JP2575682B2 - Reactive power compensator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactive power compensator for compensating a power receiving point voltage, and in particular, can simultaneously compensate a power receiving point voltage fluctuation caused by both reactance and resistance of a power supply system. The present invention relates to a simple reactive power compensator.

[Prior Art] FIG. 5 is described in, for example, SPC-86-92, “Reactive Power Compensation Device Using Active Filter”, published by the Institute of Electrical Engineers of Japan on November 27, 1986. FIG. 6 is a circuit diagram showing a connection state of a conventional reactive power compensator, and FIG. 6 is a control block diagram showing a functional configuration of the reactive power compensator in FIG.

In FIG. 5, (1) is an AC power supply constituting a power supply system, (2) is a power supply reactance included in the power supply system,
(3) trans supplies power current is corresponding to the receiving point voltage Vs applied from the power supply system, (4) generates a reactive power is supplied the load before flow i _F via a transformer (3) A load (5) is a reactive power compensator for supplying an output current i _ACF for reactive power compensation to the load (4). In this case, the reactive power compensator (5) is an active type reactive power compensator, and includes a PWM inverter (51) and a capacitor (52) connected to the PWM inverter (51).

In FIG. 6, reference numerals (11a) and (11b) denote three-phase to two-phase conversion circuits, and the three-phase current i _F supplied from the power supply system to the load (4) via the transformer (3) and the receiving point. each two-phase current the voltage _{Vs (i F α, i F} β) and the two-phase voltages (Vsα,
Vsβ). (12) is the instantaneous active power reactive power detection circuit detects the instantaneous active power p _F and the instantaneous reactive power q _F based on the 2-phase currents and the two-phase voltages.

(13) is a high-pass filter for passing only a predetermined frequency or more components Delta] p _F of the instantaneous active power p _F. (1
4) is an instantaneous current reference value calculation circuit, which has an instantaneous active power p _F
And the instantaneous reactive power q _F based on the control reference value * p _ACF and *
q A two-phase instantaneous current reference value is calculated by matrix multiplication using the _ACF and the two-phase voltages Vsα and Vsβ, and the two-phase instantaneous current reference values are converted into three-phase instantaneous current reference values * i _CR and * i. _CS
And * i _CT and output.

(15) is a DC voltage control circuit (indicated by AVR) which multiplies a deviation voltage ΔVd between the capacitor voltage Vd and the voltage reference value * Vd by a predetermined control function Gv (S) to obtain a current reference operation value ΔVd ·
Gv (S) is output. (16) is a current control circuit (indicated by ACR), and a predetermined control function G is applied to a deviation current Δi _ACF between the final instantaneous current reference value * i _ACF and the output current i _ACF of the reactive power compensator (5). _A (S) is multiplied by the current control signal Δi _ACF
G _A (S) is output.

(20b) is inserted adder on the output side of the current control circuit (16), the current control signal Δi _ACF · G _A (S) and the receiving point voltage Vs (Vs _R, Vs _S and Xs _T) and the Add the PWM control signal Δ
i _ACF · G _A (S) to output a + Vs. (17) is an adder (20
This is a PWM control circuit that controls the PWM inverter (51) by the PWM control signal from b).

(18a) Nominal (18) is the instantaneous current reference value calculation circuit (14)
Code converter inserted on the input side of the
p _F of predetermined frequency components Delta] p _F and the instantaneous reactive power q _F each code converted control reference value * p outputs an _ACF and * q _ACF.

(19) is the current reference calculation value ΔVd · Gv (S) and the receiving point voltage
Multiplier for calculating the three-phase current reference value * i _AVR for voltage control of the capacitor (52) by multiplying by Vs, and (20a) for the three-phase current reference value * i _AVR for the three-phase instantaneous current reference This is an adder for calculating the final instantaneous current reference value * i _ACF by adding the values i _CR to * i _CT .

Next, the operation of the conventional reactive power compensator shown in FIGS. 5 and 6 will be described.

First, the three-phase to two-phase conversion circuits (11a) and (11b) and the instantaneous active power reactive power detection circuit (12) include three-phase receiving point voltages Vs _R , Vs _S , and Vs _T with respect to the load (4). Phase load current
From i _FR , i _FS , and i _FT , the following matrix calculation is performed to determine the instantaneous active power p _F and instantaneous reactive power q _F of the load (4).

Instantaneous obtained from the above equation the active power p _F and the instantaneous reactive power q _F is the fundamental active power, a DC component p _F d and q _F d corresponding to the fundamental wave reactive power, harmonic active power and reactive harmonics consisting of an AC component p _F a and q _F a corresponding to the power.

The DC component p _F d corresponding to the fundamental active power is
Since it should be supplied from the AC power supply (1), it is removed by the high-pass filter (13).

In addition, of the AC component p _Fa corresponding to the harmonic active power, the frequency of the region that affects the waveform distortion of the power supply current is (here,
Only the component Δp _F (for example, 30 Hz or more) passes through the high-pass filter (13).

This is because, if the low-frequency component of the AC component p _F a is also passed through a high pass filter (13), when the compensated reactive power compensator of an active type (5), a direct current reactive power compensator (5) power supply unit, a low-frequency component of the AC component p _F corresponding to the harmonic active power also becomes possible to supply, when the voltage of the DC power source part low-frequency fluctuations are occurring in the voltage of the DC power supply fluctuates, the reactive power This is because an error occurs in the compensation operation of the compensator (5), so that a large-capacity DC capacitor is required to absorb the fluctuation, and the DC power supply unit has a large capacity.

On the other hand, the instantaneous reactive power q _F, and compensated for the reactive power compensator detected value itself (5).

The frequency component Δp _F and the instantaneous reactive power q _F selected as compensation targets in this way are detection amounts generated from the load (4), and the active type reactive power compensator (5) cancels these detection amounts. Should work. Therefore, the code converters (18a) and (18) perform code conversion on each detection amount to obtain * p
_ACF and * q _ACF , these are reactive power compensators (5)
Control reference value.

The instantaneous current reference value calculation circuit (14) is a two-phase receiving point voltage.
By the matrix operation of the following equation using Vsα and Vsβ,
The control reference values * p _ACF and * q _ACF are used as the instantaneous current reference values * i of the three-phase current i _ACF to be generated by the reactive power compensator (5).
Convert to _CR , * i _CS and * i _CT .

As the reactive power compensator (5), there are a current type PWM inverter type and a voltage type PWM inverter type.
Here, the latter voltage-source inverter method is taken as an example. As the DC voltage source of the reactive power compensator (5), a DC capacitor (52) of a type in which DC power is taken in from the power supply side by a feedback diode of an inverter and charged is used.

That is, the DC voltage control circuit (15) detects the deviation voltage ΔVd between the capacitor voltage reference value * Vd and the actual capacitor voltage Vd, and multiplies this by the control function Gv (S) to calculate the current reference calculation value ΔVd · Gv. (S) is obtained.

Further, the multiplier (19) calculates the current reference operation value ΔVd · Gv
For (S), the following equation is calculated to determine a three-phase current reference value * i _AVR (* i _AVRR , * i _AVRS and * i _AVRT ) for capacitor voltage control.

The current reference values * i _AVRR , * i _AVRS and * i _AVRT obtained from the above equation are added to the three-phase instantaneous current reference values * i _CR , * i _CS and * for reactive power compensation in the adder (20a). i _CT is added.

As a result, the final instantaneous current reference value * i _ACF (* i _ACFR , * i
_ACFS and * i _ACFT ) are obtained.

The three-phase instantaneous current reference value * i _ACFR obtained from the above equation,
* I _ACFS and * i _ACFT are compared with the output currents i _ACFR , i _ACFS and i _ACFT of the reactive power compensator (5) for each phase in the current control circuit (16) for use in feedback control. . As a result, the deviation current Δi _ACF is obtained,
Further, the deviation current Δi _ACF is multiplied by the control function G _A (S),
Current control signal Δi _ACF · G _A (S) is obtained. Further, in the adder (20b), the receiving point voltage Vs is added to the current control signal Δi _ACF · G _A (S), and the PWM control signal Δi _ACF · G
_A (S) + Vs is obtained.

This PWM control signal is input to the PWM control circuit (17),
PWM control circuit (17), so as to compensate for the reactive power q _F of the load (4), to PWM control the PWM inverter (51) of the reactive power compensator (5) within.

Here, the reason why the PWM control signal is obtained from the adder (20b) is that in the reactive power compensator (5) using the voltage type PWM inverter (51), the PWM control circuit (17) not only the current control signal for PWM control _{Δi ACF · G a (S)} , receiving point voltage Vs _R, the voltage control signal for combating Vs _S and Vs _T (receiving point voltage Vs itself) also to be entered Because it does not become.

As described above, the conventional reactive power compensator (5), the variation ΔVs of receiving point voltage Vs, the reactance value Xs of the reactance 2 reactive power q _F and power supply system of the load (4),
From the viewpoint that ΔVs ≒ q _F · Xs occurs, load (4)
Is configured to compensate for the reactive power q _F of

[Problems to be Solved by the Invention] Since the conventional reactive power compensator is configured as described above, the reactive power compensator (5) cannot be disregarded at the end of the distribution line where the voltage drop due to the resistance of the power supply system cannot be ignored. ), There is a problem that voltage compensation cannot be sufficiently performed.

For example, the ratio of the reactance to the resistance of the power system viewed from the end of the distribution line in a mountainous region was 3: 0 to 2: 1 and could not be ignored.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and compensates for a voltage drop caused by both reactance and resistance components of a power supply system without compensating for active power fluctuations of a load. It is an object of the present invention to obtain a reactive power compensator that can simultaneously compensate only by using the reactive power compensator.

Means for Solving the Problems A reactive power compensator according to the present invention is a reactive power compensator including a PWM inverter and a capacitor connected to the PWM inverter, and includes a three-phase current supplied to a load from a power supply system. And a three-phase to two-phase conversion circuit for converting a receiving point voltage into a two-phase current and a two-phase voltage, and an instantaneous active power reactive power detection circuit for detecting an instantaneous active power and an instantaneous reactive power based on the two-phase current and the two-phase voltage And a low-pass filter that passes each DC component of instantaneous active power and instantaneous reactive power as fundamental active power and fundamental reactive power, and multiplies the ratio of the resistance to the reactance of the impedance of the power supply system by the fundamental active power. A coefficient unit for calculating an active power multiplication value by using
An adder and a code converter for adding the reactive power of the fundamental wave to the multiplied value of the active power and performing code conversion to calculate the reactive power compensation reference value; and a two-phase matrix by multiplying the reactive power compensation reference value by the two-phase voltage. While calculating the instantaneous current reference value,
An instantaneous current reference value calculation circuit for converting a two-phase instantaneous current reference value to a three-phase instantaneous current reference value; and a current reference calculation value obtained by multiplying a deviation voltage between a capacitor voltage and a voltage reference value by a predetermined control function. A DC voltage control circuit that outputs a current reference value, a multiplier that calculates a three-phase current reference value for controlling the voltage of the capacitor by multiplying the current reference calculation value and the receiving point voltage, and a three-phase current reference value that controls the voltage of the capacitor. An adder for adding a three-phase instantaneous current reference value to the current reference value to calculate a final instantaneous current reference value;
A current control circuit that outputs a current control signal by multiplying a deviation current between the final instantaneous current reference value and the output current of the reactive power compensator by a predetermined control function; and adding a receiving point voltage to the current control signal. An adder that outputs a PWM control signal and a PWM control circuit that performs PWM control of a PWM inverter based on the PWM control signal are provided for compensating and controlling the reactive power of the fundamental wave.

[Operation] In the present invention, the active power and the reactive power of the load are separately detected, the ratio of the resistance to the reactance of the power supply system is multiplied by the active power detection value, and the reactive power detection value is algebraically added thereto. The calculated value is used as the reactive power compensation reference value.
That is, the control reference value * q _{ACF, which} is the fundamental reactive power reference value of the reactive power compensator, is calculated using the fundamental active power p _F d of the load, the resistance R of the power supply system, and the reactance Xs using the following equation: * q _ACF = - it is given by _{{q F d + (R /} Xs) p F d}.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a connection state of an embodiment of the present invention, (1) ~ (4) , (52), Vd, Vs, is, i F and i _ACF
Are the same as those described above (see FIG. 5). Also, (5A)
And (51A) correspond to the reactive power compensator (5) and the PWM inverter (51), respectively.

In FIG. 1, (6) is a resistance of a power supply system connected in series to the AC power supply (1), and R is a resistance value of the resistance (6).

The second is a control block diagram showing a functional configuration of an embodiment of the present invention, in which (11a), (11b), (12), (14)-
(19), (20a), (20b) * Vd, Vsα, Vsβ, p _F , q _F ,
* Ic _R , * ic _S , * ic _T , ΔVd · Gv (S), * i _AVR and * i
_{The ACF} is the same as described above (see FIG. 6).

In FIG. 2, (21a) and (21b) is a low-pass filter connected to the output terminals of the instantaneous active power reactive power detection circuit (12), the instantaneous active power p _F and the instantaneous reactive power
each DC component of the q _F, is passed as an effective fundamental wave power p _F d and the fundamental wave reactive power q _F d.

(20c) is a low-pass filter (21b) and a code converter (1
8). (22) is an adder of the fundamental wave active power p _F d side low-pass filter (21a) (20
c) is a coefficient multiplier inserted between the power supply system and the ratio (R / Xs) of the resistance R to the reactance Xs of the impedance of the power supply system, and multiplied by the detected fundamental active power p _F d. Outputs the active power multiplication value.

The code converter (18) calculates the addition value q from the adder (20c).
_F d 'is sign-converted to calculate a reactive power compensation reference value, that is, a control reference value * q _ACF.
Enter in 4).

The instantaneous current reference value calculation circuit (14) calculates the reactive power compensation reference value (control reference value) * q _ACF and the two-phase receiving point voltages Vsα and Vs
by a matrix multiplication of the beta, together with the instantaneous current reference value of two phases, the instantaneous current reference value of the instantaneous current reference value of two-to-three phase * ics _R, into a * ics _S and * ics _T.

Next, the operation of the embodiment of the present invention shown in FIGS. 1 and 2 will be described.

First, the variation ΔVs of the receiving point voltage Vs, the reactance Xs of the power supply system, the resistance R, the fundamental wave active power at the receiving point
The relationship between p _F d and the fundamental reactive power q _F d is expressed by the following equation.

_{ΔVs ≒ q F d · Xs +} p F d · R ...... usually reactance Xs than the resistance component R is very large, since the relationship between the Xs >> R holds, the above equation is expressed by the following equation.

ΔVs ≒ q _F d · Xs ...... Incidentally, the conventional reactive power compensator (5) is operating on the basis of the above equation, to detect the fundamental wave reactive power q _F d of the receiving point or load (4) , The sign-converted fundamental reactive power −q _F d
The power receiving point voltage fluctuation ΔVs is suppressed as shown in the following equation.

_{ΔVs ≒ (q F d-q} F d) · Xs = 0 ...... However, as described above, the impedance of the power supply system as seen from the receiving point of the distribution line end of the mountainous, the reactance Xs and resistance component R Is 3: 1 to 2: 1 and Xs>
> R does not hold, so p _F d · R in the above equation
Term cannot be ignored.

Therefore, in the present invention, the term p _F d · R in the equation is also compensated by the reactive power compensator (5A), so that the reactive power compensation reference value * q _ACF of the reactive power compensator (5A) is Determined by the formula.

_{ΔVs ≒ q F d · Xs +} p F d · R = Xs (q F d + p F d · R / Xs) = Xs · q F d '∴ * q ACF = -q F d' = - (q F d + p F d · R / Xs) ...... i.e., instantaneous active power p _F and the instantaneous reactive power q _F outputted from the instantaneous active power reactive power detection circuit (12), passes through the low-pass filter (21a) and (21b), the fundamental wave DC component only active power p _F d and the fundamental wave reactive power q _F d.

After the fundamental active power p _F d is multiplied by R / Xs via the coefficient unit (22), the fundamental reactive power q via the adder (20c)
_F d is added, the addition value q _F d '.

Further, the addition value q _F d ′ is converted to (−1) through a code converter.
And the reactive power compensation reference value * q _ACF (= -q _F d ')
And is input to the instantaneous current reference value calculation circuit (14).

In this case, the three-phase instantaneous current reference value calculation circuit (14)
The same matrix operation as in the above equation is performed, but in the equation, assuming that * p _ACF = 0, matrix multiplication of the reactive power compensation reference value * q _ACF and the two-phase voltages Vsα and Vsβ is performed, and the two-phase instantaneous current reference Calculate the values * icα and * icβ. Similarly, the matrix calculation formula, the instantaneous current reference value of 2 phases * Icarufa and * Icbeta three-phase instantaneous current reference value * ics _R,
Convert to * ic _S and * ic _T.

Thereby, the voltage drop due to both the reactance component Xs and the resistance component R of the power supply system can be simultaneously compensated only by compensating for the reactive power without compensating the active power fluctuation portion of the load (4).

For example, when a general AC line is considered as shown in FIG. 3, the line impedance is R '[Ω], X' [Ω], the transmitting end voltage is Es [V], and the receiving end voltage is Er [V]. , The line current is I [A], the receiving end active power is P [W], the receiving end reactive power is Q [VA], the transmitting end power factor angle is φs, and the receiving end power factor angle is φ.
Assuming that r, the following equation (A) is established from the vector diagram of FIG.

Es−Er = IR ′ + jIX ′ (A) In the above equation (A), the vertical axis in the vector diagram shown in FIG. 4 is the imaginary axis (j axis).

Normally, the power factor angles φs and φr satisfy the relationship of φs ≒ φr, so if φs = φr, the voltage drop Δ
With respect to V ′, the following equations (a) to (d) hold.

ΔV ′ = Es−Er = IR′cosφr + IX′sinφr (A) Er · ΔV ′ = Er · Icosφr · R ′ + Er · Isinφr · X ′ = P′R ′ + Q′K ′ (C) ΔV ′ / Er = (P′R ′ + Q′K ′) / Er ² (E) where ΔV ′ / Er represented by the equation (E) is a voltage drop standardized by the receiving end voltage Er [V]. ΔV [pu (reference is 1
Is the ratio when it is set as “)”.

When the reference apparent power is S [VA], the reference impedance Z is represented by the following equation (E).

Z = Er ² / S [Ω] (E) Here, the line impedances R ′ [Ω] and X ′
[Ω] is the pu value for the reference impedance Z, R [p
u] and X [pu], the following equations (f) and (g) are obtained.

R ′ = RZ = REr ² / S (f) X ′ = XZ = XEr ² / S (g) Also, the receiving end active power P ′ [W] and the receiving end reactive power Q ′ [VA] , Pu value for reference apparent power S [VA], P
When expressed by [pu] and Q [pu], the following equations (h) and (h) are obtained.

P ′ = PS (Q) Q ′ = QS (K) Therefore, by substituting the above equations (K) to (K) into the equation (D), it is standardized by the receiving end voltage Er [V]. Voltage drop ΔV [p
u] is represented by the following equation (K).

ΔV = {PS · REr ² / S + QS · XEr ² / S} / Er ² = PR + QX [pu] (E) From the expression (E), to make the voltage drop ΔV zero, P
And Q must be zero, but cannot be zero because P is the active power required by the load.

However, according to the present invention, ΔV can be reduced to 0 by correcting the voltage drop PR due to P by compensating power for Q, that is, reactive power, as shown in the following equation (c).

ΔV = PR + QX − ｛(R / X) P + Q｝ X = 0 (sa) In the conventional reactive power compensator, only −Q in the above equation (sa) is generated. And-(R / X)
P has been added.

That is, in the above equation (P), P is detected, this is regarded as reactive power, and a value obtained by multiplying the reactive power by R / X is set as a target value for the additional power.

As described above, of the voltage drop due to the line impedance of the three-phase AC line, the resistance component and the drop due to the fundamental wave active power of the line are determined by using the fundamental wave active power accurately obtained based on the three-phase to two-phase conversion. As a result, the voltage drop due to the reactance and the reactive power of the fundamental wave is increased by these drops, and the voltage drop can be compensated by the reactive power compensation.

Further, since the voltage drop to be compensated for is due to the fundamental wave of power or current passing through the line, it is required to accurately detect the fundamental wave, but this fundamental wave can be accurately detected. .

[Effects of the Invention] As described above, according to the present invention, the PWM inverter and the P
A reactive power compensator including a capacitor connected to a WM inverter, which converts a three-phase current and a receiving point voltage supplied from a power supply system to a load into a two-phase current and a two-phase voltage.
A phase-to-two phase conversion circuit, an instantaneous active power reactive power detection circuit for detecting instantaneous active power and instantaneous reactive power based on a two-phase current and a two-phase voltage, and a fundamental wave for each DC component of instantaneous active power and instantaneous reactive power A low-pass filter that passes as active power and fundamental reactive power, a coefficient device that calculates a real power multiplication value by multiplying a ratio of a resistance component to a reactance component of an impedance of a power supply system to calculate a real power multiplication value, and a real power multiplication value Adder and code converter for adding the reactive power of the fundamental wave and performing code conversion to calculate a reactive power compensation reference value, and a two-phase instantaneous current reference value by matrix multiplication of the reactive power compensation reference value and the two-phase voltage And an instantaneous current reference value calculation circuit for converting a two-phase instantaneous current reference value to a three-phase instantaneous current reference value, and a difference voltage between a capacitor voltage and a voltage reference value. DC voltage control circuit for multiplying the current control function to output a current reference operation value, and a multiplier for multiplying the current reference operation value and the receiving point voltage to calculate a three-phase current reference value for controlling the voltage of the capacitor An adder for adding a three-phase instantaneous current reference value to a three-phase current reference value for capacitor voltage control to calculate a final instantaneous current reference value; a final instantaneous current reference value and reactive power A current control circuit that outputs a current control signal by multiplying a deviation current from the output current of the compensator by a predetermined control function, an adder that adds a receiving point voltage to the current control signal and outputs a PWM control signal, A PWM control circuit that performs PWM control of the PWM inverter based on the PWM control signal and performs compensation control of the fundamental wave reactive power, so that the power receiving point voltage fluctuation (voltage drop due to both reactance and resistance components of the power supply system) ), The active power of the load Only compensation for reactive power without compensating for the dynamic component can be compensated at the same time by the effect of active reactive power compensator can be obtained, particularly when installed in a distribution line end of the mountainous.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a connection state of one embodiment of the present invention,
FIG. 2 is a control block diagram showing a functional configuration of one embodiment of the present invention, FIG. 3 is a circuit diagram showing a general power supply system for explaining the operation and effect of one embodiment of the present invention, and FIG. Is a vector diagram schematically showing each electric quantity (current and voltage) in FIG. 3, FIG. 5 is a circuit diagram showing a connection state of the conventional reactive power compensator, and FIG. 6 is a conventional reactive power compensator. FIG. 3 is a control block diagram showing a functional configuration of the first embodiment. (1) AC power supply, (2) reactance of power supply system,
(4) load, (5A) reactive power compensator, (6) power system resistance, (11a), (11b) three-phase two-phase conversion circuit,
(12) Instantaneous active power reactive power detection circuit, (14) Instantaneous current reference value calculation circuit, (15) DC voltage control circuit, (1)
6) is a current control circuit, (17) is a PWM control circuit, (18) is a code converter, (19) is a multiplier, (20a) to (20c) are adders, (21a) and (21b) are low-pass. Filter, (22) is a coefficient unit, (51A) is a PWM inverter, (52) is a capacitor,
i _ACF is the output current of the reactive power compensator, * ic _R , * ic _S , *
ics _T is the instantaneous current reference value of 3-phase, * i _ACF final instantaneous current reference value, p _F is the instantaneous active power, p _F d is the fundamental active power, q
_F is the instantaneous reactive power, q _F d is the fundamental reactive power, * q _ACF is the reactive power compensation reference value, Vd is the capacitor voltage, Vs is the receiving point voltage, ΔVd · Gv (S) is the current reference calculated value, Δi _ACF・ G
_A (S) is a current control signal. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A reactive power compensator including a PWM inverter (51A) and a capacitor (52) connected to the PWM inverter, which is supplied from a power supply system (1, 2, 6) to a load (4). 3
A three-phase / two-phase conversion circuit (11a, 11b) for converting a phase current and a receiving point voltage into a two-phase current and a two-phase voltage; and an instantaneous active power and an instantaneous reactive power based on the two-phase current and the two-phase voltage. An instantaneous active power reactive power detection circuit (12) for detecting, a low-pass filter (21a, 21b) for passing each DC component of the instantaneous active power and the instantaneous reactive power as a fundamental active power and a fundamental reactive power, A coefficient unit (22) for multiplying a ratio of a resistance to a reactance of an impedance of a power supply system by the active power of the fundamental wave to calculate an active power multiplied value; and adding the reactive power of the fundamental wave to the active power multiplied value. Adder (20c) and code converter (18) for performing code conversion and calculating a reactive power compensation reference value, and a two-phase instantaneous current reference value by matrix multiplication of the reactive power compensation reference value and the two-phase voltage. An instantaneous current reference value calculation circuit (14) for calculating and converting the two-phase instantaneous current reference value to a three-phase instantaneous current reference value; and controlling a deviation voltage between the voltage of the capacitor and the voltage reference value to a predetermined value. A DC voltage control circuit (15) for multiplying a function to output a current reference operation value, and multiplying the current reference operation value and the receiving point voltage to obtain a three-phase current reference value for controlling the voltage of the capacitor. A multiplier (19) for calculating, and an adder (20a) for adding the three-phase instantaneous current reference value to the three-phase current reference value for controlling the voltage of the capacitor to calculate a final instantaneous current reference value. A current control circuit (16) for multiplying a deviation current between the final instantaneous current reference value and an output current of the reactive power compensator by a predetermined control function to output a current control signal; And the PWM signal is output. And a PWM control circuit (17) for performing PWM control of the PWM inverter based on the PWM control signal, wherein the basic wave reactive power is compensated and controlled. Power compensator.