JPH07177748A - Controller of system interconnection inverter - Google Patents

Abstract

PURPOSE:To obtain a controller capable of continuously supplying stable power to a load by an inverter alone even though interocnnection with an AC system is interrupted when an inverter is interconnected with the AC system and power is transferred to/from the AC system. CONSTITUTION:An controller for system interconnection inverter comprises an active/reactive current reference generator 101, a phase detector 103, an active/reactive current detector 104, a current control circuit 105, a gate control circuit 106, a frequency detector 107, active/reactive voltage detector 108, a voltage amplitude detection circuit 109, an adding circuit 110, a frequency standard generator 122, a frequency correction arithmetic circuit 131, a voltage amplitude correction and arithmetic circuit 132, a voltage amplitude reference generating circuit 133, a voltage control circuit 145, and a switch circuit 146. And an active current reference signal from 101 is added to a voltage amplitude correction signal from the voltage amplitude correction arithmetic circuit 132, the result is output to 105 as an active current correction reference signal, and the adding circuit 110 adds the reactive current reference signal to a frequency correction signal and output the result as a reactive current reference signal to 105.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter control device for connecting and receiving power to and from an alternating current system, and the present invention relates to an inverter device even when the connection to the alternating current system is interrupted. The present invention relates to a control device for a grid interconnection inverter, which is intended to continuously supply power to a load independently.

[0002]

2. Description of the Related Art A system for the purpose of supplying power from a DC power source such as a fuel cell or a secondary battery or a DC power source such as a rectifier to a load, or exchanging power between the DC power source and an AC system. An interconnecting inverter is used.

FIG. 9 is a diagram showing an example of a conventional system interconnection inverter control device of this type, which comprises a voltage type self-excited inverter 10 and an inverter control device 100. The voltage type self-excited inverter 10 is composed of an inverter main circuit 1, a DC capacitor 2 and a transformer 3 which will be described later, and the inverter main circuit 1 includes the controllable rectifying elements GU and G.
V, GW, GX, GY, GZ and rectifying elements DU, DV, D
It has W, DX, DY and DZ. Controllable rectifier element G
As U, GV, GW, GX, GY, GZ, GTO
(Gate turn-off thyristor), power transistor, IGBT (insulated gate bipolar transistor),
An element having self-extinguishing ability such as SI (static induction type) thyristor is used. The voltage type self-excited inverter 10 is connected to the three-phase AC system 6 via the interconnection breaker 5 and is also connected to the load 7.

The inverter control device 100 includes an active / reactive current reference generator 101, a phase detector 103, an active / reactive current detector 104, a current control circuit 105, a gate control circuit 106, or Hall CTs 201 and 202. It is composed of 203.

The inverter main circuit 1 can control the three-phase output voltage of the inverter main circuit 1 by changing the energization period of each controllable rectifying element GU, GV, GW, GX, GY, GZ. . The phase and amplitude of the three-phase output voltage of the inverter main circuit 1 are determined by the system voltage V of the AC system 6.
By adjusting according to the phases and amplitudes of R, VS, and VT, the current exchanged with the AC system 6 via the impedance of the transformer 3 is controlled.

By this current control, the inverter 10
The DC power of the DC voltage source 4 is converted into active power or the active power is converted into DC power, the active power is exchanged with the AC system 6 through the interconnection breaker 5, and the reactive power is supplied. Similarly, the inverter 10 also supplies active power and reactive power to the load 7.

The current control of the inverter 10 is performed by the inverter control device 100 as follows. Phase detector 10
3 detects the system voltage phases of the system voltages VR, VS, and VT of the three-phase AC system 6 as the phase signal θ on the side of the inverter 10 of the interconnection breaker 5.

The active / reactive current detector 104 is a Hall CT2.
The active current component and the reactive current component are detected from the inverter output AC currents iR, iS, and iT detected by 01, 202, and 203, respectively.
Detect as d.

In the current control circuit 105, the active current detection signal iq from the active / reactive current detector 104 and the reactive current detection signal id are the active current reference signal iqc and the reactive current reference signal idc from the active / reactive current reference generator 101. Inverter output voltage reference signals VRc, VSc, VT that determine the output voltages of the three phases of the inverter main circuit 1 so as to be equal to
Calculate c. This inverter output voltage reference signal VR
In the calculation of c, VSc, and VTc, the inverter output voltage phase is determined with respect to the phases of the system voltages VR, VS, and VT of the AC system 6, so the phase signal θ which is the system voltage phase detected by the phase detector 103. To use.

The gate control circuit 106 controls the inverter output voltage reference signals VRc, VSc, VTc and the gate control circuit 1.
The controllable rectifying elements GU, GV, G that constitute the inverter main circuit 1 are compared with the triangular wave carrier signal generated inside
It outputs a gate signal that determines the energization period of W, GX, GY, and GZ.

The details of the operation of the grid interconnection inverter and the control device thereof shown in FIG. 9 described above are described in the following documents, and therefore the description thereof is omitted here.

Reference: Shun-ichi Hirose et al “Applic
ation of a digital instantaneouscurrent control fo
r static induction thyristor converters in the uti
lity line ”, PCIM Proceeding, pp343-349, Dec.8,1988
An example is disclosed in Japan.

Further, regarding the operation of the gate control circuit 106, reference is made to: "Semiconductor Power Conversion Circuit", pages 108 to 112, edited by the Institute of Electrical Engineers of Japan, Research Committee for Semiconductor Power Conversion Systems, pages 108 to 112, The Institute of Electrical Engineers, March 31, 1987. Is disclosed as PWM control.

[0014]

The conventional control device for the grid interconnection inverter shown in FIG. 9 has the following problems.
That is, when a failure or the like occurs in the AC system 6 and the interconnection breaker 5 opens, the inverter 10 cannot transfer electric power to and from the AC system 6 and cannot detect the phase of the AC voltage of the AC system 6. Inverter output AC current iR,
The active current detection signal iq and the reactive current detection signal id detected from iS and iT cannot be output according to the active current reference signal iqc and the reactive current reference signal idc from the active and reactive current reference generator 101. As a result, the output voltage and frequency of the inverter 10 increase or decrease and the electric power cannot be properly supplied to the load 7. Therefore, the operation of the inverter 10 must be stopped.

Conventionally, in order to solve such a problem, an effective / ineffective voltage detector 108 and an effective / ineffective voltage reference generator 14 are provided.
1, a voltage control circuit 145 and a switch circuit 146 are provided. The switch circuit 146 can input signals from a voltage control circuit 145 and a current control circuit 105 described later, and is an open signal of the interconnection breaker 5 (obtained when the inverter shifts from the grid interconnection state to the islanding state). ) Is input, the input is switched from the current control circuit 105 side to the voltage control circuit 145 side.

The active / reactive voltage reference generator 141 generates an active voltage reference signal iqc and a reactive voltage reference signal idc. The valid / reactive voltage detector 108 detects a valid voltage component and a reactive voltage component from the output AC voltages VR, VS, VT of the inverter 10 as a valid voltage detection signal vq and a reactive voltage detection signal vd, respectively.

In the voltage control circuit 145, the effective voltage detection signal vq from the effective / ineffective voltage detector 108 and the ineffective voltage detection signal vd are the effective voltage reference signal vqc and the ineffective voltage reference signal vdc from the effective / ineffective voltage reference generator 141. Inverter output voltage reference signal VR that determines the output voltage of the three phases of the main circuit 1 of the inverter 10
Calculate V, VSV, and VTV.

In such a configuration, when the inverter 10 shifts from the system interconnection state to the islanding operation state,
The switch circuit 146 receives the open signal of the interconnection breaker 5. Then, the input of the switch circuit 146 is switched from the current control circuit 105 side to the voltage control circuit 145, and the phase signal θ output from the phase detector 103 is fixed. As a result, it is possible to stably shift from the interconnected state to the isolated operation state.

However, in the operation of the grid interconnection inverter and its controller as shown in FIG. 9, the inverter 10 receives the open signal of the grid breaker when the grid breaker 5 is opened, and the voltage control is changed from the current control to the voltage control. There is an assumption that the transition to will be carried out immediately. This may cause a problem. That is, when the reception of the open signal of the interconnection breaker 5 is delayed from the actual opening time of the interconnection breaker 5, the inverter 10 continues the current control. Therefore, since the output voltage of the inverter 10 is determined depending on the output current of the inverter 10 and the impedance of the load 7, an overvoltage or a low voltage with respect to the load is generated, and the operation must be stopped. This is the case.

The present invention has been made to solve the problems of the conventional example. When the inverter is connected to the AC system to transfer power to and from the AC system, the connection to the AC system is interrupted. Even in such a case, it is an object of the present invention to provide a control device for a grid interconnection inverter that can continuously supply stable power to a load by an inverter alone.

[0021]

In order to achieve the above object, the invention corresponding to claim 1 supplies an alternating voltage from an alternating current system to a load via a system interconnection breaker, and connects to the alternating current system. An active current reference signal and a reactive current reference signal are generated in a grid interconnection inverter that is connected and converts direct current power from a direct current power source to alternating current power to transfer active power or reactive power to the load and the alternating current system. Active / reactive current reference generating means, active / reactive voltage reference generating means for generating an active voltage reference signal and a reactive voltage reference signal, and an active current component and a reactive current component of the output current of the inverter, respectively. And the effective and reactive current detecting means for outputting the effective voltage component and the reactive voltage component of the output voltage of the inverter, respectively. As the active and reactive voltage detecting means, the phase detecting means for detecting the phase of the AC voltage and outputting it as a phase signal, and controlling the active current signal to be equal to the active current reference signal together with the reactive current signal. A current control unit that outputs the output voltage reference signal of the inverter by controlling the reactive voltage reference signal to be equal to the reactive current reference signal, and controls the active voltage signal to be equal to the active voltage reference signal. A voltage control means for controlling the output voltage reference signal of the inverter so as to be equal to the reactive voltage reference signal; and a switchable output from the current control means or the voltage control means. Switching means for switching from the current control means to the voltage control means when the interconnection breaker is opened; and the current control hand. Alternatively, gate control means for determining an energization period of an element forming the inverter based on the output voltage reference signal of the inverter from the voltage control means and the phase signal, and detecting the frequency of the AC voltage and outputting it as a frequency signal. Frequency detecting means, voltage amplitude detecting means for detecting the amplitude of the AC voltage and outputting it as a voltage amplitude signal, frequency reference generating means for outputting a frequency reference signal, and voltage amplitude reference generating means for outputting a voltage amplitude reference signal. A frequency correction calculation means for outputting a frequency correction signal based on a deviation between the frequency reference signal and the frequency signal; and a voltage amplitude correction for outputting a voltage amplitude correction signal based on a deviation between the voltage amplitude reference signal and the voltage amplitude signal. The calculation means adds the active current reference signal and the voltage amplitude correction signal to obtain an active current correction reference signal, A controller for a grid interconnection inverter, comprising: an addition unit that outputs the current to the current control unit and that adds the reactive current reference signal and the frequency correction signal to the current control unit as a reactive current correction reference signal. Is.

According to a second aspect of the invention for achieving the above object, an AC voltage is supplied from an AC system to a load through a system interconnection breaker, and the load is connected to the AC system and a DC power source is used. In the system interconnection inverter for converting the DC power of the above into AC power and transferring active power or reactive power to the load and the AC system, an active / reactive current reference generating means for generating an active current reference signal and a reactive current reference signal An effective / reactive voltage reference generating means for generating an effective voltage reference signal and a reactive voltage reference signal, and an active / reactive current for outputting an active current component and a reactive current component of the output current of the inverter as an active current signal and a reactive current signal, respectively Detecting means and outputs an effective voltage component and a reactive voltage component of the output voltage of the inverter as an effective voltage signal and a reactive voltage signal, respectively. Effective / reactive voltage detection means, phase detection means for detecting the phase of the AC voltage and outputting it as a phase signal, and controlling the active current signal to be equal to the active current reference signal, and the reactive current signal to the reactive current. Current control means for controlling the output voltage reference signal of the inverter to be controlled to be equal to a reference signal, and controlling the effective voltage signal to be equal to the effective voltage reference signal, and the reactive voltage signal to be the reactive voltage reference. A voltage control means for outputting an output voltage reference signal of the inverter by controlling so as to be equal to a signal, and the output from the current control means and the voltage control means are switchable, and the system interconnection cutoff Switching means for switching from the current control means to the voltage control means when the container is opened, and the current control means or the voltage Gate control means for determining the energization period of the element forming the inverter based on the output voltage reference signal of the inverter and the phase signal from the control means, and frequency detection for detecting the frequency of the AC voltage and outputting it as a frequency signal. Means, voltage amplitude detection means for detecting the amplitude of the AC voltage and outputting it as a voltage amplitude signal, frequency reference generation means for outputting a frequency reference signal, voltage amplitude reference generation means for outputting a voltage amplitude reference signal, and A frequency correction calculation means with a dead band, which has a dead band for outputting the deviation component only when the deviation between the frequency reference signal and the frequency signal exceeds a certain level, and which outputs a frequency correction signal from the deviation component; , A dead band that outputs the deviation only when the deviation between the voltage amplitude reference signal and the voltage amplitude signal exceeds a certain level. Further, a voltage amplitude correction calculation means with dead band for outputting a voltage amplitude correction signal from the deviation, and the current control means as an active current correction reference signal by adding the active current reference signal and the voltage amplitude correction signal to the current control means. While outputting
A control device for a grid interconnection inverter, comprising: an addition unit that adds the reactive current reference signal and the frequency correction signal and outputs the result as a reactive current correction reference signal to the current control unit.

[0023]

According to the invention corresponding to claim 1, when the inverter shifts from the interconnected operation to the isolated operation, the active current reference signal of the current reference signal is divided by the deviation amount between the AC system voltage rated amplitude and the AC voltage amplitude. The inverter is controlled so that the output voltage becomes equal to the rated amplitude and rated frequency of the AC system voltage by correcting the reactive current reference signal by the deviation between the AC system voltage rated frequency and the AC voltage frequency. .
It is possible to suppress disturbance of the output voltage and frequency of the inverter until receiving the open signal of the interconnection breaker, switch to constant voltage operation after receiving the open signal, and supply stable power to the load.

According to the second aspect of the invention, since the frequency correction calculation means and the voltage amplitude correction calculation means are provided with dead zones respectively, unnecessary control operations due to voltage fluctuations and frequency fluctuations occurring in an unstable system are performed. Can be suppressed. The inverter operates due to output overvoltage, low voltage, etc. even when the inverter is supplying power to the load independently when the inverter is not receiving the disconnection breaker open signal. It never stops.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention. The difference from the conventional example of FIG. 9 is that the frequency detector 107 that constitutes the frequency detection means, the voltage amplitude detection circuit 109 that constitutes the voltage detection means, the addition circuit 110 that constitutes the addition means, and the frequency that constitutes the frequency reference generation means. A reference generator 122, a frequency correction arithmetic circuit 131 constituting a frequency correction arithmetic means, a voltage amplitude correction arithmetic circuit 132 constituting a voltage amplitude correction arithmetic means, and a voltage amplitude reference generation circuit 133 constituting a voltage amplitude reference generation means are added. The other points are the same as those in FIG. 9.

The frequency detector 107 detects the frequency of the AC voltage on the inverter 10 side of the interconnection breaker 5 and outputs a frequency signal F. The voltage amplitude detection circuit 109 detects the amplitude of the AC voltage on the inverter 10 side of the interconnection breaker 5 and outputs a voltage amplitude signal V.

The frequency reference generator 122 outputs a frequency reference signal Fc corresponding to the rated frequency of the voltage of the AC system 6. The voltage amplitude reference generation circuit 133 outputs a voltage amplitude reference signal Vc corresponding to the rated amplitude of the voltage of the AC system 6.

As shown in FIG. 2, the frequency correction calculation circuit 131 has a frequency reference signal F from the frequency reference generator 122.
c and the frequency signal F from the frequency detector 107 are input, and after the difference is added by the adder 1311, the proportional-plus-integral arithmetic circuit 131
The frequency correction signal EF is output via 2.

The voltage amplitude correction calculation circuit 132, as shown in FIG. 3, has a voltage amplitude reference signal Vc from the voltage amplitude reference generation circuit 133 and a voltage amplitude signal V from the voltage amplitude detection circuit 109.
Is input and the difference is calculated by the adder 1321, and then the voltage amplitude correction signal EV is output via the proportional-plus-integral calculation circuit 1322.

The adder circuit 110 has an adder 111 and an adder 112, and the adder 111 outputs the active current reference signal iqc output from the active / reactive current reference generator 101 from the voltage amplitude correction arithmetic circuit 132. The voltage amplitude correction signal EV is subtracted to output the active current correction reference signal iqm to the current control circuit 105, and the adder 112 outputs the reactive current reference signal id output from the active / reactive current reference generator 101.
The frequency correction signal EF output from the frequency correction arithmetic circuit 131 is subtracted from c and the reactive current correction reference signal idm is output to the current control circuit 105.

The current control circuit 105 inputs the reactive current correction reference signal idm output from the adder circuit 110 in place of the reactive current reference signal idc in FIG. 9, and replaces the active current reference signal iqc in FIG. 9 with the adder circuit. The active current correction reference signal iqm output from 110 is input, and the active current detection signal iq and the reactive current detection signal id from the active and reactive current detector 104 become the active current correction reference signal iqc and the reactive current correction reference signal idc. Inverter output voltage reference signals VRc, VSc, VTc that determine the output voltages of the three phases of the inverter main circuit 1 are calculated so as to be equal.

FIG. 2 shows a concrete circuit example of the frequency correction arithmetic circuit 131, which comprises an adder 1311 and a proportional integral arithmetic circuit 1312.
Reference numeral 12 is composed of an operational amplifier A, resistors R1, R2 and R3, and a capacitor C.

FIG. 3 shows the voltage amplitude correction arithmetic circuit 132 of FIG.
Shows a concrete circuit example of the adder 1321.
And a proportional-plus-integral arithmetic circuit 1322. The proportional-plus-integral arithmetic circuit 1322 includes an operational amplifier A and resistors R1, R2.
It is composed of R3 and a capacitor C.

The operation of the control device thus constructed will be described below. The frequency detector 107 detects the frequency of the AC voltage of the AC system 6 and outputs the frequency signal F when the interconnection breaker 5 is closed and the inverter 10 is connected to the AC system 6. The voltage amplitude detection circuit 109 detects the amplitude of the AC voltage of the AC system 6 as the voltage amplitude signal V. The frequency signal F and the frequency reference signal Fc from the frequency reference generator 122 are equal, and the voltage amplitude signal V and the voltage amplitude reference signal Vc from the voltage amplitude reference generation circuit 133 are equal.

As a result, the frequency correction signal EF output from the frequency correction calculation circuit 131 and the voltage amplitude correction signal EV output from the voltage amplitude correction calculation circuit 132 become zero,
Active current correction reference signal iqm and reactive current correction reference signal i
Since dm is equal to the active current reference signal iqc and the reactive current reference signal idc, respectively, the inverter 10 outputs the active current and the reactive current according to the active current reference signal iqc and the reactive current reference signal idc from the active and reactive current reference generator 101. Supply to AC system and load.

When the interconnecting circuit breaker 5 is opened but the open signal of the interconnecting circuit breaker 5 is not received by the inverter 10, when the inverter 10 is independently supplying power to the load 7, the frequency detector Frequency signal F detected at 107
Is different from the frequency of the AC voltage of the AC system 6, and the voltage amplitude signal V detected by the voltage amplitude detection circuit 109 is also different from the amplitude of the AC voltage of the AC system 6, so that the frequency signal F and the frequency reference signal Fc are Causes deviation. Further, a deviation also occurs between the voltage amplitude signal V and the voltage amplitude reference signal Vc. As a result, correction values are output to the frequency correction signal EF of the frequency correction calculation circuit 131 and the voltage amplitude correction signal EV of the voltage amplitude correction calculation circuit 132.

The adder circuit 110 corrects the reactive current reference signal idc and the active current reference signal iqc by the frequency correction signal EF and the voltage amplitude correction signal EV, respectively, and controls the reactive current correction reference signal idm and the active current correction reference signal iqm by current control. Circuit 1
Output to 05.

The inverter 10 supplies the active current and the reactive current to the load in accordance with the active current reference signal iqm and the reactive current reference signal idm from the adder circuit 110, thereby determining the frequency and the amplitude of the inverter output voltage to the frequency reference signal Fc.
And the voltage amplitude reference signal Vc can be controlled in the vicinity.

Further, after receiving the open signal of the interconnection breaker 5, the phase signal θ output from the phase detector 103 is fixed to the rated frequency, and the output of the current control circuit 105 is output to the gate control circuit 106 by the switch circuit 146. From the current state, the output of the voltage control circuit 145 is changed so as to be output to the gate control circuit 106, and the inverter 10 is shifted to the constant voltage / constant frequency operation.

According to the first embodiment described above, when the grid interconnection inverter receives the open signal of the grid breaker 5 and shifts to the independent operation, the transmission of the open signal of the grid breaker 5 is delayed. Even if there is, the operation can be changed from the interconnection state to the independent state without stopping the operation of the inverter 10 and appropriate electric power can be supplied to the load 7. Therefore, the reliability of the power generation system using the grid interconnection inverter can be improved. , Its application range can be expanded.

The detailed operation will be described below with reference to FIGS. 4 and 5. FIG. 4 is a diagram showing FIG. 1 in a single line connection diagram, and is a diagram for explaining the movement of various amounts of the main circuit when the inverter is switched from the interconnected operation to the isolated operation.
FIG. 5 is a vector diagram for explaining a change in load voltage at the time when the inverter switches from the interconnected operation to the isolated operation.

In FIG. 4, the inverter output current output from the inverter 10 is Ic and the load current flowing through the load 7 is Ic.
s, the system current flowing in the AC system 6 through the interconnection breaker 5 is Ig, the load voltage generated by the load 7 is Vs, the system voltage of the AC system 6 is Vg, and the load impedance is Z. Shows.

To simplify the explanation, the AC system 6 is an infinite bus. The inverter 10 has an inverter output current I equal to the current reference signal of the inverter control device 100.
c is output.

First, the interconnection breaker 5 is closed and the inverter 1
Consider the case where 0 is in interconnection operation. The AC system 6 has a system voltage V regardless of the current exchanged with the inverter.
g maintains the rated voltage amplitude and rated frequency. The inverter 10 and the load 7 are connected to the AC system 6 via the interconnection breaker 5.
Therefore, the load voltage Vs has the same rated voltage amplitude and rated frequency as the system voltage Vg.

The equation (1) holds for the load voltage Vs and the system voltage Vg. Vs = Vg (1) Further, with respect to the inverter output current Ic, the load current Is, and the system current Ig, the equation (2) is established.

Ic = Is + Ig (2) Further, the equation (3) holds for the load voltage Vs and the load current Is. Vs = Z · Is (3) Next, when the interconnecting circuit breaker 5 is opened and the inverter 10 is in the independent operation, the AC system is operated during the interconnecting operation unless the current reference value is changed by the inverter control device 100. The current Ig flowing in 6 flows into the load 7. When the load voltage at this time is Vs1, the equation (4) is established.

Vs1 = Z · Ic = Z · (Is + Ig) = Vg + Z · Ig (4) That is, the voltage of Z · Ig is added to the rated voltage Vg of the AC system 6 in the load 7.

FIG. 5 is a diagram for explaining this state with a vector. In FIG. 5, a vector is drawn on the orthogonal dq coordinate system, and the system voltage Vg is taken on the q axis. Although the system voltage Vg and the load voltage Vs are equal on the q-axis during the interconnection operation, the current Ig flowing in the AC system 6 during the interconnection flows to the load 7 in the independent operation, so that the load voltage Vs is equal to the load voltage Vs. It changes to Vs1 according to the impedance Z. Next, the inverter 10 is Is according to the current reference value with respect to Vs1.
In order to flow c, the load voltage is further changed. This shows that when the inverter 10 switches from the interconnected operation to the isolated operation, the amplitude and frequency of the load voltage change unless the current reference value is changed by the inverter control device 100. In other words, the d-axis component changes the frequency and the q-axis component changes the amplitude among the voltage components that change due to the current Ig flowing in the AC system 6 and the load impedance Z during the interconnection.

From the above, the active current reference signal Iqc of the current reference signal Ic is corrected by the deviation between the AC system voltage rated amplitude and the AC voltage amplitude when the inverter 10 shifts from the interconnected operation to the isolated operation. By correcting the reactive current reference signal Idc by the deviation between the AC system voltage rated frequency and the AC voltage frequency, the inverter can control the output voltage to be equal to the AC system voltage rated amplitude and rated frequency. .

In the embodiment of FIG. 1, utilizing this action,
The disturbance of the output voltage and frequency of the inverter 10 until receiving the open signal of the interconnection breaker 5 is suppressed, and after receiving the open signal,
The operation is switched to constant voltage constant frequency operation and stable power is supplied to the load 7.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a block diagram showing its schematic configuration. Here, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. The difference from FIG. 1 is that
The frequency correction arithmetic circuit 131 of FIG. 1 is changed to a frequency correction arithmetic circuit 131A with a dead band, and the voltage amplitude correction arithmetic circuit 132 of FIG. 1 is changed to a voltage amplitude correction arithmetic circuit 132A with a dead zone to calculate arithmetic circuits 131A and 132A. The output of is input to the adder circuit 110.

FIG. 7 is a frequency correction arithmetic circuit 1 with dead band.
It is a figure which shows the specific example of a circuit of 31A, This is the adder 1
331, a dead band generation circuit 1333, and a proportional-plus-integral calculation circuit 1332. The proportional-plus-integral calculation circuit 1332 includes an operational amplifier A, resistors R11, R21, R31, and a capacitor C. The dead band generation circuit 1333 includes It is composed of Zener diodes ZD11 and ZD11 and a resistor R41. After inputting the frequency reference signal Fc from the frequency reference generator 122 and the frequency signal F from the frequency detector 107 and subtracting the difference with the adder 1331, the frequency is passed through the dead band generation circuit 1333 and the proportional-plus-integral calculation circuit 1332. The correction signal EF is output.

FIG. 8 is a diagram showing a concrete circuit example of the voltage amplitude correction operation circuit 132A with dead band, which comprises an adder 1341, a dead band generation circuit 1343, and a proportional-plus-integral operation circuit 1342. The arithmetic circuit 1342 includes an operational amplifier A, resistors R11, R21 and R31, and a capacitor C. The dead band generation circuit 1343 includes zener diodes ZD11 and ZD11 and a resistor R41.
It consists of The voltage amplitude reference signal Vc from the voltage amplitude reference generation circuit 133 and the voltage amplitude signal V from the voltage amplitude detection circuit 109 are input, and after the difference is added by the adder 1341, the dead band generation circuit 1343 and the proportional-plus-integral calculation circuit. The voltage amplitude correction signal EV is output via 1342.

By adding the dead zone in this way, the following operational effects can be obtained. The deviation between the frequency signal F and the frequency reference signal Fc and the deviation between the voltage amplitude signal V and the voltage amplitude reference signal Vc due to the fluctuation of the system condition are set within the dead band of the dead band generation circuits 1333 and 1343, so that the interconnection is achieved. Active current correction reference signal iqm during operation
Therefore, the generation of the reactive current correction reference signal idm can be suppressed. Therefore, this embodiment is suitable when applied to a system in which fluctuations in voltage and frequency are likely to occur.

When the inverter 10 is independently supplying power to the load 7 while the inverter 10 is not receiving the open signal of the interconnection breaker 5 while the interconnection breaker 5 is open, the frequency is The frequency signal F detected by the detector 107 is different from the frequency of the AC voltage of the AC system 6, and the voltage amplitude signal V detected by the voltage amplitude detector 109 is also the AC system 6.
Since the amplitude of the AC voltage is different from that of the AC voltage, the frequency signal F and the frequency reference signal Fc have a deviation exceeding the dead band, and the voltage amplitude signal V and the voltage amplitude reference signal Vc also have a deviation exceeding the dead band. .

As a result, the frequency correction signal EF output by the frequency correction arithmetic circuit with dead band 131A and the voltage amplitude correction signal EV output by the voltage amplitude correction arithmetic circuit with dead band 132A are not zero.

The adder circuit 110 corrects the reactive current reference signal idc and the active current reference signal iqc by the frequency correction signal EF and the voltage amplitude correction signal EV, respectively, and controls the reactive current correction reference signal idm and the active current correction reference signal iqm by current control. Circuit 1
Output to 05.

The inverter 10 supplies the active current and the reactive current to the load 7 in accordance with the active current reference signal iqm and the reactive current reference signal idm from the adder circuit 110, thereby determining the frequency and the amplitude of the inverter output voltage.
And the voltage amplitude reference signal Vc can be controlled in the vicinity.

According to this embodiment, the frequency and amplitude of the inverter output voltage are changed by the frequency reference signal F due to the influence of the dead zone.
Although c and the voltage amplitude reference signal Vc do not completely match, the problem is finally solved by receiving the open signal of the interconnection breaker 5.

While the interconnection breaker 5 is open, the interconnection breaker 5
Even when the inverter 10 is independently supplying power to the load 7 in a state in which the inverter 10 has not received the open signal, the inverter 10 does not stop due to output overvoltage, low voltage, or the like.

The present invention is not limited to the embodiments described above. For example, the adder circuit 110, the frequency correction calculation circuit 131, and the voltage amplitude correction calculation circuit 13 of the embodiment of FIG.
2 can be realized by an electronic circuit, or can be realized by software using a microcomputer or the like.

In this case, in the conventional example of FIG. 9, if the current control circuit 105 and the active / reactive current detector 104 are realized by the software of the microcomputer, the adding circuit 110 and the frequency correction arithmetic circuit of FIG. By adding the functions of 131 and the voltage amplitude correction calculation circuit 132 as software, there is an advantage that the present invention can be easily incorporated into a conventional control device.

Also in FIG. 6, similarly, the frequency correction arithmetic circuit 131A with dead band and the voltage amplitude correction arithmetic circuit 132A with dead band can be realized by software.

[0064]

According to the present invention, even when the interconnection with the AC system is interrupted while the inverter is interconnected with the AC system to transfer electric power to and from the AC system, the inverter alone acts as a load. It is possible to provide a control device for a grid interconnection inverter that can continuously supply stable power.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of a control device for a grid interconnection inverter according to the present invention.

FIG. 2 is a diagram showing a specific circuit example of the frequency correction arithmetic circuit of FIG.

FIG. 3 is a diagram showing a specific circuit example of the voltage amplitude correction arithmetic circuit of FIG.

FIG. 4 is a diagram for explaining the movement of various quantities of the main circuit when the inverter of FIG. 1 is switched from the interconnected operation to the isolated operation.

5 is a vector diagram for explaining a change in load voltage at the time when the inverter of FIG. 1 switches from interconnected operation to isolated operation.

FIG. 6 is a block diagram showing the configuration of a second embodiment of the control device for the grid interconnection inverter according to the present invention.

FIG. 7 is a diagram showing a specific circuit example of the frequency correction arithmetic circuit with dead band shown in FIG. 6;

8 is a diagram showing a specific circuit example of the voltage amplitude correction arithmetic circuit with dead band in FIG.

FIG. 9 is a block diagram showing a configuration of an example of a conventional grid interconnection inverter and its control device.

[Explanation of symbols]

1 ... Inverter main circuit, 2 ... DC capacitor, 3
... Transformer, 4 ... DC voltage source, 5 ... Interconnection breaker, 6 ... AC system, 7 ... Load,
100 ... Inverter control device, 101 ... Active / reactive current reference generator, 103 ... Phase detector, 1
04 ... Effective / Reactive current detector, 105 ... Current control circuit,
106 ... Gate control circuit, 107 ... Frequency detector,
108 ... Effective / ineffective voltage detector, 109 ... Voltage amplitude detection circuit, 110 ... Addition circuit, 111, 112 ... Adder, 122 ... Frequency reference generator, 131 ... Frequency correction arithmetic circuit, 132 ... Voltage amplitude correction arithmetic circuit, 131A …
Dead band frequency correction operation circuit, 132A ... Dead band voltage amplitude correction operation circuit, 141 ... Effective / ineffective voltage reference generator, 145 ... Voltage control circuit, 146 ... Switch circuit, 201, 202 and 203 ... Hole CT, G
U, GV, GW, GX, GY, GZ ... Controllable rectifying element,
DU, DV, DW, DX, DY, DZ ... Rectifying element, 13
11, 1321 ... Adder, 1312, 1322 ... Proportional-integral arithmetic circuit, 1331, 1341 ... Adder, 1333,
1343 ... Dead band generation circuit, 1332, 1342 ... Proportional integral calculation circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimito Oyama 2-30 Kanda Jimbocho, Chiyoda-ku, Tokyo Tokyo Electric Power Co., Inc. Research & Development Laboratory (72) Inventor Nobukazu Takashima 1st Toshiba Town, Fuchu City, Tokyo Stocks Shares Company Toshiba Fuchu Factory (72) Inventor Shunichi Hirose 1 Toshiba Town, Fuchu-shi, Tokyo Toshiba Corporation Fuchu Factory (72) Inventor Susumu Tanaka 1-1-1, Shibaura, Minato-ku, Tokyo Toshiba Head Office Office

Claims (2)

[Claims] 1. An AC voltage is supplied from an AC system to a load via a system interconnection breaker, and is connected to the AC system.
In a grid interconnection inverter that converts direct current power from a direct current power source to alternating current power to transfer active power or reactive power to the load and the alternating current system, an active and reactive current that generates an active current reference signal and a reactive current reference signal Reference generating means, active / reactive voltage reference generating means for generating an active voltage reference signal and a reactive voltage reference signal, and an active current component and a reactive current component of the output current of the inverter are output as an active current signal and a reactive current signal, respectively. Active / reactive current detection means, active / reactive voltage detection means for outputting an active voltage component and a reactive voltage component of the output voltage of the inverter as an active voltage signal and a reactive voltage signal, respectively, and detects the phase of the AC voltage as a phase signal. Phase detecting means for outputting, and a control for equalizing the active current signal with the active current reference signal. And controlling the reactive current signal to be equal to the reactive current reference signal to output an output voltage reference signal of the inverter, and controlling the active voltage signal to be equal to the active voltage reference signal. Along with, the voltage control means for controlling the reactive voltage signal to be equal to the reactive voltage reference signal and outputting the output voltage reference signal of the inverter, and switching to either the current control means or the output from the voltage control means. A switching means for switching from the current control means to the voltage control means when the grid interconnection breaker is opened; and an output voltage reference signal of the inverter from the current control means or the voltage control means. And a gate control means for determining an energization period of an element forming the inverter according to the phase signal, Frequency detection means for detecting the frequency of the voltage and outputting it as a frequency signal; voltage amplitude detection means for detecting the amplitude of the AC voltage and outputting it as a voltage amplitude signal; frequency reference generation means for outputting a frequency reference signal; and voltage amplitude A voltage amplitude reference generating means for outputting a reference signal, a frequency correction calculating means for outputting a frequency correction signal from the deviation between the frequency reference signal and the frequency signal, and a deviation between the voltage amplitude reference signal and the voltage amplitude signal A voltage amplitude correction calculation unit that outputs a voltage amplitude correction signal, and adds the active current reference signal and the voltage amplitude correction signal to output to the current control unit as an active current correction reference signal, and the reactive current reference signal Adding means for adding the frequency correction signal and outputting to the current control means as a reactive current correction reference signal; Control device for system interconnection inverter, characterized in that. 2. An AC voltage is supplied from an AC system to a load via a system interconnection breaker, and is connected to the AC system.
In a grid interconnection inverter that converts direct current power from a direct current power source to alternating current power to transfer active power or reactive power to the load and the alternating current system, an active and reactive current that generates an active current reference signal and a reactive current reference signal Reference generating means, active / reactive voltage reference generating means for generating an active voltage reference signal and a reactive voltage reference signal, and an active current component and a reactive current component of the output current of the inverter are output as an active current signal and a reactive current signal, respectively. Active / reactive current detection means, active / reactive voltage detection means for outputting an active voltage component and a reactive voltage component of the output voltage of the inverter as an active voltage signal and a reactive voltage signal, respectively, and detects the phase of the AC voltage as a phase signal. Phase detecting means for outputting, and a control for equalizing the active current signal with the active current reference signal. And controlling the reactive current signal to be equal to the reactive current reference signal to output an output voltage reference signal of the inverter, and controlling the active voltage signal to be equal to the active voltage reference signal. Along with, the voltage control means for controlling the reactive voltage signal to be equal to the reactive voltage reference signal and outputting the output voltage reference signal of the inverter, and switching to either the current control means or the output from the voltage control means. A switching means for switching from the current control means to the voltage control means when the grid interconnection breaker is opened; and an output voltage reference signal of the inverter from the current control means or the voltage control means. And a gate control means for determining an energization period of an element forming the inverter according to the phase signal, Frequency detection means for detecting the frequency of the voltage and outputting it as a frequency signal; voltage amplitude detection means for detecting the amplitude of the AC voltage and outputting it as a voltage amplitude signal; frequency reference generation means for outputting a frequency reference signal; and voltage amplitude A voltage amplitude reference generating means for outputting a reference signal, and a dead band for outputting a deviation component only when the deviation between the frequency reference signal and the frequency signal exceeds a certain level, and the frequency from the deviation component A frequency correction calculation means with a dead band that outputs a correction signal, and a dead band that outputs the deviation only when the deviation between the voltage amplitude reference signal and the voltage amplitude signal becomes a certain level or more, and, A voltage amplitude correction calculation means with a dead band that outputs a voltage amplitude correction signal from the deviation, and the active current reference signal and the voltage amplitude correction signal are added. Addition means for outputting to the current control means as an active current correction reference signal, and adding the reactive current reference signal and the frequency correction signal and outputting to the current control means as a reactive current correction reference signal. A control device for a grid interconnection inverter.