspect, the voltage of the power system is sequentially stored, and the average value for the predetermined number of the latest voltage (A) and the past voltage closest to the voltage (A) (hereinafter, immediately before) Is compared with the predetermined ratio (for example, 0.85) of the past voltage (B)), for example, at an appropriate frequency. During the execution of this process, if A ≦ B × 0.85, that is, if the current voltage is reduced by, for example, 15% or more from the previous past voltage, the inverter control unit starts controlling the inverter. By doing so, for example, power for compensating the voltage (B-A) corresponding to the decrease is supplied from the capacitor to the compensation voltage supply unit via the inverter. That is, the voltage of the AC power supplied from the power system is compensated so that the current voltage (A) that has been instantaneously reduced becomes the previous past voltage (B). In the present embodiment, since the electric power for causing the control unit to function is supplied from the capacitor, the above control can be performed even if the current voltage supplied from the electric power system is instantaneously decreasing. Become.

In the instantaneous voltage drop compensation device, the capacitor may be an electric double layer capacitor.
By using an electric double layer capacitor, it is possible to reduce the size and increase the capacity of the capacitor, so that the instantaneous voltage drop compensator can be further reduced in size, and more stable voltage can be applied to the load device and control unit. Can be made available. In addition, the electric double layer capacitor does not require maintenance and has a long product life as compared with the battery. Therefore, the use of the electric double layer capacitor can simplify the maintenance and reduce the cost.

The instantaneous voltage drop compensator includes a DC / DC converter that is interposed between the capacitor and the control unit and converts a voltage of DC power stored in the capacitor into an operating voltage of the control unit. It can also be.
With such an aspect, it is not necessary to match the operating voltage of the control unit with the voltage output from the capacitor. As a result, the degree of freedom in designing the instantaneous voltage drop compensator increases, and even when the operating voltage of the control unit and the output voltage of the capacitor are different, power for operating the control unit is supplied from the capacitor. It becomes possible to do.

In the instantaneous voltage drop compensation device, the load device is interposed between the power system and the load device and compensates for the reduced voltage when the voltage of the AC power supplied from the power system is instantaneously reduced. An AC / DC converter for converting a part of AC power supplied from the power system into DC power, and a capacitor for storing DC power supplied from the AC / DC converter An inverter that converts DC power supplied from the capacitor into AC power, a control unit that controls the inverter in accordance with the voltage of AC power supplied to the load device, and AC supplied from the inverter A compensation voltage supply unit that compensates the voltage of the AC power supplied from the power system with the power and supplies the compensated voltage to the load device. Department functions by DC power supplied from the capacitor, wherein the control unit includes a first voltage detector for sequentially detecting a voltage of the AC power supplied to the load device, wherein the first voltage detecting unit A first voltage storage unit that stores the voltage detected by the first voltage storage unit; a first average value calculation unit that calculates an average value of a predetermined number of past voltages stored in the first voltage storage unit; A first comparison of a voltage newly detected by the first voltage detection unit with a first determination value obtained by multiplying the average value calculated by the first average value calculation unit by a predetermined ratio. When the voltage newly detected by the voltage comparison unit and the first voltage detection unit becomes equal to or lower than the first determination value, the voltage of the AC power supplied to the load device is the first voltage. It will be the average value calculated by the average value calculator of 1 It is detected and the first inverter control unit, and the second voltage detecting unit for sequentially detecting a voltage of the AC power supplied from the electric power system, by the second voltage detecting unit for starting the control of the inverter A second voltage storage unit that stores a voltage; a second average value calculation unit that calculates an average value of a predetermined number of past voltages stored in the second voltage storage unit; and the said average value newly calculated by the average value calculating unit, obtained by multiplying a predetermined ratio to the average value calculated by the second average value calculating section immediately before the control of the inverter is started When the average value newly calculated by the second voltage comparison unit for comparing with the determination value of 2 and the second average value calculation unit becomes equal to or greater than the second determination value, A second inverter control unit for stopping control You can also make it.

According to the instantaneous voltage drop compensator, while the control for compensating the voltage of the AC power supplied from the power system is performed by the first inverter control unit, the voltage near the voltage on the power system side is close. A comparison between an average value for a predetermined number in the past (hereinafter referred to as a voltage (C) near the present) and a predetermined ratio (for example, 0.9) of the past voltage (B) immediately before the momentary decrease described above is, for example, as appropriate. It is carried out frequently. During the execution of this process, if C ≧ B × 0.9, that is, if the voltage (C) in the vicinity of the current becomes 90% or more of the past voltage (B) immediately before the instantaneous decrease, for example, The compensation operation can be ended by the second inverter control unit stopping the control of the inverter. Also in this embodiment, since the electric power for causing the control unit to function is supplied from the capacitor, the above control can be performed even if the current voltage supplied from the power system is being instantaneously reduced. Become.

In the instantaneous voltage drop compensator, the compensation voltage supply unit transforms the voltage of the AC power supplied from the power system with the AC power supplied from the inverter and supplies the voltage to the load device. And a bypass switch that bypasses the series transformer and connects the power system and the load device, and the first inverter control unit is newly provided by the first voltage detection unit. When the detected voltage is equal to or lower than the first determination value, the bypass switch is opened, and the voltage of the AC power supplied to the load device is the first average value calculation unit. controlling said inverter so that the calculated the mean value was initiated by the second inverter control unit, the newly calculated by the second average value calculating section When the average value becomes the second judgment value or more, the bypass switch while in the closed state, may be adapted to stop the control of the inverter.

According to this instantaneous voltage drop compensator, the bypass switch is opened (in an open state) while the first inverter control unit performs the control to compensate the voltage of the AC power supplied from the power system. The voltage is compensated so that the voltage of the AC power output from the series transformer becomes the average value calculated by the first average value calculation unit. Further, after the control for compensating the voltage of the AC power supplied from the power system is completed, the bypass switch is turned on (closed), and the voltage on the power system side is applied to the load, and thus the load Switching from compensation to constant power supply. By doing in this way, when the instantaneous voltage drop has generate | occur | produced, the electric power system side and the load apparatus side can be prevented from being electrically connected directly. Thereby, it can prevent that the influence of the electric power fall by the side of an electric power grid reaches the load apparatus side. When no instantaneous voltage drop occurs, the power system side and the load device side can be electrically connected directly. This makes it possible to minimize power loss when passing through the instantaneous voltage drop compensator. Further, by controlling the inverter with the operation of the bypass switch, it is possible to reduce the voltage difference when switching to the constant power supply after the instantaneous voltage drop is restored.

Further, in the instantaneous voltage drop compensator, the second inverter control unit determines that the average value newly calculated by the second average value calculation unit is equal to or greater than the second determination value continuously for a predetermined number of times. In such a case, the control of the inverter can be stopped. By such an aspect, the control which compensates for a voltage can be stopped, after the voltage by the side of an electric power grid | system | rate certainly return | restored. For this reason, it is possible to supply more stable power to the load device.

  In the instantaneous voltage drop compensator, the voltage storage unit may be configured to store at least the predetermined number of the past voltages that have been updated. With such an aspect, the storage capacity of the voltage storage unit can be reduced. Thereby, a low-cost instantaneous voltage drop compensation device can be provided.

The inverter may be provided with a PLL circuit for matching the phase of the AC power output from the inverter with the phase of the AC power supplied from the power system. As a result, the voltage of the AC power supplied from the power system can be controlled more accurately.

The predetermined ratio used for calculating the determination value or the first determination value is preferably approximately 0.85, and the predetermined ratio used for calculating the second determination value is approximately 0. .9.
By setting such a predetermined ratio, it is possible to prevent the voltage compensation control from being started every time a minute voltage fluctuation on the power system side that occurs on a daily basis, and when an instantaneous voltage drop occurs Thus, it is possible not to stop the voltage compensation control until the voltage is reliably restored.

  In addition, the problems disclosed by the present application and the solutions thereof will be clarified by the column of the best mode for carrying out the invention and the drawings.

  The instantaneous voltage drop compensator can be reduced in size and weight, and the maintenance burden can be reduced.

=== Example of Overall Configuration ===
FIG. 1 is a block diagram showing the configuration of the instantaneous voltage drop compensator 10 according to the present embodiment.
The instantaneous voltage drop supplementary device 10 according to the present embodiment is interposed between the power system 100 and the load device 200, and when the voltage of the AC power supplied from the power system 100 is instantaneously reduced due to lightning strikes, The reduced voltage is compensated and supplied to the load device 200.

  The instantaneous voltage drop supplementary device 10 according to the present embodiment includes a series transformer 20, an inverter 30, an electric double layer capacitor 40, a power system side voltage sensor (first voltage detection unit, PT1) 50A, and a load device side voltage. A sensor (second voltage detection unit, PT2) 50B, an input conversion unit 60, a memory unit 70, a controller unit 80, a bypass switch 90, a charger (AC / DC converter) 120, and a DC / DC converter 130 are provided.

The series transformer 20 transforms the voltage of the AC power supplied from the power system 100 with the AC power supplied from the inverter 30 and supplies it to the load device 200.

  The bypass switch 90 is provided in parallel with the series transformer 20 between the power system 100 and the load device 200. That is, the bypass switch 90 bypasses the series transformer 20 and connects the power system 100 and the load device 200. When the voltage of the electric power system 100 decreases instantaneously and the control for compensating the voltage supplied to the load device 200 by the series transformer 20 is performed, the bypass switch 90 is opened (opened). Further, when the voltage of the power system 100 is not instantaneously reduced and the control for compensating the voltage supplied to the load device 200 is not performed, the bypass switch 90 is connected (closed state). By doing in this way, when the instantaneous voltage drop has generate | occur | produced, the electric power grid | system 100 side and the load apparatus 200 side can be prevented from being electrically connected directly. Thereby, it is possible to prevent the influence of the voltage drop on the power system 100 side from reaching the load device 200 side. Moreover, when the instantaneous voltage drop has not occurred, the electric power system 100 side and the load device 200 side can be electrically connected directly. As a result, it is possible to minimize power loss caused by supplying power from the power system 100 to the load device 200 via the instantaneous voltage drop compensation device 10.

The inverter 30 converts the DC power supplied from the electric double layer capacitor 40 into AC power. The converted AC power is supplied to the series transformer 20. The voltage of the AC power supplied from the power system 100 can be compensated and supplied to the load device 200 by the AC power supplied from the inverter 30 to the series transformer 20. The voltage of the AC power output from the series transformer 20 can be controlled by controlling the voltage and phase of the AC power supplied from the inverter 30. That is, by controlling the AC power output from the inverter 30, the compensation amount of the AC power voltage supplied from the power system 100 can be controlled. Control of the inverter 30 is performed by the controller unit 80. Details will be described later. The inverter 30 is provided with a PLL circuit (not shown), and the PLL circuit detects the phase of the voltage to be compensated for the load device 200 when the three-phase AC voltage on the power system 100 side instantaneously drops. It has a function to match the phase of the voltage on the power system 100 side.

  The charger 120 converts a part of the AC power supplied from the power system 100 into DC power. The converted DC power is supplied to the electric double layer capacitor 40. At this time, the charger 120 controls the charging so that the voltage reaches the target value while monitoring the voltage of the electric double layer capacitor 40. The electric double layer capacitor 40 stores DC power supplied from the charger 120. Here, the electric double layer capacitor 40 may be another capacitor such as an electrolytic capacitor. Of course, since the electric double layer capacitor 40 has a characteristic such as a large capacity, in an apparatus that compensates for a voltage drop in the power system such as the instantaneous voltage drop compensator 10 according to the present embodiment, the electric double layer capacitor It can be said that the use of the capacitor 40 is more preferable for reducing the size, performance, and weight of the instantaneous voltage compensator 10. By using the electric double layer capacitor 40, it is possible to further reduce the size of the instantaneous voltage drop compensator 10 and supply a more stable voltage to the load device 200, the controller unit 80, and the like.

  The power system side voltage sensor 50 </ b> A sequentially detects the voltage of the AC power supplied from the power system 100. The load device side voltage sensor 50 </ b> B sequentially detects the voltage of the AC power supplied to the load device 200. The detected voltage is sent to the input conversion unit 60. The power system side voltage sensor 50 </ b> A and the load device side voltage sensor 50 </ b> B are also collectively referred to as a voltage sensor (voltage detection unit) 50 hereinafter.

  The input conversion unit 60 converts the AC voltage detected by the power system side voltage sensor 50A and the load device side voltage sensor 50B into a DC voltage. For example, when the AC power supplied from the power system 100 to the load device 200 is three-phase AC power, the three-phase AC voltages detected by the power system-side voltage sensor 50A and the load device-side voltage sensor 50B are used. First, αβ conversion is performed to obtain a two-phase AC voltage, and then the two-phase AC voltage is dq-converted to obtain two DC voltage values. Further, the square root (Veff) of the sum of the square values of the respective DC voltages is obtained. Ask. Veff thus obtained is an effective voltage of a three-phase AC voltage.

  The memory unit 70 stores the effective voltage Veff of the three-phase AC voltage detected by the voltage sensor 50 at an appropriate frequency and converted by the input conversion unit 60 in the order of detection and conversion. Further, as will be described later, the memory unit 70, with respect to Veff, displays an average voltage (average value) Vav between the Veff and (n−1) Veff stored immediately before the Veff together with the Veff. It also has a memory function. The Vav is calculated by the controller unit 80. Furthermore, the memory unit 70 of the present embodiment may store, for example, at least the aforementioned n Veffs while updating them.

  The controller unit 80 averages a plurality of effective voltages Veff stored in the memory unit 70 to obtain an average voltage Vav, and compares the magnitude relationship between Veff and a determination value obtained by multiplying the immediately preceding Vav by a predetermined ratio, The bypass switch 90 and the inverter 30 are controlled based on the comparison result. Details will be described later.

  The controller includes the controller unit 80, the input conversion unit 60, the memory unit 70, and the voltage sensor 50 described above. Here, the controller unit 80 includes an average value calculation unit, a first average value calculation unit, a second average value calculation unit, a voltage comparison unit, a first voltage comparison unit, a second voltage comparison unit, and an inverter control. , A first inverter control unit, and a second inverter control unit. The memory unit 70 includes a voltage storage unit, a first voltage storage unit, and a second voltage storage unit.

  The DC / DC converter 130 is interposed between the electric double layer capacitor 40 and the control unit, and converts the voltage of DC power stored in the electric double layer capacitor 40 into an operating voltage of the control unit. As a result, it is possible to cover the power for causing the control unit to function with the power stored in the electric double layer capacitor 40. As described above, since the electric double layer capacitor 40 serving as a power supply source to the control unit is always charged by the charger 120, stable power is always supplied to the control unit. Further, when an instantaneous voltage drop of the power system 100 occurs, the amount of power stored in the electric double layer capacitor 40 is temporarily reduced. Supply is not a problem. That is, even when an instantaneous voltage drop of the power system 100 occurs, a stable voltage can be supplied to the control unit.

  This eliminates the need for mounting the UPS 1140 in the instantaneous voltage drop compensator 1010 as in the normal instantaneous voltage drop compensator 1010 shown in FIG. For this reason, in the instantaneous voltage drop compensator 10 according to the present embodiment, it is possible to realize a reduction in size and weight, and to eliminate the need for maintenance such as battery replacement of the UPS 1140. In addition, when the control unit functions by supplying the output voltage of the electric double layer capacitor 40 to the control unit as it is, the DC / DC converter 130 may be omitted.

=== Instantaneous voltage drop compensation control ===
Next, in the power system 100, for example, an instantaneous voltage drop occurs due to lightning strikes, and the voltage on the load 200 side is compensated by the instantaneous voltage drop compensator 10, and the controller unit 80 is switched to normal power supply after the voltage drop is restored. The process will be described.

<<< Before executing compensation operation >>>
As illustrated in the flowchart of FIG. 2, the power system side voltage sensor (PT1) 50A is controlled by the controller unit 80, and the power system 100 side three-phase AC voltage (V1u (i), V1v (i), V1w (i)) is detected, and the load device side voltage sensor (PT2) 50B detects a three-phase AC voltage (V2u (i), V2v (i), V2w (i)) on the load device 200 side. Also, controlled by the controller unit 80, the input conversion unit 60 performs αβ conversion and dq conversion on these three-phase AC voltages to obtain V1eff (i) and V2eff (i), respectively. Here, “i” represents an appropriate number indicating the order of detection and conversion (S300).

 Next, the controller unit 80 stores V1eff (i) and V2eff (i) in the memory unit 70. Here, for example, when storing these two voltages and the total storage amount in the memory unit 70 exceeds the allowable amount, the two voltages are overwritten on the voltage stored in the past (S301). .

  Next, the controller unit 80 includes V1eff (i), V1eff (i-1), V1eff (i-2), and V2eff, which are the nearest three (predetermined number) voltages including the “i” -th effective voltage. (I), V2eff (i-1), and V2eff (i-2) are read from the memory unit 70, and the average value of each is calculated. The controller unit 80 stores the average voltages V1av (i) and V2av (i) calculated in this way in the memory unit 70 in association with the order “i” together with V1eff (i) and V2eff (i). Here, in the present embodiment, the nearest three voltages are used, but the present invention is not limited to this, and any number may be used as long as it is plural (S302).

  Next, under the control of the controller unit 80, the voltage sensors (PT1, PT2) 50 newly detect a three-phase AC voltage, and the input conversion unit 60 newly obtains voltages V1eff (i + 1) and V2eff (i + 1) ( S303).

  Next, the controller unit 80 has a predetermined ratio (0) to the effective voltage V2eff (i + 1) on the load device 200 side obtained “i + 1” th and the average voltage on the load device 200 side obtained up to the “i” th. .85) is compared with a determination value (first determination value) obtained by multiplying by .85), that is, V2av (i) × 0.85. Here, “0.85” is an instantaneous drop determination parameter (predetermined ratio) for determining an instantaneous voltage drop (S304).

  If V2eff (i + 1) is larger than V2av (i) × 0.85 (S304: NO), the controller unit 80 repeats the operation of S300. As described above, when the controller unit 80 repeats the operations of S300 to S304 to obtain a new current voltage V2eff (i + 1), 85% of the average three past voltages V2av (i) are averaged. The operation of comparing the magnitude relationship with is always executed.

<<< During compensation operation >>>
If V2eff (i + 1) is equal to or less than V2av (i) × 0.85 (S304: YES), the controller unit 80 opens the bypass switch 90, and a predetermined target voltage (predetermined voltage) on the load device 200 side. Controls inverter 30 as much as V2av (i). By controlling the inverter 30 by the controller unit 80, the DC power stored in the electric double layer capacitor 40 is converted into AC power and applied to the series transformer 20, and the voltage from the series transformer 30 is reduced. A voltage in which (for example, V2av (i) −V2eff (i + 1)) is compensated is supplied to the load device 200 (S305).
It should be noted that S304: YES is that the voltage on the load device 200 side significantly decreased by 15 (= 100−85)% or more with respect to the previous past voltage only after the “i + 1” th detection and conversion. Means.

Next, as in the case of S300 described above, the controller 80 controls the voltage sensors (PT1, PT2) 50 to detect a three-phase AC voltage, and the input converter 60 detects V1eff (j) and V2eff (j ) Here, “j” represents an appropriate number indicating the order of detection and conversion. The relationship with “i” described above is, for example, “j> i + 1” (S306).
Next, as in S301 described above, the controller unit 80 stores V1eff (j) and V2eff (j) in the memory unit 70 (S307).
Next, under the control of the controller unit 80, the voltage sensors (PT1, PT2) 50 newly detect a three-phase AC voltage, and the input conversion unit 60 newly obtains voltages V1eff (j + 1) and V2eff (j + 1) ( S308).

  Next, the controller unit 80 includes three (predetermined) voltages V1eff (j + 1), V1eff (j), V1eff (j-1), V2eff (j + 1), V2eff (j), and V2eff (j-1). ) From the memory unit 70, and the average value of each is calculated. The controller unit 80 stores the average voltages V1av (j + 1) and V2av (j + 1) in the memory unit 70 in association with the order “j + 1” together with V1eff (j + 1) and V2eff (j + 1). Here, in the present embodiment, the nearest three voltages are used, but the present invention is not limited to this, and any number may be used as long as it is plural (S309).

  Next, the controller unit 80 reads the average voltage V1av (i) immediately before the instantaneous voltage drop on the power system 100 side (until the "i" th in S304) from the memory unit 70, and V1av (j + 1) and V1av (i) Is compared with a determination value (second determination value) obtained by multiplying a predetermined ratio (0.9), that is, V1av (i) × 0.9. Here, “0.9” is a return determination parameter (predetermined ratio) for determining whether or not there is an instantaneous voltage drop return (S310).

  If V1av (j + 1) is smaller than V1av (i) × 0.9 (S310: NO), the controller unit 80 repeats the operation of S306. As described above, the controller unit 80 repeats the operations from S306 to S310: NO, so that the three past voltages V1av (j + 1) averaged including the new current voltage and the average immediately before the instantaneous voltage drop are averaged. The operation of comparing the magnitude relationship with 90% of the three past voltages V1av (i) that have been performed is always executed.

  If V1av (j + 1) is V1av (i) × 0.9 or more (S310: YES) and “I = I + 1” is set (S311) and “I = m” (S312: YES) The controller unit 80 turns on the bypass switch 90 and stops the control of the inverter 30 in order to end the compensation operation.

  Here, S312: YES means that “V1av (j + 1) ≧ V1av (i) × 0.9” is continuously determined m times (predetermined number of times). That is, S312: YES means that the past voltage including the present on the power system 100 side is significantly maintained at 90% or more of the past voltage immediately before the instantaneous voltage drop. Accordingly, it is determined that the voltage on the power system 100 side has returned to normal, and the power supplied from the power system 100 side is supplied to the load device 200 side through the bypass switch 90 (S313). In this way, when the voltage on the power system 100 side returns to normal, it is possible to supply power from the power system 100 to the load device 200 while minimizing power loss.

  Although the best mode for carrying out the present invention has been described above, the above embodiment is intended to facilitate understanding of the present invention and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

It is a block diagram which shows the structure of the instantaneous voltage drop compensation apparatus which concerns on this Embodiment. It is a flowchart which shows the flow of the voltage compensation control at the time of the instantaneous voltage fall which concerns on this Embodiment. It is a block diagram which shows the structure of the instantaneous voltage drop compensation apparatus which concerns on other embodiment.

Explanation of symbols

10 Instantaneous voltage drop compensation device 20 Series transformer 30 Inverter 40 Electric double layer capacitor 50A Power system side voltage sensor (PT1)
50B Load device side voltage sensor (PT2)
60 Input Conversion Unit 70 Memory Unit 80 Controller Unit 90 Bypass Switch 100 Power System 110 Compensation Voltage Supply Unit 120 Charger 130 DC / DC Converter 200 Load Device

Claims (10)

An instantaneous voltage drop compensator that is interposed between an electric power system and a load device and compensates the reduced voltage and supplies the reduced voltage to the load device when the voltage of the AC power supplied from the electric power system drops instantaneously. And
An AC / DC converter that converts a part of AC power supplied from the power system into DC power;
A capacitor for storing DC power supplied from the AC / DC converter;
An inverter that converts DC power supplied from the capacitor into AC power;
A control unit for controlling the inverter according to the voltage of the AC power supplied to the load device ;
A compensation voltage supply unit that compensates for the voltage of the AC power supplied from the power system by the AC power supplied from the inverter and supplies the voltage to the load device;
With
The control unit functions by DC power supplied from the capacitor ,
The controller is
A voltage detector for sequentially detecting the voltage of the AC power supplied to the load device;
A voltage storage unit for storing a voltage detected by the voltage detection unit;
An average value calculating unit for calculating an average value of a predetermined number of past voltages stored in the voltage storage unit;
A voltage comparison unit that compares the voltage newly detected by the voltage detection unit with a determination value obtained by multiplying the average value calculated by the average value calculation unit by a predetermined ratio;
An inverter control unit for starting control of the inverter so that the voltage of the AC power supplied to the load device becomes the average value when the newly detected voltage becomes equal to or less than the determination value; ,
Instantaneous voltage drop compensating device according to claim <br/> comprise a. The instantaneous voltage drop compensator according to claim 1, wherein the capacitor is an electric double layer capacitor. A DC / DC converter that is interposed between the capacitor and the control unit and converts a voltage of DC power stored in the capacitor into an operating voltage of the control unit;
The instantaneous voltage drop compensator according to claim 1. An instantaneous voltage drop compensator that is interposed between an electric power system and a load device and compensates the reduced voltage and supplies the reduced voltage to the load device when the voltage of the AC power supplied from the electric power system drops instantaneously. And
An AC / DC converter that converts a part of AC power supplied from the power system into DC power;
A capacitor for storing DC power supplied from the AC / DC converter;
An inverter that converts DC power supplied from the capacitor into AC power;
A control unit for controlling the inverter according to the voltage of the AC power supplied to the load device;
A compensation voltage supply unit that compensates the voltage of the AC power supplied from the power system and supplies the voltage to the load device by the AC power supplied from the inverter;
With
The control unit functions by DC power supplied from the capacitor,
The controller is
A first voltage detector for sequentially detecting the voltage of the AC power supplied to the load device ;
A first voltage storage unit for storing a voltage detected by the first voltage detection unit;
A first average value calculation unit for calculating an average value of a predetermined number of past voltages stored in the first voltage storage unit;
A first comparison of a voltage newly detected by the first voltage detection unit with a first determination value obtained by multiplying the average value calculated by the first average value calculation unit by a predetermined ratio. The voltage comparator of
When the voltage newly detected by the first voltage detection unit becomes equal to or lower than the first determination value, the voltage of the AC power supplied to the load device is the first average value calculation unit. A first inverter control unit for starting control of the inverter to be the average value calculated by:
A second voltage detector that sequentially detects the voltage of the AC power supplied from the power system ;
A second voltage storage unit for storing a voltage detected by the second voltage detection unit;
A second average value calculation unit that calculates an average value of a predetermined number of past voltages stored in the second voltage storage unit;
Wherein the second average value the average value newly calculated by the calculating section, by multiplying a predetermined ratio to the average value calculated by the second average value calculating section immediately before the control of the inverter is started A second voltage comparison unit for comparing with the obtained second determination value;
A second inverter control unit that stops control of the inverter when the average value newly calculated by the second average value calculation unit is equal to or greater than the second determination value;
An instantaneous voltage drop compensation device comprising: The compensation voltage supply unit transforms the voltage of AC power supplied from the power system with AC power supplied from the inverter and supplies the voltage to the load device, and bypasses the series transformer. And a bypass switch that connects the power system and the load device,
The first inverter control unit includes:
When the voltage newly detected by the first voltage detection unit becomes equal to or lower than the first determination value, the bypass switch is opened and the AC power supplied to the load device is reduced. Start control of the inverter so that the voltage becomes the average value calculated by the first average value calculation unit,
The second inverter control unit
When the average value newly calculated by the second average value calculation unit is equal to or greater than the second determination value, the bypass switch is closed and control of the inverter is stopped. The instantaneous voltage drop compensator according to claim 4 . The second inverter control unit
If the average value newly calculated by the second average value calculating section has reached a predetermined number of times consecutively the second judgment value or more, wherein, characterized in that the stop control of the inverter Item 5. The instantaneous voltage drop compensator according to Item 4 . The instantaneous voltage drop compensation device according to claim 1 , wherein the voltage storage unit is capable of storing at least the predetermined number of the past past voltages while being updated. The PLL circuit for making the phase of the alternating current power output from the inverter coincide with the phase of the alternating current power supplied from the electric power system is provided in the inverter. Instantaneous voltage drop compensation device. 2. The instantaneous voltage drop compensator according to claim 1 , wherein the predetermined ratio used for calculating the determination value is approximately 0.85. Wherein the predetermined ratio used to calculate the first determination value is approximately 0.85, the predetermined ratio used in the calculation of the second decision value preceding claims, characterized in that approximately 0.9 4. The instantaneous voltage drop compensator according to 4 .

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