JP2008289274A - Voltage fluctuation compensator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage fluctuation compensator which reduces the capacitance of a phase-advancing capacitor. <P>SOLUTION: A compensation value calculation unit 4 calculates a compensation value equivalent to voltage fluctuation generated at a power distribution line 51 when a motor M is driven. A discrimination circuit 5 discriminates the compensation value for starting the motor M to output the compensation value to the number of inputs calculation circuit 6 of the phase-advancing capacitor. The number of inputs calculation circuit 6 of the phase-advancing capacitor calculates the number of inputs of the phase-advancing capacitor 27 so as to compensate the voltage fluctuation of the power distribution line 51 based on the compensation value when the motor M discriminated by the discrimination circuit 5 is started. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a voltage fluctuation compensation device that compensates for voltage fluctuations caused by fluctuations in a load in a distribution line that supplies power to the load.

  As shown in FIG. 5 (a), an inductive load, for example, a pump motor installed in a pumping station or the like (hereinafter referred to as an electric motor) is activated (in the example of the figure, by a known condorfa activation). ) Requires a very large amount of power, but the power consumption becomes almost constant when the state is shifted to a steady operation state. Therefore, the voltage drop of the distribution line that supplies electric power to the electric motor greatly fluctuates when the electric motor is started up, and becomes a substantially constant value in the steady operation state.

However, even if the electric motor is in a steady operation state, a voltage drop occurs as long as the electric motor operates and consumes electric power. Therefore, an electric motor voltage fluctuation compensator that compensates for voltage fluctuation generated in a distribution line that supplies electric power to the electric motor has a plurality of phase advance capacitors connected in parallel to the electric motor via a semiconductor switch. As shown in b), the phase advance capacitor is continuously turned on to maintain the voltage so that the voltage is the same as when the motor is stopped (see, for example, Patent Document 1).
Japanese Utility Model Publication No. 7-29611

  In order to maintain the same voltage as when the motor is stopped when the motor is operating at startup or in a steady state, the voltage fluctuation caused by the active power is compensated together with the voltage fluctuation caused by the reactive power. There is a need.

  In the conventional voltage drop compensator, as long as the electric motor is started or operated in a steady state, the phase advance capacitor installed in the apparatus is continuously supplied so that the voltage is the same as that when the electric motor is stopped.

The voltage drop value that occurs when the motor is in operation can be calculated by equation (1).
ΔV = P × (% R × cos θ +% X × sin θ) / (10 × 10 ⁶ ) (1)
ΔV: Voltage drop value (%)
P: Apparent power of motor (VA)
% R: Resistance impedance of distribution line (% per 10 MVA)
cosθ: power factor of motor% X: impedance for reactance of distribution line (% per 10 MVA)
sin θ: calculated from the power factor of the motor (θ = cos ⁻¹ θ)

And the voltage rise value which a phase advance capacitor has can be calculated by Formula (2).
ΔV _UP = Q ×% X / (10 × 10 ⁶ ) (2)
△ V _UP : Voltage increase value (%)
Q: Phase advance capacitor capacity (var)
% X: impedance of reactance of distribution line (% per 10 MVA)

For example, when the apparent power P = 500 kVA of the motor in the steady operation state, the power factor 0.8, and the distribution line impedance% R = 50 and% X = 100, the voltage drop value ΔV is
ΔV = 500 × 10 ³ × (50 × 0.8 + 100 × 0.6) / (10 × 10 ⁶ )
= 5 (%)
Is calculated.

Therefore, if the voltage drop in the steady state is compensated by the phase advance capacitor,
ΔV _UP = Q ×% X / (10 × 10 ⁶ ) = 5 (%)
Than,
Q = 5 × (10 × 10 ⁶ ) / 100 = 500 × 10 ³ (var) = 500 (kvar)
The phase-advancing capacitor capacity is required.

Here, the reactive power generated in the electric motor can be calculated by Equation (3).
Q ′ = P × sin θ (3)
Q ': Reactive power (var) generated in the motor
P: Apparent power of motor (VA)
sin θ: calculated from the power factor of the motor (θ = cos ⁻¹ θ)

Therefore, the reactive power generated in the motor of the above example is
Q ′ = 500 × 10 ³ × 0.6 = 300 × 10 ³ (var) = 300 (kvar)
Is calculated.

  In other words, in the above example, in order to compensate for the voltage drop in the distribution line, the phase-advancing capacitor capacity that the voltage fluctuation compensator should supply is generated in the motor even though there is almost no fluctuation in the steady operation state of the motor. It is necessary to keep the state of the advanced phase exceeding the reactive power being 500-300 = 200 (kvar).

Further, assuming that the apparent power P at the start-up of the motor is P = 1500 kVA and the power factor is 0.6, the voltage drop value ΔV is
ΔV = 1500 × 10 ³ × (50 × 0.6 + 100 × 0.8) / (10 × 10 ⁶ )
= 16.5 (%)
Is calculated.

Therefore, if the voltage drop at startup is compensated by the phase advance capacitor,
ΔV _UP = Q ×% X / (10 × 10 ⁶ ) = 16.5 (%)
Than,
Q = 16.5 × (10 × 10 ⁶ ) / 100 = 1650 × 10 ³ (var)
= 1650 (kvar)
The phase-advancing capacitor capacity is required.

  In general, a plurality of pump motors are installed in the pumping station. For example, in a pumping station in which three motors are installed, if a voltage fluctuation compensator is installed in each motor, the total capacity is 1650 in total. × 3 = 4950 (kvar) The equipment has a huge phase advance capacitor capacity.

  Even if three motors are not activated at the same time, the maximum voltage fluctuation is the case where two motors are activated in a steady state, and 500 × 2 + 1650 = 2650 (kvar) is enormous. Equipment having a capacity of the phase advance capacitor is required.

  The phase-advancing capacitor is divided into a plurality of capacitance groups, and, for example, four capacitance groups are formed by weighting the capacitances 1, 2, 4, and 8, and 15-level control (4 groups 15) is performed by combining these capacitance groups. A voltage fluctuation compensator is known in which the number of phase-advancing capacitors and the number of open / close switches for the capacitor current are reduced by performing stage control. However, when the phase advance capacitor capacity increases, the capacitor current of a circuit having a large weight increases, making it difficult to obtain a semiconductor switch that opens and closes.

  For example, in the case of a 15-stage control capacity 2700 (kvar) close to 2650 (kvar), the capacity group is 180/360/720/1440 (kvar). A semiconductor switch capable of opening and closing such a large-capacity 1440 (kvar) group is difficult to obtain and very expensive.

  Accordingly, an object of the present invention is to provide a voltage fluctuation compensator capable of reducing the capacity of a phase advance capacitor.

The voltage fluctuation compensating device of the present invention includes a voltage detection unit that detects a voltage of a distribution line connected to a load, a current detection unit that detects a current flowing through the distribution line, and a parallel connection to the load on the distribution line A phase advance capacitor circuit having a plurality of shunts in which a series reactor, a semiconductor switch and a phase advance capacitor are connected in series; and a control means for controlling on / off of the semiconductor switch of the phase advance capacitor circuit; It has.
Compensation value calculating means for calculating a compensation value for compensating voltage fluctuation generated in the distribution line based on detection results of the voltage detecting means and the current detecting means, and the compensation value calculating means A discrimination means for discriminating a compensation value when the load fluctuates from the calculated compensation value, and the number of input of the phase advance capacitor is set so that voltage fluctuation is compensated based on the compensation value discriminated by the discrimination means. Capacitor insertion number calculation means for calculating, and input command means for controlling on / off of the semiconductor switch so that the phase advance capacitor is input by the number of insertions calculated by the capacitor insertion number calculation means. It is characterized by.

In the present invention, the compensation value calculation means calculates a compensation value related to active power and a compensation value related to reactive power, respectively, and the discrimination means relates to a compensation value related to active power and reactive power calculated by the compensation value calculation means. You may discriminate | determine the fluctuation | variation part when the said motor starts with respect to each of a compensation value.
In the present invention, the discriminating means may comprise a CR integrating circuit and a differential amplifier circuit.
Examples of semiconductor switches include thyristors, FETs, IGBTs, and the like.

  As described above, the voltage drop that occurs when an inductive load such as an electric motor shifts to a steady operation state is smaller than the voltage drop that occurs when the motor starts, and is substantially constant.

  Therefore, when the motor finishes starting and shifts to the steady operation state, the compensation value fluctuations become smaller with time and become constant. At this time, since the compensation value is reduced by the discrimination circuit, the number of phase-advancing capacitors to be input is reduced and finally becomes zero.

In other words, by shifting the start-up timing of the plurality of electric motors, the voltage fluctuation compensator having a compensation capacity (capacitance of the phase advance capacitor) corresponding to one of the plurality of electric motors can be handled.
Thus, according to the present invention, it is possible to reduce the capacity of the phase advance capacitor of the voltage fluctuation compensator that compensates for the voltage fluctuation of the plurality of electric motors. This makes it possible to use an easily available and inexpensive semiconductor switch.

[Constitution]
Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating an installation state of a voltage fluctuation compensating apparatus according to an embodiment of the present invention in a pumping station provided with three pump motors M (hereinafter referred to as “motor M”).
As shown in FIG. 1, a distribution line 51 is drawn from a high voltage receiving point outside the premises via a transformer T into the pumping station yard, and three electric motors M are connected to the distribution line 51 in parallel. The motor M is a three-phase induction motor, and its activation is performed by a known condorfa method (see FIG. 3).

  The voltage fluctuation compensator 1 includes an instrument transformer (voltage detection means) 2, three current transformers (current detection means) 3, a phase advance capacitor circuit 8, and a control device (control means) 9. ing.

The instrument transformer 2 detects the voltage of the distribution line 51 that supplies electric power to the electric motor M.
The three current transformers 3 detect currents supplied to the corresponding electric motors M, respectively.

The phase advance capacitor circuit 8 has a plurality of shunts connected to the distribution line 51 in parallel with the electric motor M. In FIG. 1, three shunts 24a to 24c are shown.
In each of the shunts 24a to 24c, a series reactor 25, a thyristor 26, and a phase advance capacitor 27 are connected in series. The series reactor 25 removes harmonic noise. The thyristor 26 is an AC semiconductor switch that is ON / OFF controlled by the control device 9. The phase advance capacitor 27 is for increasing the voltage of the wiring line 51.
When the thyristor 26 is turned on by the control device 9, the corresponding shunts 24 a to 24 c are electrically connected to the distribution line 51. In other words, the corresponding phase advance capacitor 27 is turned on, and the voltage of the wiring line 51 rises according to the capacity of the phase advance capacitor 27 that has been turned on.

The control device 9 will be described with reference to FIG. FIG. 2 is a functional block diagram of the voltage fluctuation compensation device 1. In FIG. 2, one electric motor M is shown among the three electric motors M.
As shown in FIG. 2, the control device 9 controls the number of input of the phase advance capacitor 27, and includes a compensation value calculation unit (compensation value calculation unit) 4, a discrimination circuit (discrimination unit) 5, and a phase advancement unit. A capacitor charging number calculating circuit (capacitor charging number calculating means) 6 and a charging command circuit (charging command means) 7 are provided.

  The compensation value calculation unit 4 calculates a compensation value corresponding to the voltage fluctuation generated in the distribution line 51 based on the detection results of the instrument transformer 2 and the three current transformers 3. Specifically, the active power and reactive power supplied to the motor M are calculated, voltage fluctuations are calculated for each of the active power and reactive power, and the compensation value is calculated by adding both. Detailed calculation capacity will be described later in detail.

The discriminating circuit 5 discriminates a compensation value when the electric motor M starts from the compensation value calculated by the compensation value calculation unit 4, and includes a CR integration circuit 21 and a differential amplifier circuit 22.
The CR integration circuit 21 is an integration circuit composed of a capacitor C and a resistor R (both not shown), and functions as a low-pass filter. That is, the CR integration circuit 21 is set so that the compensation value is output as it is as the amount of change in the compensation value becomes smaller, based on the time constant determined by the combination of CR. The compensation value that has passed through the CR integration circuit 21 is output to the differential amplifier circuit 22.
The differential amplifier circuit 22 outputs a value obtained by subtracting the compensation value passed through the CR integration circuit 21 from the compensation value calculated by the compensation value calculation unit 4 to the phase advance capacitor input number calculation circuit 6.
In this manner, the discrimination circuit 5 discriminates the compensation value when the compensation value calculated by the compensation value calculation unit 4 is large, that is, when the motor M starts up, and outputs it to the phase advance capacitor input number calculation circuit 6. To do.

Based on the compensation value discriminated by the discriminating circuit 5, the phase-advancing capacitor charging number calculating circuit 6 calculates the number of phase-advancing capacitors 27 charged so that the voltage fluctuation of the distribution line 51 is compensated.
The input command circuit 7 controls on / off of the thyristor 26 of the phase advance capacitor circuit 8 so that the number of phase advance capacitors 27 calculated by the phase advance capacitor input number calculation circuit 6 is input.

[Operation]
Next, the operation of the voltage fluctuation compensating apparatus 1 will be described with further reference to FIG. Hereinafter, the description will proceed under the condition that a plurality of electric motors M are not started simultaneously. 3 (a) to 3 (d) are various time charts when the electric motor M is started. FIG. 3 (a) shows changes in the current supplied to the electric motor M, and FIG. 3C shows the change in the output of the CR integration circuit, FIG. 3C shows the change in the compensation value discriminated by the discrimination circuit 5, and FIG. 3D shows the phase advance capacitor 27 calculated by the phase advance capacitor input number calculation circuit 6. The change in the number of inputs is shown respectively.

  First, the electric motor M is started by starting supply of electric power to the electric motor M through the distribution line 51. In addition, starting of the electric motor M shall be by condorfa starting. As shown in FIG. 3A, the current supplied to the electric motor M increases rapidly at the time of startup, and then becomes constant when the normal operation state is reached. When the current supplied to the motor M suddenly increases, voltage fluctuations in the distribution line 51 occur in synchronization with the change in current.

  At this time, the compensation value calculation unit 4 of the control device 9 applies the distribution line 51 to the distribution line 51 from the voltage of the distribution line 51 detected by the instrument transformer 2 and the current supplied to the electric motor M detected by the current transformer 3. A compensation value corresponding to the generated voltage fluctuation is calculated. As described above, the compensation value calculation unit 4 calculates active power and reactive power in the motor M, respectively, and calculates a compensation value by adding voltage fluctuations related to each of the active power and reactive power. Detailed calculation capacity will be described later in detail.

  Further, the discrimination circuit 5 discriminates the compensation value when the compensation value calculated by the compensation value calculation unit 4 is large, that is, when the motor M is started up, and outputs it to the phase advance capacitor input number calculation circuit 6. At this time, as shown in FIG. 3B, the output of the CR integration circuit 21 gradually increases without following the fluctuation of the current value. Further, as shown in FIG. 3C, the compensation value discriminated by the discrimination circuit 5 is abruptly increased at the time of start-up in synchronization with the change of the current flowing through the electric motor M. In the normal operation state, the difference between the two inputs of the differential amplifier circuit becomes small, so that the compensation value gradually decreases and finally becomes zero.

  The number-of-phase-advancing capacitor calculation circuit 6 calculates the number of phase-advancing capacitors 27 to be compensated for the voltage fluctuation of the distribution line 51 based on the compensation value discriminated by the discrimination circuit 5 when the motor M is started. Is calculated. At this time, as shown in FIG. 3 (d), the number of advanced phase capacitors 27 calculated by the advanced phase capacitor input number calculating circuit 6 is synchronized with the change of the compensation value discriminated by the discriminating circuit 5 at the time of start-up. Suddenly grows at In the normal operation state, the compensation value gradually decreases by one step and finally becomes zero.

  The start-up load fluctuation of the motor M lasts for several tens of seconds at the longest. If the time constant of the CR integration circuit 21 of the discrimination circuit 5 is set to several minutes, the start-up load fluctuation can be sufficiently discriminated. Further, if a time several times the time constant elapses, the number of input stages of the phase advance capacitor 27 becomes zero.

  The turn-on command circuit 7 controls on / off of the thyristor 26 of the phase advance capacitor circuit 8 so that the number of phase advance capacitors 27 calculated by the phase advance capacitor input number calculation circuit 6 is turned on.

As described above, since the load in the steady operation state of the motor M is almost constant, the compensation value output by the discrimination circuit 5 gradually decreases. For this reason, the number of input of the phase advance capacitor 27 is decreased by one, the voltage fluctuation generated in the distribution line 51 does not become a large value, and the influence on other customers is reduced.
In addition, the voltage drop that occurs during steady operation gradually increases as the number of phase-advancing capacitors 27 decreases, but in order to ensure the voltage to be maintained as defined by the Electricity Business Law for the power company distribution lines, It is customary to install an automatic voltage regulator for supplying a voltage that should compensate and maintain voltage fluctuations due to steady load capacity. Therefore, if the number of phase-advancing capacitors 27 is decreased at intervals at which the installed automatic voltage regulator can respond, it can be expected that the voltage fluctuation is automatically adjusted.

  In the present embodiment, the calculation of the compensation value in the compensation value calculation unit 4 and the calculation of the number of input of the phase advance capacitor 27 in the phase advance capacitor input number calculation circuit 6 are performed in a specific manner described below. Is called.

First, when starting up the electric motor M, a voltage drop ΔV calculated from the equation (1) described in the section of the related art occurs. At this time, the voltage drop ΔV is calculated by calculating the active power W and reactive power Q. of the motor from the pump current and the circuit voltage.
In the present embodiment, a method is adopted in which the addition of the voltage drop due to the active power and the reactive power shown in Expression (1) is compensated by the phase advance reactive current supplied from the phase advance capacitor 27. That is, in this embodiment, since the voltage drop at the time of start-up is compensated by turning on the phase advance capacitor 27, the voltage drop value ΔV in the equation (1) immediately corresponds to the voltage rise value ΔVUP in the phase advance capacitor 27. Become.
Therefore, the compensation value calculation unit 4 calculates the voltage drop value ΔV or the voltage rise value ΔVUP in the phase advance capacitor 27 as a compensation value.
In addition, the voltage drop of Formula (1) is the sum of the (active power) term of P × cos θ ×% R and the (reactive power) term of P × sin θ ×% X. The method of calculating active power and reactive power from the input voltage and current is already used in another device or a conventionally known voltage fluctuation compensator, and the voltage fluctuation compensator of the present invention also calculates the power by the same method. The voltage drop can be obtained by multiplying the impedance.

  Here, by using the fact that the voltage increase value ΔVUP in the phase advance capacitor 27 is obtained from the equation (2), it is possible to calculate the phase advance capacitor capacity and the number of the phase advance capacitor 27 required at the time of start-up. . Therefore, the phase advance capacitor input number calculation circuit 6 can calculate the phase advance capacitor capacity and the number of phase advance capacitors 27 required at the time of start-up by the compensation value and the equation (2).

  At the time of start-up, if the required number of phase advance capacitors 27 is obtained, the on / off of each thyristor 26 is directly applied from the input command circuit 7 so as to input the required number of phase advance capacitors 27 based on the required number. An off signal is transmitted.

Here, the introduction of the phase advance capacitor 27 corresponds to giving a voltage increase due to the phase advance current.
Thus, according to the present embodiment, the voltage drop ΔV shown in the equation (1) can be compensated by the phase advance current flowing in the phase advance capacitor 27.

  In the case of the electric motor according to the above example (see the column of the prior art), among the voltage fluctuation compensator capacity 1650 kvar required for one electric motor, the required amount of the phase advance capacitor in steady operation is 500 kvar, When using 4 groups and 15-stage control (capacitance groups of 110, 220, 440, and 880 [kvar] if the capacitance is weighted as 1, 2, 4, and 8), the phase advance capacitor closest to this A capacity of 550 kvar corresponds to five stages. If the time constant of the CR integrating circuit 21 of the discriminating circuit 5 is set to 3 minutes, for example, the number of advanced phase capacitors may be reduced to zero in about 10 minutes. I can expect.

  When the calculation is performed under the above-described conditions, the steady operation is 500 kvar and the startup is 1650 kvar. When conventional control is performed, the three pumps require 2650 kvar of phase advance capacitors. When this is the control method of the present invention, it may be 1650 kvar of only the voltage fluctuation compensation capacity generated when the motor M1 is started. In the case where the phase advance capacitor capacity is 2650 kvar, the maximum capacity when the four-group 15-stage control is configured is 1440 kvar in the conventional example, but in the present invention, it is 880 kvar, which is about 60% of the capacity of the conventional example. Products (phase-advancing capacitors and thyristors) are now applicable.

  As described above, according to the present embodiment, the discrimination circuit 5 discriminates the compensation value when the electric motor M starts up and outputs the compensation value to the phase advance capacitor input number calculation circuit 6. The phase advance capacitor input number calculation circuit 6 Based on the compensation value when the electric motor M discriminated by the discriminating circuit 5 is started, the input number of the phase advance capacitor 27 is calculated so that the voltage fluctuation of the distribution line 51 is compensated. For this reason, after the start-up of one electric motor M, it is possible to gradually reduce the number of phase-advancing capacitors 27 that are being turned on in a steady state and finally make the number of turns zero, thereby achieving a steady state. When the other motor M is started, the phase advance capacitor circuit 8 having the compensation capacity for one motor used for starting the motor M can be put into a state where it can be operated as if the compensator dedicated to the motor M is used. It becomes possible.

  Therefore, it is possible to cope with a plurality of motors M with a compensation capacity for one motor, and the capacity of the phase advance capacitor 27 can be reduced. Thereby, the thyristor 26 which is easy to obtain and inexpensive can be used. For this reason, cost reduction of the voltage fluctuation compensation apparatus 1 can be achieved.

[Modification]
Although the present invention has been specifically described with reference to one embodiment and the like, the present invention is not limited to the configuration described in the embodiment and the like, and various design changes are possible.

  For example, in the above embodiment, the phase advance capacitor circuit 8 is configured with a capacity of one unit, but a capacity may be appropriately provided for the capacitor capacity. As a result, even after one motor M shifts to the steady operation state, the third motor M is changed to the second motor even when the second motor M sequentially turns off the phase-advancing capacitor 27 being turned on. It becomes possible to start the capacitor before the capacity of the capacitor being supplied to M becomes zero.

The use to which the present invention is applied is not limited to the pumping station. The present invention can be easily applied to facilities in which a plurality of inductive loads such as electric motors are connected in parallel.
For example, the present invention can be applied to a lighting device that is an inductive load. In this case, the present invention functions as a voltage flicker compensation device and reduces blanking (flicker) of the proving device due to voltage fluctuation.
The type of the pump motor is not limited to the three-phase induction motor. Regarding the activation method, in addition to the condorpha method mentioned in the above example, a known activation method can be used alone or in combination.

The specific calculation method of the compensation value or the required number of input phase-advancing capacitors 27 is not limited to the one described in each of the above examples, and a known method can be appropriately employed.
For example, as shown in FIG. 4, the active power compensation value calculation unit 104 a calculates a compensation value corresponding to the voltage fluctuation of the active power generated in the distribution line 51, and the reactive power compensation value calculation unit 104 b is generated in the distribution line 51. The compensation value corresponding to the voltage fluctuation of the active power to be calculated is calculated, and in the discrimination circuit 105, the electric motor M uses the compensation value calculated by each of the active power compensation value calculation unit 104a and the reactive power compensation value calculation unit 104b. The configuration may be such that the compensation values at the time of starting are individually discriminated, and those compensation values added by the adder circuit 123 are output as compensation values for calculating the number of input of the phase advance capacitor 27. .

  Thus, the present invention is not limited to the configurations described in the above embodiments and the like. It is obvious that those skilled in the art can devise various modifications based on the basic technical idea and teachings disclosed above.

It is a schematic block diagram which shows the state which installed the voltage fluctuation compensation apparatus which concerns on one Embodiment of this invention in the pumping station. It is a functional block diagram of the voltage fluctuation compensation apparatus shown in FIG. It is various time charts when the electric motor for pumps shown in FIG. 2 starts. It is a functional block diagram of the voltage fluctuation compensation apparatus which concerns on a modification. It is a time chart which concerns on the conventional Example.

Explanation of symbols

1 Voltage fluctuation compensation device 2 Instrument transformer (voltage detection means)
3 Current transformer (current detection means)
4 Compensation value calculation unit (compensation area calculation means)
5 Discrimination circuit (discrimination means)
Hexadecimal phase capacitor number calculation circuit (capacitor number calculation means)
7 Input command circuit (input command means)
Eight-phase capacitor circuit 9 Control device (control means)
21 integrating circuit 22 differential amplifier circuit 24a-24c shunt 25 series reactor 26 thyristor 27 phase advance capacitor 51 distribution line 104a active power compensation value calculation unit 104b reactive power compensation value calculation unit 105 discrimination circuit 123 addition circuit M motor for pump

Claims (3)

Voltage detection means for detecting the voltage of the distribution line connected to the load;
Current detection means for detecting a current flowing through the distribution line;
A phase advance capacitor circuit having a plurality of shunts connected in series to the distribution line and in parallel with the load, a series reactor, a semiconductor switch, and a phase advance capacitor;
Control means for controlling on / off of the semiconductor switch of the phase advance capacitor circuit,
The control means is
Compensation value calculation means for calculating a compensation value for compensating for voltage fluctuations generated in the distribution line according to the detection results of the voltage detection means and the current detection means;
Discriminating means for discriminating a compensation value when the load fluctuates from the compensation value calculated by the compensation value calculating means;
Capacitor input number calculation means for calculating the number of input of the phase advance capacitor so that voltage fluctuation is compensated based on the compensation value discriminated by the discrimination means;
A voltage fluctuation compensator comprising: charge command means for controlling on / off of the semiconductor switch so that the phase advance capacitor is charged by the charge number calculated by the capacitor charge number calculating means. The compensation value calculation means calculates a compensation value for active power and a compensation value for reactive power,
2. The difference according to claim 1, wherein the discriminating unit discriminates a variation due to a variation in the load with respect to each of a compensation value related to active power and a compensation value related to reactive power calculated by the compensation value calculating unit. Voltage fluctuation compensation device.   3. The voltage fluctuation compensating apparatus according to claim 1, wherein the discriminating means includes a CR integrating circuit and a differential amplifier circuit.

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