JP2009106017A - Active filter function device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely restrain harmonic current even if a reactor exists between a high speed switch and a load, and load voltage is distorted by the harmonic current flowing into the reactor, in an active filter function device such as an instantaneous-drop compensation device having the active filter function. <P>SOLUTION: In order to restrain the harmonic current caused by the load 3, a control unit 10 outputs a command S for controlling the operation of a power converter 4 so as to output a compensation current from the power converter 4. The command S is made to include a deviation command according to a difference between a harmonic compensation command for compensating the harmonic components of the load current and an inverter output current, and include not only a reference voltage command indicating the reference voltage but also a deviation voltage command according to a difference between a reference voltage and the load voltage. Since the deviation voltage command is included in the command S, even if the load voltage is distorted, the compensation current, taking into consideration of the distortion of the load voltage, is output, to surely cancel the harmonic current caused by the load. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an active filter function device, and since a reactor is connected to a load or the load itself has a reactor component, a harmonic current flows through the reactor, a voltage drop occurs, and the voltage drop causes a load voltage. Even if distortion occurs, it is devised so that harmonic current can be surely suppressed.

  In this specification, the “active filter function device” means a single active filter having an active filter function, a sag compensator having not only a sag compensation function but also an active filter function, a reactive power compensation function, It is used to mean various devices having an active filter function such as a power line conditioner having not only a negative phase power compensation function but also an active filter function.

  Among the loads connected to the power system, there are loads that generate harmonic currents. For example, power converters such as rectifiers and inverter devices generate harmonic currents. When the harmonic current generated from such a load flows into the power system, the power quality of the power system is degraded, and other loads are also adversely affected.

  Therefore, an active filter is connected to the load in order to suppress the harmonic current. The active filter outputs a compensation current having a polarity opposite to that of the harmonic current generated by the load, and cancels the harmonic current by the compensation current. Thereby, the harmonic current generated from the load is suppressed, and the harmonic current generated from the load is prevented from flowing into the power system.

On the other hand, in a load such as an IT-related device, if an instantaneous voltage drop (hereinafter referred to as “instantaneous drop”) occurs in the power system, it may be a major obstacle. Therefore, for a load in which a failure due to a sag is a problem, a sag compensator is provided.
Note that the instantaneous drop is a temporary voltage drop that occurs before a transmission line accident caused by a lightning strike is removed by a transmission line protection relay.

  The voltage sag compensator instantaneously disconnects a load and a power system when a voltage sag occurs in the power system, and supplies power to the load in an uninterruptible state.

  Furthermore, there is a parallel type voltage sag compensator in which the voltage sag compensator has an active filter function. This parallel type voltage sag compensator that also has an active filter function outputs a compensation current that suppresses (cancels) the harmonic current generated from the load during normal times, and instantaneously connects the load and power system when a sag occurs. In addition to disconnection, three-phase power is supplied to the load in an uninterruptible state.

  Here, the circuit configuration of the parallel sag compensator having the active filter function will be described with reference to FIG.

  As shown in FIG. 2, a load 3 is connected to a power system L <b> 1 including a commercial power source 1 via a high-speed switch 2. The high speed switch 2 is configured by, for example, an IGBT or the like.

  The power converter 4 includes an inverter device that can perform a reverse conversion operation (inverter operation) and a forward conversion operation (converter operation). An electric double layer capacitor (DC charging unit) 5 is connected to the DC side of the power converter 4, and a load 3 is connected to the AC side via a power line L2.

The power converter 4 performs the following operation function.
(1) By performing a forward conversion operation (converter operation), an alternating current obtained from the power system L1 is converted into a direct current, and the electric double layer capacitor 5 is charged by the direct current.
(2) When an instantaneous drop occurs, a reverse conversion operation (inverter operation) is performed to convert a direct current charged in the electric double layer capacitor 5 into an alternating current, and this alternating current is sent to the load 3. That is, the operation function as a voltage sag compensator is achieved.
(3) A compensation current having a polarity opposite to that of the harmonic current generated from the load 3 is output, and the harmonic current is canceled by this compensation current. That is, it functions as an active filter.

  The control unit 10 controls the operating state of the power converter 4 so as to operate the power converter 4 as a voltage sag compensator, as an active filter, or as a charging device. The switching operation is controlled.

  The control unit 10 will be described in detail. As the detector, the control unit 10 detects a system voltage of the power system L1 and outputs a system voltage signal Vs indicating the detected value, and the power system L1. Current detector 11b for detecting a system current of the power converter 4 and outputting a system current signal Is indicating the detected value, and an AC output current for detecting the AC output current (inverter output current) of the power converter 4 and indicating the detected value A current detector 11c that outputs a signal (inverter output current signal) Iinv; a voltage detector 11d that detects a load voltage that is a voltage applied to the load 3 and outputs a load voltage signal Vload indicating the detected value; A current detector 11e that detects a load current that is a current flowing through the load 3 and outputs a load current signal Iload indicating the detected value, and a charging voltage of the electric double layer capacitor 5 It detects a certain capacitor voltage (DC charging voltage) and a voltage detector 11f to output the capacitor voltage signal indicating the detected value (DC charging voltage signal) Vc.

  The control unit 10 further includes a PLL (Phase Locked Loop) circuit 12, a sine wave generator 13, a PWM (Pulse Width Modulation) modulator 14, a switch operation unit 15, and a command creation unit 20.

The command creation unit 20 outputs a command S for operating the power converter 4.
The command content of this command S is
(1) a charge command for instructing to charge the electric double layer capacitor 5 by causing the power converter 4 to perform a forward conversion operation (converter operation);
(2) A voltage sag compensation command that commands the AC power to be sent to the load 3 by performing an inverse conversion operation (inverter operation) of the power converter 4 when a voltage sag occurs.
(3) A harmonic compensation command that outputs a compensation current having a polarity opposite to that of the harmonic current generated from the load 3 and instructs the compensation current to cancel the harmonic current is included.

  The command S is PWM-modulated by the PWM modulator 14 to become a gate control signal g, and the gate control of the power converter 4 is performed by the gate control signal g, that is, the PWM-modulated command S.

  During normal times when no instantaneous drop occurs in the power system L1, the high-speed switch 2 is in a conductive state, and the power of the commercial power supply 1 is supplied from the power system L1 to the load 3 via the high-speed switch 2.

  In such a normal state, when the capacitor voltage signal Vc detected by the voltage detector 11f is lower than the rated voltage of the electric double layer capacitor 5, the charge command is included in the command S. The power converter 4 performs a converter operation in response to the command S including “” and floats the electric double layer capacitor 5. Thereby, the voltage of the electric double layer capacitor 5 is maintained at the rated voltage.

  In addition, in a normal state where no sag occurs, when a harmonic current is included in the load current signal Iload detected by the current detector 11e, a harmonic compensation command is included in the command S. In response to the command S including the compensation command, the power converter 4 outputs a compensation current toward the load 4. Thereby, the function as an active filter is exhibited.

  When an instantaneous drop occurs in the power system L1 and the system voltage signal Vs detected by the voltage detector 11a decreases, the high speed switch 2 is disconnected by the switch operation unit 15. At the same time, the command S includes a voltage sag compensation command, and the command S including the voltage sag compensation command causes the power converter 4 to perform an inverter operation so that the electric double layer capacitor 5 is charged with a direct current. Is converted into an alternating current and sent to the load 4. Thereby, the instantaneous drop compensation function is exhibited.

Here, a conventional method for creating a command S including a harmonic compensation command so that the power converter 4 performs an active filter function operation will be described with reference to FIG. 3 which is a block diagram.
FIG. 3 shows only functional blocks necessary for creating the command S so that the function as an active filter is exhibited, among the control unit 10.

  As shown in FIG. 3, the charge command unit 201 outputs charge commands S1u, S1v, and S1w according to the capacitor voltage (DC charge voltage) signal Vc detected by the voltage detector 11f. The command values of the charging commands S1u, S1v, S1w are 0 when the capacitor voltage (DC charging voltage) signal Vc is the rated voltage of the electric double layer capacitor 5, and the capacitor voltage (DC charging voltage) signal Vc is the electric double layer capacitor. It becomes higher as it becomes lower than the rated voltage of 5.

The PLL circuit 12 performs a PLL calculation based on the system voltage signals Vsu, Vsv, Vsw detected by the voltage detector 11a, and obtains and outputs the phase θ of the positive phase of the three-phase AC voltage flowing through the power system L1.
The sine wave oscillator 13 obtains a sine wave signal sin θ and a cosine wave signal cos θ using the phase θ, and the sine wave signal sin θ and the cosine wave signal cos θ are converted into a three-phase / dq coordinate conversion circuit 202 and a dq / three-phase coordinate. The data is sent to the conversion circuit 203.

The three-phase / dq coordinate conversion circuit 202 converts the three-phase load current signals Iloadu, Iloadv, Iloadw detected by the current detector 11e into dq coordinates, and outputs a d-axis current id and a q-axis current iq.
The deviation calculation unit 204 obtains the d-axis harmonic component idh by subtracting the fundamental wave component obtained by filtering the d-axis current id by the low-pass filter 205 from the d-axis current id.
The deviation calculation unit 206 obtains the q-axis harmonic component iqh by subtracting the fundamental wave component obtained by filtering the q-axis current iq by the low-pass filter 207 from the q-axis current iq.

  The dq / three-phase coordinate conversion circuit 203 converts the d-axis harmonic component idh and the q-axis harmonic component iqh into a three-phase rotational coordinate and outputs a three-phase harmonic component. Harmonic compensation commands S2u, S2v, and S2w are obtained by inverting the sign (that is, multiplying by "-1") by the inverting circuit 208.

  In the end, the three-phase / dq coordinate conversion circuit 202, the dq / three-phase coordinate conversion circuit 203, the deviation calculation units 204 and 206, the low-pass filters 205 and 207, and the determination circuit 208 enable the harmonic compensation command generation function unit. It is configured.

  In the adding unit 209, the charging commands S1u, S1v, S1w and the harmonic compensation commands S2u, S2v, S2w are added.

  In the subtracting unit 210, the inverter output current signals Iinvu, Iinvv, Iinvw detected by the current detector 11c are subtracted from the addition command obtained by adding the charging commands S1u, S1v, S1w and the harmonic compensation commands S2u, S2v, S2w. , Deviation commands ΔSu, ΔSv, ΔSw are output.

  The current control unit 211 performs proportional / integral (P · I) calculations on the deviation commands ΔSu, ΔSv, ΔSw, and outputs proportional / integral deviation commands dsu, dsv, dsw.

  After all, the subtraction unit 210 and the current control unit 211 constitute a current control deviation command creation function unit.

  The reference voltage command unit 212 takes in the phase θ from the PLL circuit 12 and indicates a voltage value of a three-phase voltage (a three-phase voltage that does not include a harmonic component and has no phase shift) supplied by the power system L. Command signals Vou, Vov, Vow are output. Since the voltage value of the three-phase voltage supplied by the power system L is known in advance, the values of the reference voltage command signals Vou, Vov, Vow are preset in the reference voltage command unit 212.

  The adding unit 213 adds the proportional / integral deviation commands dsu, dsv, dsw output from the current control unit 211 and the reference voltage command signals Vou, Vov, Vow output from the reference voltage command unit 212 to obtain a final result. Commands Su, Sv, and Sw are output. The final commands Su, Sv, Sw are shown as the command S in FIG.

  The final commands Su, Sv, Sw are PWM-modulated by the PWM modulator 14 to be sent to the power converter 4 as a gate signal g.

  Therefore, when the load current includes a harmonic current, the load current detection signals Iloadu, Iloadv, and Iloadw include a harmonic component, and d-axis harmonic component idh and q-axis harmonic component iqh are generated. Thus, harmonic compensation commands S2u, S2v, and S2w are generated, and the final commands Su, Sv, and Sw include compensation commands for compensating for harmonics.

  When the commands Su, Sv, Sw including the compensation commands for compensating the harmonics (compensation commands indicated by the harmonic compensation commands S2u, S2v, S2w) are sent to the power converter 4, the power converter 4 A compensation current for compensating the generated harmonic current is output to the load 3 side through the power line L2. Thus, the operation function as an active filter is exhibited by canceling the harmonic current.

JP 2002-320331 A Japanese Patent Laid-Open No. 11-103527

By the way, in the parallel type voltage sag compensator having an active filter function as described above, a high-frequency current is connected between the high-speed switch 2 and the load 3 or on the commercial power source side when viewed from the high-speed switch 2 in the power system L. In some cases, a reactor that functions as a passive filter that suppresses this is interposed.
Further, the load 3 itself may have a large reactor component.
In FIG. 2, a reactor L generally indicates a reactor of a passive filter when a passive filter is interposed, or a reactor when a large reactor component is included in the load 3 itself.
In addition, when the reactor which functions as a passive filter is interposed on the commercial power supply 1 side as viewed from the high-speed switch 2 in the power system L, the reactor L should be described on the commercial power supply side rather than the high-speed switch 2. In FIG. 2, including this, the reactor L is shown as a representative on the load 3 side of the high-speed switch 2.

  As described above, when the reactor L exists, the harmonic current generated from the load 3 flows to the reactor L, so that a voltage drop occurs in the reactor L. This voltage drop value is obtained by multiplying the reactance of the reactor L by the harmonic current.

  In this way, a voltage drop caused by the harmonic current flowing through the reactor L occurs, so that the load voltage is distorted.

  However, conventionally, as shown in FIG. 3, a command S for exhibiting an operation function as an active filter has been obtained without considering the distortion of the load voltage. Therefore, even if the power converter 4 is operated as an active filter using the command S obtained without considering the distorted load voltage, there is a problem that the harmonic current cannot be completely compensated. .

For example, when the reactor L is generated by interposing a passive filter, if the command S is created in consideration of the inductance design value of the passive filter, even if the load voltage is distorted, some harmonics are generated. Suppression can be performed.
However, when the inductance of the passive filter has changed due to aging or the like, if the load voltage is distorted, the conventional technology cannot completely compensate for the harmonic current.

  Further, when the reactor L is included in the load 3 itself, the reactance of the reactor L cannot be specified. Therefore, when the load voltage is distorted, the related art can completely compensate the harmonics. Can not.

  In the present invention, in view of the above-described prior art, due to the presence of the reactor element (reactor L1) (in other words, the presence of the reactor element on the load side of the power converter), the harmonic current generated from the load flows to the reactor element. Therefore, an object of the present invention is to provide an active filter function device capable of reliably suppressing harmonic current generated from a load even when the load voltage is distorted.

The configuration of the present invention that solves the above problem suppresses a harmonic component of the load current flowing in the load (3) connected to the power system (L1), and therefore, a compensation current having a polarity opposite to that of the harmonic component of the load current. In the active filter function device that outputs the load toward the load (3),
A power converter (4) connected to the load (3);
A control unit (10) for sending a gate control signal to the power converter (4) and operating the power converter (4) according to the gate control signal to output the compensation current;
The control unit (10)
Harmonic compensation command creation function unit for taking out harmonic components of the load current and obtaining harmonic compensation commands (S2u, S2v, S2w);
A deviation command (ΔSu, ΔSv, ΔSw) is obtained from a deviation between the AC output current signal (Iinvu, Iinvv, Iinvw) of the power converter (4) and the harmonic compensation command (S2u, S2v, S2w). A current control deviation command creating function unit for obtaining a current control deviation command (dSu, dSv, dSw) by calculating a command (ΔSu, ΔSv, ΔSw) by a current control unit (211);
A reference voltage command unit (212) for outputting a reference voltage command signal (Vou, Vov, Vow) synchronized with the phase of the system voltage of the power system (L1);
A deviation voltage signal (ΔVu, ΔVv, ΔVw) is obtained from a deviation between a load voltage signal (Vloadu, Vloadv, Vloadw) applied to the load (3) and the reference voltage command signal (Vou, Vov, Vow). A multiplication deviation voltage signal generation function unit for multiplying the deviation voltage signals (ΔVu, ΔVv, ΔVw) by a proportional coefficient to obtain a multiplication deviation voltage signal (KpΔVu, KpΔVv, KpΔVw);
A signal obtained by adding the reference voltage command signal (Vou, Vov, Vow) and the multiplication deviation voltage signal (KpΔVu, KpΔVv, KpΔVw) to the current control deviation command (dSu, dSv, dSw) is added to the PWM modulator. And (14) a command creation unit that creates commands (Su, Sv, Sw) to be input.

  Further, the configuration of the present invention is characterized in that the power converter (4) is connected to a DC charging unit (5) in addition to the load (3).

According to the present invention, when the power converter is controlled to output a compensation current to exert the function as an active filter, the deviation voltage signal indicating the distortion of the load voltage is included in the command sent to the power converter. Added.
For this reason, since the load itself has a reactor component or a reactor as a passive filter is connected to the load, the harmonic current generated from the load is distorted to the load voltage due to the voltage drop generated by the reactor. Even if this occurs, a compensation current that can reliably compensate for the harmonic current can be output from the AC converter.

  The best mode for carrying out the present invention will be described below in detail based on examples.

In the first embodiment according to the present invention, a control block for causing the power converter 4 to function as an active filter in the control unit 10 shown in FIG. 2 is devised, and details thereof will be described with reference to FIG.
In FIG. 1, portions having the same functions as those in FIG.

  As shown in FIG. 1, in the first embodiment, a configuration in which a subtractor 220, a multiplier 221, and an adder 222 are further added to the “control block that causes the power converter 4 to function as an active filter” shown in FIG. 3. It has become.

The subtraction unit 220 obtains a deviation between the reference voltage command signals Vou, Vov, Vow output from the reference voltage command unit 212 and the load voltage signals Vloadu, Vloadv, Vloadw detected by the voltage detector 11d, and outputs a deviation voltage signal. ΔVu, ΔVv, and ΔVw are output.
The deviation voltage signals ΔVu, ΔVv, and ΔVw indicate the values of the distortion voltage (distortion) when the load voltage is distorted due to the harmonic current generated from the load 3 flowing to the reactor L. ing.

  The multiplier 221 multiplies the deviation voltage signals ΔVu, ΔVv, ΔVw by a proportional gain Kp, and outputs multiplication deviation voltage signals KpΔVu, KpΔVv, KpΔVw.

  After all, the subtraction unit 220 and the multiplication unit 221 constitute a multiplication deviation voltage signal generation function unit.

  The adder 222 adds the product deviation voltage signals KpΔVu, KpΔVv, KpΔVw to the reference voltage command signals Vou, Vov, Vow output from the reference voltage command unit 212 and outputs the result.

  For this reason, the adding unit 213 multiplies the proportional / integral deviation commands dsu, dsv, dsw output from the current control unit 211 corresponding to the distortion of the load voltage as well as the reference voltage command signals Vou, Vov, Vow. Deviation voltage signals KpΔVu, KpΔVv, KpΔVw are also added, and the added value is output as commands Su, Sv, Sw.

  After all, the adder 222 and the adder 213 constitute a command creation unit.

  The commands Su, Sv, Sw including the multiplication deviation voltage signals KpΔVu, KpΔVv, KpΔVw corresponding to the distortion of the load voltage as commands are PWM-modulated by the PWM modulator 14 to become the gate signal g to the power converter 4. Sent.

As a result, the power converter 4 outputs a compensation current that compensates for the harmonic current generated from the load 3. At this time, since the commands Su, Sv, Sw also include multiplication deviation voltage signals KpΔVu, KpΔVv, KpΔVw corresponding to the distortion of the load voltage, distortion of the load voltage is caused by the harmonic current flowing through the reactor L. Even if it occurs, the harmonic current can be reliably compensated by the compensation current in consideration of the distortion.
That is, when a distortion occurs in the load voltage due to the harmonic current flowing through the reactor L, feedforward control is performed by the multiplication deviation voltage signals KpΔVu, KpΔVv, KpΔVw so as to compensate for the distortion.

For this reason, even if a passive filter is provided or there is a reactor component in the load 3, the power converter 4 can output a compensation current that reliably suppresses the harmonic current generated from the load 3. it can.
As a result, even if the reactor L exists, the active filter which can suppress a harmonic current reliably can be implement | achieved.

  The present invention is not limited to a parallel type sag compensator having an active filter function as described in the embodiment, but a single active filter having an active filter function, a reactive power compensation function, and a negative phase power compensation function. In addition, the present invention can be applied to various active filter function devices such as a power line conditioner having an active filter function.

It is a block block diagram which shows the active filter function part of the control part which concerns on the Example of this invention. It is a circuit block diagram which shows the parallel type sag compensation apparatus which has an active filter function together. It is a block diagram which shows the active filter function part of the control part in a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 High speed switch 3 Load 4 Power converter 5 Electric double layer capacitor 10 Control part

Claims (2)

In order to suppress the harmonic component of the load current flowing in the load (3) connected to the power system (L1), a compensation current having a polarity opposite to that of the harmonic component of the load current is output toward the load (3). In the active filter function device,
A power converter (4) connected to the load (3);
A control unit (10) for sending a gate control signal to the power converter (4) and operating the power converter (4) according to the gate control signal to output the compensation current;
The control unit (10)
Harmonic compensation command creation function unit for taking out harmonic components of the load current and obtaining harmonic compensation commands (S2u, S2v, S2w);
A deviation command (ΔSu, ΔSv, ΔSw) is obtained from a deviation between the AC output current signal (Iinvu, Iinvv, Iinvw) of the power converter (4) and the harmonic compensation command (S2u, S2v, S2w). A current control deviation command creating function unit for obtaining a current control deviation command (dSu, dSv, dSw) by calculating a command (ΔSu, ΔSv, ΔSw) by a current control unit (211);
A reference voltage command unit (212) for outputting a reference voltage command signal (Vou, Vov, Vow) synchronized with the phase of the system voltage of the power system (L1);
A deviation voltage signal (ΔVu, ΔVv, ΔVw) is obtained from a deviation between a load voltage signal (Vloadu, Vloadv, Vloadw) applied to the load (3) and the reference voltage command signal (Vou, Vov, Vow). A multiplication deviation voltage signal generation function unit for multiplying the deviation voltage signals (ΔVu, ΔVv, ΔVw) by a proportional coefficient to obtain a multiplication deviation voltage signal (KpΔVu, KpΔVv, KpΔVw);
A signal obtained by adding the reference voltage command signal (Vou, Vov, Vow) and the multiplication deviation voltage signal (KpΔVu, KpΔVv, KpΔVw) to the current control deviation command (dSu, dSv, dSw) is added to the PWM modulator. An active filter function device comprising: a command creation unit that creates a command (Su, Sv, Sw) that is an input of (14).   The said power converter (4) is connected to the direct-current charging part (5) besides the said load (3), The active filter function apparatus characterized by the above-mentioned.

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