JP2016099192A - Ground fault detection circuit failure diagnosis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground fault detection circuit failure diagnosis device capable of determining whether the ground fault detected during power generation of a solar cell is a ground fault of the solar cell or a failure of the ground fault detection circuit.SOLUTION: A ground fault detection circuit failure diagnosis device for detecting a ground fault of a solar cell 1 comprises: a ground fault detection circuit 21 which outputs voltage based on the ground fault current detected by a zero-phase current transformer 4 which detects ground fault current from the solar cell 1; a self-diagnosis circuit 22 which diagnoses whether the ground fault detection circuit 21 is faulty when the output voltage from the ground fault detection circuit 21 during power generation of the solar cell 1 is a value indicative of a ground fault of the solar cell 1; and a control unit 23 which controls the display of the ground fault of the solar cell 1 or the failure of the ground fault detection circuit 21 on the basis of the diagnosis results of the self-diagnosis circuit 22.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ground fault detection circuit failure diagnosis device that detects a ground fault of a solar cell in a solar power generation system.

  Conventionally, some solar power generation systems include a ground fault detection circuit that detects a failure due to a ground fault of a solar cell. The ground fault detection circuit can detect the ground fault of the solar cell, but if the ground fault detection circuit itself is faulty, the solar cell will be accidentally grounded even though the solar cell is not ground fault. May be falsely detected. The following Patent Document 1 discloses a technique for self-diagnosis whether a ground fault detection circuit is faulty at the time of starting a photovoltaic power generation system and displaying an abnormality of the ground fault detection circuit when an abnormality is detected. Yes.

JP-A-9-215203

  However, according to the above-described conventional technology, even when the start-up is normal, when the ground fault detection circuit fails after the start of operation, or when the output from the ground fault detection circuit fluctuates due to a temperature change, etc. There is a problem that it cannot be determined whether or not the ground fault detection circuit is actually operating normally at the time when the ground fault is detected. Even if the ground fault detection circuit detects a fault in the ground fault detection circuit even if the ground fault detection circuit detects that the ground fault detection circuit is normal at the start-up, The ground fault will be investigated, and it will take time to find the cause of the failure.

  The present invention has been made in view of the above, and when a ground fault of a solar cell is detected during power generation of the solar cell, it is possible to determine whether the ground fault of the solar cell or the fault of the ground fault detection circuit is detected. An object is to obtain a detection circuit fault diagnosis device.

  In order to solve the above-described problems and achieve the object, the present invention is a ground fault detection circuit fault diagnosis device that detects a ground fault of a solar cell, and detects a ground fault current from the solar cell. A ground fault detection circuit that outputs a voltage based on the ground fault current detected by the current detection unit, and an output voltage from the ground fault detection circuit during power generation of the solar battery is a value indicating a ground fault of the solar battery. If there is, a self-diagnosis circuit for diagnosing whether or not the ground fault detection circuit is faulty, and indicating a ground fault of the solar cell or a fault of the ground fault detection circuit based on a diagnosis result of the self-diagnosis circuit And a control unit for performing control.

  According to the present invention, when a ground fault of a solar battery is detected during power generation of the solar battery, it is possible to determine whether the ground fault of the solar battery or the fault of the ground fault detection circuit can be determined.

The figure which shows the structural example of the solar energy power generation system provided with the ground-fault detection circuit failure diagnostic apparatus concerning embodiment of this invention. Flow chart showing operation for fault diagnosis of ground fault detection circuit Diagram showing wiring status of DC wiring and test wiring in zero phase current transformer The figure which shows the relation between the ground fault current detected by the zero phase current transformer and the output voltage from the normal ground fault detection circuit

  Hereinafter, a ground fault detection circuit failure diagnosis apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram illustrating a configuration example of a photovoltaic power generation system 100 including a ground fault detection circuit failure diagnosis device according to an embodiment of the present invention.

  The solar power generation system 100 includes a solar cell 1 that performs solar power generation and outputs DC power, a connection box 2 that connects the solar cell 1 and the power conditioner 10, and a connection box 2 and a power conditioner 10. A DC switch 3 that turns on or off the connection, and a zero-phase current transformer (ZCT) that is a DC current detection unit that detects fluctuations in a ground fault current that is a DC current due to a ground fault of the solar cell 1 ) 4, a converter 5 that boosts the voltage of the DC power from the solar cell 1, an inverter 6 that converts the DC power boosted by the converter 5 into AC power, and a filter circuit 7 that filters the AC power from the inverter 6 And an interconnection relay 8 for turning on and off the connection between the power conditioner 10 and the AC system 9, and supplying AC power to the power conditioner 10. AC system 9 that can be supplied with AC power from the power conditioner 10, a control circuit 11 that controls the operation of the power conditioner 10, and an external display 12 that displays the operating state of the photovoltaic power generation system 100. And comprising.

  In the photovoltaic power generation system 100 shown in FIG. 1, the power conditioner 10 is configured by the DC switch 3, the zero-phase current transformer 4, the converter 5, the inverter 6, the filter circuit 7, and the interconnection relay 8.

  In addition, about the zero phase current transformer 4, if the fluctuation | variation of the ground fault current of the solar cell 1 can be detected, you may use another structure. The connection between the control circuit 11 and the external display 12 may be either a wired connection or a wireless connection. Since the external display 12 only needs to acquire information necessary for display from the control circuit 11, the communication method between the control circuit 11 and the external display 12 is not particularly limited.

  The control circuit 11 constituting the ground fault detection circuit failure diagnosis device includes a ground fault detection circuit 21 that outputs a voltage based on the ground fault current detected by the zero-phase current transformer 4, and whether the ground fault detection circuit 21 is normal. The self-diagnosis circuit 22 for diagnosing the fault, the control unit 23 for performing control to display a ground fault of the solar cell 1 or a fault of the ground fault detection circuit 21 based on the diagnosis result of the self-diagnosis circuit 22, And a display unit 24 that displays a ground fault or a fault of the ground fault detection circuit 21.

  The control circuit 11 controls the operation of the converter 5, the inverter 6, and the like to control the interconnection operation with the AC system 9. However, the general operation is the same as the conventional one, and detailed description thereof is omitted. Here, in the control circuit 11, the configuration and operation necessary for the fault diagnosis of the ground fault detection circuit 21 will be described with respect to the ground fault detection circuit fault diagnosis device. In the control circuit 11, the display unit 24 may be deleted and various displays may be displayed only on the external display 12.

  Subsequently, an operation of diagnosing the fault of the ground fault detection circuit 21 in the ground fault detection circuit fault diagnosis apparatus will be described. FIG. 2 is a flowchart showing an operation for diagnosing a fault in the ground fault detection circuit 21. First, in the solar power generation system 100, when solar radiation is obtained, the solar cell 1 starts power generation by sunlight and outputs DC power. When the power generated by the solar cell 1 increases to such an extent that the power conditioner 10 can be operated, the power conditioner 10 starts a control power source (not shown) for operating the control circuit 11 (step S1).

  After the control power supply of the power conditioner 10 is started, the control circuit 11 performs self-diagnosis of the ground fault detection circuit 21 (step S2). Here, a method for performing the self-diagnosis of the ground fault detection circuit 21 will be described. FIG. 3 is a diagram illustrating a wiring state of the DC wiring 41 and the test wiring 42 in the zero-phase current transformer 4. FIG. 4 is a diagram showing the relationship between the ground fault current detected by the zero-phase current transformer 4 and the output voltage from the normal ground fault detection circuit 21. The ground fault detection circuit 21 outputs a voltage with the characteristics shown in FIG. 4 with respect to the magnitude of the ground fault current detected by the zero-phase current transformer 4.

  In FIG. 3, a DC wiring 41 indicates a wiring between the DC switch 3 and the converter 5 illustrated in FIG. 1, and a test wiring 42 is a wiring for flowing a test current from the self-diagnosis circuit 22. Both the DC wiring 41 and the test wiring 42 are wirings that penetrate the zero-phase current transformer 4. The self-diagnosis method of the ground fault detection circuit 21 in the control circuit 11 is based on the output voltage from the ground fault detection circuit 21 when the self-diagnosis circuit 22 changes the test current passed through the test wiring 42. It is determined whether the circuit 21 is normal.

  The self-diagnosis circuit 22 outputs the output voltage from the ground fault detection circuit 21 corresponding to the ground fault current 0 mA detected by the zero-phase current transformer 4 in a state where the test current is 0 mA, that is, the test current is not passed through the test wiring 42. Measure. The self-diagnosis circuit 22 diagnoses that the offset of the ground fault detection circuit 21 is normal when the output voltage from the ground fault detection circuit 21 is 2.5 V corresponding to the ground fault current 0 mA of FIG. On the other hand, the self-diagnosis circuit 22 diagnoses that the ground fault detection circuit 21 is abnormal when the output voltage from the ground fault detection circuit 21 is not less than a specified value from 2.5 V, and is based on the initial setting failure or the like. Judged as an offset failure.

  The self-diagnosis circuit 22 measures the output voltage from the ground fault detection circuit 21 corresponding to the ground fault current +50 mA detected by the zero-phase current transformer 4 in a state where a test current of +50 mA is passed through the test wiring 42. To do. The self-diagnosis circuit 22 diagnoses that the gain of the ground fault detection circuit 21 is normal when the output voltage from the ground fault detection circuit 21 is 3.5 V corresponding to the ground fault current +50 mA in FIG. On the other hand, the self-diagnosis circuit 22 diagnoses that the ground fault detection circuit 21 is abnormal when the output voltage from the ground fault detection circuit 21 is not less than a specified value from 3.5 V, and the zero-phase current transformer 4 The detected variable current value is converted into a correct voltage value and determined as a gain failure that cannot be output.

  The self-diagnosis circuit 22 outputs an output voltage from the ground fault detection circuit 21 corresponding to the ground fault current of −50 mA detected by the zero-phase current transformer 4 in a state where a test current of −50 mA is passed through the test wiring. Measure. The self-diagnosis circuit 22 diagnoses that the gain of the ground fault detection circuit 21 is normal when the output voltage from the ground fault detection circuit 21 is 1.5 V corresponding to the ground fault current of −50 mA in FIG. On the other hand, if the output voltage from the ground fault detection circuit 21 deviates by more than a specified value from 1.5V, the self-diagnosis circuit 22 diagnoses the ground fault detection circuit 21 as abnormal and determines that it is a gain failure.

  When the output voltage characteristic of the ground fault detection circuit 21 that is normal with respect to the current detected by the zero-phase current transformer 4 is a straight line as shown in FIG. 4, the self-diagnosis circuit 22 determines whether the gain is normal. In the measurement for determining whether or not a test current of +50 mA is applied to the test wiring 42 or a test current of −50 mA is applied to the test wiring 42, only one measurement is performed and the other measurement is omitted. Also good. In the self-diagnosis circuit 22, a current value other than +50 mA or −50 mA may be used as the test current flowing through the test wiring 42. Since the self-diagnosis circuit 22 only needs to be able to confirm the characteristics shown in FIG. 4 for the ground fault detection circuit 21, the gain can be confirmed using a test current other than 0 mA.

  Returning to the flowchart of FIG. When the ground fault detection circuit 21 is normal as a result of the diagnosis in the self-diagnosis circuit 22 (step S3: Yes), the control unit 23 notifies the self-diagnosis circuit 22 that the ground fault detection circuit 21 is normal. In response, the converter 5 and the inverter 6 are operated, the interconnection relay 8 is turned on, AC power is output to the AC system 9, and the interconnection operation is started (step S4).

  After starting the interconnection operation, the self-diagnosis circuit 22 and the control unit 23 monitor the output voltage from the ground fault detection circuit 21 to confirm whether or not the ground fault of the solar cell 1 has been detected (step S5). Here, corresponding to the characteristics shown in FIG. 4, when the current level in the zero-phase current transformer 4 is greater than −50 mA and less than +50 mA, the solar cell 1 is not grounded, that is, the ground fault detection circuit 21. When the output voltage from is greater than 1.5V and less than 3.5V, it is assumed that the solar cell 1 is not grounded. When the output voltage from the ground fault detection circuit 21 is greater than 1.5V and less than 3.5V, the self-diagnosis circuit 22 and the control unit 23 determine that the solar cell 1 is not grounded (No in step S5). The monitoring of the output voltage from the ground fault detection circuit 21 is continued. While the ground fault of the solar cell 1 is not detected, the control unit 23 continues the interconnection operation with the AC system 9.

  The self-diagnosis circuit 22 and the control unit 23 determine that the ground fault of the solar cell 1 has been detected when the output voltage from the ground fault detection circuit 21 is 1.5 V or less or 3.5 V or more (step S5: Yes). .

  When the ground fault of the solar cell 1 is detected (step S5: Yes), the control unit 23 turns off the interconnection relay 8 and stops the interconnection operation with the AC system 9 (step S6).

  When the self-diagnosis circuit 22 detects a ground fault of the solar cell 1 (step S5: Yes), the self-diagnosis circuit 22 performs a self-diagnosis of the ground fault detection circuit 21 after receiving notification of the interconnection operation stop from the control unit 23 (step S5). S7). The self-diagnosis method in the control circuit 11 is the same as that in step S2.

  As a result of self-diagnosis, the self-diagnosis circuit 22 has a normal output voltage from the ground fault detection circuit 21 when the test current of the test wiring 42 is 0 mA, that is, the offset of the ground fault detection circuit 21 is normal (step S8: Yes), when the output voltage from the ground fault detection circuit 21 is normal when the test current of the test wiring 42 is +50 mA or −50 mA, that is, the gain of the ground fault detection circuit 21 is normal (step S9: Yes), the ground fault The detection circuit 21 notifies the control unit 23 that it is normal.

  The control unit 23 receives a notification from the self-diagnosis circuit 22 and determines that the solar cell 1 is grounded because the ground fault detection circuit 21 is normal, and the solar cell 1 is displayed on the external display 12 and the display unit 24. 1 ground fault is displayed (step S10). Although the method for displaying the ground fault of the solar cell 1 on the external indicator 12 and the display unit 24 by the control unit 23 includes a method of displaying an error code, for example, “E-29”, it is not limited to this. The control unit 23 may display the ground fault of the solar cell 1 either by the external display 12 or the display unit 24.

  The self-diagnosis circuit 22 determines that the output voltage from the ground fault detection circuit 21 is abnormal when the test current of the test wiring 42 is 0 mA, that is, the offset of the ground fault detection circuit 21 is abnormal (step). S8: No), it is determined that the ground fault detection circuit 21 has an offset fault (step S11), and the control unit 23 is notified of the offset fault of the ground fault detection circuit 21.

  The control unit 23 receives the notification from the self-diagnosis circuit 22, and displays the failure of the ground fault detection circuit 21 on the external display 12 and the display unit 24 (step S13). There is a method in which the control unit 23 displays a failure of the ground fault detection circuit 21 on the external display 12 and the display unit 24, but there is a method of displaying an error code, for example, “E-31”, but is not limited thereto. . The control unit 23 may display the failure of the ground fault detection circuit 21 either in the external display 12 or the display unit 24.

  In addition, the control unit 23 can display not only that the ground fault detection circuit 21 is faulty but also display that the ground fault detection circuit 21 is faulty. The control unit 23 receives notification from the self-diagnosis circuit 22 that the ground fault detection circuit 21 has an offset failure. Therefore, for example, when an operation that cannot be easily performed by a general user is received from a service person corresponding to the failure repair, the control unit 23 displays “E3100” indicating the offset failure by further displaying “E-31”. It can be displayed on the external display 12 and the display unit 24. The control unit 23 may display “E3100” from the beginning.

  As a result of self-diagnosis, the self-diagnosis circuit 22 has a normal output voltage from the ground fault detection circuit 21 when the test current of the test wiring 42 is 0 mA, that is, the offset of the ground fault detection circuit 21 is normal (step S8). : Yes), when the output voltage from the ground fault detection circuit 21 when the test current of the test wiring 42 is +50 mA or −50 mA is abnormal, that is, the gain of the ground fault detection circuit 21 is abnormal (step S9: No). Then, it is determined that there is a gain failure in the ground fault detection circuit 21 (step S12), and the control unit 23 is notified of the gain failure in the ground fault detection circuit 21.

  The control unit 23 receives the notification from the self-diagnosis circuit 22, and displays the failure of the ground fault detection circuit 21 on the external display 12 and the display unit 24 (step S13). There is a method in which the control unit 23 displays a failure of the ground fault detection circuit 21 on the external display 12 and the display unit 24, but there is a method of displaying an error code, for example, “E-31”, but is not limited thereto. . The control unit 23 may display the failure of the ground fault detection circuit 21 either in the external display 12 or the display unit 24.

  Further, the control unit 23 can not only display that the ground fault detection circuit 21 has failed, but can also display that the ground fault detection circuit 21 has failed. The control unit 23 receives a notification from the self-diagnosis circuit 22 that the ground fault detection circuit 21 has a gain failure. Therefore, for example, when an operation that cannot be easily performed by a general user is received from a service person corresponding to the failure repair, the control unit 23 displays “E- 311” indicating the gain failure by further displaying “E-31”. It can be displayed on the external display 12 and the display unit 24. The control unit 23 may display “E3101” from the beginning.

  In the flowchart of FIG. 2, when the ground fault detection circuit 21 is abnormal (step S <b> 3: No) as a result of the self-diagnosis (step S <b> 2) after starting the control power supply of the power conditioner 10, the self-diagnosis circuit 22 Determines whether the ground fault detection circuit 21 has an offset fault or a gain fault by the operation after step S8 and notifies the control unit 23 of it. Then, the control unit 23 causes the external display 12 and the display unit 24 to display a fault of the ground fault detection circuit 21, and further an offset fault or a gain fault.

  As described above, according to the present embodiment, in the control circuit 11, the output voltage from the ground fault detection circuit 21 based on the DC current detected by the zero-phase current transformer 4 during power generation of the solar cell 1. Is a value indicating the ground fault of the solar cell 1, the self-diagnosis circuit 22 performs a self-diagnosis as to whether the ground fault detection circuit 21 has failed, and as a result of the self-diagnosis, the solar cell 1 has a ground fault. Or the ground fault detection circuit 21 is notified to the control unit 23, and the control unit 23 indicates the ground fault of the solar cell 1 or the fault of the ground fault detection circuit 21 by the display unit 24 and the external indicator 12. It was decided to display. In the control circuit 11, the output voltage from the ground fault detection circuit 21 indicates the ground fault of the solar cell 1 during the power generation of the solar cell 1, that is, during the operation of the power conditioner 10 in addition to the start of the operation of the power conditioner 10. Even if it is a value, a self-diagnosis is performed to determine whether the ground fault detection circuit 21 has failed, and it is determined whether the solar cell 1 has a ground fault or the ground fault detection circuit 21 has failed. To do. As a result, a user, a service person who handles repairs, and the like can determine whether the ground fault of the solar battery 1 or the fault of the ground fault detection circuit 21 can be detected, so that the failure can be detected at an early stage and repairs can be performed quickly.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  DESCRIPTION OF SYMBOLS 1 Solar cell, 2 Junction box, 3 DC switch, 4 Zero phase current transformer, 5 Converter, 6 Inverter, 7 Filter circuit, 8 interconnection relay, 9 AC system, 10 Power conditioner, 11 Control circuit, 12 External Display, 21 Ground fault detection circuit, 22 Self-diagnosis circuit, 23 Control unit, 24 Display unit, 100 Solar power generation system.

Claims (3)

A ground fault detection circuit fault diagnosis device for detecting a ground fault of a solar cell,
A ground fault detection circuit that outputs a voltage based on the ground fault current detected by a ground fault current detection unit that detects a ground fault current from the solar cell;
A self-diagnosis circuit for diagnosing whether or not the ground fault detection circuit is faulty when an output voltage from the ground fault detection circuit is a value indicating a ground fault of the solar cell during power generation of the solar power generation system; ,
Based on the diagnosis result of the self-diagnosis circuit, a control unit that performs control to display a ground fault of the solar cell or a fault of the ground fault detection circuit;
A ground fault detection circuit fault diagnosis device comprising: The self-diagnosis circuit controls a test current passed through the DC current detection unit, and the fault of the ground fault detection circuit is an offset fault due to an abnormality in the output voltage when the DC current is zero, or the DC current To determine if the gain is faulty due to an abnormality in the output voltage when is non-zero,
The control unit performs control to display an offset failure or a gain failure of the ground fault detection circuit based on a determination result of the self-diagnosis circuit.
The ground fault detection circuit failure diagnosis apparatus according to claim 1. The self-diagnosis circuit performs control to perform diagnosis of the ground fault detection circuit while the photovoltaic power generation system is stopped.
The ground fault detection circuit failure diagnosis apparatus according to claim 1 or 2, wherein the ground fault detection circuit fault diagnosis apparatus is provided.

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