JP2021029070A - Active filter device for power system - Google Patents

Abstract

To provide an active filter device for power system capable of compensating harmonics in cooperation with a separate harmonic suppression circuit being present in the same power distribution system.SOLUTION: A main circuit 110A has a configuration in which an interconnection reactor 112 and an inverter device 114 are connected in series. A voltage detector 120 detects an interconnection point voltage. A current detector detects an interconnection point current. An inverter controller 130 calculates a harmonic current command value by multiplying a transfer function which is determined based on a harmonic suppression circuit that is used together with an active filter device 100 for power system, generates a voltage command value on the basis of the harmonic current command value and is capable of controlling the inverter device 114 on the basis of the voltage command value.SELECTED DRAWING: Figure 2

Description

The present invention relates to an active filter device for an electric power system.

The load device connected to the power system generates a harmonic current and injects it into the power system. As a result, a harmonic voltage is generated in the power system. Especially in the power distribution system, it is known that a harmonic expansion phenomenon may occur due to resonance with a phase-advancing capacitor provided for improving the power factor.

As a countermeasure against the harmonic expansion phenomenon, in the 1998 JIS revision, a series reactor with a reactance of 6% or 13% of the phase-advancing capacitor was connected in series to the phase-advancing capacitor, and a phase-advancing capacitor with a series reactor was installed. It was decided that it should be composed. As a result, the phase-advancing capacitor with a series reactor operates as an inductive impedance for the fifth and higher harmonic components, and divides the harmonic current orthogonal to the harmonic voltage. As a result, the phase-advancing capacitor with a series reactor can absorb the fifth and higher harmonic currents injected by the load equipment of the same distribution system, and can reduce the harmonic voltage of the power system. For this reason, it is widely used in existing distribution systems.

As another circuit configuration for avoiding the harmonic expansion phenomenon, a distribution system active filter device (for example, Patent Document 2) has been proposed. The voltage at the connection point with the system is detected, and the gain Kv is multiplied to generate the current command value. According to this current command value, the inverter injects a harmonic current into the interconnection point. The magnitude of the gain Kv changes dynamically according to the detected harmonic voltage. As a result, the harmonic expansion phenomenon due to resonance can be avoided.

Jikkenhei No. 2-2723 Japanese Patent No. 3661012

However, the above-mentioned conventional power distribution system active filter device has a problem that it is difficult to absorb harmonic current in cooperation with a phase-advancing capacitor with a series reactor which is already widely used in a power distribution system.

Specifically, if the gain Kv of the distribution system active filter device is large, the distribution system active filter device absorbs a large amount of harmonic current, while the surrounding phase-advancing capacitor with a series reactor absorbs a small amount of harmonic current. become. In this case, the harmonic compensation effect of the existing phase-advancing capacitor with a series reactor cannot be utilized, and the required capacity of the distribution system active filter device increases.

Further, even if the harmonic current absorbed by the distribution system active filter device is reduced by lowering the gain Kv, the same harmonic current as that of the phase-advancing capacitor with a series reactor cannot be divided. This is because the harmonic current command value generated by multiplying the harmonic voltage by the gain Kv has the same phase as the harmonic voltage. Unlike a phase-advancing capacitor with a series reactor, it does not operate as an inductive impedance, and it cannot be expected to have the effect of reducing the harmonic voltage of the power system as much as a phase-advancing capacitor with a series reactor.

As described above, when the conventional power distribution system active filter device and the phase-advancing capacitor with a series reactor are installed side by side, it is difficult to evenly share the harmonic current to be absorbed according to the installed capacity ratio. Furthermore, since the harmonics existing in the distribution system are present in a plurality of frequency bands with the fifth, seventh, eleventh, and thirteenth orders as the main components, the harmonics of each order existing in the distribution system can be obtained only by adjusting the gain Kv. It is difficult to evenly share each of the wave components according to the installed capacity ratio.

On the other hand, the phase-advancing capacitor with a series reactor has a reactor with an iron core, and when an inrush current flows, the reactance decreases due to the saturation of the iron core. It is also known that a harmonic lead-in phenomenon is generated due to this, and the equipment is burnt out due to an overload.

The present invention has been made in view of such a problem, and one of the exemplary purposes of the embodiment is to compensate for harmonics in cooperation with another harmonic suppression circuit existing in the same distribution system. It is possible to provide an active filter device for a power system.

One aspect of the present invention relates to an active filter device for an electric power system. The active filter device for the power system consists of a main circuit in which an interconnection reactor and an inverter device are connected in series, a voltage detector that detects the interconnection point voltage, a current detector that detects the interconnection point current, and an interconnection point. Multiply the voltage by the transfer function determined based on the harmonic suppression circuit used in combination with the active filter device for the power system, calculate the harmonic current command value, and calculate the voltage command value based on the harmonic current command value. It includes an inverter controller that can generate and control the inverter device based on the voltage command value.

According to the active filter device for a power system according to an aspect of the present invention, harmonics can be compensated in cooperation with a harmonic suppression circuit existing in the same distribution system.

It is a block diagram of the electric power system including the active filter apparatus which concerns on Embodiment 1. FIG. It is a block diagram of the active filter apparatus for power system which concerns on Embodiment 1. FIG. It is a block diagram of an inverter controller. It is a block diagram of the harmonic current command value generation part of FIG. It is a block diagram of a voltage command value generation part. 6 (a) and 6 (b) are diagrams showing simulation results of a power system including an active filter device. 7 (a) and 7 (b) are simulation waveform diagrams of a comparison circuit. It is a block diagram of the active filter apparatus for a power system which concerns on Embodiment 2. FIG. It is a block diagram of the voltage command value generation part which concerns on Embodiment 2. FIG. It is a block diagram of the active filter apparatus which concerns on Embodiment 3. It is a block diagram of the active filter apparatus which concerns on Embodiment 4. FIG.

(Outline of Embodiment)
One embodiment disclosed herein relates to an active filter device for an electric power system. The active filter device for the power system consists of a main circuit in which an interconnection reactor and an inverter device are connected in series, a voltage detector that detects the interconnection point voltage, a current detector that detects the interconnection point current, and an interconnection point. Multiply the voltage by the transfer function determined based on the harmonic suppression circuit used in combination with the active filter device for the power system, calculate the harmonic current command value, and calculate the voltage command value based on the harmonic current command value. It includes an inverter controller that can generate and control the inverter device based on the voltage command value.

According to this power system active filter device, the harmonic current of the distribution system can be shared and absorbed according to the installed capacity ratio in cooperation with another harmonic suppression circuit existing in the same distribution system. ..

In one embodiment, the main circuit may further include a phase-advancing capacitor connected in series with the interconnection reactor and inverter device.

According to this configuration, the ineffective power of the fundamental wave component is output, and at the same time, the harmonic current of the distribution system is shared according to the installed capacity ratio in cooperation with the phase-advancing capacitor with a series reactor existing in the same distribution system. Can be absorbed. In addition, the installed capacity of the inverter can be reduced as compared with the configuration without the phase-advancing capacitor, and the size and cost can be reduced as compared with the case where the active filter device for the power system and the phase-advancing capacitor are arranged separately. Further, unlike the series reactor, the reactance does not decrease when the inrush current flows in, so that it is possible to avoid the burnout of the equipment due to the harmonic lead-in phenomenon.

In one embodiment, the inverter device may include a single three-phase inverter and a DC capacitor.

The inverter device may include three sets of a single-phase inverter and a DC capacitor.

A power supply device may be connected to the DC terminal of the three-phase inverter. According to this configuration, the active power and the inactive power of the fundamental wave component are output, and at the same time, the harmonic current of the distribution system is adjusted according to the installed capacity ratio in cooperation with the phase-advancing capacitor with a series reactor existing in the same distribution system. Can be shared and absorbed. In addition, the increase in the installed capacity of the inverter due to the addition of the active filter function for the power system is small, and the size and cost can be reduced as compared with arranging the active filter device for the power system and the grid interconnection inverter separately.

(Embodiment)
Hereinafter, the present invention will be described with reference to the drawings based on preferred embodiments. The same or equivalent components, members, and processes shown in the drawings shall be designated by the same reference numerals, and redundant description will be omitted as appropriate. Further, the embodiment is not limited to the invention but is an example, and all the features and combinations thereof described in the embodiment are not necessarily essential to the invention.

In the present specification, the "state in which the member A is connected to the member B" means that the member A and the member B are physically directly connected, or the member A and the member B are electrically connected to each other. It also includes the case of being indirectly connected via other members, which does not substantially affect the connection state or does not impair the functions and effects performed by the combination thereof.

Similarly, "a state in which the member C is provided between the member A and the member B" means that the member A and the member C, or the member B and the member C are directly connected, and their electricity. It also includes the case of being indirectly connected via other members, which does not substantially affect the connection state, or does not impair the functions and effects performed by the combination thereof.

Further, in the present specification, the reference numerals attached to electric signals such as voltage signals and current signals, or circuit elements such as resistors and capacitors have their respective voltage values, current values, resistance values and capacitance values as required. It shall be represented.

(Embodiment 1)
FIG. 1 is a block diagram of a power system 200 including the active filter device 100A according to the first embodiment. The power system 200 includes a high-voltage distribution system 202, a load 204, a phase-advancing capacitor 206 with a series reactor, and an active filter device 100A.

The load 204 includes a source of _{harmonic current i h.} The phase-advancing capacitor 206 with a series reactor functions as a harmonic suppression circuit that absorbs the harmonic _{current i h.} The phase-advancing capacitor 206 with a series reactor includes a phase-advancing capacitor C and a series reactor L connected in series with the phase-advancing capacitor C, and mainly _{absorbs a harmonic current i h} of the fifth order or higher to obtain a harmonic voltage of the power system. Reduce. In many cases, the phase-advancing capacitor 206 with a series reactor is widely used as existing equipment.

The active filter device 100A is added to the power system having the phase-advancing capacitor 206 with a series reactor, and absorbs the _{harmonic current i h in cooperation with the phase-advancing capacitor 206 with a series reactor.} Hereinafter, the configuration of the active filter device 100A will be described in detail.

FIG. 2 is a block diagram of the power system active filter device 100A according to the first embodiment. The active filter device 100A includes a main circuit 110A, a voltage detector 120, a current detector 122, and an inverter controller 130.

The main circuit 110A is connected to the interconnection point 4 with the three-phase AC power distribution system 2. The main circuit 110A includes an interconnection reactor 112_1 to 112_3 connected in series and a self-excited inverter device 114 (converter). The interconnection reactors 112_1 to 112_3 are designed to have a reactance value that allows current control of the inverter device 114. For example, it is designed to be about 5 to 10% of the inverter capacity. Although FIG. 2 shows the case where three single-phase reactors are used, one three-phase coupled reactor may be used.

In the present embodiment, the inverter device 114 includes a three-phase inverter and a DC capacitor Cdc connected to the DC terminal of the three-phase inverter. The inverter device 114 outputs the fundamental wave and the harmonic AC voltage, and controls the harmonic current flowing through the interconnection point 4. The inverter device 114 is designed so that it can output a voltage obtained by adding the magnitude of harmonic voltage distortion to the fundamental wave voltage amplitude of the distribution system 2. For example, the inverter device 114 is designed so that it can output a voltage of about 120% of the fundamental AC voltage.

The voltage detector 120 is connected to the interconnection point 4 and detects a three-phase AC voltage (interconnection point voltage). For example, the voltage detector 120 can include a voltage transformer for stepping down a three-phase AC voltage and an A / D converter for converting the voltage after stepping down into a digital value.

The current detector 122 detects the current flowing through the interconnection point 4 (interconnection point current). For example, the current detector 122 is connected between the interconnection point 4 and the main circuit 110A to detect a three-phase alternating current. Specifically, the current detector 122 converts an alternating current into a low-voltage analog signal by a current transformer and a detection resistor, and then converts it into a digital signal by an A / D converter.

The inverter controller 130 controls the inverter device 114 based on the detection results of the voltage detector 120 and the current detector 122.

FIG. 3 is a block diagram of the inverter controller 130. The inverter controller 130 includes a harmonic current command value generation unit 132, a voltage command value generation unit 134, a pulse modulator 136, and a gate driver 138.

The harmonic current command value generator 132 multiplies the interconnection point voltage V _gx detected by the voltage detector 120 by the transfer function Y (s) of the phase-advancing capacitor with a series reactor, and the harmonic current command value i _h. * Calculate. The voltage command value generation unit 134 generates a voltage command value v * based on _{the harmonic current command value i h *.} The pulse modulator 136 generates a pulse signal having a duty ratio corresponding to the voltage command value v *. The gate driver 138 drives the inverter device 114 based on the pulse signal.

FIG. 4 is a block diagram of the harmonic current command value generation unit 132 of FIG. In the following description, the following subscripts shall be used to distinguish each phase.
Three-phase quantity: a, b, c,
Two-phase amount obtained by converting the three-phase amount into αβ: α, β
Amount obtained by dq conversion (rotational coordinate conversion) of two-phase quantities α and β: d, q

The αβ converter 140 performs αβ conversion (three-phase two-phase conversion) of the detected interconnection point three-phase voltages v _ga , v _gb , and v _{g c} to generate _{two-phase voltages v g α and v g β.} The phase detector 142 generates phase information θ based on the two-phase voltages v _{g α} and v _{g β.} The dq converter 144 converts the two-phase interconnection point voltages v _gα and v _{g β} by dq using the phase information θ, and generates the voltages v _gd and v _{gq of the rotating coordinate system.} In Fig. 4, e- ^jθ means dq transformation and e ^jθ means inverse dq transformation.

The high-pass filter 146 removes the fundamental wave component from _{the voltages v gd} and v _gq in the rotating coordinate system, and extracts only the _{harmonic components v ghd} and v _{gh q.} These v _ghd and v _ghq correspond to the harmonic components of the interconnection point voltage. The inverse dq converter 148 converts the harmonic components v _ghd and v _ghq into inverse dq to _obtain v gh α and v _{gh β} .

As shown in FIG. 1, the active filter device 100A is used together with a phase-advancing capacitor 206 with a series reactor. A transfer function (conductance) Y (s) from the voltage v of the phase-advancing capacitor 206 with a series reactor to which the harmonics are to be compensated in cooperation with the current i is set in the filter 149. Specifically, if there is a phase-advancing capacitor with a 6% series reactor in the same distribution line, the transfer function of the phase-advancing capacitor with a 6% series reactor is set. The phase-advancing capacitor 206 with a series reactor is modeled as a series circuit of a resistor having a resistance value R (not shown in FIG. 1), a reactor having an inductance L, and a capacitor having a capacitance C. The following relationship (1) holds between the voltage V _RLC (s) and I _{RLC (s) of this series circuit.}
I _RLC (s) = V _RLC (s) / (R + sL + 1 / sC)… (1)
In this case, the transfer function Y (s) = I _RLC (s) / V _RLC (s) from the voltage to the current to be simulated is given by Eq. (2).
Y (s) = 1 / (R + sL + 1 / sC)
The resistance R, reactor L, and capacitor C are given values corresponding to the resistance value, inductance, and capacitance of the phase-advancing capacitor with a series reactor to be simulated. However, since the resistance R of the phase-advancing capacitor with a series reactor is sufficiently small, the equation (3) may be used with R = 0.
Y (s) = 1 / (sL + 1 / sC)… (3)

When the two-phase quantities v _ghα and v _ghβ pass through the filter 149, the transfer function Y (s) of the phase-advancing capacitor with a series reactor is multiplied, and the instantaneous values of the _{harmonic current command values i hα} * and i _{hβ * are obtained.} It is calculated.

FIG. 5 is a block diagram of the voltage command value generation unit 134. Subscripts 1, 5, 7, etc. represent orders, and h represents harmonics of all orders.

The fundamental wave current command value generation unit 150 generates the fundamental wave current command values i _1α * and i _1β *. The DC voltage controller 151 is a PI (proportional / integral) controller that receives a deviation between the DC voltage Vdc and its target value Vdc *, and generates a _{fundamental wave current command value i 1d *.} The reactive power controller 152 is a PI controller that receives a deviation between the reactive power q calculated from the interconnection _{point voltage V g} x and the interconnection point current ix and its command value q *, and generates _{a fundamental wave current command value i 1q *.} To do. Note reactive power q from interconnection node voltage V _gx and interconnection point current i _x, obtained from _{q = v gα i β -v gβ} i α. _{The fundamental wave current command values i 1d} * and i _1q * generated by the DC voltage controller 151 and the reactive power controller 152 are converted into the fundamental wave current command values i _1α * and i _1β * by the inverse dq conversion.

The current detector 154 uses the interconnection point currents i _α and i _β as the fundamental wave components (coupling point fundamental wave currents) i _1α and i _{1 β} and the harmonic components (coupling point harmonic currents) i _{h α} and i. Separate into _{hβ and.} The current detector 154 includes a high-pass filter (HPF) and a low-pass filter (LPF), a dq converter (e- ^jθ ) and an inverse dq converter (e ^jθ ).

The fundamental wave current deviation detector 156 generates deviations Δi _1α and Δi _{1β of interconnection point fundamental wave currents i 1α} and i _1β and their target values of fundamental wave current command values i _1α * and i _{1β *.} Further, the harmonic current deviation detector 158 _{generates the} interconnection point harmonic currents i hα and i _hβ and the deviations Δi _hα and Δi _hβ of the harmonic current command values i _hα * and i _hβ * which are the target values thereof.

In the fundamental wave current controller 160, the voltage command values v _1α * and v _1β * of the fundamental wave component are calculated in order to control the current of the fundamental wave component. First, Δi _1α and Δi _1β are dq-transformed using the phase θ. Multiply this by the transfer function of the integral controller (integral gain k _I1 ) and perform inverse dq conversion using the phase θ to calculate the voltage command values v _1α * and v _1β * of the fundamental wave component. In addition, by adding the value obtained by multiplying the fundamental wave current command values i _1d * and i _1q * by the interconnection reactance ωL, the voltage drop in the interconnection reactance is compensated and the current control characteristics are improved.

In the negative phase 5th order current controller 162 and the positive phase 7th order current controller 164, the voltage command value v _5α * of the negative phase 5th order component is used to control the current of the main harmonic components existing in the distribution system. _{Calculate the voltage command values v 7α} * and v _7β * for v _5β * and the 7th-order components of the positive phase. In the reverse phase fifth-order current controller 162, the deviations Δi _hα and Δi _hβ are dq-transformed using -5θ obtained by multiplying the phase θ by -5, and multiplied by the transfer function of _{the integral controller (integral gain k I5).} Inverse dq conversion is performed using 5θ, and the voltage command values v _5α * and v _5β * of the antiphase fifth harmonic component are calculated.

In the positive-phase 7th-order current controller 164, the deviations Δi _hα and Δi _hβ are dq-transformed using 7θ obtained by multiplying the phase θ by 7, then multiplied by _{the transfer function of the integral controller (integral gain k I7} ), and 7θ is used. The reverse dq conversion is performed to calculate _{the voltage command values v 7α} * and v _7β * of the positive-phase 7th harmonic component.

The wide-area current controller 166 is intended for current control over all bands _{, and is obtained by multiplying the sum of Δi 1α} and Δi _{hα and} the sum of Δi _1β and Δi _hβ by a proportional gain k _P , and the voltage command value v _Pα *, v _{Calculate Pβ} *.

The voltage command values v _α * and v _β * are calculated by adding each voltage command value calculated as described above to the interconnection point voltages v _{g α} and v _{g β.} Based on the voltage command values v _α * and v _β *, the pulse modulator 136 in the subsequent stage performs pulse width modulation, the gate signal of the inverter is generated, and the inverter is driven by the driver 138.

The above is the configuration of the active filter device 100A. This power system active filter device 100A can absorb a harmonic current equivalent to that of the phase-advancing capacitor 206 with a series reactor, which is a harmonic suppression circuit used in combination. As a result, it is possible to compensate for the harmonic currents of each order existing in the distribution system in cooperation with the phase-advancing capacitor 206 with a series reactor installed in the same distribution system.

The result of simulating the electric power system 200 shown in FIG. 1 will be described. As shown in FIG. 1, for the high-voltage distribution system 202, a load 204 that generates an active filter device 100A, a phase-advancing capacitor 206 with a series reactor, and a harmonic current i _{h including the 5th and 7th harmonics.} Is connected.

6A and 6B are diagrams showing simulation results of a power system 200 including an active filter device 100A. i _LSC indicates the current flowing through the phase-advancing capacitor 206 with a series reactor, and i _invSC indicates the current flowing through the active filter device 100A. i _h indicates the harmonic current generated by the load 204.

FIG. 6A shows the current waveform, and FIG. 6B shows the amount of current of each harmonic component. As can be seen from FIGS. _{6A and 6B , the current i invSC flowing through the active filter device 100A is substantially equal to the current i LSC} flowing through the phase-advancing capacitor 206 with a series reactor, and the active filter device 100A It can be seen that the phase-advancing capacitor 206 with the series reactor absorbs the harmonic current evenly.

The result of performing the same simulation on the distribution system active filter apparatus described in Patent Document 2 will be described. The simulation is performed on a circuit (referred to as a comparison circuit) provided with the distribution system active filter device disclosed in Patent Document 2 in place of the active filter device 100A in the power system 200 of FIG.

7 (a) and 7 (b) are simulation waveform diagrams of a comparison circuit. FIG. 7A shows a state when the gain Kv is set large, and FIG. 7B shows a state when the gain Kv is set small.

As shown in FIG. 7A, when the gain Kv is large, _{most of the harmonic current i h} injected by the load 204 is absorbed by the active filter device, and the harmonics diverted to the phase-advancing capacitor 206 with a series reactor. The wave current i _LSC is very small.

In FIG. 7B, the gain Kv is set so that the amplitudes of the fifth wave tuning currents are equal in the active filter device and the phase-advancing capacitor 206 with a series reactor. Even if _{the amplitudes of the 5th harmonic currents of i inv SC} and i _LSC are matched, the same 5th harmonic current cannot be shared because the phases of the currents are different. Further, for the 7th harmonic current, neither the amplitude nor the phase can be matched.

As described above, in the prior art, it is difficult to cooperate with the existing harmonic suppression circuit such as the phase-advancing capacitor 206 with a series reactor. On the other hand, according to the active filter device 100A, the control system is constructed in consideration of the conductance of the other harmonic suppression circuits, so that the harmonic current is absorbed in cooperation with the other harmonic suppression circuits. be able to.

(Embodiment 2)
FIG. 8 is a block diagram of the power system active filter device 100B according to the second embodiment. The differences from the active filter device 100A according to the first embodiment will be mainly described.

The active filter device 100B can be grasped as a phase-advancing capacitor having an active filter function for a power system. The main circuit 110B of the active filter device 100B includes phase advance capacitors 116_1 to 116_3 in addition to the main circuit 110A of FIG. The phase advance capacitors 116_1 to 116_3 are connected in series with the interconnection reactor 112_1 to 112_3 and the inverter device 114.

Specifically, the main circuit 110B is composed of three phases, and the phase advancing capacitor 116_ # of the corresponding phase, the interconnection reactor 112_ #, and the leg of the inverter device 114 are connected in series. The order of these connections may be changed. Three sets of these are connected and connected to the interconnection point 4 with the three-phase AC distribution system 2.

The fundamental AC voltage of the distribution system 2 is applied to the phase-advancing capacitor 116. The phase advance capacitor 116 is selected based on this fundamental voltage and the required phase adjustment capacitance.

The interconnection reactor 112 is designed to have a reactance value that allows current control of the inverter device 114. For example, it is designed to be about 1% of the phase adjustment capacity. Although FIG. 8 shows the case where three single-phase reactors are used, one three-phase coupled reactor may be used.

The inverter device 114 is a three-phase bridge circuit, outputs a harmonic AC voltage, and controls a harmonic current flowing through the interconnection point. The output voltage is designed based on the magnitude of the voltage distortion of the distribution system. For example, it is designed to be about 20% of the fundamental AC voltage.

The inverter controller 130 is configured in the same manner as in FIG. 2, and includes a harmonic current command value generation unit 132, a voltage command value generation unit 134, a pulse modulator 136, and a gate driver 138.

FIG. 9 is a block diagram of the voltage command value generation unit 134B according to the second embodiment. The DC voltage command value generation unit 180 includes a deviation detector (subtractor) 181, a DC voltage controller 182, and an inverse dq converter (e ^jθ ). The deviation detector 181 generates a deviation _{between the DC voltage v dc} and its command value v _{dc *.} The DC voltage controller 182 is a PI controller that receives a deviation of the DC voltage, and generates a _{fundamental wave voltage command value v 1q * which is a target value of the q-axis component of the fundamental wave voltage. The target value v 1d} * of the d-axis component of the fundamental wave voltage is 0. The target values v _1q * and V _1d * of the fundamental wave voltage are inversely dq-converted, and the fundamental wave voltage command values v _1α * and v _1β * are generated.

The harmonic current deviation detector 172 generates deviations Δi _hα and Δi _{hβ of the interconnection point harmonic currents i hα} and i _hβ and their target harmonic current command values i _hα * and i _{hβ *.}

The harmonic current controller 174 is a P (proportional) controller, which _{multiplies the deviations Δi hα} and Δi _hβ by the proportional gain, and adds _{the harmonic components v gh α} and v _gh β of the interconnection point voltage Vg.

The negative-phase 5th-order current controller 176 and the positive-phase 7th-order current controller 178 are the same as the negative-phase 5th-order current controller 162 and the positive-phase 7th-order current controller 164 in FIG. The outputs of the harmonic current controller 174, the reverse phase 5th order current controller 176, the positive phase 7th order current controller 178, and the DC voltage command value generator 180 are added to generate the voltage command values v _α * and v _β *. Will be done.

The above is the configuration of the active filter device 100B according to the second embodiment. Subsequently, the advantages of the active filter device 100B will be described.

The active filter device 100B according to the second embodiment performs an operation of compensating for a harmonic current equivalent to that of a phase-advancing capacitor with a series reactor. As a result, the harmonic current of the distribution system can be compensated in cooperation with the phase-advancing capacitor with a series reactor installed in the same distribution system.

Further, since the active filter device 100B does not control the current of the fundamental wave component, the phase advance capacitor 116 causes the current of the fundamental wave component corresponding to the amount of compensation for the reactive power to flow, and outputs the reactive power. That is, the phase advance capacitor has the original phase adjustment function as a phase adjustment equipment.

Further, the active filter device 100A according to the first embodiment outputs a voltage obtained by adding the magnitude of the harmonic voltage to the fundamental wave voltage amplitude of the distribution system. Therefore, for example, when outputting a harmonic voltage corresponding to 20% of the rated voltage of the fundamental wave, it is necessary for the inverter device 114 to output 120% of the rated voltage of the fundamental wave. On the other hand, in the active filter device 100B according to the second embodiment, since the phase advance capacitor 116 shares the fundamental wave voltage, the inverter device 114 shares only the harmonic voltage. Therefore, for example, the inverter device 114 may output a harmonic voltage corresponding to 20% of the rated voltage of the fundamental wave. As a result, the installed capacity of the inverter device 114 can be reduced, and the size and cost can be reduced as compared with the case where the active filter device 100A and the phase advance capacitor according to the first embodiment are arranged separately. Further, unlike the series reactor, the reactance does not decrease when the inrush current flows in, so that it is possible to avoid the burnout of the equipment due to the harmonic lead-in phenomenon.

(Embodiment 3)
FIG. 10 is a block diagram of the active filter device 100C according to the third embodiment. The active filter device 100C according to the third embodiment has a function as a phase-advancing capacitor having an active filter function for a power system as in the second embodiment, and therefore is a modification of the active filter device 100B according to the second embodiment. It can be understood as an example.

In FIG. 10, the inverter device 114C includes a plurality of N units (N ≧ 2) of single-phase bridge circuits (full bridge circuits) 115_1 to 115_3. Although the case of N = 3 is shown in FIG. 10, the number N of the single-phase bridge circuits 115 may be further increased. Further, although FIG. 10 shows three phase-advancing capacitors 116_1 to 116_3 star-connected, a delta-connected capacitor may be used.

The configuration of the inverter controller 130 can be the same as that of the second embodiment.

The above is the configuration of the active filter device 100C. According to this active filter device 100C, the same effect as that of the active filter device 100B of the second embodiment can be obtained.

(Embodiment 4)
FIG. 11 is a block diagram of the active filter device 100D according to the fourth embodiment.
This active filter device 100D can be grasped as a grid interconnection inverter having an active filter function for a power system.

The active filter device 100D includes a power supply device 190 in addition to the main circuit 110D, the voltage detector 120, and the inverter controller 130. The main circuit 110D, the voltage detector 120, and the inverter controller 130 are the same as those in the first embodiment.

The power supply device 190 is a power storage device, a power generation device, or a combination thereof, and is connected to a DC terminal of the inverter device 114D. Although not limited to this, the power supply device 190 may be a photovoltaic power generation panel or a secondary battery.

The inverter device 114D has both a function as a grid interconnection inverter for bidirectional or unidirectional transmission between the distribution system 2 and the power supply device 190 and a function of the inverter device as the above-mentioned active filter.

The above is the configuration of the active filter device 100D. Next, the advantages will be described. The active filter device 100D performs an operation of compensating for a harmonic current equivalent to that of a phase-advancing capacitor with a series reactor. As a result, the harmonic current of the distribution system can be compensated in cooperation with the phase-advancing capacitor with a series reactor installed in the same distribution system.

In addition, the current of the fundamental wave component is controlled in the same way as a general grid-connected inverter, and the current of the fundamental wave component is passed based on the fundamental wave current command value output by the power controller. , Outputs active power and reactive power. That is, it possesses the original conversion function as a grid-connected inverter.

Further, the increase in the installed capacity of the inverter due to the addition of the active filter function for the power system corresponds to the harmonic voltage, for example, about 20%. Therefore, the active filter device 100D outputs 120% of the rated voltage of the fundamental wave. This is a voltage similar to that of the active filter device 100A according to the first embodiment.

Therefore, the size and cost can be reduced as compared with arranging the active filter device 100A and the grid interconnection inverter of FIG. 2 separately.

Although the present invention has been described using specific terms based on the embodiments, the embodiments merely indicate the principles and applications of the present invention, and the embodiments are defined in the claims. Many modifications and arrangement changes are permitted without departing from the ideas of the present invention.

2 Distribution system 4 Interconnection point 6 Power generation / storage device 100 Active filter device 110 Main circuit 112 Interconnective reactor 114 Inverter device 116 Phase-advancing capacitor 120 Voltage detector 122 Current detector 130 Inverter controller 132 Harmonic current command value generator 134 Current controller 136 Pulse modulator 138 Gate driver 140 αβ converter 142 Phase detector 144 dq converter 146 High pass filter 148 Inverse dq converter 149 filter 150 Fundamental current command value generator 151 DC voltage controller 152 Disabled power control Instrument 154 Current detector 156 Fundamental wave current deviation detector 158 Harmonic current deviation detector 160 Fundamental wave current controller 162 Reverse phase 5th order current controller 164 Positive phase 7th order current controller 166 Wide area current controller 170 Current detector 172 Harmonic current deviation detector 174 Harmonic current controller 176 Negative phase 5th current controller 178 Positive phase 7th current controller 180 DC voltage command value generator 182 DC voltage controller 190 Power supply device 200 Power system 202 High pressure distribution System 204 Load 206 Phase-advancing capacitor with series reactor

Claims (6)

An active filter device for the power system
The main circuit in which the interconnection reactor and the inverter device are connected in series,
A voltage detector that detects the interconnection point voltage and
A current detector that detects the interconnection point current, and
The interconnection point voltage is multiplied by a transmission function determined based on the harmonic suppression circuit used in combination with the power system active filter device to calculate a harmonic current command value, and the harmonic current command value is calculated. An inverter controller that can generate a voltage command value based on the voltage command value and control the inverter device based on the voltage command value.
An active filter device for an electric power system, which comprises. The active filter device for an electric power system according to claim 1, wherein the main circuit further includes a interconnection reactor and a phase-advancing capacitor connected in series with the inverter device. The active filter device for an electric power system according to claim 1 or 2, wherein the inverter device includes a single three-phase inverter and a DC capacitor. The active filter device for an electric power system according to claim 2, wherein the inverter device includes three sets of a single-phase inverter and a DC capacitor. The active filter device for a power system according to claim 3, wherein a power supply device is connected to the DC terminal of the three-phase inverter. The active filter device for an electric power system according to any one of claims 1 to 5, wherein the harmonic suppression circuit includes a phase-advancing capacitor with a series reactor.

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