JP2009247162A - Single-phase voltage ac/dc converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a single-phase voltage AC/DC converter which enables self-regulative parallel operation in which a plurality of parallelly connected devices operating in parallel at a single-phase alternating current individually controls output deflection in a self-regulative manner, and surely detects standalone operation when a power system fails. <P>SOLUTION: A single-phase alternating current having a given phase difference from the phase of a single-phase AC output voltage from an AC terminal is generated, and PWM control over an inverter is carried out using the generated single-phase alternating current and the single-phase AC output voltage from the AC terminal. The single-phase alternating current having a given phase difference from the phase of the single-phase AC output voltage from the AC terminal is positively fed back. When a standalone operation occurs, the standalone operation is detected using the resulting automatic fluctuation of an output frequency, to prevent the operation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a single-phase voltage type AC / DC converter applicable to a grid interconnection device serving as a power source for a power system.

  In the synchronous generator which is the main power source of the current power system, each output deviation can be automatically corrected because each generator has a synchronizing power. For this reason, it can drive | operate autonomously, without performing cross current suppression control. Further, in an inverter (AC / DC converter) that performs power conversion using a semiconductor, a technique of autonomous parallel operation (APRun) is proposed for a three-phase machine (see, for example, Patent Document 1). The three-phase voltage type AC / DC converter of Patent Document 1 UM-converts the three-phase output voltage on the dq rotation coordinates, and each axis component is independent so that the amplitude and frequency of the power system approach the command value by the upper command vector. I try to control it. In addition, by synchronizing the generated value generated from the component related to the frequency difference of the three-phase output voltage with the rotation angle of the conversion matrix in the UM conversion circuit, the rotation angle of the three-phase output voltage is made to follow the frequency of the power system. Can do. Further, there is known a three-phase voltage type AC / DC converter that can reliably detect that the AC power system has been operated independently when a power failure occurs (see, for example, Patent Document 3). The three-phase voltage type AC / DC converter of Patent Document 3 performs system interconnection operation by adding control for positive feedback of the AC voltage of the three-phase voltage type AC / DC converter, and the AC power system is cut off and becomes a single operation. In this case, the frequency or / and amplitude of the output voltage is changed, and the change is detected to determine that the operation has been performed independently.

  On the other hand, in a single phase voltage type | mold AC / DC converter, the protection method of the grid connection inverter which can prevent a single operation and the reverse charge to an electric power grid | system is known (for example, refer patent document 4). Patent Document 4 describes “frequency shift method”, “bandpass filter method”, “power fluctuation method”, and “harmonic voltage monitoring method”. Here, FIG. 13 shows a schematic diagram showing a configuration of a conventional single-phase voltage type AC / DC converter 10. When the power system is cut off, the voltage detector 450, the frequency detector 416, the voltage effective value detector 417, the zero cross distortion detector 418, the frequency calculator 413, the voltage calculator 414, and the distortion change calculator 415 are connected to the inverter bridge 401. The output voltage frequency, frequency change rate, and distortion voltage near zero crossing are detected and calculated. Based on the calculation result, the coefficient setting circuit 412 and the gain phase adjuster 411 change the current phase, so that the frequency of the output voltage of the inverter bridge 401 changes to a predetermined value. The voltage relay 451, the frequency relay 452, the distortion relay 453, and the abnormality detector 454 detect this and stop the inverter bridge 401.

In the present specification, the voltage used for alternating current such as “output voltage”, “phase difference voltage”, and “internal electromotive voltage” means a function having time as a variable.
JP 2007-236083 A Japanese Patent Application No. 2008-039132 Japanese Patent Application No. 2007-005918 Japanese Patent Laid-Open No. 06-311653

  However, UM conversion as described in Patent Document 1 cannot be performed in single-phase alternating current, and autonomous parallel operation is difficult for a single-phase inverter. Also, the single-phase voltage type AC / DC converter described in Patent Document 2 cannot be applied with the grid-connected inverter protection method described in Patent Document 4. Therefore, in the present invention, even when a plurality of units are connected in parallel with single-phase alternating current and operated in parallel, autonomous parallel operation in which individual devices autonomously control output deviation is possible, and the power system has failed. It is an object of the present invention to provide a single-phase voltage type AC / DC converter that can reliably detect the case of single operation.

  In order to achieve the above object, the present invention generates a single-phase alternating current having a predetermined phase difference from the phase of the single-phase alternating-current output voltage of the alternating-current terminal, and the generated single-phase alternating current and the single-phase alternating-current output voltage of the alternating-current terminal. And the inverter is PWM controlled. That is, the single-phase AC output voltage of the AC terminal is the first axis corresponding to the α-axis component when the three-phase AC is M-converted. A single-phase alternating current having a predetermined phase difference is set as a second axis corresponding to a β-axis component when the three-phase alternating current is M-converted. The single-phase voltage type AC / DC converter of the present invention controls the first axis and the second axis independently, and uses the inherent electrical angle generated by the frequency control circuit to convert the single-phase AC output voltage to the frequency of the power system. I made it follow.

  Further, the present invention positively feeds back a single-phase alternating current having a predetermined phase difference from the phase of the single-phase alternating-current output voltage at the alternating current terminal, and the output frequency is automatically changed in the case of single operation. It was decided to detect and prevent isolated operation using.

  Specifically, the single-phase voltage type AC / DC converter according to the present invention has an internal equivalent impedance when viewed from the AC terminal, and outputs from the DC voltage source according to the pulse width of the gate signal generated based on the PWM command. A single-phase voltage type AC / DC converter circuit that converts electric power into single-phase AC power and outputs the same from the AC terminal, and a phase-delay unit that generates a delayed single-phase AC that is delayed in phase from the single-phase AC output voltage of the AC terminal. A phase AC generator, which generates a phase difference voltage corresponding to a phase difference between a single phase AC output voltage of the AC terminal and an internal electromotive voltage of the single phase voltage type AC / DC converter based on the delayed single phase AC A phase difference generation circuit, a voltage command value for the amplitude of the single-phase AC output voltage of the AC terminal and a high-order command vector consisting of a frequency command value for the frequency are input, the high-order command vector that is input, Based on the phase difference voltage from the phase difference generation circuit and the single-phase AC output voltage of the AC terminal, the voltage generated so that the amplitude and frequency of the single-phase AC output voltage of the AC terminal approach the command value by the upper command vector An upper voltage control circuit that outputs a command signal and a frequency command signal, a reference frequency that defines a frequency of a single-phase AC output voltage of the AC terminal, a frequency command signal from the upper voltage control circuit, and a phase difference generation circuit A frequency control circuit that determines an electrical angle of the internal electromotive voltage of the single-phase voltage type AC / DC converter circuit based on an output signal and generates a generated electrical angle; a single-phase AC output voltage of the AC terminal; and the frequency control circuit Based on the generated electrical angle and the voltage command signal from the upper voltage control circuit, the amplitude, frequency and phase of the single-phase AC output voltage are A lower voltage control circuit that outputs, as the PWM command, a reference voltage that defines the amplitude of the output voltage, a signal generated so as to approach the combined value of the voltage command signal and the generated electrical angle, and is input to the upper voltage control circuit. A positive feedback circuit that positively feeds back a phase difference voltage output from the phase difference generation circuit to a frequency command value of the higher order command vector, and a single-phase AC frequency output from the single-phase voltage type AC / DC converter circuit. A frequency fluctuation detector that detects that the frequency to be monitored has deviated from a preset range as a frequency fluctuation, and a gate signal stop function for stopping the gate signal in the single-phase voltage type AC / DC converter circuit, and / or the A switching function between the single-phase voltage type AC / DC converter circuit and the AC terminal has a shut-off function for cutting off the single-phase AC power from the single-phase voltage type AC / DC converter circuit. Inverter output stopping means for stopping output of single-phase AC power from the AC terminal when the frequency variation detector detects frequency variation.

  In the present invention, a single-phase voltage type AC / DC converter circuit having an internal equivalent impedance is used so that it can be operated by being connected to a power system even if it operates as a voltage source. The phase difference generation circuit generates a phase difference voltage corresponding to the voltage phase difference between both ends of the internal equivalent impedance, and the frequency control circuit generates the generated electric current generated from the reference frequency, the frequency command signal from the higher voltage control circuit, and the phase difference voltage. Synchronize the internal electromotive force to the corner. Thereby, a single phase alternating current output voltage can be made to track the frequency of an electric power system.

  In the upper voltage control circuit, the voltage command signal is generated so that the amplitude and frequency of the single-phase output voltage approach the command value by the upper command vector. Thereby, even if the amplitude and frequency of the power system change, it is possible to detect respective deviations of the amplitude and frequency of the single-phase output voltage of the single-phase voltage type AC / DC converter with respect to the amplitude and frequency. Therefore, it is possible to compensate for the deviation by controlling the amplitude and phase of the single-phase voltage type AC / DC converter so as to match the amplitude and phase of the power system in the lower voltage control circuit.

  As described above, the single-phase voltage type AC / DC converter according to the present invention can be operated by connecting to a power system as a voltage source, and autonomous parallel operation for autonomously compensating for a power deviation with respect to the power system is possible. It is. As a result, the reliability of the apparatus is increased and distributed arrangement is possible. Further, when a plurality of units are operated in parallel, the units can be operated without any limitation.

  Further, the phase difference voltage output from the phase difference generation circuit is positively fed back to the frequency command value of the upper command vector input to the upper voltage control circuit by the positive feedback circuit. Thereby, the frequency of the single-phase alternating current output from the single-phase voltage type | mold AC / DC converter circuit when it interrupts | blocks from an electric power grid | system and becomes a single operation changes. A frequency fluctuation detector detects this frequency fluctuation and stops the output of single-phase AC power from the AC terminal. Note that “single-phase alternating current frequency fluctuation” includes fluctuation of the single-phase alternating current waveform.

  Therefore, the present invention is capable of autonomous parallel operation in which individual devices autonomously control output deviation even when a plurality of units are connected in parallel with single-phase alternating current, and the power system has failed. In this case, it is possible to provide a single-phase voltage type AC / DC converter that can reliably detect that it has become a single operation.

  The single-phase voltage type AC / DC converter according to the present invention includes a switch that cuts off the positive feedback circuit and / or a gain adjuster that sets the gain of the positive feedback circuit to 0, and stops positive feedback performed by the positive feedback circuit. Feedback circuit stopping means is further provided. Whether or not to positively feed back the phase difference voltage to the frequency command value of the upper command vector can be switched by the positive feedback circuit stop means.

  The positive feedback circuit stop means of the single-phase voltage type AC / DC converter according to the present invention is the positive feedback performed by the positive feedback circuit after the inverter output stop means stops the output of single-phase AC power from the AC terminal. Is preferably stopped. The positive feedback circuit can be automatically stopped after detecting the single operation and cutting off the single-phase AC power from the AC terminal. It is possible to prevent the frequency from becoming unstable when the single-phase voltage type AC / DC converter is restarted.

  Each structure of the single phase voltage type | mold AC / DC converter which concerns on this invention is demonstrated more concretely. In the single-phase voltage type AC / DC converter, the upper voltage control circuit includes a first multiplier that multiplies the signal based on the generated electrical angle of the frequency control circuit and the upper command vector, and the first multiplier outputs A first subtracter for subtracting the AC output voltage of the AC terminal from the signal to be transmitted, and a signal from the first subtractor so that the single-phase AC output voltage of the AC terminal approaches the command value by the upper command vector. A first upper control amplifier that amplifies and outputs the voltage command signal; a second subtracter that subtracts a phase difference voltage from the phase difference generation circuit from the upper command vector; and a single-phase AC output voltage of the AC terminal. A second upper control amplifier that amplifies the signal from the second subtractor so as to approach the command value by the upper command vector and outputs the amplified signal as the frequency command signal. The voltage control circuit includes a reference voltage setter that sets and outputs the reference voltage, a second multiplier that multiplies a signal based on a generated electrical angle of the frequency control circuit and a reference voltage from the reference voltage setter, and A first adder for adding and outputting a voltage command signal from the higher voltage control circuit and a signal output from the second multiplier, and a single phase of the AC terminal from the signal output from the first adder. A third subtractor for subtracting the AC output voltage, and the third subtractor outputs so that the single-phase AC output voltage of the AC terminal approaches the combined value of the reference voltage, the voltage command signal, and the generated electrical angle. And a voltage controller that outputs a PWM command, and the frequency control circuit adds the frequency command signal from the higher voltage control circuit and the phase difference voltage from the phase difference generation circuit. Second adder A loop filter for adding a low-pass filtering element to the frequency component of the signal output from the second adder, a reference frequency setting unit for setting the reference frequency, and an output value of the loop filter for the reference frequency It is desirable to have a third adder for adding the output values of the setter and a time integrator for time-integrating a signal output from the third adder and outputting the resultant electrical angle.

  In the present invention, the subtracter of the upper voltage control circuit subtracts the phase difference voltage from the phase difference generation circuit and the upper command vector to output a frequency command signal. The frequency control circuit adds the frequency command signal and the phase difference voltage from the phase difference generation circuit, adds a low-pass filter element in the loop filter of the frequency control circuit, and outputs the result. In addition, the signal from the loop filter is added to the reference frequency output from the reference frequency setter, and the generated electric angle is generated by time integration with the time integrator, and the electric voltage of the internal electromotive voltage of the single-phase voltage type AC / DC converter circuit is generated. Synchronize the corners. Thereby, the rotation angle of the single-phase AC output voltage can be made to follow the frequency of the power system.

  On the other hand, the subtracter of the upper voltage control circuit subtracts the single-phase AC output voltage and the upper command vector to output a voltage command signal. As a result, even if the amplitude and frequency of the power system change, the respective error components of the amplitude and frequency of the single-phase output power of the single-phase voltage type AC / DC converter for the amplitude and frequency are detected, and the lower voltage control circuit The error can be compensated.

  Specifically, the voltage command signal from the higher voltage control circuit is added to the reference voltage from the reference voltage setter in the lower voltage control circuit. Furthermore, the single-phase AC voltage of the AC terminal is subtracted from the signal obtained by adding the reference voltage and the voltage command signal, and the difference between the amplitude and phase of the power system is converted into the combined value of the reference voltage and the voltage command vector by the voltage controller. It converts so that it may approach, and outputs it as a PWM command. An auxiliary signal described later may be added to the PWM command. Thereby, it is possible to control the amplitude and phase of the single-phase AC output voltage of the single-phase voltage type AC / DC converter so as to coincide with the amplitude and phase of the power system.

  As described above, the single-phase voltage type AC / DC converter according to the present invention can be operated by being connected to a power system as a voltage source, and can be operated autonomously in parallel with the power system or another AC power source. . As a result, the reliability of the apparatus is increased and distributed arrangement is possible. Further, when a plurality of units are operated in parallel, the units can be operated without any limitation. Accordingly, the present invention provides a single-phase voltage type AC / DC converter capable of autonomous parallel operation in which individual devices autonomously control output deviation even when a plurality of units are connected in parallel with single-phase AC. Can be provided.

  In the single-phase voltage type AC / DC converter according to the present invention, the single-phase voltage type AC / DC converter circuit has the internal equivalent impedance when viewed from the AC terminal, and from the DC voltage source according to the pulse width of the gate signal. A single-phase voltage type AC / DC converter that converts electric power into single-phase AC power and outputs it, and detects a single-phase AC output current of the single-phase voltage type AC / DC converter, and according to the magnitude of the single-phase AC output current A current detection circuit for outputting the generated signal, a gate signal generator for generating and outputting the gate signal so that a difference between the PWM command and the output from the current detection circuit approaches zero, and the single-phase voltage It is desirable to have a single-phase AC filter circuit that removes a high-frequency component caused by the gate signal in the single-phase voltage type AC / DC converter from the single-phase AC output voltage of the type AC / DC converter and outputs the result.

  In the present invention, since the single-phase AC filter circuit is provided, a high-frequency component caused by the gate signal in the single-phase voltage type AC / DC converter can be removed from the output from the single-phase voltage type AC / DC converter. In addition, the current detection circuit detects the current from the single-phase voltage type AC / DC converter, and the gate signal generator generates a gate signal so that the difference between the PWM command and the output from the current detection circuit approaches zero. Control can be performed so that the current error falls within an allowable range.

  In the single-phase voltage type AC / DC converter according to the present invention, the single-phase voltage type AC / DC converter circuit has the internal equivalent impedance when viewed from the AC terminal, and the DC voltage source according to the pulse width of the gate signal. A single-phase voltage type AC / DC converter that converts electric power from the output into single-phase AC power and outputs the single-phase AC output voltage of the single-phase voltage type AC / DC converter and detects the magnitude of the single-phase AC output voltage. A voltage detection circuit that outputs a signal generated in response to the signal, a gate signal generator that generates and outputs the gate signal so that a difference between the PWM command and the output from the voltage detection circuit approaches zero, and the unit It is desirable to have a single-phase AC filter circuit that removes a high-frequency component due to the gate signal in the single-phase voltage type AC / DC converter from the single-phase AC output voltage of the phase voltage type AC / DC converter.

  In the present invention, since the single-phase AC filter circuit is provided, a high-frequency component caused by the gate signal in the single-phase voltage type AC / DC converter can be removed from the output from the single-phase voltage type AC / DC converter. In addition, the voltage detection circuit detects the voltage from the single-phase voltage type AC / DC converter, and the gate signal generator generates a gate signal so that the difference between the PWM command and the output from the voltage detection circuit approaches zero. The output voltage can be made to follow the PWM command.

  Next, a single-phase voltage type AC / DC converter that adds an auxiliary signal to a PWM signal will be described. The single-phase voltage type AC / DC converter according to the present invention further includes an output current detection circuit that detects a single-phase AC output current of the AC terminal, and the lower-level voltage control circuit is included in the single-phase voltage type AC / DC converter circuit. A filter current compensator that outputs a current compensation value defined so as to compensate for a current loss in a single-phase AC filter circuit, and a current deviation of a single-phase AC output current from the single-phase voltage type AC / DC converter circuit A PWM current deviation compensator that outputs a current deviation compensation value defined as described above and a value of a single-phase AC output current detected by the output current detection circuit are input to compensate the current for the load at the AC terminal. A feedforward amplifier that amplifies and outputs with a predetermined feedforward gain, a current compensation value of the filter current compensator, and a current bias from the PWM current deviation compensator; A fourth adder for adding an output value from the compensation value and the feed-forward amplifier to the PWM command value from the voltage controller, it is desirable to have.

  In the present invention, the current deviation in the single-phase voltage type AC / DC converter circuit when the PWM command is set to zero command is set in advance in the PWM current deviation compensator, and the current deviation is added to the PWM command from the voltage controller. Minutes can be compensated. In addition, the current loss in the single-phase AC filter circuit of the single-phase voltage type AC / DC converter circuit is set in advance in the filter current compensator and added to the PWM command from the voltage controller to compensate for the current loss. it can. Furthermore, the value of the single-phase AC output current at the AC terminal is amplified by a feedforward amplifier and added to the PWM command from the voltage controller, so that a stable output voltage can be generated even if the output current changes. . That is, in the present invention, signals from the PWM current deviation compensator, the filter current compensator and the feedforward amplifier are added as auxiliary signals to the PWM command from the voltage controller.

  The single-phase voltage type AC / DC converter according to the present invention may further include a limiter that determines an upper limit and a lower limit of the upper command vector, and the upper command vector is input to the upper voltage control circuit via the limiter. desirable.

  An excessively high order command vector can be prevented from being input, and an abnormal single-phase AC output current can be prevented from being output to the power system.

  In the present invention, even when multiple units are connected in parallel with single-phase alternating current and operated in parallel, autonomous parallel operation in which individual devices autonomously control output deviation is possible, and when the power system fails. It is possible to provide a single-phase voltage type AC / DC converter that can reliably detect that it has become an independent operation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to embodiment shown below. In the present specification and drawings, the same reference numerals denote the same components.

  FIG. 9 is a diagram illustrating a connection relationship of control blocks in the single-phase voltage type AC / DC converter. As in the case of the three-phase voltage type AC / DC converter, a higher order command vector B1, an uppermost control block B2, an ac-AVR block B3, an ETM-PWM block B4, and a main switch B5 are included. For the ac-AVR block B3, by applying the single-phase ac-AVR mainly composed of the internal equivalent impedance described in Patent Document 2, there is a risk of demagnetization in the transformer connected to the output circuit of the inverter. Disappear. Furthermore, since the internal equivalent impedance can be a parallel circuit of a resistance component and an inductance component, the degree of freedom in design increases.

  FIGS. 1 to 3 show schematic configuration diagrams of the single-phase voltage type AC / DC converter according to the present embodiment, and each block shown in FIG. 9 will be described in more detail.

  The single-phase voltage type AC / DC converter 11 shown in FIG. 1 has an internal equivalent impedance when viewed from the AC terminal 22 and is supplied from a DC voltage source (not shown) according to the pulse width of the gate signal generated based on the PWM command. The phase is delayed with respect to the single-phase voltage type AC / DC conversion circuit 40 that receives the power at the DC terminal 21, converts it into single-phase AC power and outputs it from the AC terminal 22, and the single-phase AC output voltage at the AC terminal 22. A phase-delayed single-phase AC generator that generates a delayed single-phase AC, and based on the delayed single-phase AC, a single-phase AC output voltage of the AC terminal 22 and an internal electromotive voltage of the single-phase voltage type AC / DC converter circuit 40 A phase difference generation circuit 30 for generating a phase difference voltage corresponding to the phase difference, and a higher order command vector 120 comprising a voltage amplitude command value for the amplitude of the single-phase AC output voltage at the AC terminal 22 and a frequency command value for the frequency are input. Based on the input higher order command vector 120, the phase difference voltage from the phase difference generation circuit 30, and the single phase AC output voltage of the AC terminal 22, the amplitude and frequency of the single phase AC output voltage of the AC terminal 22 An upper voltage control circuit 70 that outputs a voltage command signal and a frequency command signal generated so as to approach the command value by the vector 120, a reference frequency that defines the frequency of the single-phase AC output voltage of the AC terminal 22, and the upper voltage control circuit 70 Frequency control for generating a generated electrical angle based on the frequency command signal from the phase difference voltage and the phase difference voltage from the phase difference generation circuit 30 and synchronizing the electrical angle of the internal electromotive voltage of the single-phase voltage type AC / DC conversion circuit 40 to the generated electrical angle. Based on the circuit 50, the single-phase AC output voltage of the AC terminal 22, the generated value from the frequency control circuit 50, and the voltage command signal from the upper voltage control circuit 70 The PWM command generates a signal generated so that the amplitude, frequency, and phase of the single-phase output voltage approach the reference voltage that defines the amplitude of the single-phase AC output voltage of the AC terminal 22, the voltage command signal, and the generated value. And a lower voltage control circuit 60 that outputs as follows. Furthermore, the single-phase voltage type AC / DC converter 11 has a positive feedback circuit 200 that positively feeds back the phase difference voltage output from the phase difference generation circuit 30 to the frequency command value of the upper command vector 120 input to the higher voltage control circuit 70. A frequency fluctuation detector 220 that monitors the frequency of the single-phase AC output from the single-phase voltage type AC / DC converter circuit 40 and detects that the monitored frequency deviates from a preset range as a frequency fluctuation, and an inverter output And a switch 230 that cuts off the single-phase AC power from the single-phase voltage type AC / DC converter circuit 40 between the single-phase voltage type AC / DC converter circuit 40 and the AC terminal 22 as a stopping means. Further, the frequency fluctuation detector 220 and the gate signal generator 41 may be connected as inverter output stopping means. When the frequency fluctuation detector 220 detects the frequency fluctuation, the gate signal can be stopped in the single-phase voltage type AC / DC converter circuit 40, and the output of the single-phase AC power from the AC terminal 22 can be stopped.

  The upper command vector 120 corresponds to the upper command vector B1 in FIG. The upper voltage control circuit 70 corresponds to the uppermost control block B2 in FIG. The lower voltage control circuit 60 and the frequency control circuit 50 correspond to the ac-AVR block B3 in FIG. The gate signal generator 41 corresponds to the ETM-PWM block B4 in FIG. The single-phase voltage type AC / DC converter included in the single-phase voltage type AC / DC converter circuit 40 corresponds to the main switch B5 of FIG.

  The single-phase voltage type AC / DC converter circuit 40 converts power from a DC voltage source (not shown) into single-phase AC power according to the pulse width of the gate signal generated by the gate signal generator 41 based on the PWM command. A DC voltage source is a voltage source that outputs a DC voltage by itself, such as a battery, a voltage source that generates and rectifies by a power generation method such as wind power generation, or outputs a DC voltage, or controls a DC capacitor voltage to generate a DC voltage. A voltage source to be output can be exemplified. In this case, a blocking inductor may be further provided between the connection point of the output voltage detection circuit 31 and the AC terminal 22, and each single-phase AC output voltage may be output from the AC terminal 22 via the blocking inductor. The outflow of the PWM component to the AC terminal 22 in the single-phase voltage type AC / DC converting circuit 40 can be prevented.

  5 and 6 show schematic configuration diagrams of the single-phase voltage type AC / DC converter circuit.

  The single-phase voltage type AC / DC converting circuit 40-1 shown in FIG. 5 has an internal equivalent impedance when viewed from the AC terminal 22 and receives power from the DC voltage source at the DC terminal 21 according to the pulse width of the gate signal. A single-phase voltage type AC / DC converter 42 that converts to AC power and outputs the signal, and a single-phase AC output current of the single-phase voltage type AC / DC converter 42 is detected and a signal generated according to the magnitude of the single-phase AC output current is generated. A current detection circuit 43 for output, a gate signal generator 41 for generating and outputting a gate signal so that the difference between the PWM command and the output from the current detection circuit 43 approaches zero, and a single-phase voltage type AC / DC converter 42. A single-phase AC filter circuit 45 that removes a high-frequency component caused by the gate signal in the single-phase voltage type AC / DC converter 42 from the single-phase AC output voltage.

  Further, the single-phase voltage type AC / DC converting circuit 40-2 shown in FIG. 6 detects the single-phase AC output voltage of the single-phase voltage type AC / DC converting unit 42 instead of the current detection circuit 43 of FIG. A voltage detection circuit 44 that outputs a signal generated according to the magnitude of the voltage is provided. In this case, the gate signal generator 41 generates and outputs a gate signal so that the difference between the PWM command and the output from the voltage detection circuit 44 approaches zero.

  The internal equivalent impedance of the single-phase voltage type AC / DC converter 42 shown in FIG. 5 and FIG. 6 can be given by the control variable in the single-phase voltage type AC / DC converter 11 of FIG. 5 and the output of the single-phase voltage type AC / DC converting circuits 40-1 and 40-2 in FIG. 6 may be provided with a resistor, a reactor, a single-phase transformer, or a combination thereof. For example, a resistor or a reactor may be connected in series to the single-phase output of each of the single-phase voltage type AC / DC converter circuits 40-1 and 40-2. You may connect in series. Moreover, you may connect a single phase transformer to the single phase output of the single phase voltage type | mold AC / DC conversion circuit 40-1, 40-2. Moreover, when a reactor is connected to the single-phase output of each of the single-phase voltage type AC / DC conversion circuits 40-1 and 40-2, a single-phase transformer may be connected to the subsequent stage of the reactor. Furthermore, when a resistor is connected to the single-phase output of each of the single-phase voltage type AC / DC converter circuits 40-1 and 40-2, and a reactor is connected in series to the subsequent stage of the resistor, a single-phase transformer is connected to the subsequent stage of the reactor. A vessel may be connected. As described above, since the single-phase voltage type AC / DC converter circuit 40 has an internal equivalent impedance, the single-phase voltage type AC / DC converter 11 of FIG. 1 can be operated as a voltage source connected to the power system. .

  The single-phase voltage type AC / DC conversion circuit 40 shown in FIG. 1 is configured as shown in FIG. 5 or FIG. 6, so that the single-phase voltage type AC / DC conversion device 11 includes a single-phase AC filter circuit 45 (FIGS. 5 and 6). Therefore, it is possible to remove a high-frequency component caused by the gate signal in the single-phase voltage type AC / DC converter 42 from the output from the single-phase voltage type AC / DC converter 42. The current detection circuit 43 or the voltage detection circuit 44 detects the current or voltage from the single-phase voltage type AC / DC converter 42, and the gate signal generator 41 outputs the PWM command and the output from the current detection circuit 43 or the voltage detection circuit 44. By generating a gate signal so that the difference between and the current value approaches zero, the current error can be controlled to be within an allowable range, or the output voltage can be made to follow the PWM command.

  Here, FIG. 7 shows a schematic configuration diagram of the single-phase voltage type AC / DC converter in FIGS. 5 and 6. FIG. 8 shows a schematic configuration diagram of the single-phase AC filter circuit in FIGS. 5 and 6.

  The single-phase voltage type AC / DC converting unit 42 shown in FIG. 7 includes four self-extinguishing switches 46g, 46h, 46k, 46l and four diodes 46a, 46b, 46e, 46f. The self-extinguishing type switches 46g, 46h, 46k, and 46l are elements that switch on / off according to on / off of an input signal. MOSFETs (MOS type field effect transistors) and IGBTs (insulated gate bipolar transistors) are used. It can be illustrated. The single-phase voltage type AC / DC converter 42 receives a gate signal from the gate signal generator 41 shown in FIG. 5 or 6 as an input signal. The single-phase voltage type AC / DC converting unit 42 switches on / off of the four switches according to the gate signal for each of the four self-extinguishing type switches 46g, 46h, 46k, and 46l by the pulse signal, so that the DC voltage source 23 Can be converted into single-phase AC power and output from AC terminals 24 and 26. The output voltage can be changed by changing the pulse width of the pulse signal. In FIG. 7, the DC terminals 21-1 and 21-2 correspond to the DC terminal 21 of FIG. 1 which is a schematic diagram.

  The single-phase AC filter circuit 45 shown in FIG. 8 receives the single-phase output from the single-phase voltage type AC / DC converter 42 of FIG. 5 or 6 at the AC terminals 24 and 26 on the input side, and receives the AC terminal 22− on the output side. Between the output from 1 and 22-3, it has the inductor 47d which controls an electric current, the resistance 47a connected between AC terminal 22-1 and AC terminal 22-3, and the capacitor | condenser 47g. The capacitances of the inductor 47d, the resistor 47a, and the capacitor 47g can be determined as appropriate according to the frequency characteristics of the output signals from the output-side AC terminals 22-1 and 22-3. The resistor 47a may be omitted and the capacitor 47g may be connected between the AC terminal 22-1 and the AC terminal 22-3. In the single-phase voltage type AC / DC conversion circuits 40-1 and 40-2 of FIGS. 5 and 6, the single-phase voltage type AC / DC conversion unit 42 is applied by applying the single-phase AC filter circuit 45 of FIG. 8 as the single-phase AC filter circuit 45. It is possible to remove high-frequency components resulting from the gate signal at. In FIG. 8, AC terminals 22-1 and 22-3 correspond to the AC terminal 22 of FIG.

  The output voltage detection circuit 31 in FIG. 1 detects the single-phase AC output voltage at the AC terminal 22 and outputs it to the phase difference generation circuit 30, the lower voltage control circuit 60, and the upper voltage control circuit 70, respectively. Further, a low-pass filter may be provided in the previous stage of the output voltage detection circuit 31, and the single-phase AC output voltage to the output voltage detection circuit 31 may be detected via the low-pass filter. The PWM component can be removed from the single-phase AC output voltage, and the control of the single-phase voltage type AC / DC converter 11 can be stabilized. Further, a low-pass filter may be provided after the output voltage detection circuit 31, and the output voltage from the output voltage detection circuit 31 may be output via the low-pass filter. The PWM component can be removed from the output voltage from the output voltage detection circuit 31 to stabilize the control of the single-phase voltage type AC / DC converter 11.

The phase difference generation circuit 30 in FIG. 1 generates a phase difference voltage corresponding to the phase difference between the single-phase AC output voltage V _FIL (t) of the AC terminal 22 and the internal electromotive voltage of the single-phase voltage type AC / DC conversion circuit 40. . FIG. 10 is an example of a schematic configuration diagram of the phase difference generation circuit 30. The phase difference generation circuit 30 is input from the terminal 33-1 and a phase-delayed single-phase AC generator 35 that generates a delayed single-phase AC delayed from a single-phase AC voltage input from the terminal 33-1 by a predetermined phase. A phase difference voltage generator 36 for generating a phase difference voltage from a single phase AC voltage, a delayed single phase AC voltage from the phase delay single phase AC generator 35 and a value input from the terminal 33-3, and a phase difference voltage Terminal 33-2. In FIG. 10, the phase-delayed single-phase AC generator 35 delays the phase of the delayed single-phase AC by approximately 90 °. However, the phase to be delayed may be any angle as long as it is not 0 ° and 180 °.

ここで、ω_ｓ：角周波数［ｒａｄ／ｓ］、θ_ｓ：位相角［ｒａｄ］、Ｅ_ｓ：実効値［Ｖ］である。なお、位相角の基準を内部起電圧におく。 The single-phase AC output voltage V _FIL (t) detected by the output voltage detection circuit 31 is input to the terminal 33-1. A generated electrical angle 57 generated by a frequency control circuit 50 described later is input to the terminal 33-3. The single-phase AC output voltage V _FIL (t) of the AC terminal 22 can be expressed by Equation 1.

Here, ω _s : angular frequency [rad / s], θ _s : phase angle [rad], and E _s : effective value [V]. The reference for the phase angle is set to the internal electromotive voltage.

When the angular frequency ω _s of the single-phase AC output voltage of the AC terminal 22 and the reference angular frequency ω _{co of the} single-phase voltage type AC / DC converter circuit 40 are equal, the single-phase AC output voltage V _FIL (t) and the phase lag single phase The phase difference from the AC voltage V ″ _FIL (t) is 90 °, and the phase-lag single-phase AC voltage V ″ _FIL (t) generated by the phase-lag single-phase AC generator 35 can be expressed by Equation 2.

θ_ｉの角速度がω_ｓに等しくなれば、数式３は定数となる。θ_ｓは内部等価インピーダンス両端電圧の位相差であるので一般的に小さい。そこで、Ｖ_ｑ（ｔ）は数式４のように近似できる。

The phase difference voltage generator 36 generates a phase difference voltage V _q (t) from the single-phase AC output voltage V _FIL (t), the phase-lag single-phase AC voltage V ″ _FIL (t) and the generated value generated by the frequency control circuit 50. The phase difference voltage V _q (t) is expressed by Equation 3.

If the angular velocity of θ _i is equal to ω _s , Equation 3 becomes a constant. Since θ _s is the phase difference of the voltage across the internal equivalent impedance, it is generally small. Therefore, V _q (t) can be approximated as Equation 4.

The phase difference generation circuit 30 outputs the generated phase difference voltage to the frequency control circuit 50 and the upper voltage control circuit 70, respectively. Although only the case where ω _s is equal to ω _co is shown here, a similar approximate solution can be obtained even when ω _s is not equal, and there is no practical problem.

  The frequency control circuit 50 is based on a reference frequency that defines the frequency of the single-phase AC output voltage at the AC terminal 22, a frequency command signal from the higher-level voltage control circuit 70, and an output signal from the phase difference generation circuit 30. The electrical angle of the internal electromotive voltage of the AC / DC converter circuit 40 is determined. Specifically, as shown in FIG. 3, the second adder 56 adds the frequency command signal from the higher voltage control circuit 70 and the phase difference voltage from the phase difference generation circuit 30. The loop filter 53 filters the low frequency component, which is a component related to the frequency difference of the single-phase AC output voltage, from the frequency component of the signal output from the second adder 56. The low-pass filtering element added in the loop filter 53 is a delay element such as a first-order delay element, for example. Thereby, the feedback loop can be stabilized.

The third adder 58 adds the reference frequency output from the reference frequency setting unit 51 and the output value of the loop filter 53. The time integrator 55 integrates the output from the third adder 58 with time. The time integrator 55 integrates the output from the third adder 58 with time to obtain a generated electrical angle 57 that becomes the natural angle θ _i .

  The generated electrical angle 57 becomes the electrical angle of the internal electromotive voltage of the single-phase voltage type AC / DC converting circuit 40 by the second multiplier 65 of the lower voltage control circuit 60. Thereby, the said rotation angle can be made to follow the frequency of an electric power grid | system.

  Here, the phase difference generation circuit 30 outputs a phase difference voltage corresponding to the phase difference between the single-phase AC output voltage of the AC terminal 22 and the internal electromotive voltage of the single-phase voltage type AC / DC conversion circuit 40 as described above. Therefore, it is considered that the signal processing in the phase difference generation circuit 30 corresponds to phase comparison processing for comparing the phases of the single-phase AC output voltage and the generated electrical angle 57 from the frequency control circuit 50. The signal processing for adding and integrating the reference frequency from the reference frequency setting unit 51 and the output value from the loop filter 53 is a VCO that varies the value of the generated electrical angle 57 in accordance with the output voltage from the loop filter 53. This is considered to correspond to the signal processing of (Voltage Controlled Oscillator). Therefore, the phase difference generation circuit 30 and the frequency control circuit 50 are considered to operate as a PLL whose generated electrical angle 57 is synchronized with the frequency of the single-phase AC output voltage of the AC terminal 22 as a whole.

  The upper voltage control circuit 70 of FIG. 1 receives a higher command vector 120 composed of a voltage amplitude command value for the amplitude of the single-phase AC output voltage at the AC terminal 22 and a frequency command value for the frequency, and is generated from the frequency control circuit 50. Based on the electrical angle 57, the phase difference voltage from the phase difference generation circuit 30, and the single-phase AC output voltage of the AC terminal 22, the amplitude and frequency of the single-phase AC output voltage at the AC terminal 22 are set to the command value by the upper command vector 120. A voltage command signal and a frequency command signal generated so as to approach each other are output. The upper voltage control circuit 70 may not be directly input with the upper command vector 120 but may be input through a limiter 121 that determines an upper limit and a lower limit of the upper command vector 120. Specifically, as shown in FIG. 3, the first multiplier 73 multiplies the sine value of the generated electrical angle 57 from the frequency control circuit 50 by √2 and the voltage amplitude command value of the upper command vector 120. Multiply. The first subtractor 71 a subtracts the AC output voltage of the AC terminal 22 from the signal from the first multiplier 73. The first upper control amplifier 72a amplifies the signal from the first subtractor 71a and outputs it as a voltage command signal so that the single-phase AC output voltage of the AC terminal 22 approaches the command value by the upper command vector 120. Further, the second subtracter 71b subtracts the phase difference voltage from the phase difference generation circuit 30 from the value obtained by multiplying the frequency command value of the higher order command vector 120 by √2. The second upper control amplifier 72b amplifies the signal from the second subtractor 71b and outputs it as a frequency command signal so that the frequency of the single-phase AC output voltage at the AC terminal 22 approaches the command value by the upper command vector 120. .

  Thereby, even if the amplitude and frequency of the power system change, it is possible to detect respective errors in the amplitude and frequency of the single-phase output power of the single-phase voltage type AC / DC converter 11 with respect to the amplitude and frequency. Here, in the first high-order control amplifier 72a and the second high-order control amplifier 72b, a low-pass filter element may be added to the outputs from the first subtractor 71a and the second subtractor 71b. Thereby, the feedback loop can be stabilized. Further, a limiter may be further provided in the subsequent stage of the first upper control amplifier 72a and the second upper control amplifier 72b, and outputs from the first upper control amplifier 72a and the second upper control amplifier 72b may be output via the limiter. . Over-output can be prevented and control can be stabilized.

  1 is based on the single-phase AC output voltage of the AC terminal 22, the electrical angle command signal including the generated electrical angle 57 of the frequency control circuit 50, and the voltage command signal from the upper voltage control circuit 70. A signal generated so that the amplitude, frequency, and phase of the single-phase AC output voltage approach the combined value of the reference voltage that defines the amplitude of the single-phase AC output voltage of the AC terminal 22, the voltage command signal, and the electrical angle command signal. Is output as a PWM command. The reference voltage is set in advance by the reference voltage setting unit 61. This reference voltage is a reference for the amplitude of the single-phase AC output voltage of the AC terminal 22.

  Specifically, as shown in FIG. 3, a reference voltage setting unit 61 sets and outputs a reference voltage. The second multiplier 65 multiplies the value obtained by multiplying the sine value of the generated electrical angle 57 from the frequency control circuit 50 by √2 and the reference voltage from the reference voltage setting unit 61. The first adder 62 adds the voltage command signal from the higher voltage control circuit 70 and the signal output from the second multiplier 65 and outputs the result. The third subtracter 63 subtracts the signal from the output voltage detection circuit 31 from the signal output from the first adder 62. The voltage controller 64 controls the signal output by the third subtractor 63 so that the single-phase AC output voltage of the AC terminal 22 approaches the combined value of the reference voltage, the voltage command signal, and the electrical angle command signal. , Output as a PWM command.

  This compensates for the deviation detected by the high-order voltage control circuit 70 and single-phase so that the amplitude and phase of the single-phase AC output voltage of the single-phase voltage type AC / DC converter 11 match the amplitude and phase of the power system. The amplitude and phase of the voltage type AC / DC converter 11 can be controlled. For example, an amplifier can be applied to the voltage controller 64. Here, a low-pass filter may be further provided between the third subtractor 63 and the voltage controller 64, and an output from the third subtractor 63 may be output via the low-pass filter. Control by the voltage controller 64 can be stabilized. Further, a voltage limiter is further provided between the third subtracter 63 and the voltage controller 64 (between the low-pass filter and the voltage controller 64 when a low-pass filter is provided at this position), and the third subtractor 63 is provided. It is good also as outputting the output from via a voltage limiter. Transient fluctuations in the output voltage when the single-phase voltage type AC / DC converter 11 is started up can be suppressed.

  The positive feedback circuit 200 positively feeds back the phase difference voltage output from the phase difference generation circuit 30 to the frequency command value of the upper command vector 120 input to the upper voltage control circuit 70. Specifically, the output of the positive feedback circuit 200 is added to the frequency command value of the upper command vector 120 by the fifth adder 210. For this reason, the host voltage control circuit 70 outputs a frequency command signal so that the frequency of the single-phase AC output from the single-phase voltage type AC / DC converter circuit 40 becomes unstable when the power system fails and becomes independent. Will be output.

  The frequency fluctuation detection circuit 220 monitors the frequency of the single-phase AC output from the single-phase voltage type AC / DC conversion circuit 40, and detects that the monitored frequency has deviated from a preset range as a frequency fluctuation. For example, the frequency fluctuation may be determined when the frequency of the single-phase alternating current from the single-phase voltage type AC / DC converter circuit 40 is shifted ± 2.5 Hz or more from the frequency of the power system. Alternatively, the frequency fluctuation may be determined when the single-phase alternating current waveform from the single-phase voltage type AC / DC converter circuit 40 collapses and the frequency cannot be measured. Alternatively, a specific frequency value may be set in advance, and the frequency fluctuation may be determined when the single-phase AC frequency from the single-phase voltage type AC / DC converter circuit 40 reaches the frequency value. For example, the frequency of ± 2.5 Hz of the single-phase AC output from the single-phase voltage type AC / DC converter circuit 40 during parallel operation can be set as the specific frequency value. When the frequency fluctuation is detected, the frequency fluctuation detection circuit 220 outputs a frequency fluctuation generation signal. The single-phase voltage type AC / DC converter 11 can determine that the frequency fluctuation detection circuit 220 has become a single operation by outputting a frequency fluctuation generation signal.

  The single-phase voltage type AC / DC converter 11 includes inverter output stopping means. The inverter output stop means has a gate signal stop function and stops the gate signal in the single-phase voltage type AC / DC converter circuit 40 in response to the frequency fluctuation generation signal from the frequency fluctuation detection circuit 220. The inverter output stop means may be a switch 230 between the single-phase voltage type AC / DC converter circuit 40 and the AC terminal 22. With the gate signal stop function or / and the switch 230, the single-phase voltage type AC / DC converter 11 detects the frequency fluctuation and detects that the single-phase operation from the AC terminal 22 is performed when the frequency fluctuation detector 220 detects the frequency fluctuation. The output of AC power can be stopped. In FIG. 1, the switch 230 is arranged between the detection point A of the frequency fluctuation detector 220 and the AC terminal 22, but the detection point A of the frequency fluctuation detector 220 and the single-phase voltage type AC / DC conversion. You may arrange | position between the circuits 40.

  The single-phase voltage type AC / DC converter 11 includes a switch 240 that cuts off a signal to the positive feedback circuit 200. After the frequency fluctuation detector 220 detects the frequency fluctuation of the single-phase AC from the single-phase voltage type AC / DC conversion circuit 40 and stops the output of the single-phase AC power from the AC terminal 22 by the inverter output stop means, the frequency fluctuation detector 220 becomes unstable. Since it is not necessary to output a single phase alternating current from the single phase voltage type AC / DC conversion circuit 40, the switch 240 blocks the phase difference voltage from the phase difference generation circuit 30 and stops the positive feedback. As long as the positive feedback can be stopped, the gain of the positive feedback circuit 200 may be set to 0 by a gain adjuster (not shown) instead of the switch 240. The switch 240 may be switched manually.

  FIG. 2 is a diagram showing another form of the single-phase voltage type AC / DC converter 11. The positive feedback circuit stop means automatically causes the positive feedback circuit 200 to stop positive feedback after the inverter output stop means stops the output of the single-phase AC power from the AC terminal 22. Specifically, the switch 240 receives the frequency fluctuation generation signal output from the frequency fluctuation detector 220 and blocks the phase difference voltage to the positive feedback circuit 200. The single-phase voltage type AC / DC converter 11 of FIG. 2 automatically stops positive feedback performed by the positive feedback circuit 200 when it is determined that the single-phase voltage-type AC / DC converter 11 has been operated independently and the output of the single-phase AC is stopped from the AC terminal 22. be able to.

  FIG. 11 is a diagram showing a simulation result of a single-phase AC waveform from the single-phase voltage type AC / DC converter circuit 40 when the single-phase voltage type AC / DC converter 11 of FIG. 1 is disconnected from the power system. The simulation conditions are as follows. The single-phase voltage type AC / DC converter 11 is 100 V, 50 Hz, and 1 kVA. A 1 kW resistive load is connected to the AC terminal 22 of the single-phase voltage type AC / DC converter 11, and the single-phase voltage type AC / DC converter 11 is operated at an output of 1 kW. For this reason, although it is linked with the power grid, the grid current is zero. Before disconnection, the power system is operated in parallel with the power supply of the power system, and even if the positive feedback circuit 200 is performing positive feedback, the single-phase AC waveform output from the single-phase voltage type AC / DC converter circuit 40 is forcibly And the frequency does not fluctuate. When disconnected from the power system, there is no significant change for several tens of milliseconds, but the single-phase AC voltage waveform of the single-phase voltage type AC / DC converter circuit 40 gradually deviates from the voltage waveform of the power system, and the frequency fluctuation increases. ing. When the frequency fluctuation detector 220 detects this frequency fluctuation, it can be determined that the single-phase voltage type AC / DC converter 11 has been operated independently. In this way, the single-phase voltage type AC / DC converter 11 can perform autonomous parallel operation control, and even in a state where the output of the single-phase voltage type AC / DC converter and the size of the load, which was difficult in the prior art, are balanced. Single operation can be detected. Since the positive feedback circuit 200 does not positively feed back to the voltage amplitude command value of the upper command vector, the single-phase AC voltage amplitude of the single-phase voltage type AC / DC converter circuit 40 is substantially constant.

  FIG. 12 is a diagram illustrating experimental results of comparing the single-phase AC output voltage and the single-phase AC output current at the AC terminal 22 of the single-phase voltage type AC / DC converter 11 of FIG. The experimental conditions are as follows. The single phase voltage type | mold AC / DC converter 11 of FIG. 1 is 200V, 50Hz, and 1 kVA. As the lower voltage control circuit 60, a circuit in which the internal equivalent impedance described in Patent Document 2 becomes an inductance is applied. A transformer is connected to the AC terminal 22 in parallel with a 200 V, 50 Hz power system. Similar to the description of FIG. 11, the waveform of the single-phase AC output voltage was identical to the voltage waveform of the power system before the disconnection, and the frequency did not change. After the disconnection, the waveform of the single-phase AC output voltage gradually deviated from the voltage waveform of the power system, and the frequency fluctuation increased as in the description of FIG. Further, the frequency fluctuation detector 220 detects this frequency fluctuation, and the inverter stop means stops the gate signal after 0.76 seconds. For this reason, the output of the single-phase alternating current output voltage after 0.76 seconds after the disconnection is stopped.

  In FIG. 4, the schematic block diagram of the single phase voltage type | mold AC / DC converter which concerns on another form is shown.

  The single-phase voltage type AC / DC converter 11 shown in FIG. 4 detects the single-phase AC output current of the AC terminal 22 via the current transformer 38 in the single-phase voltage type AC / DC converter 11 shown in FIG. The output from the voltage controller 64 is further added to the output from the filter current compensator 66, the PWM current deviation compensator 67 and the feedforward amplifier 68 in the fourth adder 69. In this case, the single-phase voltage type AC / DC conversion circuit 40 can apply any of the single-phase voltage type AC / DC conversion circuits 40-1 and 40-2 described in FIG. 5 or FIG. 6. Therefore, in FIG. 4, it is assumed that the single-phase voltage type AC / DC conversion circuits 40-1 and 40-2 in FIG. 5 or 6 are applied.

  The filter current compensator 66 outputs a current compensation value defined so as to compensate for a current loss in the single-phase AC filter circuit 45 (FIG. 5 or FIG. 6) in the single-phase voltage type AC / DC converter circuit 40. Thus, in the single-phase voltage type AC / DC converter 11, the current loss in the single-phase AC filter circuit 45 of FIG. 5 or 6 is set in advance in the filter current compensator 66 and added to the output vector from the voltage controller 64. By doing so, the current loss can be compensated. The PWM current deviation compensator 67 outputs a current deviation compensation value defined so as to compensate for the current deviation of the single-phase AC output current from the single-phase voltage type AC / DC converter circuit 40. Thus, in the single-phase voltage type AC / DC converter 11, the current deviation in the single-phase voltage type AC / DC converter circuit 40 when the PWM command is set to zero is set in advance in the PWM current deviation compensator 67, and the voltage controller 64. Can be compensated for by adding to the output vector from. The feedforward amplifier 68 receives the value of the single-phase AC output current detected by the output current detection circuit 34, amplifies it with a predetermined feedforward gain so as to compensate the current for the load at the AC terminal 22, and outputs the amplified signal. . As a result, in the single-phase voltage type AC / DC converter 11, the output current detection circuit 34 detects the single-phase AC output current of the AC terminal 22, and the value passes through the feedforward amplifier 68 and is output from the voltage controller 64. By adding to, a stable output voltage can be generated even if the load current changes.

  The limiter 121 sets an upper limit and a lower limit of the upper command vector 120 and prevents an excessive upper command vector 120 from being input to the upper voltage control circuit 70.

  As described above, the single-phase voltage type AC / DC converter 11 of FIGS. 1 to 4 has an internal equivalent impedance, so that it can be operated as a voltage source connected to the power system, and the frequency control circuit 50 Since the upper voltage control circuit 70 and the lower voltage control circuit 60 are provided, autonomous parallel operation that autonomously compensates for power deviation with respect to the power system is possible. As a result, the reliability of the apparatus is increased and distributed arrangement is possible. Further, when a plurality of units are operated in parallel, the units can be operated without any limitation.

  A single-phase voltage type AC / DC converter according to the present invention includes an inverter for photovoltaic power generation, an inverter for fuel cell, an inverter for storage system, an inverter for wind power generation with DC link, a rectifier, and SVC (reactive power compensation). Device). The present invention can also be applied to a single-phase three-wire inverter.

It is a schematic block diagram of the single phase voltage type | mold AC / DC converter which concerns on this invention. It is a schematic block diagram of the single phase voltage type | mold AC / DC converter which concerns on this invention. It is a schematic block diagram of the single phase voltage type | mold AC / DC converter which concerns on this invention. It is a schematic block diagram of the single phase voltage type | mold AC / DC converter which concerns on this invention. It is a schematic block diagram of the single phase voltage type | mold AC / DC conversion circuit with which the single phase voltage type | mold AC / DC converter which concerns on this invention is provided. It is a schematic block diagram of the single phase voltage type | mold AC / DC conversion circuit with which the single phase voltage type | mold AC / DC converter which concerns on this invention is provided. It is a schematic block diagram of the single phase voltage type | mold AC / DC conversion part with which the single phase voltage type | mold AC / DC converter which concerns on this invention is provided. It is a schematic block diagram of the single phase alternating current filter circuit with which the single phase voltage type | mold AC / DC converter which concerns on this invention is provided. It is the figure which showed the connection relation of the control block in the single phase voltage type | mold AC / DC converter which concerns on this invention. It is a schematic block diagram of the phase difference production | generation circuit with which the single phase voltage type | mold AC / DC converter which concerns on this invention is provided. It is the figure which showed the simulation waveform of the single phase alternating current from the single phase voltage type | mold AC / DC conversion circuit at the time of separating the single phase voltage type | mold AC / DC converter 11 (100V, 50Hz, 1kVA) of FIG. 1 from an electric power grid | system. It is the figure which showed the experimental waveform of the single phase alternating current in the alternating current terminal at the time of separating the single phase voltage type | mold AC / DC converter 11 (200V, 50Hz, 1kVA) of FIG. 1 from an electric power grid | system. It is a schematic block diagram of the conventional three-phase voltage type | mold AC / DC converter.

Explanation of symbols

11: Single-phase voltage type AC / DC converters 21, 21-1, 21-2: DC terminals 22, 22-1, 22-3: AC terminal 23: DC voltage source 24, 26: AC terminal 30: phase difference generation circuit 31: Output voltage detection circuit 33-1 to 33-3: Terminal 34: Output current detection circuit 35: Phase lag single phase AC generator 36: Phase difference voltage generator 38: Current transformer 40: Single phase voltage type AC / DC conversion Circuits 40-1, 40-2: Single-phase voltage type AC / DC converter circuit 41: Gate signal generator 42: Single-phase voltage type AC / DC converter 43: Current detection circuit 44: Voltage detection circuit 45: Single-phase AC filter circuit 46a, 46b, 46e, 46f: Diodes 46g, 46h, 46k, 46l: Self-extinguishing switch 47a: Resistor 47d: Inductor 47g: Capacitor 50: Frequency control circuit 51: Reference frequency setting unit 52: Rotation coordinate transformation matrix 3: loop filter 55: time integrator 56: second adder 57: generated electrical angle 58: third adder 60: lower voltage control circuit 61: reference voltage setter 62: first adder 63: third subtractor 64: voltage controller 65: second multiplier 66: filter current compensator 67: PWM current deviation compensator 68: feedforward amplifier 69: fourth adder 70: upper voltage control circuit 71a: first subtractor 71b: first Two subtracters 72a: first upper control amplifier 72b: second upper control amplifier 73: first multiplier 120: upper command vector 121: limiter 200: positive feedback circuit 210: fifth adder 220: frequency fluctuation detector 230: Switch 240: Switch 401: Inverter bridge 402: Coil 403: Capacitor 404: Resistor 406: Current command 407: Drive unit 408: Gate signal generation (PWM)
409: Amplifier 410: Current reference 411: Gain or / and phase adjuster 412: Coefficient setting circuit 413: Frequency calculator 414: Voltage calculator 415: Distortion change calculator 416: Frequency detector 417: Voltage effective detector 418: Zero cross distortion detector 450: Voltage detector 451: Voltage relay 452: Frequency relay 453: Distortion relay 454: Abnormality detector B1: High order command vector B2: Most significant control block B3: ac-AVR block B4: ETM-PWM block B5 : Main switch

Claims (9)

Single-phase having internal equivalent impedance when viewed from the AC terminal, and converting the power from the DC voltage source into single-phase AC power according to the pulse width of the gate signal generated based on the PWM command and outputting from the AC terminal A voltage type AC / DC converter circuit;
A phase-delayed single-phase alternating current generator for generating a delayed single-phase alternating current with a phase delayed from the single-phase alternating current output voltage of the alternating current terminal, and the single-phase alternating current output voltage of the alternating current terminal based on the delayed single-phase alternating current And a phase difference generation circuit that generates a phase difference voltage corresponding to a phase difference between the internal electromotive voltage of the single-phase voltage type AC / DC conversion circuit, and
An upper command vector comprising a voltage amplitude command value for the amplitude of the single-phase AC output voltage of the AC terminal and a frequency command value for the frequency is input, the input upper command vector, the phase difference voltage from the phase difference generation circuit, and Based on the single-phase AC output voltage of the AC terminal, a voltage command signal and a frequency command signal generated so that the amplitude and frequency of the single-phase AC output voltage of the AC terminal approach the command value by the upper command vector are output. Upper voltage control circuit;
Based on the reference frequency that defines the frequency of the single-phase AC output voltage of the AC terminal, the frequency command signal from the higher voltage control circuit, and the output signal from the phase difference generation circuit, the single-phase voltage type AC / DC conversion circuit A frequency control circuit for determining an electrical angle of an internal electromotive voltage and generating a generated electrical angle;
Based on the single-phase AC output voltage of the AC terminal, the generated electrical angle of the frequency control circuit, and the voltage command signal from the upper voltage control circuit, the amplitude, frequency and phase of the single-phase AC output voltage are A reference voltage that regulates the amplitude of a single-phase AC output voltage, a low-order voltage control circuit that outputs a signal generated so as to approach the combined value of the voltage command signal and the generated electrical angle as the PWM command;
A positive feedback circuit that positively feeds back a phase difference voltage output from the phase difference generation circuit to a frequency command value of the upper command vector input to the upper voltage control circuit;
A frequency fluctuation detector that monitors the frequency of the single-phase AC output from the single-phase voltage type AC / DC converter circuit and detects that the monitored frequency deviates from a preset range as a frequency fluctuation;
The gate signal stop function for stopping the gate signal in the single phase voltage type AC / DC conversion circuit or / and the single phase voltage type AC / DC conversion by a switch between the single phase voltage type AC / DC conversion circuit and the AC terminal. An inverter output stopping means having a cutoff function for cutting off single-phase AC power from the circuit, and stopping output of single-phase AC power from the AC terminal when the frequency fluctuation detector detects frequency fluctuation;
A single-phase voltage type AC / DC converter.   A positive feedback circuit stop means for stopping positive feedback performed by the positive feedback circuit with a switch for interrupting the positive feedback circuit and / or a gain adjuster for setting the gain of the positive feedback circuit to 0 is further provided. The single phase voltage type | mold AC / DC converter of Claim 1.   The positive feedback circuit stop means stops positive feedback performed by the positive feedback circuit after the inverter output stop means stops the output of single-phase AC power from the AC terminal. 3. The three-phase voltage type AC / DC converter according to 2. The upper voltage control circuit includes a first multiplier that multiplies a signal based on a generated electrical angle of the frequency control circuit and the upper command vector, and an AC output voltage of the AC terminal from a signal output from the first multiplier. A first subtractor for subtracting the signal, and a signal from the first subtracter is amplified and output as the voltage command signal so that the single-phase AC output voltage of the AC terminal approaches the command value by the upper command vector A first upper control amplifier, a second subtracter for subtracting a phase difference voltage from the phase difference generation circuit from the upper command vector, and a single-phase AC output voltage of the AC terminal to the command value by the upper command vector A second upper control amplifier that amplifies the signal from the second subtractor so as to approach and outputs as the frequency command signal,
The lower voltage control circuit is configured to set and output the reference voltage, and a second multiplication that multiplies a signal based on a generated electrical angle of the frequency control circuit and a reference voltage from the reference voltage setter. A first adder for adding and outputting a voltage command signal from the upper voltage control circuit and a signal output from the second multiplier, and a signal output from the first adder from the AC terminal. A third subtractor for subtracting a single-phase AC output voltage, and the third subtractor so that a single-phase AC output voltage at the AC terminal approaches the combined value of the reference voltage, the voltage command signal, and the generated electrical angle. A voltage controller that controls a signal output from the controller and outputs a PWM command.
The frequency control circuit includes a second adder that adds a frequency command signal from the higher voltage control circuit and a phase difference voltage from the phase difference generation circuit, and a frequency component of a signal output from the second adder. A loop filter for adding a low-pass filter element to output, a reference frequency setter for setting the reference frequency, a third adder for adding the output value of the reference frequency setter to the output value of the loop filter, 4. The single-phase voltage type AC / DC conversion according to claim 1, further comprising: a time integrator that time-integrates a signal output from the third adder and outputs the signal as the generated electrical angle. 5. apparatus. An output current detection circuit for detecting a single-phase AC output current of the AC terminal;
The lower voltage control circuit includes a filter current compensator that outputs a current compensation value defined to compensate for a current loss in a single-phase AC filter circuit included in the single-phase voltage type AC / DC converter circuit, and the single-phase voltage A PWM current deviation compensator that outputs a current deviation compensation value defined so as to compensate for the current deviation of the single-phase AC output current from the AC / DC conversion circuit, and the single-phase AC output current detected by the output current detection circuit A feed-forward amplifier that receives a value and amplifies and outputs with a predetermined feed-forward gain so as to compensate the current to the load at the AC terminal, a current compensation value of the filter current compensator, and a PWM current deviation compensator A fourth adder that adds the current deviation compensation value of the current and the output value from the feedforward amplifier to the PWM command value from the voltage controller. Single-phase voltage-type AC-DC converter according to claim 4, characterized in Rukoto.   The single-phase voltage type AC / DC converter circuit has an internal equivalent impedance when viewed from the AC terminal, and converts the power from the DC voltage source into single-phase AC power according to the pulse width of the gate signal and outputs the single-phase AC power. A phase voltage type AC / DC converter, a current detection circuit that detects a single phase AC output current of the single phase voltage type AC / DC converter, and outputs a signal generated according to the magnitude of the single phase AC output current; and the PWM A gate signal generator that generates and outputs the gate signal so that a difference between the command and an output from the current detection circuit approaches zero, and a single-phase AC output voltage of the single-phase voltage type AC / DC converter. 6. A single-phase voltage filter according to claim 1, further comprising: a single-phase AC filter circuit that removes and outputs a high-frequency component caused by the gate signal in a phase voltage type AC / DC converter. Type exchange conversion Location.   The single-phase voltage type AC / DC converter circuit has an internal equivalent impedance when viewed from the AC terminal, and converts the power from the DC voltage source into single-phase AC power according to the pulse width of the gate signal and outputs the single-phase AC power. A phase voltage type AC / DC converter, a voltage detection circuit for detecting a single phase AC output voltage of the single phase voltage type AC / DC converter and outputting a signal generated according to the magnitude of the single phase AC output voltage; and the PWM A gate signal generator that generates and outputs the gate signal so that a difference between the command and an output from the voltage detection circuit approaches zero, and a single-phase AC output voltage of the single-phase voltage type AC / DC converter. 6. A single-phase voltage filter according to claim 1, further comprising: a single-phase AC filter circuit that removes and outputs a high-frequency component caused by the gate signal in a phase voltage type AC / DC converter. Type exchange conversion Location. The phase delay single-phase AC generator of the phase difference generation circuit is:
8. The single-phase voltage type AC / DC converter according to claim 1, wherein the phase of the delayed single-phase alternating current is delayed by 90 ° from the single-phase alternating-current output voltage of the alternating-current terminal. 9.   9. The single unit according to claim 1, further comprising a limiter that determines an upper limit and a lower limit of the upper command vector, wherein the upper command vector is input to the upper voltage control circuit via the limiter. Phase voltage AC / DC converter.

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