JP5637236B2 - Isolated operation detection device, power conditioner, distributed power supply system, program, and isolated operation detection method - Google Patents

Description

  The present invention relates to an isolated operation detection device, a power conditioner, a distributed power supply system, a program, and an isolated operation detection method.

Patent Document 1 discloses an isolated operation detection device that detects an isolated operation of a power conditioner linked to a system power supply.
Japanese Patent Application Laid-Open No. 2008-54366

  The isolated operation detection device must detect the isolated operation of the inverter in a short time. However, when the isolated operation detection device is modularized separately from the control device that controls the power conditioner, there is no guarantee that the control device immediately executes an instruction from the isolated operation detection device.

  An isolated operation detection device according to one aspect of the present invention is an isolated operation detection device that detects an isolated operation of a power conditioner linked to a system power supply, and includes a synchronization processing unit that receives or transmits a synchronization signal, and a synchronization process The control device accesses a request signal for causing the control device that controls the power conditioner to execute a process of changing the current output from the power conditioner in response to the reception or transmission of the synchronization signal by the unit. A request signal registration unit for registering in a possible storage unit.

  The isolated operation detection device is registered in advance in a response signal receiving unit that receives a response signal indicating that the current output from the power conditioner is fluctuated based on the request signal from the control device and the storage unit. When the response signal receiving unit does not receive the response signal within the given period, the signal processing unit may further include a stop signal transmitting unit that transmits a stop signal for stopping the power conditioner to the control device.

  In the above isolated operation detection device, when the response signal receiving unit receives an operation continuation signal indicating that it is necessary to continue the operation of the power conditioner, instead of the response signal, from the control device, the stop signal transmission unit Even if the response signal receiving unit does not receive the response signal within the period, the stop signal may not be transmitted.

  The isolated operation detection device includes a current value acquisition unit that acquires a current value of a current output from a power conditioner, a current value of a current that the power conditioner should output based on a request signal, and a current value acquisition unit. When the difference with the acquired electric current value is larger than a predetermined reference difference, a stop signal transmitting unit that transmits a stop signal for stopping the power conditioner to the control device may be further provided.

  The isolated operation detection device includes a response signal receiving unit that receives a response signal indicating that the current output from the power conditioner is fluctuated based on the request signal, and a current signal output from the power conditioner. The difference between the current value acquisition unit for acquiring the current value, the current value of the current that the power conditioner should output based on the request signal, and the current value acquired by the current value acquisition unit is based on a predetermined reference difference. In the case of being large, it is further provided with a stop signal transmitting unit that transmits a stop signal for stopping the power conditioner to the control device, and the response signal receiving unit needs to continue operating the power conditioner instead of the response signal from the control device. When the operation continuation signal indicating that the inverter is present is received, the stop signal transmission unit determines the current value of the current to be output by the inverter. The difference between the current value acquired by the current value acquiring unit even larger than the reference difference may not transmit a stop signal to the controller.

  The isolated operation detection device associates the current value of the current to be output by the power conditioner based on the request signal with the current value acquired by the current value acquisition unit and registers the current value in the current value holding unit. May be further provided.

  The isolated operation detection device further includes a frequency deviation deriving unit for deriving a frequency deviation of the voltage output from the power conditioner, and the request signal registration unit varies the current output from the power conditioner according to the frequency deviation. A request signal for causing the control device to execute the process to be executed by the interrupt process may be registered in the storage unit.

  A power conditioner according to an aspect of the present invention includes the above-described islanding detection device, an inverter that interconnects power from a distributed power source with power from a system power source, and a control device that controls the output of the inverter. The control device includes a request signal receiving unit that receives a request signal from the isolated operation detection device, and a control unit that controls the output of the inverter based on the request signal.

  The distributed power supply system which concerns on 1 aspect of this invention may be provided with the said power conditioner and a distributed power supply.

  The program which concerns on 1 aspect of this invention is a program for functioning a computer as said independent operation detection apparatus.

  An isolated operation detection method according to an aspect of the present invention is an isolated operation detection method for detecting an isolated operation of a power conditioner linked to a system power supply, receiving or transmitting a synchronization signal, and receiving a synchronization signal Alternatively, a request signal for causing the control device that controls the power conditioner to execute a process of changing the current output from the power conditioner in response to the transmission is registered in a storage unit accessible to the control device. A stage of performing.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

1 is a system configuration diagram illustrating an example of an overall configuration of a solar cell system according to an embodiment. It is a figure which shows an example of the functional block of an isolated operation detection apparatus. It is a figure which shows another example of the functional block of an isolated operation detection apparatus. It is a figure which shows an example of the reactive power q1-frequency deviation characteristic. It is a figure which shows an example of the functional block of a control apparatus. It is a figure which shows an example of the flowchart in case an isolated operation detection apparatus transmits a request signal.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a system configuration diagram showing an example of the overall configuration of the solar cell system according to the present embodiment. The solar cell system includes a solar cell array 200 and a power conditioner 10. In the solar cell array 200, a plurality of solar cell strings in which a plurality of solar cell modules are connected in series are connected in parallel. The solar cell array 200 is an example of a distributed power source. As the distributed power source, a gas engine, a gas turbine, a micro gas turbine, a fuel cell, a wind power generator, an electric vehicle, a power storage system, or the like may be used.

  The power conditioner 10 boosts the DC voltage output from the solar cell array 200, converts the boosted DC voltage into an AC voltage, and outputs the AC voltage to the system power supply 300 side. The power conditioner 10 includes a capacitor C1, a booster circuit 20, a capacitor C2, an inverter 40, a coil L, a capacitor C3, a relay 50, a control device 100, and an isolated operation detection device 400. The isolated operation detection device 400 may be provided outside the power conditioner 10 without being incorporated in the power conditioner 10.

  One end and the other end of the capacitor C <b> 1 are electrically connected to the positive terminal and the negative terminal of the solar cell array 200 to smooth the DC voltage output from the solar cell array 200. The booster circuit 20 may be a so-called chopper type switching regulator. The booster circuit 20 boosts the voltage from the solar cell array 200. The booster circuit 20 may be constituted by an insulating booster circuit having a transformer winding such as a half-bridge booster circuit or a full-bridge booster circuit.

  Capacitor C2 smoothes the DC voltage output from booster circuit 20. The inverter 40 includes a switch. When the switch is turned on / off, the inverter 40 converts the DC voltage output from the booster circuit 20 into an AC voltage and outputs the AC voltage to the system power supply 300 side. The inverter 40 may be constituted by, for example, a single-phase full-bridge PWM inverter that includes four semiconductor switches that are bridge-connected. Of the four semiconductor switches, one pair of semiconductor switches is connected in series. Of the four semiconductor switches, the other pair of semiconductor switches are connected in series and connected in parallel with the one pair of semiconductor switches.

  Between the inverter 40 and the system power supply 300, a coil L and a capacitor C3 are provided. The coil L and the capacitor C3 remove noise from the AC voltage output from the inverter 40. A relay 50 is provided between the capacitor C3 and the system power supply 300. Relay 50 switches whether to electrically disconnect between inverter 40 and system power supply 300. When the relay 50 is turned on, the power conditioner 10 and the system power supply 300 are electrically connected. When the relay 50 is turned off, the power conditioner 10 and the system power supply 300 are electrically disconnected.

  The power conditioner 10 further includes voltage sensors 12, 16, and 17 and current sensors 14, 18, and 19. The voltage sensor 12 detects a voltage V1 corresponding to a potential difference between both ends of the solar cell array 200. The voltage sensor 16 detects a voltage V2 corresponding to a potential difference between both ends on the output side of the booster circuit 20. The voltage sensor 17 detects a voltage V3 corresponding to a potential difference between both ends on the output side of the inverter 40.

  The current sensor 14 detects a current I1 output from the solar cell array 200 and flowing to the input side of the booster circuit 20. The current sensor 18 detects the current I2 output from the booster circuit 20. The current sensor 19 detects the current I3 output from the inverter 40.

  Control device 100 includes voltage booster circuit 20 and an inverter based on the voltage and current detected by voltage sensors 12, 16 and 17 and current sensors 14, 18 and 19 so that the maximum power can be obtained from solar cell array 200. The switching operation of 40 is controlled, the DC voltage output from the solar cell array 200 is boosted, the boosted DC voltage is converted into an AC voltage, and output to the system power supply 300 side.

  In the power conditioner 10 configured as described above, when the system power supply 300 is stopped, the relay 50 must be turned off to electrically disconnect the power conditioner 10 and the system power supply 300. Further, the power conditioner 10 must control the voltage so that the voltage output to the system power supply 300 does not exceed the upper limit voltage.

  The islanding detection device 400 causes the control device 100 to adjust the phase difference between the phase of the current output from the inverter 40 and the phase of the voltage, and the amplitude of the current output from the inverter 40, thereby adjusting the power condition. The reactive power is output to the na 10. The isolated operation detection device 400 detects the frequency fluctuation of the voltage of the system power supply 300 accompanying the supply of reactive power, thereby detecting that the system power supply 300 is stopped, that is, the power conditioner 10 is operating independently. To do.

  In addition, the isolated operation detection device 400 has a phase difference between the phase of the current output from the inverter 40 and the phase of the voltage when the voltage output from the power conditioner 10 exceeds the upper limit voltage, and By causing the control device 100 to adjust the amplitude of the current output from the inverter 40, the reactive power supplied to the system power supply 300 side in the power conditioner 10 is increased. By increasing the reactive power, the voltage of the system power supply 300 decreases. Accordingly, the control device 100 can control the voltage output from the power conditioner 10 to be smaller than the upper limit voltage. The upper limit voltage may be a value based on an upper limit value defined by the grid connection regulations.

  In the present embodiment, the control device 100 and the isolated operation detection device 400 are configured as individual modules, and the control device 100 and the isolated operation detection device 400 are connected via a transmission cable 60. The control device 100 and the isolated operation detection device 400 are each configured by a substrate and a microcomputer provided on the substrate. The substrate of the control device 100 and the substrate of the isolated operation detection device 400 have connectors, and the respective connectors are connected via the transmission cable 60.

  As described above, when the control device 100 and the isolated operation detection device 400 are configured as separate modules, the isolated operation detection device 400 simply instructs the control device 100 to provide the isolated operation detection device 400. It is not possible to confirm that it is operating reliably according to the instructions. Therefore, in the present embodiment, the isolated operation detection device 400 confirms that the control device 100 has operated in response to an instruction from the isolated operation detection device 400.

  FIG. 2A is a diagram illustrating an example of functional blocks of the isolated operation detection device 400. The isolated operation detection apparatus 400 includes a frequency measurement unit 402, a moving average value derivation unit 404, a frequency deviation derivation unit 406, a first reactive power derivation unit 408, an output voltage acquisition unit 410, a second reactive power derivation unit 412, and a reactive power addition. Unit 414, current value acquisition unit 416, request signal transmission unit 420, response signal reception unit 422, current value holding unit 424, current value comparison unit 426, stop signal transmission unit 428, confirmation signal reception unit 430, isolated operation detection unit 432 And a synchronization processing unit 440.

  The frequency measuring unit 402 acquires the voltage of the system power supply 300 via the voltage sensor 17 and measures the system frequency indicating the frequency of the system power supply 300 from the acquired voltage. The frequency measuring unit 402 measures, for example, a time difference between the intermediate value between the falling and rising edges of the voltage signal detected from the voltage sensor 17 and the next falling and rising intermediate value as one cycle. When the system period of the system power supply 300 is 50 Hz (one system period is 20 milliseconds), the measurement period of the system period may be 1/3 or less of the system period, for example, 5 milliseconds.

  The moving average value deriving unit 404 sequentially derives the moving average value of the system cycle for a predetermined moving average time based on the system cycle measured by the frequency measuring unit 402. The moving average time may be longer than one cycle of the system cycle, for example, 20 msec, and may be equal to or less than the time allowed until the isolated operation state is detected after entering the isolated operation state. The moving average time may be, for example, shorter than 100 milliseconds, and the moving average time may be, for example, 40 milliseconds.

  The frequency deviation deriving unit 406 calculates a difference between the latest moving average value derived by the moving average value deriving unit 404 and a past moving average value before a predetermined time, for example, 200 ms before the latest moving average value. Is derived as a frequency deviation. The frequency deviation deriving unit 406 may derive the frequency deviation every cycle that is the same as the measurement cycle of the system cycle, for example, every 5 milliseconds.

  The first reactive power deriving unit 408 derives the reactive power q1 based on the frequency deviation of the system power supply 300. The first reactive power deriving unit 408 may derive the reactive power q1 so that the reactive power q1 increases in proportion to the frequency deviation of the system power supply 300. For example, the first reactive power deriving unit 408 may derive the reactive power q1 corresponding to the frequency deviation by referring to the reactive power q1-frequency deviation characteristic as illustrated in FIG.

  The output voltage acquisition unit 410 detects the voltage V3 of the system power supply 300 detected by the voltage sensor 17. The second reactive power deriving unit 412 determines whether or not the detected voltage V3 is equal to or higher than a predetermined upper limit voltage Vth. When the detected voltage V3 is equal to or higher than the upper limit voltage Vth, the second reactive power deriving unit 412 increases the reactive power to be supplied to the system power supply 300 side and suppresses an increase in the output voltage of the power conditioner 10. Therefore, the reactive power q2 is derived.

  The reactive power adding unit 414 derives the reactive power Q by adding the reactive power q1 derived by the first reactive power deriving unit 408 and the reactive power q2 derived by the second reactive power deriving unit 412. . The reactive power addition unit 414 provides the derived reactive power Q to the request signal transmission unit 420.

  The request signal transmission unit 420 receives the reactive power Q from the request signal transmission unit 420 and controls the power conditioner 10 with a request signal that requests the current output from the power conditioner 10 to vary. Send to.

  Here, the reactive power Q is a value that also serves as an index for changing the current output from the power conditioner 10 in accordance with the frequency deviation of the voltage of the system power supply 300. The control device 100 varies the phase or amplitude of the current output from the power conditioner 10 in accordance with the reactive power Q with respect to the voltage of the system power supply 300, so that the reactive power corresponding to the reactive power Q is supplied to the system power supply. Supply to the 300 side. Therefore, the request signal may indicate the current value of the current to be output by the power conditioner 10 in which the phase or amplitude based on the reactive power Q is determined. The request signal may be a signal indicating the reactive power Q that the power conditioner 10 should output. The request signal may be a combination of a voltage level indicating the reactive power Q and a pulse signal that requests reading from the control device 100. Thereby, the arrangement of the communication procedure between the control device 100 and the isolated operation detection device 400 can be simplified.

  The synchronization processing unit 440 may receive a synchronization signal from the control device 100 in order to synchronize with the control device 100. Alternatively, the synchronization processing unit 440 may transmit a synchronization signal to the control device 100. The synchronization processing unit 440 may receive a synchronization signal from a synchronization generator other than the control device 100.

  The detection of the independent operation of the power conditioner 10 is required to be performed within a relatively short time, for example, within 5 msec. Therefore, after receiving the request signal, the control device 100 needs to output reactive power corresponding to the request signal to the power conditioner 10 immediately.

  Here, if synchronization is established between the control device 100 and the isolated operation detection device 400, the control device 100 generates reactive power from the power conditioner 10 in response to a request signal from the isolated operation detection device 400. There is a high possibility that the output process can be executed immediately. On the other hand, if the control device 100 and the isolated operation detection device 400 are not synchronized, the control device 100 may not normally process the request signal from the isolated operation detection device 400. Therefore, the request signal transmission unit 420 causes the synchronization processing unit 440 to output the synchronization signal so that the control device 100 immediately outputs the reactive power based on the request signal to the power conditioner 10 in response to the request signal. In response to the transmission or reception, a request signal for causing the control device 100 to output reactive power may be transmitted.

  The request signal transmission unit 420 may transmit a request signal for causing the control device 100 to output reactive power by interrupt processing in response to the synchronization signal transmitted or received by the synchronization processing unit 440. . The request signal may indicate, for example, a flag indicating that processing should be performed by interrupt processing. When the signal received from the isolated operation detection device 400 is attached with a flag or the like to be executed as interrupt processing, the control device 100 executes processing based on the signal as interrupt processing.

  Moreover, the control apparatus 100 may notify the timing which the independent operation detection apparatus 400 may transmit a request signal regularly or at arbitrary timing with a polling signal. When the synchronization processing unit 440 receives a polling signal from the control device 100, the request signal transmission unit 420 may transmit a request signal to the control device 100 as a response to the polling signal. The control device 100 may transmit a polling signal at a timing convenient to itself. The control device 100 may transmit a polling signal to the isolated operation detection device 400 at a timing when the load of control processing of each switch of the booster circuit 20 and the inverter 40 is small.

  When it is confirmed that the control device 100 and the isolated operation detection device 400 are synchronized as described above, the isolated operation detection device 400 transmits a request signal to the control device 100, so that The driving | running | working detection apparatus 400 can make the power conditioner 10 output the reactive power according to a request signal with respect to the control apparatus 100 immediately. Therefore, the isolated operation detection device 400 cannot immediately detect the isolated operation of the power conditioner 10 and can prevent the power conditioner 10 from continuing to operate independently.

  The current value acquisition unit 416 acquires the current value of the current I3 output from the inverter 40 through the current sensor 19 as the current value of the current output from the power conditioner 10. The current value holding unit 424 outputs the current value corresponding to the reactive power Q to be output by the power conditioner 10 according to the reactive power Q and the actual value detected via the current sensor 19 from the power conditioner 10. The current value of the current is associated and stored as a log. By referring to the log held in the current value holding unit 424, it is possible to confirm whether the control device 100 has issued an instruction to correctly operate the power conditioner 10 in accordance with an instruction from the isolated operation detection device 400.

  The response signal receiving unit 422 receives from the control device 100 a response signal indicating that the current output from the power conditioner 10 is varied based on the request signal. The response signal may indicate the current value of the current that the control device 100 outputs to the power conditioner 10 based on the request signal. By receiving the response signal, the isolated operation detection device 400 can confirm whether the control device 100 has correctly operated the power conditioner 10 in accordance with an instruction from the isolated operation detection device 400.

  The stop signal transmission unit 428 sends a stop signal to the control device 100 to stop the power conditioner 10 when the response signal reception unit 422 does not receive the response signal within a predetermined period T1 after the request signal is transmitted. Send. When the response signal is not received from the control device 100 in response to the request signal, the control device 100 may not supply reactive power corresponding to the request signal to the system power supply 300 side. In this case, the isolated operation detection device 400 may not be able to reliably detect the isolated operation of the power conditioner 10 due to the stop of the system power supply 300 or the like. Therefore, when the response signal receiving unit 422 does not receive a response signal within the period T1, the stop signal transmitting unit 428 transmits a stop signal to the control device 100. The control device 100 may receive the stop signal, open the relay 50, and electrically disconnect between the inverter 40 and the system power supply 300. Thereby, it is possible to prevent the power conditioner 10 from continuing to operate independently without the isolated operation detection device 400 detecting the isolated operation of the power conditioner 10. The stop signal transmission unit 428 transmits a stop signal when the synchronization processing unit 440 does not synchronize with the control device 100, that is, when the synchronization signal is not normally transmitted or received. May be.

  Here, the period T <b> 1 may be determined based on the system cycle of the system power supply 300. When the system period of the system power supply 300 is 50 Hz (one system period is 20 milliseconds), the period T1 of the system period may be 1/3 or less of the system period, for example, 5 milliseconds.

  The current value comparison unit 426 detects the current value corresponding to the reactive power Q to be output by the power conditioner 10 according to the reactive power Q held in the current value holding unit 424, and is detected via the current sensor 19. The current value of the current actually output from the power conditioner 10 is compared. As a result of the comparison, when the difference between the current value corresponding to the reactive power Q and the current value of the actual current is larger than a predetermined reference difference, the control device 100 correctly supplies the reactive power to the system power supply 300 based on the request signal. The stop signal transmission unit 428 transmits a stop signal to the control device 100 by determining that it is not supplied to the control device 100. Thereby, it is possible to prevent the power conditioner 10 from continuing to operate independently without the isolated operation detection device 400 detecting the isolated operation of the power conditioner 10.

  The confirmation signal receiving unit 430 receives the confirmation signal transmitted by the control device 100 in response to receiving the request signal before the response signal receiving unit 422 receives the response signal. When the control signal is received, the control device 100 transmits a confirmation signal indicating that the request signal has been received to the isolated operation detection device 400. If the confirmation signal receiving unit 430 has not received a confirmation signal in response to the request signal, for example, there is a high possibility that the communication interface of the control device 100 is not operating normally. In this case, there is a high possibility that the control device 100 cannot cause the power conditioner 10 to supply reactive power to the system power supply 300 side according to the request signal.

  Therefore, the stop signal transmission unit 428 may transmit the stop signal when the confirmation signal reception unit 430 does not receive the confirmation signal within a predetermined period T2 shorter than the period T1 after the request signal is transmitted. The period T2 may be determined based on the system cycle of the system power supply 300. For example, when the period T1 is 5 milliseconds, the period T2 may be 2.5 milliseconds. Before determining whether or not to receive a response signal, whether or not the control device 100 is operating normally can be determined based on whether or not the control device 100 has received a confirmation signal. Therefore, when the control apparatus 100 is not operating normally, the power conditioner 10 can be stopped earlier.

  When detecting a change in voltage or frequency of the system power supply 300, the islanding operation detection unit 432 determines that the system power supply 300 is stopped and the power conditioner 10 is operating independently, and causes the control device 100 to A stop signal is transmitted to stop the controller 10. The control device 100 may receive the stop signal, open the relay 50, and electrically disconnect between the inverter 40 and the system power supply 300. The isolated operation detection unit 432 may transmit a stop signal when the synchronization processing unit 440 is not synchronized with the control device 100.

  FIG. 2B is a diagram illustrating another example of functional blocks of the isolated operation detection device 400. An isolated operation detection device 400 shown in FIG. 2B is different from the isolated operation detection device 400 shown in FIG. 2A in that a request signal registration unit 421 and a storage unit 450 are provided instead of the request signal transmission unit 420.

  The request signal registration unit 421 is a request signal for causing the control device 100 to execute a process of changing the current output from the power conditioner 10 in response to the synchronization processing unit 440 receiving or transmitting the synchronization signal. Are registered in the storage unit 450 accessible by the control device 100. The control device 100 periodically acquires a request signal stored in the storage unit 450, and controls the power conditioner 10 to supply reactive power to the system power supply 300 side based on the acquired request signal.

  The isolated operation detection device 400 may include a display unit that displays the request signal stored in the storage unit 450 as an analog signal. In this case, the control device 100 derives the reactive power corresponding to the value displayed on the display unit by referring to a table indicating the relationship between the value displayed on the display unit, for example, the voltage value and the reactive power. May be. The control device 100 controls the power conditioner 10 to supply the derived reactive power to the system power supply 300 side.

  In response to acquiring the request signal from storage unit 450, control device 100 may transmit a response signal indicating that the current output from power conditioner 10 is varied based on the request signal. Then, the response signal receiving unit 422 may receive a response signal from the control device 100. By receiving the response signal, the isolated operation detection device 400 can confirm whether the control device 100 has correctly operated the power conditioner 10 in accordance with an instruction from the isolated operation detection device 400.

  The stop signal transmission unit 428 is configured such that the response signal reception unit 422 does not receive the response signal within a predetermined period T1 after the request signal is registered in the storage unit 450 or after the request signal is displayed on the display unit. In addition, a stop signal for stopping the power conditioner 10 may be transmitted to the control device 100. When the response signal is not received from the control device 100 in response to the request signal, the control device 100 may not supply reactive power corresponding to the request signal to the system power supply 300 side. In this case, the isolated operation detection device 400 may not be able to reliably detect the isolated operation of the power conditioner 10 due to the stop of the system power supply 300 or the like. Therefore, when the response signal receiving unit 422 does not receive a response signal within the period T1, the stop signal transmitting unit 428 may transmit a stop signal to the control device 100.

  FIG. 4 is a diagram illustrating an example of functional blocks of the control device 100. The control device 100 includes a request signal receiving unit 102, a confirmation signal transmitting unit 103, a response signal generating unit 104, a response signal transmitting unit 106, a control unit 108, a stop signal receiving unit 110, and a relay control unit 112.

  The request signal receiving unit 102 receives a request signal from the isolated operation detection device 400. The confirmation signal transmission unit 103 transmits a confirmation signal to the isolated operation detection device 400 when the request signal can be normally received. In response to the request signal receiving unit 102 receiving the request signal, the response signal generating unit 104 generates a response signal indicating that the current output from the power conditioner 10 is changed based on the request signal. The response signal may indicate the current value of the current that the control device 100 outputs to the power conditioner 10 based on the request signal.

  The response signal transmission unit 106 transmits the response signal generated by the response signal generation unit 104 to the isolated operation detection device 400. The control unit 108 controls the inverter 40 based on the request signal to cause the inverter 40 to output reactive power corresponding to the request signal to the system power supply 300 side. For example, the control unit 108 controls each switch of the inverter 40 so that the current value indicated by the request signal is output. As a result, the current output from the inverter 40 is output with the phase difference and amplitude required from the isolated operation detection device 400 with respect to the voltage of the system power supply 300, and the required reactive power is output to the system power supply 300 side. Is done.

  The stop signal receiving unit 110 receives a stop signal from the isolated operation detection device 400. When the stop signal receiving unit 110 receives a stop signal, the relay control unit 112 electrically disconnects the inverter 40 and the system power supply 300 by opening the relay 50.

  Here, in a region where a distributed power source such as a solar cell array is widespread, when a plurality of power conditioners 10 in the region are stopped all at once, the power supply becomes unstable and may adversely affect the power quality. is there. Therefore, the power conditioner 10 may be required to satisfy the requirement of FRT (Fault Ride Through) requirement. The FRT requirement is a requirement for the operation continuity of the distributed power source when the system is disturbed, which is necessary for ensuring power quality. In order to satisfy this requirement, even if the isolated operation detection device 400 detects the isolated operation of the power conditioner 10, the control device 100 needs to continue the operation without stopping the power conditioner 10. There is a case.

  Therefore, when it is necessary to satisfy the FRT requirement, it is desirable that the isolated operation detection device 400 does not transmit a stop signal to the control device 100 even if it does not receive a response signal to the request signal from the control device 100. There is a case. Therefore, the response signal transmission unit 106 may transmit an operation continuation signal indicating that the operation of the power conditioner 10 needs to be continued instead of transmitting the response signal when it is necessary to satisfy the FRT requirement. Good. When the response signal receiving unit 422 receives an operation continuation signal instead of receiving the response signal, the stop signal transmitting unit 428 may not transmit a stop signal to the control device 100.

  Thereby, when it is necessary to satisfy the FRT requirement at the time of system disturbance, it is possible to prevent the power conditioner 10 from stopping by the isolated operation detecting device 400 transmitting a stop signal.

  FIG. 5 shows an example of a flowchart when the isolated operation detection device 400 transmits a request signal.

  For example, when the frequency deviation deriving unit 406 derives a frequency deviation based on the voltage detected via the voltage sensor 17, and the first reactive power deriving unit 408 derives reactive power corresponding to the frequency deviation, the request signal The receiving unit 102 transmits a request signal corresponding to the derived reactive power to the control device 100 (S100). Next, when the confirmation signal receiving unit 430 does not receive the confirmation signal within the period T2 after the request signal is transmitted (S102), the stop signal transmitting unit 428 stops the control device 100. A signal is transmitted (S104).

  When the response signal receiving unit 422 does not receive the response signal from the control device 100 within the period T1 after receiving the confirmation signal within the period T2 (S106), the stop signal transmitting unit 428 Then, a stop signal is transmitted to the control device 100 (S104).

  As described above, according to the present embodiment, the isolated operation detecting device 400 can confirm whether or not the control device 100 is operating normally according to the instruction from the isolated operation detecting device 400. Therefore, the isolated operation detecting device 400 can reliably confirm that the control device 100 does not supply the required reactive power to the power conditioner 10 according to the instruction of the isolated operation detecting device 400. Therefore, it is possible to prevent the power conditioner 10 from continuing to operate independently without the isolated operation detection device 400 being able to detect the isolated operation of the power conditioner 10.

  Each unit included in the isolated operation detection device 400 according to the present embodiment installs a program recorded on a computer-readable recording medium that performs various processes related to the isolated operation detection of the power conditioner 10, and installs the program on the computer. You may comprise by making it perform. That is, even if the isolated operation detecting device 400 is configured by causing the computer to execute programs that perform various processes related to the isolated operation detection of the power conditioner 10, the computer functions as each unit included in the isolated operation detecting device 400. Good.

  The computer has various memories such as CPU, ROM, RAM, EEPROM (registered trademark), communication bus, and interface, and the CPU reads out the processing program stored in the ROM as firmware in advance and sequentially executes it, thereby detecting the isolated operation. It functions as the device 400.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 Power conditioner 20 Booster circuit 40 Inverter 50 Relay 60 Transmission cable 100 Control apparatus 102 Request signal receiving part 103 Confirmation signal transmission part 104 Response signal generation part 106 Response signal transmission part 108 Control part 110 Stop signal reception part 112 Relay control part 200 Solar cell array 300 System power source 400 Isolated operation detection device 402 Frequency measurement unit 404 Moving average value deriving unit 406 Frequency deviation deriving unit 408 First reactive power deriving unit 410 Output voltage acquiring unit 412 Second reactive power deriving unit 414 Reactive power adding unit 416 Current value acquisition unit 420 Request signal transmission unit 421 Request signal registration unit 422 Response signal reception unit 424 Current value holding unit 426 Current value comparison unit 428 Stop signal transmission unit 430 Confirmation signal reception unit 432 Independent operation detection unit 440 Synchronization processing unit

Claims (11)

An isolated operation detection device for detecting isolated operation of a power conditioner linked to a system power supply,
A synchronization processing unit for receiving or transmitting a synchronization signal;
A request signal for causing the control device that controls the power conditioner to execute a process of changing the current output from the power conditioner in response to the synchronization processing unit receiving or transmitting the synchronization signal. An isolated operation detection device comprising: a request signal registration unit for registering the information in a storage unit accessible by the control device. A response signal receiving unit that receives from the control device a response signal indicating that the current output from the power conditioner is changed based on the request signal;
When the response signal receiving unit does not receive the response signal within a predetermined period after the request signal is registered in the storage unit, a stop signal for stopping the power conditioner is transmitted to the control device. The isolated operation detection device according to claim 1, further comprising a stop signal transmission unit.   When the response signal reception unit receives an operation continuation signal indicating that it is necessary to continue the operation of the power conditioner, instead of the response signal, from the control device, the stop signal transmission unit, The islanding operation detection device according to claim 2, wherein the stop signal is not transmitted even when the response signal receiving unit does not receive the response signal within the period. A current value acquisition unit for acquiring a current value of a current output from the power conditioner;
When the difference between the current value of the current to be output by the power conditioner based on the request signal and the current value acquired by the current value acquisition unit is larger than a predetermined reference difference, the power conditioner The isolated operation detection device according to any one of claims 1 to 3, further comprising: a stop signal transmission unit that transmits a stop signal for stopping the operation to the control device. A response signal receiving unit that receives from the control device a response signal indicating that the current output from the power conditioner is changed based on the request signal;
A current value acquisition unit for acquiring a current value of a current output from the power conditioner;
When the difference between the current value of the current to be output by the power conditioner based on the request signal and the current value acquired by the current value acquisition unit is larger than a predetermined reference difference, the power conditioner A stop signal transmitter for transmitting a stop signal to stop the control device to the control device,
When the response signal reception unit receives an operation continuation signal indicating that it is necessary to continue the operation of the power conditioner, instead of the response signal, from the control device, the stop signal transmission unit, The stop signal is not transmitted to the control device even when the difference between the current value of the current to be output by the power conditioner and the current value acquired by the current value acquisition unit is greater than the reference difference. The islanding operation detection device according to any one of claims 1 to 3.   A current value registering unit that associates the current value of the current to be output by the power conditioner based on the request signal and registers the current value acquired by the current value acquiring unit in a current value holding unit; The isolated operation detection device according to claim 4 or 5, further comprising: A frequency deviation derivation unit for deriving a frequency deviation of the voltage output from the inverter;
The said request signal registration part registers the said request signal for making the said control apparatus perform the process which fluctuates the electric current output from the said power conditioner according to the said frequency deviation in the said storage part. The isolated operation detection device according to any one of claims 6 to 7. An isolated operation detection device according to any one of claims 1 to 7,
An inverter interconnecting power from a distributed power source with power from the system power source;
The control device for controlling the output of the inverter,
The controller is
A request signal receiving unit for receiving the request signal stored in the storage unit;
And a control unit that controls an output of the inverter based on the request signal. A power conditioner according to claim 8;
A distributed power supply system comprising the distributed power supply.   The program for functioning a computer as an isolated operation detection apparatus as described in any one of Claims 1-7. An isolated operation detection method for detecting isolated operation of a power conditioner linked to a system power supply,
Receiving or transmitting a synchronization signal;
In response to receiving or transmitting the synchronization signal, a request signal for causing the control device that controls the power conditioner to execute a process of changing the current output from the power conditioner, And a step of registering in an accessible storage unit.

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