JP7086741B2 - Grid interconnection inverter device and stabilization control method - Google Patents

Description

The present invention relates to a grid interconnection inverter device that is interconnectably connected to a power system (for example, a commercial power system) and converts DC power into AC power.

FIG. 8 is a schematic circuit diagram showing a configuration example of a grid interconnection system including a conventional three-phase grid interconnection inverter device with an LC filter described in Patent Document 1 and Non-Patent Document 1 and the like.

This grid interconnection system is a three-phase with LC filter connected between a direct current (DC) power supply 1 and, for example, a commercial power system three-phase U, V, W AC (AC) power system 2. The grid interconnection inverter device 10 is provided. The power system 2 is connected to the output terminal of the grid interconnection inverter device 10 via a three-phase circuit breaker 3 and a three-phase transformer (hereinafter referred to as “transformer”) 4. A load device 5 is connected in parallel between the output terminal of the grid interconnection inverter device 10 and the transformer 4.

The grid interconnection inverter device 10 is a device that is interconnectably connected to the power system 2 and converts the DC power supplied from the DC power supply 1 into three-phase AC power, and has a DC / DC converter 11. ing. The DC / DC converter 11 is a device whose switching operation is controlled by a control unit (not shown) to convert a DC voltage supplied from the DC power supply 1 into a predetermined DC voltage, and a charge connected in parallel to the output side. A three-phase U, V, W DC / AC inverter 13 is connected via a storage capacitor 12. The DC / DC converter 11 may be omitted.

The DC / AC inverter 13 is a device whose switching operation is controlled by a control unit (not shown) and converts the DC voltage Vdc stored in the capacitor 12 into a three-phase U, V, W system voltage Vac, and has six switch elements. (For example, an insulated gate type bipolar transistor, hereinafter referred to as "IGBT".) 13a is configured by being bridge-connected. A body diode 13b is connected to each IGBT 13a in antiparallel. An L-shaped three-phase LC filter circuit 14 is connected to the output side of the DC / AC inverter 13.

The L-shaped three-phase LC filter circuit 14 is a circuit that removes harmonic components of the AC voltage Vinv and the inverter current Iinv output from the DC / AC inverter 13, and is composed of a three-phase inductor 14a and a three-phase capacitor 14b. ing. The output terminal of the grid interconnection inverter device 10 is connected to the output side of the LC filter circuit 14 via a three-phase switch 15 whose opening and closing is controlled by a control unit (not shown).

In the grid interconnection system configured in this way, the DC voltage supplied from the DC power supply 1 is converted into a predetermined DC voltage by the DC / DC converter 11 in the grid interconnection inverter device 10 and stored in the capacitor 12. To. The DC voltage Vdc stored in the capacitor 12 is converted into a three-phase U, V, W AC voltage Vinv by the DC / AC inverter 13, and then the harmonic component is generated by the inductor 14a and the capacitor 14b of the three-phase filter circuit 14. Will be removed. The three-phase alternating current output current Io and the system voltage Vac from which the harmonic component has been removed are output to the load device 5 and the power system 2 side via the three-phase switch 15. When a power failure or the like occurs in the power system 2, the breaker 3 is turned off, the grid interconnection inverter device 10 is disconnected from the power grid 2 and becomes an independent operation state, and the output output from the grid interconnection inverter device 10 is set. The current Io and the system voltage Vac are supplied to the load device 5.

In the L-shaped three-phase LC filter circuit 14 used in the grid interconnection inverter device 10 of FIG. 8, there is only one set of series three-phase inductors 14a, and the coupling between the input and output of the LC filter circuit 14 ( Since the coupling) becomes too large, the harmonic component may not be sufficiently attenuated. In order to improve this, a three-phase system interconnection inverter device with an LCL filter using a T-shaped three-phase filter circuit is known.

FIG. 9 is a schematic circuit diagram showing a configuration example of a grid interconnection system including a conventional three-phase grid interconnection inverter device with an LCL filter.
In the three-phase grid interconnection inverter device 10A with an LCL filter used in this grid interconnection system, a T-shaped three-phase LCL filter circuit 14A is provided in place of the L-shaped three-phase LC filter circuit 14 in FIG. Has been done. The three-phase LCL filter circuit 14A is composed of two sets of three-phase inductors 14a and 14c and one set of three-phase capacitors 14b.

In the three-phase LC filter circuit 14A in such a three-phase system interconnection inverter device 10A, two sets of three-phase inductors 14a and 14c in series are used, so that the amount of attenuation in the harmonic attenuation band is L-shaped. It is significantly improved as compared with the three-phase LC filter circuit 14, and further, the coupling between the input and output in the three-phase LCL filter circuit 14A is significantly reduced.

FIG. 10 is a schematic equivalent circuit diagram of the grid interconnection system of FIG.
In the grid interconnection inverter device 10 of FIG. 8, since it is connected to the power system 2 (for example, three-phase (3φ) 200V) via the distribution line and the transformer 4, the resistors Rs and the resistors Rs and There is a system impedance 6 composed of the inductor Ls. Therefore, the three-phase AC output current Io of the grid interconnection inverter device 10 flows through the grid impedance 6.

FIG. 11 is a schematic equivalent circuit diagram of the grid interconnection system of FIG.
Since the grid interconnection inverter device 10A of FIG. 9 is also connected to the power system 2 via the distribution line and the transformer 4 as in FIG. 8, the power system 2 side of FIG. 11 is composed of resistors Rs and inductors Ls. There is a system impedance 6. Therefore, the three-phase AC output current Io of the grid interconnection inverter device 10A flows through the grid impedance 6.

FIG. 12 is an operation waveform diagram when, for example, an inductor Ls having a constant reactance value or more is connected as the system impedance 6 on the power system 2 side in the conventional grid interconnection system shown in FIGS. 10 and 11. The upper part of FIG. 12 is a waveform diagram of the system voltage Vac including the harmonic component, and the lower part of FIG. 12 is a waveform diagram of the output current Io including the harmonic component. The horizontal axis of FIG. 12 is the time.

On the power system 2 side of FIGS. 10 and 11, a system impedance 6 composed of resistors Rs and inductor Ls exists. Therefore, as shown in FIG. 12, due to the influence of resonance between the inductor Ls on the power system 2 side and the capacitors 14b in the filter circuits 14 and 14A, the system interconnection system may become unstable and normal operation may not be possible.

As a countermeasure, in the technique of Patent Document 1, the harmonic voltage of the system voltage Vac shown in FIGS. 8 and 9 is calculated, and when the harmonic voltage becomes equal to or higher than the threshold value, the resonance of the system interconnection system is detected. By repeatedly adjusting the control parameters (proportional control parameters described in claim 5 of Patent Document 1) that control the switching of the DC / AC inverter 13, the resonance of the grid interconnection system is suppressed. If the resonance phenomenon does not disappear even if the control parameters are changed, a resistance circuit is connected in parallel to the three-phase capacitors 14b in the filter circuits 14 and 14A to suppress the resonance phenomenon.

Further, in the technique of Non-Patent Document 1, an impedance canceling circuit for canceling the system impedance 6 is added to suppress the resonance phenomenon.

Japanese Unexamined Patent Publication No. 2016-63742

Y. He, H. S. H. Chung, J. et al. C. T. Lai, X. Zhang and W. Wu, "Active Consultation of Electrical and Electronics Engineer for Impedance StabiIity and Injected Power Electronics Engineer

However, the conventional grid interconnection inverter devices 10 and 10A of FIGS. 8 and 9 have the following problems (a) to (e).

(A) When a load device 5 through which a harmonic current flows is connected to the power system 2, a harmonic voltage is generated even if it is not resonance, so that the control may malfunction.
(B) In the technique of Patent Document 1, since the control for suppressing resonance operates only when a harmonic voltage equal to or higher than the threshold value is detected, the resonance phenomenon cannot be accurately suppressed. In particular, it is difficult to realize a high-speed response in the calculation of the harmonic voltage because a delay of an AC cycle or longer occurs. If the resonance phenomenon does not disappear, a resistance circuit is connected in parallel to the three-phase capacitor 14b in the filter circuits 14 and 14A to suppress the resonance phenomenon, but the power loss increases due to the resistance circuit. There is a problem to do.
(C) In the technique of Patent Document 1, since there is a possibility that the harmonic amplitude and the resonance amplitude are confused and read, the resonance phenomenon cannot be suppressed accurately.
(D) In the technique of Non-Patent Document 1, since an impedance canceling circuit is added in order to suppress the resonance phenomenon, the circuit configuration becomes complicated and there is a problem of cost increase.
(E) In the conventional grid interconnection system shown in FIGS. 10 and 11, when vibration (hunting) occurs in the output current Io, an inductor is inserted in the portion where the output current Io flows to prevent hunting. is doing. However, by inserting the inductor, the number of parts increases, and it becomes difficult to reduce the size of the grid interconnection inverter devices 10 and 10A.

The grid-connected inverter device of the first invention of the present invention includes an inverter that is interconnectably connected to a power system and switches input power to convert it into predetermined power, and a control circuit that controls the switching. A filter circuit that removes harmonic components of the predetermined power and outputs the power system to the power system is provided. Then, the control circuit calculates the q-axis voltage by performing rotational coordinate conversion on the measured value of the system voltage between the filter circuit and the power system, and uses it as a q-axis current control command for q-axis current control. It is configured to control the switching by feeding back.

The grid interconnection inverter device of the second invention is connected to an electric power system so as to be interconnectable, and has an inverter that switches input power and converts it into predetermined power, a control circuit that controls the switching, and the predetermined power. It is provided with a filter circuit that removes harmonic components and outputs the power system to the power system. The control circuit is configured to detect the instantaneous phase angle from the measured value of the system voltage between the filter circuit and the power system and feed it back to the q-axis current control to control the switching.

The grid interconnection inverter device of the third invention is connected to an electric power system so as to be interconnectable, and has an inverter that switches input power and converts it into predetermined power, a control circuit that controls the switching, and the predetermined power. It is provided with a filter circuit that removes harmonic components and outputs the power system to the power system. Then, the control circuit performs rotational coordinate conversion on the measured value of the system voltage between the filter circuit and the power system to calculate the d-axis voltage and the q-axis voltage, and uses the q-axis voltage as the q-axis. In addition to feeding back to the current control, the difference between the d-axis voltage and the d-axis voltage adjustment value is fed back to the d-axis current control to control the switching.

The grid-connected inverter device of the fourth invention includes an inverter that is interconnectably connected to a single-phase power system and switches single-phase input power to convert it into predetermined power, a control circuit that controls the switching, and the like. It includes a filter circuit that removes harmonic components of the predetermined power and outputs the power to the single-phase power system side. Then, the control circuit is based on the system voltage measurement value between the filter circuit and the single-phase power system, the voltage amplitude obtained from the system voltage measurement value of the pre-AC cycle, and the phase angle of phase synchronization. The switching is controlled by feeding back the difference between the calculated fundamental voltage and the current control to the current control.

The stabilization control method of the fifth invention comprises an inverter that is interconnectably connected to an electric power system and switches input power to convert it into a predetermined electric power, and the electric power system that removes harmonic components of the predetermined electric power. It is a stabilization control method of a grid interconnection inverter device equipped with a filter circuit that outputs to the side, and performs rotational coordinate conversion on the measured value of the grid voltage between the filter circuit and the power system. The q-axis voltage is calculated and fed back to the q-axis current control command of the q-axis current control to control the switching.

The stabilization control method of the sixth invention comprises an inverter that is interconnectably connected to an electric power system and switches input power to convert it into a predetermined electric power, and the electric power system that removes harmonic components of the predetermined electric power. It is a stabilization control method of a grid interconnection inverter device equipped with a filter circuit that outputs to the side, and detects an instantaneous phase angle from the measured value of the grid voltage between the filter circuit and the power system, and q The switching is controlled by feeding back to the shaft current control.

The stabilization control method of the seventh invention comprises an inverter that is interconnectably connected to a power system and switches input power to convert it into a predetermined power, and the power system that removes harmonic components of the predetermined power. It is a stabilization control method of a grid interconnection inverter device equipped with a filter circuit that outputs to the side, and performs rotational coordinate conversion on the measured value of the grid voltage between the filter circuit and the power system. The d-axis voltage and the q-axis voltage are calculated, the q-axis voltage is fed back to the q-axis current control, and the difference between the d-axis voltage and the d-axis voltage adjustment value vdd is fed back to the d-axis current control. It controls switching.

The stabilization control method of the eighth invention is connected to a single-phase power system so as to be interconnectable, and removes an inverter that switches a single-phase input power to convert it into a predetermined power, and a harmonic component of the predetermined power. A method for stabilizing and controlling a grid interconnection inverter device including a filter circuit that outputs to the single-phase power system side, wherein the system voltage measurement value between the filter circuit and the single-phase power system is used. The switching is controlled by feeding back the difference between the voltage amplitude obtained from the system voltage measurement value of the previous AC cycle and the fundamental wave voltage calculated based on the phase angle of phase synchronization to the current control.

In the first and fifth inventions of the present invention, for example, resonance suppression is performed by detecting a voltage fluctuation on the q-axis using a vector operation of three-phase alternating current and feeding it back to a q-axis current control command for current control. It is carried out. In the second and sixth inventions, resonance is suppressed by calculating the instantaneous phase angle of the system voltage and feeding back the difference from the phase angle of the phase synchronization stabilization control result to the q-axis current control, for example. In the third and seventh inventions, in addition to the q-axis control, the d-axis voltage is calculated and the difference from the d-axis voltage adjustment value is fed back to the d-axis current control to suppress resonance. Further, in the fourth and eighth inventions, the difference between the system voltage and the system voltage amplitude calculated from the system voltage of the previous AC cycle and the fundamental wave voltage calculated from the phase angle of the phase synchronization is fed back to the system current. Resonance is suppressed.

Therefore, the following effects (1) to (4) are obtained.
(1) High-quality and stable power output can be performed even in a high-impedance power system environment.
(2) Since the impedance canceling circuit as in Non-Patent Document 1 is not required, the circuit configuration is simplified and the cost can be reduced.
(3) Since the resistance circuit for suppressing resonance as in Patent Document 1 is not required, low loss and low cost are possible.
(4) When the inductor in the filter circuit is made smaller, it is necessary to make the capacitor in the filter circuit larger in order to improve the efficiency of removing harmonic components, but the capacitor tends to resonate with the inductor in the system impedance. .. Further, if the inductor in the filter circuit is made small, the control characteristics of the filter are deteriorated, so that hunting becomes easy. In the present invention, these problems can be solved and the inductor in the filter circuit can be miniaturized.

Schematic equivalent circuit diagram of the grid interconnection system of FIG. Schematic circuit diagram showing a configuration example of the grid interconnection system according to the first embodiment of the present invention. Operation waveform diagram in the grid interconnection system of FIG. Schematic equivalent circuit diagram of the grid interconnection system according to the second embodiment of the present invention. Schematic equivalent circuit diagram of the grid interconnection system according to the third embodiment of the present invention. Schematic circuit diagram showing a configuration example of the grid interconnection system according to the fourth embodiment of the present invention. Schematic equivalent circuit diagram of the grid interconnection system of FIG. Schematic circuit diagram showing a configuration example of a conventional grid interconnection system Schematic circuit diagram showing a configuration example of a conventional grid interconnection system Schematic equivalent circuit diagram of FIG. Schematic equivalent circuit diagram of FIG. Operation waveform diagram of the grid interconnection system shown in FIGS. 10 and 11.

The embodiments for carrying out the present invention will become clear when the following description of preferred embodiments is read in light of the accompanying drawings. However, the drawings are for illustration purposes only and do not limit the scope of the present invention.

(Structure of Example 1)
FIG. 2 is a schematic circuit diagram showing a configuration example of a grid interconnection system including a three-phase grid interconnection inverter device with an LC filter according to the first embodiment of the present invention.

This grid interconnection system is connected between the DC power supply 1 and, for example, the three-phase U, V, W AC (3φ200V) power grid 2 which is a commercial power grid, as in FIG. , A three-phase system interconnection inverter device 20 with an LC filter having a different configuration from the conventional one is provided. The power system 2 is connected to the output terminal of the grid interconnection inverter device 20 via a three-phase circuit breaker 3, a three-phase transformer 4, and the like, as in FIG. A load device 5 is connected in parallel between the output terminal of the grid interconnection inverter device 20 and the transformer 4 .

The grid interconnection inverter device 20 of the first embodiment is a device that is interconnectably connected to the power system 2 and converts the DC power supplied from the DC power supply 1 into three-phase AC power, and is a converter (for example,). , DC / DC converter) 21. The DC / DC converter 21 is a device that converts a DC voltage supplied from a DC power supply 1 into a predetermined DC voltage, for example, by a bridge connection of a plurality of switch elements whose switching operation is controlled by a control unit (not shown). It is configured. A three-phase U, V, W inverter (for example, a DC / AC inverter) 23 is connected to the output side of the DC / DC converter 21 via a capacitor 22 for charge storage connected in parallel.
The DC / DC converter 21 may be omitted.

The DC / AC inverter 23 is a device whose switching operation is controlled by the control circuit 30 and converts the input power (for example, DC voltage Vdc) stored in the capacitor 22 into a three-phase U, V, W AC voltage Vinv. , Six switch elements (eg, IGBT) 23a are bridge-connected. A body diode 23b is connected to each IGBT 23a in antiparallel. A three-phase filter circuit (for example, an L-shaped three-phase LC filter circuit) 24 is connected to the output side of the DC / AC inverter 23.

The L-shaped three-phase LC filter circuit 24 is a circuit that removes the harmonic components of the AC voltage Vinv and the inverter current Iinv output from the DC / AC inverter 23 and sends out the output current Io. It is composed of a three-phase capacitor 24b. The output terminal of the grid interconnection inverter device 20 is connected to the output side of the LC filter circuit 24 via a three-phase switch 25 such as a relay whose opening and closing is controlled by a control unit (not shown). Between the three-phase inductor 24a and the three-phase capacitor 24b, a three-phase current measuring instrument (for example, an instrument current transformer, hereinafter referred to as "CT") that measures the inverter current Iinv and outputs the current measured value iinv. ".) 26 is provided. When measuring three-phase alternating current using CT26, the currents Iu and Iw for two phases (for example, U phase and W phase) are measured with two CT26s, and the current Iv for the remaining one phase (V phase). May be calculated from the equation (Iv = -Iu-Iw).

Further, between the three-phase capacitor 24b and the three-phase switch 25, a voltage measuring instrument for three-phase (for example, a voltage transformer for an instrument, hereinafter referred to as a transformer) that measures a system voltage Vac and outputs a voltage measurement value vac is used. It is referred to as "VT".) 27 is connected.

A control circuit 30 is connected to the output side of the three-phase CT26 and the three-phase VT27. The control circuit 30 is a circuit that generates six switching drive signals S30 based on the current measured value iinv and the voltage measured value vac, and turns the six IGBTs 23a on and off, respectively.

FIG. 1 is a schematic equivalent circuit diagram of a grid interconnection system including the three-phase grid interconnection inverter device with an LC filter of FIG. In FIG. 1, a power conversion unit including a DC / AC inverter 23, a filter circuit 24, and the like is schematically shown.
The control circuit 30 has a first current control mechanism and a second current control mechanism for controlling the switching operation of the DC / AC inverter 23, and has a central processing unit (hereinafter referred to as “CPU”) and a processor. It is composed of individual circuits and the like.

The first current control mechanism performs rotation coordinate conversion with respect to the voltage measurement value vac in the system voltage Vac of the three-phase U, V, W to calculate the q-axis voltage vq of the dq coordinate system which is the rotation coordinate system. It feeds back to the q-axis current control to control the switching operation of the DC / AC inverter 23. This first current control mechanism switches with a first three-phase / two-phase voltage conversion unit 31, a first rotation coordinate conversion unit 32, a phase-locked loop (hereinafter referred to as “PLL”) control unit 33, and a gain adjustment unit 34. It is composed of first and second subtraction units 41 and 42, a first current control unit 44, and a modulation control unit 46 in the drive signal generation unit 40.

The second current control mechanism performs rotational coordinate conversion on the current measured value iinv in the inverter currents Iinv of the three phases U, V, and W to calculate the d-axis current id and the q-axis current iq of the dq coordinate system. The switching operation of the DC / AC inverter 23 is controlled by feeding back to the d-axis current control and the q-axis current control. This second current control mechanism includes a second three-phase / two-phase current conversion unit 35, a second rotation coordinate conversion unit 36, and second and third subtraction units 42, 43 and first in the switching drive signal generation unit 40. , The second current conversion unit 44, 45 and the modulation control unit 46.

In the first current control mechanism, in the first three-phase / two-phase voltage conversion unit 31, the system voltage Vac of the three-phase U, V, W is the voltage of the three-phase U, V, W measured by the three-phase VT27. The measured value vac is input, and this voltage measured value vac is converted into the two-phase voltages α and β of the fixed coordinate system. A first rotating coordinate conversion unit 32 is connected to the output side of the first three-phase / two-phase voltage conversion unit 31. The first rotation coordinate conversion unit 32 converts the two-phase voltages α and β into the q-axis voltage vq of the dq coordinate system based on the phase angle φpl, and the PLL control unit 33 and the gain adjustment unit are on the output side. 34 is connected.

The PLL control unit 33 performs phase synchronization control with respect to the input q-axis voltage vq to generate a phase angle φpl, and the phase angle φpll is used by the first and second rotation coordinate conversion units 32 and 36. Given. The gain adjustment unit 34 adjusts the gain of the q-axis voltage vq to generate a gain adjustment value vqc which is a corresponding value of the q-axis voltage vq, and the switching drive signal generation unit 40 is located on the output side of the gain adjustment unit 34. The first subtraction unit 41 of the above is connected.

The first subtraction unit 41 subtracts the gain adjustment value vqc from the supplied q-axis current control command (hereinafter referred to as “iq command”), and the second subtraction unit 42 is connected to this output side. There is. The second subtraction unit 42 subtracts the q-axis current iq output from the second rotation coordinate conversion unit 36 from the subtraction result of the first subtraction unit 41, and the first current control unit is on the output side. 44 is connected. The first current control unit 44 performs feedback control (for example, proportional integration control or the like, hereinafter referred to as “PI control or the like”) with respect to the subtraction result of the second subtraction unit 42, and the output side thereof. , The modulation control unit 46 is connected. The modulation control unit 46 performs modulation (for example, pulse width modulation or the like) on the control result of the first current control unit 44 and the control result of the second current control unit 45, which will be described later, in the DC / AC inverter 23. It generates six switching drive signals S30 for controlling the on / off of the six IGBTs 23a.

In the second current control mechanism, in the second three-phase / two-phase current conversion unit 35, the system current Iinv of the three-phase U, V, W is the three-phase U, V, W current measured by the three-phase CT26. The measured value iinv is input, and the current measured value iinv is converted into the two-phase currents α and β of the fixed coordinate system, and the second rotation coordinate conversion unit 36 is connected to this output side. .. The second rotation coordinate conversion unit 36 converts the two-phase currents α and β into the d-axis current id and the q-axis current iq of the dq coordinate system based on the phase angle φpl. The second and third subtraction units 42 and 43 in the generation unit 40 are connected. The third subtraction unit 43 subtracts the d-axis current id from the supplied d-axis current control command (hereinafter referred to as “id command”), and the second current control unit 45 is connected to this output side. Has been done. The second current control unit 45 performs feedback control (for example, PI control or the like) with respect to the subtraction result of the third subtraction unit 43, and the modulation control unit 46 is connected to the output side.

(Overall operation of the grid interconnection system of Example 1)
In the grid interconnection system of FIG. 2, the DC voltage supplied from the DC power supply 1 is converted into a predetermined DC voltage by the DC / DC converter 21 in the grid interconnection inverter device 20 and stored in the capacitor 22. The DC voltage Vdc stored in the capacitor 22 is converted into a three-phase U, V, W AC voltage Vinv by the DC / AC inverter 23, and then harmonics are generated by the three-phase inductor 24a and the three-phase capacitor 24b of the filter circuit 24. The component is removed. The three-phase alternating current output current Io and the system voltage Vac from which the harmonic components have been removed are output to the load device 5 and the three-phase power system 2 side via the three-phase switch 25. When a power failure or the like occurs in the three-phase power system 2, the three-phase breaker 3 is turned off, the grid-connected inverter device 20 is disconnected from the power system 2, and the system is in an independent operation state. The output output current Io and the system voltage Vac are supplied to the load device 5.

(Stabilization control method of Example 1)
The control circuit 30 of FIG. 1 performs the following stabilization control.
When the three-phase U, V, W inverter current Iinv flows through the filter circuit 24 and the three-phase U, V, W output current Io and the system voltage Vac are output from the filter circuit 24, the three-phase U, The system voltage Vac of V and W is measured by VT27, and the inverter current Iinv of the three phases U, V and W is measured by CT26. The voltage measurement values vac of the three-phase U, V, and W measured by the VT 27 are converted into the two-phase voltages α and β of the fixed coordinate system by the first three-phase / two-phase voltage conversion unit 31. The converted two-phase voltages α and β are converted into the q-axis voltage vq of the dq coordinate system by the first rotation coordinate conversion unit 32 based on the phase angle φpll given by the PLL control unit 33, and the PLL control unit 33 and the PLL control unit 33 and It is output to the gain adjustment unit 34. The PLL control unit 33 controls the phase synchronization with respect to the q-axis voltage vq to generate a phase angle φpl, which is given to the first and second rotating coordinate conversion units 32 and 36. The gain adjustment unit 34 adjusts the gain of the input q-axis voltage vq and outputs the gain adjustment value vqc to the first subtraction unit 41 in the switching drive signal generation unit 40. The first subtraction unit 41 subtracts the gain adjustment value vqc from the supplied iq command, and outputs the subtraction result to the second subtraction unit 42.

On the other hand, the three-phase U, V, and W current measurement values iinv measured by the CT 26 are converted into the two-phase currents α and β in the fixed coordinate system by the second three-phase / two-phase current conversion unit 35. The converted two-phase currents α and β are converted into the d-axis current id and the q-axis current iq of the dq coordinate system by the second rotation coordinate conversion unit 36 based on the phase angle φpll given by the PLL control unit 33. , Is output to the second and third subtraction units 42 and 43 in the switching drive signal generation unit 40. The second subtraction unit 42 subtracts the q-axis current iq from the subtraction result of the first subtraction unit 41, and outputs this subtraction result to the first current control unit 44. The first current control unit 44 performs feedback control such as PI control on the input subtraction result, and outputs this control result to the modulation control unit 46.

Further, the third subtraction unit 43 subtracts the d-axis current id from the supplied id command, and outputs the subtraction result to the second current control unit 45. The second current control unit 45 performs feedback control such as PI control on the input subtraction result, and outputs this control result to the modulation control unit 46. The modulation control unit 46 performs modulation such as pulse width modulation on the control results of the first and second current control units 44 and 45, generates six switching drive signals S30, and 6 in the DC / AC inverter 23. On / off control of one IGBT 23a. As a result, the output current Io of the filter circuit 24 is foot-back controlled so as to match the id command and the iq command.

(Effect of Example 1)
Since the system impedance 6 composed of the resistors Rs and the inductor Ls exists on the power system 2 side of FIG. 1, the system interconnection is affected by the resonance between the inductor Ls on the power system 2 side and the capacitor 24b in the filter circuit 24. The system may become unstable and normal operation may not be possible.

As a countermeasure, in the first embodiment, a three-phase alternating current vector operation is performed by the first three-phase / two-phase voltage conversion unit 31 and the first rotation coordinate conversion unit 32 for the voltage measurement value vac of the system voltage Vac. Rotational coordinate conversion is performed to calculate the q-axis voltage Vq, which is fed back to the iq command side to control switching of the DC / AC inverter 23 and suppress resonance of the grid interconnection system. Therefore, there are the following effects (i) to (iv).

(I) FIG. 3 is an operation waveform diagram when, for example, an inductor Ls having a constant reactance value or more is connected as the system impedance 6 on the power system 2 side in the system interconnection system of FIG. The upper part of FIG. 3 is a waveform diagram of the system voltage Vac including the harmonic component, and the lower part of FIG. 3 is a waveform diagram of the output current Io including the harmonic component. The horizontal axis of FIG. 3 is time.
According to the first embodiment, as shown in FIG. 3, high quality and stable power output can be performed even in a high impedance power system environment.
(Ii) Since the impedance canceling circuit as in Non-Patent Document 1 is not required, the circuit configuration can be simplified and the cost can be reduced.
(Iii) Since the resistance circuit for suppressing resonance as in Patent Document 1 is not required, low loss and low cost can be achieved.
(Iv) When the inductor 24a in the filter circuit 24 is made small, it is necessary to make the capacitor 24b in the filter circuit 24 large in order to improve the efficiency of removing harmonic components, but the capacitor 24b is in the system impedance 6. It becomes easy to resonate with the inductor Ls. Further, if the inductor 24a in the filter circuit 24 is made small, the control characteristics of the filter are deteriorated, so that hunting becomes easy. In the first embodiment, these problems can be solved and the inductor 24a in the filter circuit 24 can be miniaturized.

(Structure of Example 2)
FIG. 4 is a schematic equivalent circuit diagram of a grid interconnection system including a three-phase grid interconnection inverter device with an LC filter according to the second embodiment of the present invention, and is the same as the elements in FIG. 1 showing the first embodiment. The elements have the same reference numerals. FIG. 4 schematically shows a power conversion unit including a DC / AC inverter 23, a filter circuit 24, and the like, as in FIG. 1.

In the grid interconnection system of the second embodiment, the configuration of the control circuit 30A provided in the three-phase grid interconnection inverter device 20A with an LC filter is different from the configuration of the control circuit 30 shown in FIG. 1 of the first embodiment. ..

The control circuit 30A of the second embodiment has a first current control mechanism and a second current control mechanism for controlling the switching operation of the DC / AC inverter 23, similarly to the control circuit 30 of the first embodiment. It is composed of a processor having a CPU, an individual circuit, and the like.

The first current control mechanism detects an instantaneous phase angle θ (t) based on the voltage measurement value vac measured by the three-phase VT27, feeds it back to the iq command side, and performs the switching operation of the DC / AC inverter 23. It controls. The first current control mechanism includes a voltage measurement circuit 51, an amplitude / phase angle calculation unit 52, a PLL control unit 53, a fourth subtraction unit 54 and a multiplication unit 55, a gain adjustment unit 34 similar to that of the first embodiment, and a switching drive. It is composed of first and second subtraction units 41 and 42, a first current control unit 44, and a modulation control unit 46 in the signal generation unit 40.

Similar to the first embodiment, the second current control mechanism includes the second three-phase / two-phase current conversion unit 35, the second rotation coordinate conversion unit 36, and the second and third subtraction in the switching drive signal generation unit 40. It is composed of units 42, 43, first and second current control units 44, 45, and a modulation control unit 46.

In the first current control mechanism, the voltage measurement circuit 51 is a circuit that converts the voltage measurement values vac of the three phases U, V, W measured by the three-phase VT27 into a digital signal, and is an analog / digital converter. It is composed of (A / D converter) and the like. An amplitude / phase angle calculation unit 52 is connected to the output side of the voltage measurement circuit 51. The amplitude / phase angle calculation unit 52 performs amplitude / phase angle calculation on the digital voltage measurement value converted into a digital signal to calculate the instantaneous phase angle θ (t) and the d-axis voltage Vd of the dq coordinate system. The PLL control unit 53 is connected to this output side. The PLL control unit 53 controls the phase synchronization of the calculated instantaneous phase angle θ (t) to obtain the phase angle φp11, and the q-axis voltage calculation unit is connected to this output side.

The q-axis voltage calculation unit subtracts the phase angle φp11 from the calculated instantaneous phase angle θ (t), multiplies this subtraction result by the d-axis voltage vd, and gain adjustment value vqc corresponding to the q-axis voltage value. Is obtained, and is composed of a fourth subtraction unit 54, a multiplication unit 55, and a gain adjustment unit 34. The fourth subtraction unit 54 subtracts the phase angle φp11 from the calculated instantaneous phase angle θ (t), and the multiplication unit 55 is connected to this output side. The multiplying unit 55 multiplies the subtraction result of the fourth subtraction unit 54 with the d-axis voltage Vd to obtain the q-axis voltage vq, and the gain adjusting unit 34 is connected to this output side. The gain adjusting unit 34 adjusts the gain of the q-axis voltage vq to generate a gain adjusting value vqc which is a corresponding value of the q-axis voltage vq, and the same switching as in the first embodiment is performed on the output side. The drive signal generation unit 40 is connected.

The switching drive signal generation unit 40 subtracts the gain adjustment value vqc, which is the corresponding value of the q-axis voltage vq, from the iq command of the q-axis current control, and controls the switching operation of the DC / AC inverter 23. It has first and second subtraction units 41 and 42, a first current control unit 44, and a modulation control unit 46.
The switching drive signal generation unit 40 is also provided with a third subtraction unit 43 and a second current control unit 45 that form a part of the second current control mechanism.

(Stabilization control method of Example 2)
The control circuit 30A of FIG. 4 performs the following stabilization control.
The system voltage Vac of the three-phase U, V, W is measured by the VT27, and the inverter current Iinv of the three-phase U, V, W is measured by the CT26. The voltage measurement values vac of the three phases U, V, and W measured by the VT 27 are converted into digital voltage measurement values by the voltage measurement circuit 51 and output to the amplitude / phase angle calculation unit 52. The amplitude / phase angle calculation unit 52 performs amplitude / phase angle calculation on the input digital voltage measurement value, calculates the instantaneous phase angle θ (t) and the d-axis voltage Vd of the dq coordinate system, and controls the PLL. Output to unit 53, fourth subtraction unit 54, and multiplication unit 55.

The PLL control unit 53 controls the phase synchronization with respect to the input instantaneous phase angle θ (t) to generate a phase angle φpl, which is given to the fourth subtraction unit 54 and the second rotation coordinate conversion unit 36. The fourth subtraction unit 54 subtracts the phase angle φpl from the instantaneous phase angle θ (t). This subtraction result and the d-axis voltage vd are multiplied by the multiplication unit 55 to generate the q-axis voltage vq. The gain of the generated q-axis voltage vq is adjusted by the gain adjusting unit 34, and the gain adjusting value vqc is output to the first subtracting unit 41 in the switching drive signal generation unit 40. The first subtraction unit 41 subtracts the gain adjustment value vqc from the supplied iq command, and outputs the subtraction result to the second subtraction unit 42.

On the other hand, the three-phase U, V, and W current measurement values iinv measured by the CT26 are converted into two-phase currents α and β by the second three-phase / two-phase current conversion unit 35, as in the first embodiment. To. The converted two-phase currents α and β are converted into d-axis current id and q-axis current iq by the second rotation coordinate conversion unit 36 based on the phase angle φpl, and the second, in the switching drive signal generation unit 40, It is output to the third subtraction units 42 and 43. The second subtraction unit 42 subtracts the q-axis current iq from the subtraction result of the first subtraction unit 41, and outputs this subtraction result to the first current control unit 44. The first current control unit 44 performs feedback control such as PI control on the input subtraction result, and outputs this control result to the modulation control unit 46.

Further, the third subtraction unit 43 subtracts the d-axis current id from the supplied id command, and outputs the subtraction result to the second current control unit 45. The second current control unit 45 performs feedback control such as PI control on the input subtraction result, and outputs this control result to the modulation control unit 46. The modulation control unit 46 performs modulation such as pulse width modulation on the control results of the first and second current control units 44 and 45, generates six switching drive signals S30A, and 6 in the DC / AC inverter 23. On / off control of one IGBT 23a. As a result, the output current Io of the filter circuit 24 is foot-back controlled so as to match the id command and the iq command.

(Effect of Example 2)
According to the second embodiment, the instantaneous phase angle θ (t) is obtained from the voltage measurement value vac of the system voltage Vac through the voltage measurement circuit 51 by the amplitude / phase angle calculation unit 52, and the phase synchronization stabilization control result is obtained. The difference from the phase angle φpl is fed back to the iq command side through the multiplication unit 55 and the gain adjustment unit 34, switching control of the DC / AC inverter 23 is performed, and resonance of the grid interconnection system is suppressed. Therefore, it is possible to obtain substantially the same effect as that of the first embodiment.

(Structure of Example 3)
FIG. 5 is a schematic equivalent circuit diagram of a grid interconnection system including a three-phase grid interconnection inverter device with an LC filter according to the third embodiment of the present invention, and is the same as the elements in FIG. 1 showing the first embodiment. The elements have the same reference numerals. FIG. 5 schematically shows a power conversion unit including a DC / AC inverter 23, a filter circuit 24, and the like, as in FIG. 1.
In the grid interconnection system of the third embodiment, the configuration of the control circuit 30B provided in the three-phase grid interconnection inverter device 20B with an LC filter is different from the configuration of the control circuit 30 shown in FIG. 1 of the first embodiment. ..

The control circuit 30B of the third embodiment has a first current control mechanism and a second current control mechanism for controlling the switching operation of the DC / AC inverter 23, similarly to the control circuit 30 of the first embodiment. It is composed of a processor having a CPU, an individual circuit, and the like.

In the first current control mechanism of the first embodiment, the d-axis voltage vd and the q-axis voltage vq are calculated by performing rotational coordinate conversion on the voltage measurement value vac measured by the VT27, and the q-axis voltage vq is commanded by the iq command. A first unit including a first three-phase / two-phase voltage conversion unit 31, a first rotation coordinate conversion unit 32, a PLL control unit 33, a first gain adjustment unit 34, and a first subtraction unit 41 for feeding back to the side. It has one arithmetic unit and. On the other hand, in the first current control mechanism of the third embodiment, the d-axis voltage vd, the d-axis voltage adjustment value (for example, the d-axis voltage harmonic component removal value or the d-axis voltage AC cycle average value) vdd In order to feed back the difference between the two to the id command side, a second calculation unit including a d-axis voltage adjustment unit 61, a fifth subtraction unit 62, a second gain adjustment unit 63, and a sixth subtraction unit 47 is added. The sixth subtraction unit 47 is provided in the switching drive signal generation unit 40B of the third embodiment. The switching drive signal generation unit 40B of the third embodiment has a configuration in which the sixth subtraction unit 47 is added to the switching drive signal generation unit 40 of the first embodiment.

In the second calculation unit of the third embodiment, the d-axis voltage adjusting unit 61 and the fifth subtraction unit 62 are connected to the output side of the first rotating coordinate conversion unit 32. The d-axis voltage adjusting unit 61 obtains the d-axis voltage adjustment value vdd of the d-axis voltage vd output from the first rotating coordinate conversion unit 32. The d-axis voltage adjustment value vdd is, for example, a d-axis voltage harmonic component removal value removed by a low-pass filter (hereinafter referred to as “LPF”) or a d-axis voltage AC period average value obtained by an arithmetic unit. The fifth subtraction unit 62 subtracts the d-axis voltage adjustment value vdd from the d-axis voltage vd, and the second gain adjustment unit 63 is connected to this output side. The second gain adjustment unit 63 adjusts the gain with respect to the subtraction result of the fifth subtraction unit 62 to obtain the gain adjustment value vdc, and the sixth subtraction in the switching drive signal generation unit 40B is on the output side. The unit 47 is connected. The sixth subtraction unit 47 subtracts the gain adjustment value vdc from the id command, and outputs the subtraction result to the third subtraction unit 43.

The second current control mechanism of the third embodiment is the same as that of the first embodiment, that is, the second three-phase / two-phase current conversion unit 35, the second rotation coordinate conversion unit 36, and the second in the switching drive signal generation unit 40. , The third subtraction unit 42, 43, the first and second current conversion units 44, 45, and the modulation control unit 46.

(Stabilization control method of Example 3)
The control circuit 30B of FIG. 5 performs the following stabilization control.
Similar to the first embodiment, the three-phase U, V, W voltage measurement values vac measured by the VT27 are converted into the two-phase voltages α and β by the first three-phase / two-phase voltage conversion unit 31, and further. , The first rotation coordinate conversion unit 32 converts the d-axis voltage vd and the q-axis voltage vq. The converted q-axis voltage vq is gain-adjusted by the first gain adjustment unit 34, and this gain adjustment value vqc is output to the first subtraction unit 41 in the switching drive signal generation unit 40B. The first subtraction unit 41 subtracts the gain adjustment value vqc from the supplied iq command, and outputs the subtraction result to the second subtraction unit 42.

The d-axis voltage vd converted by the first rotation coordinate conversion unit 32 is adjusted by the d-axis voltage adjustment unit 61, and the d-axis voltage adjustment value (for example, the d-axis voltage harmonic component removal value removed by the LPF, or the d-axis voltage harmonic component removal value). , D-axis voltage AC period average value obtained by the arithmetic unit) vdd is obtained and output to the fifth subtraction unit 62. The fifth subtraction unit 62 subtracts the d-axis voltage adjustment value vdd from the d-axis voltage vd, and outputs the subtraction result to the second gain adjustment unit 63. The second gain adjustment unit 63 adjusts the gain of the subtraction result of the fifth subtraction unit 62 to obtain the gain adjustment value vdc, and outputs the gain adjustment value vdc to the sixth subtraction unit 47 in the switching drive signal generation unit 40B.

On the other hand, the three-phase U, V, and W current measurement values iinv measured by the CT26 are converted into two-phase currents α and β by the second three-phase / two-phase current conversion unit 35, as in the first embodiment. Further, it is converted into a d-axis current id and a q-axis current iq by the second rotation coordinate conversion unit 36, and is output to the second and third subtraction units 42 and 43 in the switching drive signal generation unit 40B.

Of the id command and the iq command supplied in the switching drive signal generation unit 40B, the gain adjustment value vdc is subtracted from the id command by the sixth subtractor 47. As for the subtraction result of the sixth subtractor 47, the d-axis current id is further subtracted by the third subtraction unit 43, and the second current control unit 45 performs feedback control such as PI control, and the control result is obtained. It is output to the modulation control unit 46. Further, in the supplied iq command, the gain adjustment value vqc is subtracted by the first subtraction unit 41, and the q-axis current iq is further subtracted by the second subtraction unit 42 to control the first current. The unit 44 performs feedback control such as PI control, and the control result is output to the modulation control unit 46.

The modulation control unit 46 performs modulation such as pulse width modulation on the control results of the first and second current control units 44 and 45, generates six switching drive signals S30B, and 6 in the DC / AC inverter 23. On / off control of one IGBT 23a. As a result, the output current Io of the filter circuit 24 is foot-back controlled so as to match the id command and the iq command.

(Effect of Example 3)
According to the third embodiment, in addition to the q-axis control, the axis voltage vd is calculated, the difference from the d-axis voltage adjustment value vdd is fed back to the id command side, and the switching control of the DC / AC inverter 23 is performed. The resonance of the grid interconnection system is suppressed. Therefore, it is possible to obtain substantially the same effect as that of the first embodiment.

(Structure of Example 4)
FIG. 6 is a schematic circuit diagram showing a configuration example of a grid interconnection system including a single-phase grid interconnection inverter device with an LC filter according to the fourth embodiment of the present invention.
This grid interconnection system includes a DC power supply 1 and, for example, a single-phase grid interconnection inverter device 20C with an LC filter connected between the power grids 2C of single-phase U and V, which are commercial power grids. There is. The power system 2C is connected to the output terminal of the grid interconnection inverter device 20C via a single-phase circuit breaker 3C, a single-phase transformer 4C, and the like. A load device 5C is connected in parallel between the output terminal of the grid interconnection inverter device 20C and the transformer 3C.

The grid interconnection inverter device 20C of the fourth embodiment is a device that is interconnectably connected to the power grid 2C and converts the DC power supplied from the DC power supply 1 into a single-phase AC power, and is a converter (for example,). , DC / DC converter) 21C. The DC / DC converter 21C is a device that converts a DC voltage supplied from a DC power supply 1 into a predetermined DC voltage, for example, by a bridge connection of a plurality of switch elements whose switching operation is controlled by a control unit (not shown). It is configured. A single-phase U, V inverter (for example, a DC / AC inverter) 23C is connected to the output side of the DC / DC converter 21C via a charge storage capacitor 22C connected in parallel.

The DC / DC converter 21C may be omitted.
The DC / AC inverter 23C is a device whose switching operation is controlled by the control circuit 30C and converts the input power (for example, DC voltage Vdc) stored in the capacitor 22C into a single-phase U, V AC voltage Vinv. Two switch elements (for example, IGBT) 23a are bridge-connected. A body diode 23b is connected to each IGBT 23a in antiparallel. A single-phase filter circuit (for example, an L-shaped single-phase LC filter circuit) 24C is connected to the output side of the DC / AC inverter 23C.

The L-shaped single-phase LC filter circuit 24C is a circuit that removes the harmonic components of the AC voltage Vinv and the inverter current Iinv and sends out the output current Io, and is composed of the single-phase inductor 24a and the single-phase capacitor 24b. .. The output terminal of the grid interconnection inverter device 20C is connected to the output side of the LC filter circuit 24C via a single-phase switch 25C such as a relay whose opening / closing is controlled by a control unit (not shown). Between the single-phase inductor 24a and the single-phase capacitor 24b, a current measuring instrument (for example, CT for single-phase) 26C that measures the inverter current Iinv and outputs the current measured value iinv is provided. Further, a voltage measuring instrument (for example, a single-phase VT) 27C that measures the system voltage Vac and outputs the measured voltage value vac is connected between the single-phase capacitor 24b and the single-phase switch 25C.

A control circuit 30C is connected to the output side of the single-phase CT26C and the single-phase VT27C. The control circuit 30C is a circuit that generates four switching drive signals S30C based on the current measured value iinv and the voltage measured value vac, and turns the four IGBTs 23a on and off, respectively.

FIG. 7 is a schematic equivalent circuit diagram of the grid interconnection system of FIG. In FIG. 7, a power conversion unit including a DC / AC inverter 23C, a filter circuit 24C, and the like is schematically shown.
The control circuit 30C is a fundamental wave voltage calculated based on the voltage measurement value vac of the system voltage Vac measured by the VT27C, the voltage amplitude vaclp obtained from the voltage measurement value vac of the AC cycle, and the phase angle φpll of the phase synchronization. It is a circuit that controls the switching operation of the DC / AC inverter 23C by feeding back the difference between the voltage and the voltage to the current command (hereinafter referred to as "i command") side, and is composed of a processor having a CPU, an individual circuit, and the like. There is.

The control circuit 30C has a voltage amplitude calculation unit (for example, a fundamental wave voltage amplitude calculation unit) 71 and a PLL control unit 72 connected to the output side of the VT27C. The fundamental wave voltage amplitude calculation unit 71 calculates the voltage amplitude vaclp from the voltage measurement value vac of the VT27C, and the multiplication unit 74 is connected to this output side. The fundamental wave voltage amplitude calculation unit 71 may be configured to calculate the effective value vrms of the AC voltage measurement value vac and regard vrms × √2 as the fundamental wave voltage amplitude vaclp.

The PLL control unit 72 controls the phase synchronization with respect to the voltage measurement value vac to obtain the phase angle φpl of the phase synchronization, and the fundamental wave voltage calculation unit is connected to this output side. This fundamental wave voltage calculation unit is composed of, for example, a sign calculation unit (hereinafter referred to as “sin calculation unit”) 73 connected to the output side of the PLL control unit 72, and a multiplication unit 74 connected to the output side. It is configured. The sin calculation unit 73 calculates a sine value sin (φpll) having a phase angle of φpl, and a multiplication unit 74 is connected to this output side. The multiplication unit 74 calculates the fundamental wave voltage vacl by multiplying the voltage amplitude vac1p and the sine and cosine value sin (φpll), and the calculation unit is connected to this output side.

The calculation unit subtracts the fundamental wave voltage vacl from the voltage measurement value vac to obtain the corresponding value (for example, gain adjustment value) vacc corresponding to the subtraction result. For example, the seventh subtraction unit 75 and the gain adjustment unit. It is composed of a part 76. The seventh subtraction unit 75 subtracts the fundamental wave voltage vac1 from the voltage measurement value vac, and outputs the subtraction result to the gain adjustment unit 76. The gain adjustment unit 76 adjusts the gain with respect to the input subtraction result, and outputs the gain adjustment value vacc to the switching drive signal generation unit 40C.

The switching drive signal generation unit 40C switches the DC / AC inverter 23C based on the i-command supplied, the gain adjustment value vacc output from the gain adjustment unit 76, and the current measurement value iinv output from the CT26C. It generates four switching drive signals S30C for controlling the operation. The switching drive signal generation unit 40C has eighth and ninth subtraction units 81 and 82, a current control unit 83, and a modulation control unit 84.

The eighth subtraction unit 81 subtracts the gain adjustment value vacc from the supplied i-command, and the ninth subtraction unit 82 is connected to this output side. The ninth subtraction unit 82 subtracts the current measurement value iinv output from the CT26C from the subtraction result of the eighth subtraction unit 81, and the current control unit 83 is connected to this output side. The current control unit 83 performs feedback control such as PI control with respect to the subtraction result of the ninth subtraction unit 82, and the modulation control unit 84 is connected to this output side. The modulation control unit 84 performs modulation such as pulse width modulation on the control result of the current control unit 83, and outputs four switching drive signals S30C for on / off control of the four IGBTs 23 in the DC / AC inverter 23C. It is what is generated.

(Overall operation of the grid interconnection system of Example 4)
In the grid interconnection system of FIG. 6, the DC voltage supplied from the DC power supply 1 becomes a predetermined DC voltage by the DC / DC converter 21C in the grid interconnection inverter device 20C, substantially as in FIG. 2 of the first embodiment. It is converted and stored in the capacitor 22C. The DC voltage Vdc stored in the capacitor 22C is converted into a single-phase U, V AC voltage Vinv by the DC / AC inverter 23C, and then the harmonic component is generated by the single-phase inductor 24a and the single-phase capacitor 24b of the filter circuit 24C. Will be removed. The single-phase alternating current output current Io and the system voltage Vac from which the harmonic component has been removed are output to the load device 5C and the power system 2C side via the single-phase switch 25C. When a power failure or the like occurs in the power system 2C, the single-phase breaker 3C is turned off, the grid interconnection inverter device 20C is disconnected from the power system 2C and becomes an independent operation state, and is output from the grid interconnection inverter device 20C. The output current Io and the system voltage Vac are supplied to the load device 5C.

(Stabilization control method of Example 4)
The control circuit 30C of FIG. 7 performs the following stabilization control.
When the system current Iinv of single-phase U and V flows through the filter circuit 24C and the output current Io of single-phase U and V and the system voltage Vac are output from this filter circuit 24C, the system voltage of the single-phase U and V is output. Vac is measured by VT27C, and its single-phase U and V inverter currents Iinv are measured by CT26C. The voltage measurement values vac of the single-phase U and V measured by the VT27C are output to the fundamental wave voltage amplitude calculation unit 71 and the PLL control unit 72. The fundamental wave voltage amplitude calculation unit 71 calculates the voltage amplitude vaclp from the voltage measurement value vac and outputs it to the multiplication unit 74. Further, the PLL control unit 72 controls the phase synchronization with respect to the voltage measurement value vac to generate the phase angle φpl of the phase synchronization, and outputs the phase angle φpl to the sin calculation unit 73.

The sin calculation unit 73 obtains a sine value sin (φpll) having a phase angle of φpl by calculation, and outputs the sine value to the multiplication unit 74. The multiplication unit 74 multiplies the voltage amplitude vac1p by the sine and cosine value sin (φpll) to calculate the fundamental wave voltage vacl, and outputs the basic wave voltage vacl to the seventh subtraction unit 75. The seventh subtraction unit 75 subtracts the fundamental wave voltage vac1 from the voltage measurement value vac, and outputs the subtraction result to the gain adjustment unit 76. The gain adjustment unit 76 adjusts the gain with respect to the subtraction result, and outputs the gain adjustment value vacc to the eighth subtraction unit 81 in the switching drive signal generation unit 40C.

The eighth subtraction unit 81 in the switching drive signal generation unit 40C subtracts the gain adjustment value vacc from the supplied i-command and outputs the gain adjustment value to the ninth subtraction unit 82. The ninth subtraction unit 82 subtracts the current measurement value iinv measured by the CT26C from the subtraction result of the eighth subtraction unit 81, and outputs the subtraction unit 82 to the current control unit 83. The current control unit 83 performs feedback control such as PI control on the subtraction result of the ninth subtraction unit 82, and outputs this control result to the modulation control unit 84.

The modulation control unit 84 performs modulation such as pulse width modulation on the control result of the current control unit 83, generates four switching drive signals S30C, and controls four IGBTs 23a in the DC / AC inverter 23C on / off. do. As a result, the output current Io of the filter circuit 24C is foot-back controlled so as to match the i command.

(Effect of Example 4)
According to the fourth embodiment, the voltage measured value vac measured by the VT27C, the voltage amplitude vaclp obtained from the voltage measured value vac of the AC cycle, and the fundamental wave voltage vaccl calculated based on the phase angle φpll. The difference is fed back to the i-command side to control the switching of the DC / AC inverter 23C, and the resonance of the grid interconnection system is suppressed. Therefore, it is possible to obtain substantially the same effect as that of the first embodiment.

(Variations of Examples 1 to 4)
The present invention is not limited to the above-mentioned Examples 1 to 4, and various usage forms and modifications are possible. Examples of this usage pattern and modification include the following (1) to (3).

(1) The power conversion unit in the grid interconnection inverter devices 20, 20A to 20C may be changed to a configuration other than shown in the figure. For example, the DC / AC inverters 23 and 23C of FIGS. 2 and 6 may be composed of other switch elements such as a MOS type field effect transistor (MOSFET), a SiC transistor, and a GaN transistor other than the IGBT 23a. Further, the LC filter circuits 24 and 24C may be replaced with the LCL filter circuit.
(2) The CT26 and 26C may be replaced with other current measuring instruments such as a shunt resistor (shunt). Further, the VT27 and 27C may be replaced with other current measuring instruments such as a resistance voltage dividing circuit.
(3) The control circuits 30, 30A to 30C may be changed to configurations other than those shown in the figure.

1 DC power supply 2 Three-phase power system 2C Single-phase power system 3,3C Breaker 4,4C Transformer 5,5C Load device 20,20A, 20B Three-phase system interconnection inverter device 20C Single-phase system interconnection inverter device 21,21C DC / DC converter 23,23C DC / AC inverter 24,24C Filter circuit 25,25C Switch 26,26C CT
27,27C VT
30, 30A to 30C Control circuit 31 Three-phase / two-phase voltage conversion unit 32,36 Rotational coordinate conversion unit 33,53,72 PLL control unit 34,63,76 Gain adjustment unit 35 Three-phase / two-phase current conversion unit 40, 40B, 40C Switching drive signal generation unit 51 Voltage measurement circuit 52 Amplitude / phase angle calculation unit 54, 62,75 Subtraction unit 55,74 Multiplying unit 61 d-axis voltage adjustment unit 71 Fundamental wave voltage amplitude calculation unit 73 sin calculation unit

Claims (14)

An inverter that is connectable to the power system and switches the input power to convert it to the specified power.
The control circuit that controls the switching and
A filter circuit that removes harmonic components of the predetermined power and outputs it to the power system side.
Equipped with
The control circuit is
Rotational coordinate conversion is performed on the measured value of the system voltage between the filter circuit and the power system to calculate the q-axis voltage, and the switching is controlled by feeding back to the q-axis current control command of the q-axis current control. It is configured to
A grid-connected inverter device characterized by this. The inverter is a three-phase inverter, the power system is a three-phase power system, and the filter circuit is a three-phase filter circuit.
The control circuit is
A three-phase / two-phase voltage converter that performs three-phase / two-phase voltage conversion to the measured value of the system voltage,
A rotating coordinate conversion unit that converts the voltage conversion result of the three-phase / two-phase voltage conversion unit into a rotating coordinate system to calculate the q-axis voltage, and a rotating coordinate conversion unit.
A switching drive signal generation unit that generates a switching drive signal that controls the switching by subtracting the corresponding value of the q-axis voltage from the q-axis current control command of the q-axis current control.
1. The grid interconnection inverter device according to claim 1. An inverter that is connectable to the power system and switches the input power to convert it to the specified power.
The control circuit that controls the switching and
A filter circuit that removes harmonic components of the predetermined power and outputs it to the power system side.
Equipped with
The control circuit is
The configuration is such that the instantaneous phase angle is detected from the measured value of the system voltage between the filter circuit and the power system and fed back to the q-axis current control to control the switching.
A grid-connected inverter device characterized by this. The control circuit is
An amplitude / phase angle calculation unit that calculates the d-axis voltage and the instantaneous phase angle by performing amplitude / phase angle calculation on the measured value of the system voltage.
The phase synchronization control unit that obtains the phase angle by performing the phase synchronization of the instantaneous phase angle,
A q-axis voltage calculation unit that subtracts the phase angle from the instantaneous phase angle and multiplies the subtraction result by the d-axis voltage to obtain the q-axis voltage value.
A switching drive signal generation unit that generates a switching drive signal that controls the switching by subtracting the q-axis voltage value from the q-axis current control command of the q-axis current control.
3. The grid interconnection inverter device according to claim 3. An inverter that is connectable to the power system and switches the input power to convert it to the specified power.
The control circuit that controls the switching and
A filter circuit that removes harmonic components of the predetermined power and outputs it to the power system side.
Equipped with
The control circuit is
Rotational coordinate conversion is performed on the measured value of the system voltage between the filter circuit and the power system to calculate the d-axis voltage and the q-axis voltage, and the q-axis voltage is fed back to the q-axis current control. The difference between the d-axis voltage and the d-axis voltage adjustment value is fed back to the d-axis current control to control the switching.
A grid-connected inverter device characterized by this. The inverter is a three-phase inverter, the power system is a three-phase power system, and the filter circuit is a three-phase filter circuit.
The control circuit is
A three-phase / two-phase voltage converter that performs three-phase / two-phase voltage conversion to the measured value of the system voltage,
A rotating coordinate conversion unit that converts the voltage conversion result of the three-phase / two-phase voltage conversion unit into a rotating coordinate system to calculate the d-axis voltage and the q-axis voltage.
The first calculation unit that subtracts the corresponding value of the q-axis voltage from the q-axis current control command of the q-axis current control,
The difference between the d-axis voltage and the d-axis voltage harmonic component removal value or the d-axis voltage AC cycle average value, which is the d-axis voltage adjustment value, is obtained, and the value corresponding to this difference is controlled by the d-axis current control. The second calculation unit to be subtracted from the d-axis current control command of
A switching drive signal generation unit that generates a switching drive signal that controls the switching based on the subtraction result of the first calculation unit and the subtraction result of the second calculation unit.
5. The grid interconnection inverter device according to claim 5. An inverter that is interconnected to a single-phase power system and switches single-phase input power to convert it to predetermined power.
The control circuit that controls the switching and
A filter circuit that removes harmonic components of the predetermined power and outputs it to the single-phase power system side.
Equipped with
The control circuit is
The system voltage measurement value between the filter circuit and the single-phase power system,
The fundamental wave voltage calculated based on the voltage amplitude obtained from the system voltage measurement value of the previous AC cycle and the phase angle of the phase synchronization, and
The difference is fed back to the current control to control the switching.
A grid-connected inverter device characterized by this. The control circuit is
A voltage amplitude calculation unit that calculates the voltage amplitude from the system voltage measurement value,
A phase synchronization control unit that obtains the phase angle of the phase synchronization from the system voltage measurement value, and
A fundamental wave voltage calculation unit that calculates the fundamental wave voltage from the voltage amplitude and the phase angle of the phase synchronization,
A calculation unit that subtracts the fundamental wave voltage from the system voltage measurement value to obtain a corresponding value corresponding to the subtraction result.
A switching drive signal generation unit that subtracts the corresponding value from the current control command of the current control and generates a switching drive signal that controls the switching based on the subtraction result.
7. The grid interconnection inverter device according to claim 7. The grid interconnection inverter device according to any one of claims 1 to 8, wherein the inverter is a DC / AC inverter that converts DC power into AC power. The grid interconnection inverter device according to any one of claims 1 to 8, wherein the filter circuit is an LC filter circuit or an LCL filter circuit. An inverter that is connectable to the power system and switches the input power to convert it to the specified power.
A filter circuit that removes harmonic components of the predetermined power and outputs it to the power system side.
It is a stabilization control method of the grid interconnection inverter device equipped with
Rotational coordinate conversion is performed on the measured value of the system voltage between the filter circuit and the power system to calculate the q-axis voltage, which is fed back to the q-axis current control command of the q-axis current control to control the switching. do,
A stabilization control method characterized by this. An inverter that is connectable to the power system and switches the input power to convert it to the specified power.
A filter circuit that removes harmonic components of the predetermined power and outputs it to the power system side.
It is a stabilization control method of the grid interconnection inverter device equipped with
The instantaneous phase angle is detected from the measured value of the system voltage between the filter circuit and the power system, and fed back to the q-axis current control to control the switching.
A stabilization control method characterized by this. An inverter that is connectable to the power system and switches the input power to convert it to the specified power.
A filter circuit that removes harmonic components of the predetermined power and outputs it to the power system side.
It is a stabilization control method of the grid interconnection inverter device equipped with
Rotational coordinate conversion is performed on the measured value of the system voltage between the filter circuit and the power system to calculate the d-axis voltage and the q-axis voltage, and the q-axis voltage is fed back to the q-axis current control. The difference between the d-axis voltage and the d-axis voltage adjustment value is fed back to the d-axis current control to control the switching.
A stabilization control method characterized by this. An inverter that is interconnected to a single-phase power system and switches single-phase input power to convert it to predetermined power.
A filter circuit that removes harmonic components of the predetermined power and outputs it to the single-phase power system side.
It is a stabilization control method of the grid interconnection inverter device equipped with
The system voltage measurement value between the filter circuit and the single-phase power system,
The fundamental wave voltage calculated based on the voltage amplitude obtained from the system voltage measurement value of the previous AC cycle and the phase angle of the phase synchronization, and
The difference between the two is fed back to the current control to control the switching.
A stabilization control method characterized by this.

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