WO2015166699A1 - Ground fault detection device, power supply system, and ground fault detection method - Google Patents

Ground fault detection device, power supply system, and ground fault detection method Download PDF

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Publication number
WO2015166699A1
WO2015166699A1 PCT/JP2015/055549 JP2015055549W WO2015166699A1 WO 2015166699 A1 WO2015166699 A1 WO 2015166699A1 JP 2015055549 W JP2015055549 W JP 2015055549W WO 2015166699 A1 WO2015166699 A1 WO 2015166699A1
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WIPO (PCT)
Prior art keywords
current value
ground fault
solar cell
output terminal
reference potential
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PCT/JP2015/055549
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French (fr)
Japanese (ja)
Inventor
康介 森田
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オムロン株式会社
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Publication of WO2015166699A1 publication Critical patent/WO2015166699A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • the present invention relates to a ground fault detection device, a power supply system, and a ground fault detection method.
  • Patent Document 1 an insulation resistance value of a solar cell array or a solar cell string is calculated in a state where the solar cell array or the solar cell string is disconnected, and the solar cell array or the solar cell is calculated based on the calculated insulation resistance value.
  • a ground fault detection device for detecting a ground fault of a string is disclosed.
  • the insulation resistance value of a DC power source such as a solar cell may fluctuate due to environmental changes such as weather. Therefore, there is a possibility that the ground fault of the DC power supply cannot be accurately detected.
  • a ground fault detection device is a ground fault detection device that detects ground faults of a plurality of DC power sources connected in series, and includes a first DC power source and a first DC power source included in the plurality of DC power sources.
  • a connection point with a second DC power source connected in series with the DC power source is connected to a reference potential point through a resistor having a predetermined resistance value, and the first output terminals of the plurality of DC power sources are used as reference potential points.
  • a first current value acquisition unit that acquires a first current value indicating a current flowing through the first output terminal, a connection point not connected to a reference potential point via a resistor, and a first output terminal
  • a second current value acquisition unit for acquiring a second current value indicating a current flowing through the first output terminal in a state of being connected to the reference potential point, and connecting the connection point to the reference potential point via a resistor; Is not connected to the reference potential point through the resistor, and the second output terminals of the plurality of DC power supplies are used as the reference potential point.
  • a third current value acquisition unit that acquires a third current value indicating the current flowing through the second output terminal in the connected state
  • a ground fault detector for detecting ground faults of a plurality of DC power supplies.
  • the ground fault detection device connects the first switching means for switching whether or not the connection point is connected to the reference potential point via a resistor, and connects either the first output terminal or the second output terminal to the reference potential point. You may further provide the 2nd switching means which switches whether to do.
  • the ground fault detection unit is configured to determine the first time at the first time point of the plurality of DC power sources based on the resistance value, the first current value, the second current value, and the third current value at the first time point.
  • a ground fault resistance value is derived, and based on the resistance value, the first current value, the second current value, and the third current value at a second time point after the first time point, Two ground fault resistance values may be derived, and ground faults of a plurality of DC power supplies may be detected based on the first ground fault resistance value and the second ground fault resistance value.
  • each of the plurality of DC power supplies may be a solar cell.
  • a power supply system includes the above ground fault detection device, a plurality of DC power sources, and a load device that consumes or converts power supplied from the plurality of DC power sources.
  • Third switching means for switching between connecting or disconnecting the plurality of DC power supplies and the load device is further provided, and the third switching means electrically disconnects the plurality of DC power supplies and the load device.
  • the first current value acquisition unit acquires a first current value indicating the current flowing through the first output terminal
  • the second current value acquisition unit acquires the second current value indicating the current flowing through the first output terminal.
  • the third current value acquisition unit acquires a third current value indicating a current flowing through the second output end.
  • a ground fault detection method is a ground fault detection method for detecting ground faults of a plurality of DC power sources connected in series, and includes a first DC power source and a first DC power source included in the plurality of DC power sources.
  • a connection point with a second DC power source connected in series with the DC power source is connected to a reference potential point through a resistor having a predetermined resistance value, and the first output terminals of the plurality of DC power sources are used as reference potential points.
  • a connected state In a connected state, obtaining a first current value indicating a current flowing through the first output terminal, connecting the connection point to the reference potential point via a resistor, and connecting the first output terminal to the reference potential point
  • the second current value indicating the current flowing through the first output terminal is obtained, and the connection point is connected to the reference potential point through the resistor, or the connection point is connected to the reference potential point through the resistor.
  • the second output Obtaining a third current value indicating a current flowing through the first current value, and detecting a ground fault of the plurality of DC power sources based on the resistance value, the first current value, the second current value, and the third current value.
  • FIG. 1 shows the circuit structure of the solar cell in 1st electric current value detection conditions in case the ground fault has arisen in the connection point between the solar cell module of the lowest potential side, and the solar cell module of the 2nd lowest potential side. It is. The figure which shows the circuit structure of the solar cell in 2nd electric current value detection conditions in case the ground fault has arisen in the connection point between the solar cell module of the lowest potential side, and the solar cell module of the 2nd lowest potential side. It is.
  • FIG. 1 shows an example of the overall configuration of a photovoltaic power generation system including a ground fault detection device 30 according to the present embodiment.
  • the solar cell 10 including the solar cell 10, the power conversion device 20, and the ground fault detection device 30 may be a solar cell string having a plurality of solar cell modules 12 connected in series.
  • the solar cell 10 will be described with respect to an example in which ten solar cell modules 12 are connected in series.
  • Solar cell 10 is an example of a DC power source.
  • a solar power generation system is an example of a power supply system.
  • the power converter 20 converts the power output from the solar cell 10.
  • the power converter 20 may be a power conditioner that boosts the direct current from the solar cell 10, converts the boosted direct current to alternating current, and links the system power supply.
  • the power conversion device 20 is an example of a load device that consumes or converts power output from the solar cell 10.
  • the ground fault detection device 30 derives a ground fault resistance value between the solar cell 10 and the ground point that is a reference potential point, and when the derived ground fault resistance value is smaller than the reference ground fault resistance value, the ground fault is detected. Is determined to have occurred.
  • the ground fault detection device 30 includes a cutting means 32, a switch 34, a switch 35, a switch 36, a detection resistor 40, an additional resistor 42, a voltage sensor 44, a current sensor 46, and a control unit 100.
  • the cutting means 32 is provided between the solar cell 10 and the power conversion device 20, and electrically disconnects the solar cell 10 and the power conversion device 20.
  • the cutting means 32 includes a relay 32a provided between an output terminal on the high potential side of the solar cell 10 and an input terminal on the high potential side of the power conversion device 20, an output terminal on the low potential side of the solar cell 10, And a relay 32b provided between the input terminal on the low potential side of the power conversion device 20.
  • the relays 32a and 32b may be relays having a b-contact that electrically disconnects the solar cell 10 and the power conversion device 20 when an operation signal is input.
  • the output terminal on the low potential side of the solar cell 10 is an example of a first output terminal.
  • the output terminal on the high potential side of the solar cell 10 is an example of the second output terminal.
  • the high potential side relay 32a of the cutting means 32 and the high potential side output terminal of the solar cell 10 are connected via a high potential side electric wire L1.
  • the low potential side relay 32b of the cutting means 32 and the low potential side output terminal of the solar cell 10 are connected via a low potential side electric wire L2.
  • One end of the switch 34 is connected to the electric wire L1 on the high potential side, and the other end of the switch 34 is connected to one end of the detection resistor 40.
  • One end of the switch 35 is connected to the electric wire L ⁇ b> 2 on the low potential side, and the other end of the switch 35 is connected to one end of the detection resistor 40. The other end of the detection resistor 40 is grounded.
  • the switch 34 and the switch 35 are an example of second switching means for switching whether or not one of the output terminal on the low potential side of the solar cell 10 and the output terminal on the high potential side of the solar cell 10 is connected to the reference potential point. It is.
  • the solar cell 10 includes a solar cell module 12a and a solar cell module 12b connected to a connection point 14 that is a midpoint of the solar cell 10.
  • the solar cell module 12a is an example of a first DC power source
  • the solar cell module 12b is an example of a second DC power source.
  • the resistance connected to the connection point 14 indicates the insulation resistance 200 of the entire solar cell 10 in a pseudo manner. In the present embodiment, it is assumed that the insulation resistance 200 is connected to the midpoint of the solar cell 10. However, the position where the insulation resistance 200 is assumed to be connected may be changed according to the electrical characteristics of the solar cell 10.
  • the switch 36 is an example of a first switching unit that switches whether the connection point 14 is connected to the reference potential point via the additional resistor 42.
  • the other end of the additional resistor 42 is grounded.
  • the additional resistor 42 is an example of a resistor having a predetermined resistance value.
  • the additional resistor 42 has a known resistance value Rc. In the present embodiment, an example in which the additional resistor 42 is connected to the connection point 14 that is the midpoint of the solar cell 10 will be described. However, the additional resistor 42 may be connected to a connection point between other solar cell modules included in the solar cell 10.
  • the voltage sensor 44 detects the voltage value Vo of the voltage output from the solar cell 10.
  • the current sensor 46 is configured so that the high potential output terminal of the solar cell 10 or the low potential output terminal of the solar cell 10 is connected to a ground point via the switch 34 or the switch 35. The current value of the current output from the output terminal on the potential side or the output terminal on the low potential side of the solar cell 10 is detected.
  • the control unit 100 controls the relay operation of the cutting means 32.
  • the control unit 100 controls the switching operations of the switch 34, the switch 35, and the switch 36. Further, the control unit 100 derives the ground fault resistance value Ra of the solar cell 10 based on the voltage value Vo detected by the voltage sensor 44 and the current value detected by the current sensor 46, and sets the ground fault resistance value Ra to the ground fault resistance value Ra. Based on this, the presence or absence of the ground fault of the solar cell 10 is detected.
  • the control unit 100 may determine that a ground fault has occurred in the solar cell 10 when the ground fault resistance value Ra is smaller than the reference ground fault resistance value.
  • FIG. 2 is a diagram illustrating an example of functional blocks of the control unit 100.
  • the control unit 100 includes a relay control unit 102, a switch control unit 104, a voltage value acquisition unit 106, a current value acquisition unit 108, and a ground fault detection unit 110.
  • Each unit included in the control unit 100 is stored in a computer-readable recording medium, and can be configured by installing a program for performing various processes related to detection of a ground fault of the solar battery 10 and causing the computer to execute the program.
  • the ground fault detection device 30 may be configured by causing a computer to function as each unit included in the control unit 100 by executing a program that performs various processes relating to detection of the ground fault of the solar cell 10.
  • the computer has various memories such as a CPU, ROM, RAM, and EEPROM (registered trademark), a communication bus, and an interface.
  • the CPU reads and sequentially executes a processing program stored in the ROM as firmware in advance, thereby causing a ground fault. It functions as the detection device 30.
  • the relay control unit 102 outputs an operation signal to the cutting means 32 at a predetermined timing at which a ground fault of the solar cell 10 is to be detected, and electrically disconnects the solar cell 10 and the power conversion device 20 from each other. To do.
  • the relay control unit 102 may output an operation signal to the disconnecting unit 32 before the power conversion device 20 is started after the power from the solar cell 10 reaches the reference power in the morning.
  • the relay control part 102 may output an operation signal to the cutting
  • the switch control unit 104 controls on / off of the switch 34, the switch 35, and the switch 36.
  • the switch control unit 104 turns off the switch 34, turns on the switch 35, and turns on the switch 36 under the first current value detection condition.
  • the switch control unit 104 turns off the switch 34, turns on the switch 36, and turns off the switch 36 under the second current value detection condition.
  • the switch control unit 104 turns on the switch 34, turns off the switch 35, and turns on the switch 36 under the third current value detection condition.
  • the switch control unit 104 turns on the switch 34, turns off the switch 35, and turns off the switch 36 under the fourth current value detection condition.
  • the voltage value acquisition unit 106 acquires the voltage value Vo of the voltage output from the solar cell 10 via the voltage sensor 44.
  • the current value acquisition unit 108 is a low potential of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned off, the switch 35 is turned on, and the switch 36 is turned on by the switch control unit 104 under the first current value detection condition.
  • the first current value IA indicating the current output from the output terminal on the side is acquired.
  • the current value acquisition unit 108 sets the connection point 14 between the solar cell module 12a and the solar cell module 12b connected in series to the solar cell module 12a as a reference potential point via an additional resistor 42 having a predetermined resistance value Ra.
  • a first current value for obtaining a first current value indicating a current flowing through the output terminal on the low potential side of the solar cell 10 in a state where the low potential side output terminal of the solar cell 10 is connected to the reference potential point It is an example of an acquisition part.
  • the current value acquisition unit 108 is connected to the low potential of the solar cell 10 via the current sensor 46 in a state where the switch 34 is turned off, the switch 35 is turned on, and the switch 36 is turned off by the switch control unit 104 under the second current value detection condition.
  • the second current value IB indicating the current output from the output terminal on the side is acquired.
  • the current value acquisition unit 108 does not connect the connection point 14 to the reference potential point via the additional resistor 42 and connects the output terminal on the low potential side of the solar cell 10 to the reference potential point.
  • It is an example of the 2nd electric current value acquisition part which acquires the 2nd electric current value which shows the electric current which flows into an output terminal.
  • the current value acquisition unit 108 has a high potential of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned on, the switch 35 is turned off, and the switch 36 is turned on by the switch control unit 104 under the third current value detection condition.
  • the third current value IC indicating the current output from the output terminal on the side is acquired.
  • the current value acquisition unit 108 has a high potential of the solar cell 10 via the current sensor 46 in a state where the switch 34 is turned on, the switch 35 is turned off, and the switch 36 is turned off by the switch control unit 104 under the fourth current value detection condition.
  • the fourth current value ID indicating the current output from the output terminal on the side is acquired.
  • the current value acquisition unit 108 connects the connection point 14 to the reference potential point via the additional resistor 42, or does not connect the connection point 14 to the reference potential point via the additional resistor 42, and the high potential of the solar cell 10.
  • 4 is an example of a third current value acquisition unit that acquires a third current value indicating a current flowing through an output terminal on the high potential side of the solar cell 10 in a state where the output terminal on the side is connected to a reference potential point.
  • the ground fault detection unit 110 includes the voltage value Vo acquired by the voltage value acquisition unit 106, the first current value IA, the second current value IB, the third current value IC, and the fourth current value acquired by the current value acquisition unit 108. Based on at least three current values of ID, the presence or absence of a ground fault of the solar cell 10 is detected.
  • the ground fault detection unit 110 is connected to the ground of the solar cell 10 based on the voltage value Vo and at least three current values of the first current value IA, the second current value IB, the third current value IC, and the fourth current value ID.
  • the fault resistance value is derived, and when the derived ground fault resistance value is smaller than the reference ground fault resistance value, it may be determined that the ground fault of the solar cell 10 has occurred.
  • 3A, 3B, 3C, and 3D show a case where a ground fault occurs at the connection point between the solar cell module 12c on the lowest potential side and the solar cell module 12d on the second lowest potential side.
  • the circuit structure of the solar cell 10 is shown.
  • FIG. 3A shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned off, the switch 35 is turned on, and the switch 36 is turned on under the first current value detection condition.
  • the first current value IA output from the output terminal on the low potential side of the solar cell 10 is the current flowing through the combined resistance of the additional resistor 42 and the insulation resistor 200 represented by Expression (1).
  • a current value I2a indicating a current flowing through the ground fault resistance 300 represented by the equation (2).
  • I1a 5Va / R (1)
  • I2a Va / Ra (2)
  • Va represents the voltage value of the voltage at both ends of one solar cell module 12.
  • Va Vo / 10.
  • R is a combined resistance of the additional resistor 42 and the insulation resistor 200.
  • R Rb ⁇ Rc / (Rb + Rc).
  • Ra represents the resistance value of the ground fault resistance 300.
  • FIG. 3B shows a circuit configuration of the solar cell 10 in a state where the switch controller 104 is turned off, the switch 35 is turned on, and the switch 36 is turned off under the second current value detection condition.
  • the first current value IB output from the output terminal on the low potential side of the solar cell 10 is the current value I1b indicating the current flowing through the insulation resistor 200 shown by the formula (4), and the formula This is the total of the current value I2b indicating the current flowing through the ground fault resistance 300 indicated by (5).
  • I1b 5Va / Rb (4)
  • I2b Va / Ra (5)
  • FIG. 3C shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is on, the switch 35 is off, and the switch 36 is on under the third current value detection condition.
  • the third current value IC output from the output terminal on the high potential side of the solar cell 10 is a current value I1c indicating a current flowing through the ground fault resistor 300 represented by Expression (7), This is the total of the current value I3c indicating the current flowing through the combined resistance of the additional resistance 42 and the insulation resistance 200 represented by Expression (8).
  • I1c 9Va / Ra (7)
  • I3c 5Va / R (8)
  • FIG. 3D shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned on, the switch 35 is turned off, and the switch 36 is turned off under the fourth current value detection condition.
  • the fourth current value ID output from the output terminal on the high potential side of the solar cell 10 is the current value I1d indicating the current flowing through the insulation resistance 200 shown by the equation (10), and the equation This is the total of the current value I3d indicating the current flowing through the ground fault resistance 300 indicated by (11).
  • the ground fault detection unit 110 derives the resistance value Ra of the ground fault resistance 300 using the formulas (3), (6), (9), and (12).
  • the ground fault detection unit 110 performs the expressions (3), (6), (9), and
  • the resistance value Ra of the ground fault resistor 300 can be derived using any two of the equations (12).
  • FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D are the connection points between the X (X ⁇ 5) th solar cell module and the (X + 1) th solar cell module from the lowest potential side of the ground fault.
  • the circuit configuration of the solar cell 10 when it occurs is shown.
  • FIG. 4A shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned off, the switch 35 is turned on, and the switch 36 is turned on under the first current value detection condition.
  • the first current value IA output from the output terminal on the low potential side of the solar cell 10 is the current flowing through the combined resistance of the additional resistor 42 and the insulation resistor 200 represented by the equation (20).
  • I1a 5Va / R (20)
  • I2a X ⁇ Va / Ra (21)
  • FIG. 4B shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned off, the switch 35 is turned on, and the switch 36 is turned off under the second current value detection condition.
  • the first current value IB output from the output terminal on the low potential side of the solar cell 10 is the current value I1b indicating the current flowing through the insulation resistor 200 shown by the equation (23), and the equation This is the total of the current value I2b indicating the current flowing through the ground fault resistance 300 indicated by (24).
  • I1b 5Va / Rb (23)
  • I2b X ⁇ Va / Ra (24)
  • FIG. 4C shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned on, the switch 35 is turned off, and the switch 36 is turned on under the third current value detection condition.
  • the third current value IC output from the output terminal on the high potential side of the solar cell 10 is a current value I1c indicating the current flowing through the ground fault resistor 300 represented by the equation (26), This is the sum of the current value I3c indicating the current flowing through the combined resistance of the additional resistance 42 and the insulation resistance 200 represented by Expression (27).
  • I1c (5 + 5-X) Va / Ra (26)
  • I3c 5Va / R (27)
  • FIG. 4D shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned on, the switch 35 is turned off, and the switch 36 is turned off under the fourth current value detection condition.
  • the fourth current value ID output from the output terminal on the high potential side of the solar cell 10 is the current value I1d indicating the current flowing through the insulation resistor 200 shown by the equation (29), and the equation This is the total of the current value I3d indicating the current flowing through the ground fault resistance 300 indicated by (30).
  • I1d (5 + 5-X) Va / Ra (29)
  • I3d 5Va / Rb (30)
  • the ground fault detection unit 110 derives the resistance value Ra of the ground fault resistance 300 using the formula (22), the formula (25), the formula (28), and the formula (31).
  • the ground fault detection unit 110 performs the expressions (22), (25), and (28).
  • the resistance value Ra of the ground fault resistor 300 can be derived using any three of the equations (31) and (31).
  • connection point between any two solar cell modules 12 constituting the solar cell 10 is connected to the ground point that is the reference potential point via the resistor having a known resistance value, and is connected.
  • the ground fault detection unit 110 can derive the resistance value Ra of the ground fault resistance 300 using any three of the four simultaneous equations.
  • the ground fault detection unit 110 regards the combined resistance obtained by combining the insulation resistance 200 and the ground fault resistance 300 as the insulation resistance of the solar cell 10, and the resistance value of the combined resistance is smaller than the reference resistance value, It may be determined that a ground fault of the solar cell 10 has occurred.
  • the resistance value of the insulation resistance 200 varies depending on environmental changes such as temperature. For example, the resistance value of the insulation resistance 200 on a rainy day may be lower than the resistance value of the insulation resistance 200 when a dry sunny day continues. Therefore, when the ground fault detection unit 110 determines the presence or absence of a ground fault based on the combined resistance obtained by synthesizing the insulation resistance 200 and the ground fault resistance 300, the ground fault detection unit 110 includes the insulation resistance 200 according to the environmental change.
  • the change in the resistance value of the solar cell 10 and the change in the resistance value of the ground fault resistor 300 as the deterioration of the solar cell 10 progresses cannot be distinguished. Therefore, when the ground fault detection unit 110 determines the presence / absence of a ground fault based on the combined resistance obtained by combining the insulation resistance 200 and the ground fault resistance 300, the accuracy of the determination of the presence / absence of the ground fault of the solar cell 10 may be reduced. There is sex.
  • the ground fault detection unit 110 distinguishes between the insulation resistance 200 and the ground fault resistance 300, and determines the presence or absence of the ground fault of the solar cell 10 based on the resistance value of the ground fault resistance 300. Yes. Therefore, according to the present embodiment, even when the resistance value of the insulation resistance 200 changes due to a change in the environment, it is possible to prevent the accuracy of the determination of the presence or absence of the ground fault of the solar cell 10 by the ground fault detection unit 110 from being lowered. it can.
  • FIG. 5 is a flowchart illustrating an example of a procedure in which the ground fault detection device 30 detects a ground fault of the solar cell 10.
  • the relay control unit 102 outputs an operation signal to the cutting means 32 at a predetermined timing at which a ground fault of the solar cell 10 is to be detected, operates the relay 32a and the relay 32b, and the solar cell 10 and the power conversion device. Electrically cuts off from 20 (S100).
  • the voltage value acquisition unit 106 acquires the voltage value Vo of the voltage output from the solar cell 10 via the voltage sensor 44 (S102).
  • the switch control unit 104 turns off the switch 34 and turns on the switch 35 to connect the output terminal on the low potential side of the solar cell 10 to the ground point that is the reference potential point (S104).
  • the switch control unit 104 turns on the switch 36 to connect the connection point 14 that is the midpoint of the solar cell 10 to the reference potential point via the additional resistor 42 (S106).
  • the current value acquisition unit 108 is output from the output terminal on the low potential side of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned off, the switch 35 is turned on, and the switch 36 is turned on by the switch control unit 104.
  • the first current value IA indicating the current to be acquired is acquired (S108).
  • the switch control unit 104 turns off the switch 36 (S110).
  • the current value acquisition unit 108 is output from the output terminal on the low potential side of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned off, the switch 35 is turned on, and the switch 36 is turned off by the switch control unit 104.
  • the second current value IB indicating the current to be acquired is acquired (S112).
  • the switch control unit 104 turns on the switch 34 and turns off the switch 35 to connect the output terminal on the high potential side of the solar cell 10 to the ground point that is the reference potential point (S114). Further, the switch control unit 104 turns on the switch 36 to connect the connection point 14 that is the midpoint of the solar cell 10 to the reference potential point via the additional resistor 42 (S116).
  • the current value acquisition unit 108 is output from the output terminal on the high potential side of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned on, the switch 35 is turned off, and the switch 36 is turned on by the switch control unit 104.
  • the third current value IC indicating the current to be acquired is acquired (S118).
  • the switch control unit 104 turns off the switch 36 (S120).
  • the current value acquisition unit 108 is output from the output terminal on the high potential side of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned on, the switch 35 is turned off, and the switch 36 is turned off by the switch control unit 104.
  • the fourth current value ID indicating the current to be acquired is acquired (S122).
  • the ground fault detection unit 110 includes at least three of a known resistance value Rc, a voltage value Vo of the additional resistor 42, a first current value IA, a second current value IB, a third current value IC, and a fourth current value ID. Based on the current value, the ground fault resistance value Ra is derived using at least three formulas (22), (25), (28), and (31) (S124). The ground fault detection unit 110 determines the presence or absence of a ground fault by comparing the derived ground fault resistance value Ra with a predetermined reference ground fault resistance value (S126).
  • the ground fault detection unit 110 can determine the presence or absence of the ground fault of the solar cell 10 based on the resistance value of the ground fault resistor 300 that does not include the resistance component of the insulation resistance 200. Therefore, according to the present embodiment, even when the resistance value of the insulation resistance 200 changes due to a change in the environment, it is possible to prevent the accuracy of the determination of the presence or absence of the ground fault of the solar cell 10 by the ground fault detection unit 110 from being lowered. it can.
  • the current value acquisition unit 108 acquires only three of the first current value IA, the second current value IB, the third current value IC, and the fourth current value ID, and the ground fault detection unit 110 A ground fault resistance value may be derived using the three acquired current values.
  • the ground fault detection unit 110 has a known resistance value Rc of the additional resistor 42 at the first time point, and at least three currents of the first current value IA, the second current value IB, the third current value IC, and the fourth current value ID.
  • the first ground fault resistance value at the first time point of the solar cell 10 may be derived based on the value.
  • the ground fault detection unit 110 includes the known resistance value Rc of the additional resistor 42 at the second time point after the first time point, the first current value IA, the second current value IB, the third current value IC, and the fourth current value.
  • the second ground fault resistance value at the second time point of the solar cell 10 may be derived based on at least three current values of the current value ID.
  • the ground fault detection part 110 may detect the ground fault of the solar cell 10 based on a 1st ground fault resistance value and a 2nd ground fault resistance value.
  • the ground fault detection unit 110 has a ground fault in the solar cell 10 or the solar cell. It may be determined that ten ground faults are in progress.
  • the ground fault detection unit 110 derives a ground fault resistance value at a first time point such as a time point when the ground fault detection device 30 is installed in the solar power generation system, and based on the ground fault resistance value at the first time point. Determine the reference ground fault resistance value.
  • the ground fault detection unit 110 may use the ground fault resistance value at the first time point as the reference ground fault resistance value.
  • the ground fault detection unit 110 may use a value obtained by subtracting a predetermined value from the ground fault resistance value at the first time point as the reference ground fault resistance value.
  • the ground fault detection unit 110 may set a value obtained by multiplying the ground fault resistance value at the first time point by a predetermined ratio as the reference ground fault resistance value. Then, the ground fault detection unit 110 compares the ground fault resistance value derived at the second time point after the first time point with the reference ground fault resistance value based on the ground fault resistance value at the first time point. The presence or absence of ten ground faults may be determined.
  • the ground fault resistance value of the solar cell 10 depends on the electrical characteristics of the solar cell 10. Therefore, the reference ground fault resistance value unique to the solar cell 10 can be set by setting the reference ground fault resistance value based on the ground fault resistance value derived by the ground fault detection unit 110. Therefore, by setting the reference ground fault resistance value based on the ground fault resistance value derived by the ground fault detection unit 110, the ground fault detection unit 110 can determine the presence or absence of the ground fault of the solar cell 10 with higher accuracy.

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  • General Physics & Mathematics (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
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Abstract

There has been a possibility of not accurately detecting a ground fault of a direct current power supply. Disclosed is a ground fault detection device wherein: a first current value indicating a current flowing to a first output terminal is acquired in a state wherein a connection point between a first direct current power supplies and second direct current power supplies connected in series to the first direct current power supplies is connected to a reference potential point via a resistor having a predetermined resistance value, said first direct current power supplies and second direct current power supplies being included in a plurality of direct current power supplies, and a first output terminal of the direct current power supplies is connected to the reference potential point; a second current value indicating a current flowing to the first output terminal is acquired in a state wherein the connection point is not connected to the reference potential point via the resistor, and the first output terminal is connected to the reference potential point; a third current value indicating a current flowing to a second output terminal is acquired in a state wherein the connection point is connected to the reference potential point via the resistor, or the connection point is not connected to the reference potential point via the resistor, and a second output terminal of the direct current power supplies is connected to the reference potential point; and a grounding fault of the direct current power supplies is detected on the basis of the resistance value, the first current value, the second current value, and the third current value.

Description

地絡検出装置、電源システム、および地絡検出方法Ground fault detection device, power supply system, and ground fault detection method
　本発明は、地絡検出装置、電源システム、および地絡検出方法に関する。 The present invention relates to a ground fault detection device, a power supply system, and a ground fault detection method.
　特許文献１には、太陽電池アレイまたは太陽電池ストリングを解列した状態で、太陽電池アレイまたは太陽電池ストリングの絶縁抵抗値を算出し、算出された絶縁抵抗値に基づいて太陽電池アレイまたは太陽電池ストリングの地絡を検出する地絡検出装置が開示されている。
　特許文献１　特開２０１２－１１９３８２号公報 In Patent Document 1, an insulation resistance value of a solar cell array or a solar cell string is calculated in a state where the solar cell array or the solar cell string is disconnected, and the solar cell array or the solar cell is calculated based on the calculated insulation resistance value. A ground fault detection device for detecting a ground fault of a string is disclosed.
Patent Document 1 JP 2012-119382 A
　太陽電池などの直流電源の絶縁抵抗値は、天候などの環境の変化によって変動することがある。したがって、直流電源の地絡を正確に検出できない可能性がある。 The insulation resistance value of a DC power source such as a solar cell may fluctuate due to environmental changes such as weather. Therefore, there is a possibility that the ground fault of the DC power supply cannot be accurately detected.
　本発明の一態様に係る地絡検出装置は、直列に接続された複数の直流電源の地絡を検出する地絡検出装置であって、複数の直流電源に含まれる第１直流電源と第１直流電源に直列に接続された第２直流電源との接続点を予め定められた抵抗値の抵抗を介して基準電位点に接続し、かつ複数の直流電源の第１出力端を基準電位点に接続した状態で、第１出力端に流れる電流を示す第１電流値を取得する第１電流値取得部と、接続点を抵抗を介して基準電位点に接続せず、かつ第１出力端を基準電位点に接続した状態で、第１出力端に流れる電流を示す第２電流値を取得する第２電流値取得部と、接続点を抵抗を介して基準電位点に接続し、または接続点を抵抗を介して基準電位点に接続せず、かつ複数の直流電源の第２出力端を基準電位点に接続した状態で、第２出力端に流れる電流を示す第３電流値を取得する第３電流値取得部と、抵抗値、第１電流値、第２電流値、および第３電流値に基づいて、複数の直流電源の地絡を検出する地絡検出部とを備える。 A ground fault detection device according to an aspect of the present invention is a ground fault detection device that detects ground faults of a plurality of DC power sources connected in series, and includes a first DC power source and a first DC power source included in the plurality of DC power sources. A connection point with a second DC power source connected in series with the DC power source is connected to a reference potential point through a resistor having a predetermined resistance value, and the first output terminals of the plurality of DC power sources are used as reference potential points. In a connected state, a first current value acquisition unit that acquires a first current value indicating a current flowing through the first output terminal, a connection point not connected to a reference potential point via a resistor, and a first output terminal A second current value acquisition unit for acquiring a second current value indicating a current flowing through the first output terminal in a state of being connected to the reference potential point, and connecting the connection point to the reference potential point via a resistor; Is not connected to the reference potential point through the resistor, and the second output terminals of the plurality of DC power supplies are used as the reference potential point. Based on the resistance value, the first current value, the second current value, and the third current value, a third current value acquisition unit that acquires a third current value indicating the current flowing through the second output terminal in the connected state And a ground fault detector for detecting ground faults of a plurality of DC power supplies.
　上記地絡検出装置は、接続点を抵抗を介して基準電位点に接続するか否かを切り替える第１切り替え手段と、第１出力端および第２出力端のいずれか一方を基準電位点に接続するか否かを切り替える第２切り替え手段とをさらに備えてよい。 The ground fault detection device connects the first switching means for switching whether or not the connection point is connected to the reference potential point via a resistor, and connects either the first output terminal or the second output terminal to the reference potential point. You may further provide the 2nd switching means which switches whether to do.
　上記地絡検出装置において、地絡検出部は、第１時点における抵抗値、第１電流値、第２電流値、および第３電流値に基づいて、複数の直流電源の第１時点における第１地絡抵抗値を導出し、第１時点より後の第２時点における抵抗値、第１電流値、第２電流値、および第３電流値に基づいて、複数の直流電源の第２時点における第２地絡抵抗値を導出し、第１地絡抵抗値と第２地絡抵抗値とに基づいて、複数の直流電源の地絡を検出してよい。 In the ground fault detection device, the ground fault detection unit is configured to determine the first time at the first time point of the plurality of DC power sources based on the resistance value, the first current value, the second current value, and the third current value at the first time point. A ground fault resistance value is derived, and based on the resistance value, the first current value, the second current value, and the third current value at a second time point after the first time point, Two ground fault resistance values may be derived, and ground faults of a plurality of DC power supplies may be detected based on the first ground fault resistance value and the second ground fault resistance value.
　上記地絡検出装置において、複数の直流電源のそれぞれは、太陽電池でよい。 In the ground fault detection device, each of the plurality of DC power supplies may be a solar cell.
　本発明の一態様に係る電源システムは、上記地絡検出装置と、複数の直流電源と、複数の直流電源から供給される電力を消費または変換する負荷装置とを備え、地絡検出装置は、複数の直流電源と負荷装置との間を電気的に接続するか切断するかを切り替える第３切り替え手段をさらに備え、第３切り替え手段により複数の直流電源と負荷装置との間を電気的に切断した状態で、第１電流値取得部は、第１出力端に流れる電流を示す第１電流値を取得し、第２電流値取得部は、第１出力端に流れる電流を示す第２電流値を取得し、第３電流値取得部は、第２出力端に流れる電流を示す第３電流値を取得する。 A power supply system according to an aspect of the present invention includes the above ground fault detection device, a plurality of DC power sources, and a load device that consumes or converts power supplied from the plurality of DC power sources. Third switching means for switching between connecting or disconnecting the plurality of DC power supplies and the load device is further provided, and the third switching means electrically disconnects the plurality of DC power supplies and the load device. In this state, the first current value acquisition unit acquires a first current value indicating the current flowing through the first output terminal, and the second current value acquisition unit acquires the second current value indicating the current flowing through the first output terminal. The third current value acquisition unit acquires a third current value indicating a current flowing through the second output end.
　本発明の一態様に係る地絡検出方法は、直列に接続された複数の直流電源の地絡を検出する地絡検出方法であって、複数の直流電源に含まれる第１直流電源と第１直流電源に直列に接続された第２直流電源との接続点を予め定められた抵抗値の抵抗を介して基準電位点に接続し、かつ複数の直流電源の第１出力端を基準電位点に接続した状態で、第１出力端に流れる電流を示す第１電流値を取得する段階と、接続点を抵抗を介して基準電位点に接続せず、かつ第１出力端を基準電位点に接続した状態で、第１出力端に流れる電流を示す第２電流値を取得する段階と、接続点を抵抗を介して基準電位点に接続し、または接続点を抵抗を介して基準電位点に接続せず、かつ複数の直流電源の第２出力端を基準電位点に接続した状態で、第２出力端に流れる電流を示す第３電流値を取得する段階と、抵抗値、第１電流値、第２電流値、および第３電流値に基づいて、複数の直流電源の地絡を検出する段階とを含む。 A ground fault detection method according to an aspect of the present invention is a ground fault detection method for detecting ground faults of a plurality of DC power sources connected in series, and includes a first DC power source and a first DC power source included in the plurality of DC power sources. A connection point with a second DC power source connected in series with the DC power source is connected to a reference potential point through a resistor having a predetermined resistance value, and the first output terminals of the plurality of DC power sources are used as reference potential points. In a connected state, obtaining a first current value indicating a current flowing through the first output terminal, connecting the connection point to the reference potential point via a resistor, and connecting the first output terminal to the reference potential point In this state, the second current value indicating the current flowing through the first output terminal is obtained, and the connection point is connected to the reference potential point through the resistor, or the connection point is connected to the reference potential point through the resistor. In the state where the second output terminals of the plurality of DC power supplies are connected to the reference potential point, the second output Obtaining a third current value indicating a current flowing through the first current value, and detecting a ground fault of the plurality of DC power sources based on the resistance value, the first current value, the second current value, and the third current value. Including.
　なお、上記の発明の概要は、本発明の特徴の全てを列挙したものではない。また、これらの特徴群のサブコンビネーションもまた、発明となりうる。 Note that the above summary of the invention does not enumerate all the features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.
本実施形態に係る地絡検出装置を含む太陽光発電システムの全体構成の一例を示す図である。It is a figure which shows an example of the whole structure of the solar energy power generation system containing the ground fault detection apparatus which concerns on this embodiment. 制御部の機能ブロックの一例を示す図である。It is a figure which shows an example of the functional block of a control part. 最も低電位側の太陽電池モジュールと２番目に低電位側の太陽電池モジュールとの間の接続点において、地絡が生じている場合の第１電流値検出条件における太陽電池の回路構成を示す図である。The figure which shows the circuit structure of the solar cell in 1st electric current value detection conditions in case the ground fault has arisen in the connection point between the solar cell module of the lowest potential side, and the solar cell module of the 2nd lowest potential side. It is. 最も低電位側の太陽電池モジュールと２番目に低電位側の太陽電池モジュールとの間の接続点において、地絡が生じている場合の第２電流値検出条件における太陽電池の回路構成を示す図である。The figure which shows the circuit structure of the solar cell in 2nd electric current value detection conditions in case the ground fault has arisen in the connection point between the solar cell module of the lowest potential side, and the solar cell module of the 2nd lowest potential side. It is. 最も低電位側の太陽電池モジュールと２番目に低電位側の太陽電池モジュールとの間の接続点において、地絡が生じている場合の第３電流値検出条件における太陽電池の回路構成を示す図である。The figure which shows the circuit structure of the solar cell in 3rd electric current value detection conditions in case the ground fault has arisen in the connection point between the solar cell module of the lowest potential side, and the solar cell module of the 2nd lowest potential side. It is. 最も低電位側の太陽電池モジュールと２番目に低電位側の太陽電池モジュールとの間の接続点において、地絡が生じている場合の第４電流値検出条件における太陽電池の回路構成を示す図である。The figure which shows the circuit structure of the solar cell in 4th electric current value detection conditions in case the ground fault has arisen in the connection point between the solar cell module of the lowest potential side, and the solar cell module of the 2nd lowest potential side. It is. 最も低電位側からＸ（Ｘ＜５）枚目の太陽電池モジュールと（Ｘ＋１）枚目の太陽電池モジュールとの間の接続点において、地絡が生じている場合の第１電流値検出条件における太陽電池の回路構成を示す図である。In the first current value detection condition when a ground fault occurs at the connection point between the X (X <5) th solar cell module and the (X + 1) th solar cell module from the lowest potential side. It is a figure which shows the circuit structure of a solar cell. 最も低電位側からＸ（Ｘ＜５）枚目の太陽電池モジュールと（Ｘ＋１）枚目の太陽電池モジュールとの間の接続点において、地絡が生じている場合の第２電流値検出条件における太陽電池の回路構成を示す図である。In the second current value detection condition when a ground fault occurs at the connection point between the X (X <5) th solar cell module and the (X + 1) th solar cell module from the lowest potential side. It is a figure which shows the circuit structure of a solar cell. 最も低電位側からＸ（Ｘ＜５）枚目の太陽電池モジュールと（Ｘ＋１）枚目の太陽電池モジュールとの間の接続点において、地絡が生じている場合の第３電流値検出条件における太陽電池の回路構成を示す図である。In the third current value detection condition when a ground fault occurs at the connection point between the X (X <5) th solar cell module and the (X + 1) th solar cell module from the lowest potential side. It is a figure which shows the circuit structure of a solar cell. 最も低電位側からＸ（Ｘ＜５）枚目の太陽電池モジュールと（Ｘ＋１）枚目の太陽電池モジュールとの間の接続点において、地絡が生じている場合の第４電流値検出条件における太陽電池の回路構成を示す図である。In the fourth current value detection condition when a ground fault occurs at the connection point between the X (X <5) th solar cell module and the (X + 1) th solar cell module from the lowest potential side. It is a figure which shows the circuit structure of a solar cell. 地絡検出装置が太陽電池の地絡を検出する手順の一例を示すフローチャートである。It is a flowchart which shows an example of the procedure in which a ground fault detection apparatus detects the ground fault of a solar cell.
　以下、発明の実施の形態を通じて本発明を説明するが、以下の実施形態は請求の範囲にかかる発明を限定するものではない。また、実施形態の中で説明されている特徴の組み合わせの全てが発明の解決手段に必須であるとは限らない。 Hereinafter, the present invention will be described through embodiments of the invention. However, 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.
　図１は、本実施形態に係る地絡検出装置３０を含む太陽光発電システムの全体構成の一例を示す。 FIG. 1 shows an example of the overall configuration of a photovoltaic power generation system including a ground fault detection device 30 according to the present embodiment.
　太陽光発電システムは、太陽電池１０、電力変換装置２０、および地絡検出装置３０を備える太陽電池１０は、直列に接続された複数の太陽電池モジュール１２を有する太陽電池ストリングでよい。本実施形態では、太陽電池１０は、１０枚の太陽電池モジュール１２が直列に接続されている例について説明する。太陽電池１０は、直流電源の一例である。太陽光発電システムは、電源システムの一例である。 In the photovoltaic power generation system, the solar cell 10 including the solar cell 10, the power conversion device 20, and the ground fault detection device 30 may be a solar cell string having a plurality of solar cell modules 12 connected in series. In the present embodiment, the solar cell 10 will be described with respect to an example in which ten solar cell modules 12 are connected in series. Solar cell 10 is an example of a DC power source. A solar power generation system is an example of a power supply system.
　電力変換装置２０は、太陽電池１０から出力される電力を変換する。電力変換装置２０は、太陽電池１０からの直流を昇圧して、昇圧された直流を交流に変換し、系統電源と連系させるパワーコンディショナでよい。電力変換装置２０は、太陽電池１０から出力される電力を消費または変換する負荷装置の一例である。 The power converter 20 converts the power output from the solar cell 10. The power converter 20 may be a power conditioner that boosts the direct current from the solar cell 10, converts the boosted direct current to alternating current, and links the system power supply. The power conversion device 20 is an example of a load device that consumes or converts power output from the solar cell 10.
　地絡検出装置３０は、太陽電池１０と基準電位点である接地点との間の地絡抵抗値を導出し、導出された地絡抵抗値が基準地絡抵抗値より小さい場合に、地絡が発生していると判定する。 The ground fault detection device 30 derives a ground fault resistance value between the solar cell 10 and the ground point that is a reference potential point, and when the derived ground fault resistance value is smaller than the reference ground fault resistance value, the ground fault is detected. Is determined to have occurred.
　地絡検出装置３０は、切断手段３２、スイッチ３４、スイッチ３５、スイッチ３６、検出抵抗４０、追加抵抗４２、電圧センサ４４、電流センサ４６、および制御部１００を備える。 The ground fault detection device 30 includes a cutting means 32, a switch 34, a switch 35, a switch 36, a detection resistor 40, an additional resistor 42, a voltage sensor 44, a current sensor 46, and a control unit 100.
　切断手段３２は、太陽電池１０と電力変換装置２０との間に設けられ、太陽電池１０と電力変換装置２０とを電気的に切断させる。切断手段３２は、太陽電池１０の高電位側の出力端子と、電力変換装置２０の高電位側の入力端子との間に設けられるリレー３２ａと、太陽電池１０の低電位側の出力端子と、電力変換装置２０の低電位側の入力端子との間に設けられるリレー３２ｂとを含む。リレー３２ａ，３２ｂは、作動信号が入力された場合に太陽電池１０と電力変換装置２０とを電気的に切断させるｂ接点を有するリレーでよい。太陽電池１０の低電位側の出力端子は、第１出力端の一例である。太陽電池１０の高電位側の出力端子は、第２出力端の一例である。 The cutting means 32 is provided between the solar cell 10 and the power conversion device 20, and electrically disconnects the solar cell 10 and the power conversion device 20. The cutting means 32 includes a relay 32a provided between an output terminal on the high potential side of the solar cell 10 and an input terminal on the high potential side of the power conversion device 20, an output terminal on the low potential side of the solar cell 10, And a relay 32b provided between the input terminal on the low potential side of the power conversion device 20. The relays 32a and 32b may be relays having a b-contact that electrically disconnects the solar cell 10 and the power conversion device 20 when an operation signal is input. The output terminal on the low potential side of the solar cell 10 is an example of a first output terminal. The output terminal on the high potential side of the solar cell 10 is an example of the second output terminal.
　切断手段３２が有する高電位側のリレー３２ａと太陽電池１０の高電位側の出力端子とは、高電位側の電線Ｌ１を介して接続されている。切断手段３２が有する低電位側のリレー３２ｂと太陽電池１０の低電位側の出力端子とは、低電位側の電線Ｌ２を介して接続されている。 The high potential side relay 32a of the cutting means 32 and the high potential side output terminal of the solar cell 10 are connected via a high potential side electric wire L1. The low potential side relay 32b of the cutting means 32 and the low potential side output terminal of the solar cell 10 are connected via a low potential side electric wire L2.
　スイッチ３４の一端は、高電位側の電線Ｌ１に接続され、スイッチ３４の他端は、検出抵抗４０の一端に接続されている。スイッチ３５の一端は、低電位側の電線Ｌ２に接続され、スイッチ３５の他端は、検出抵抗４０の一端に接続されている。検出抵抗４０の他端は、接地されている。スイッチ３４およびスイッチ３５は、太陽電池１０の低電位側の出力端子および太陽電池１０の高電位側の出力端子のいずれか一方を基準電位点に接続するか否かを切り替える第２切り替え手段の一例である。 One end of the switch 34 is connected to the electric wire L1 on the high potential side, and the other end of the switch 34 is connected to one end of the detection resistor 40. One end of the switch 35 is connected to the electric wire L <b> 2 on the low potential side, and the other end of the switch 35 is connected to one end of the detection resistor 40. The other end of the detection resistor 40 is grounded. The switch 34 and the switch 35 are an example of second switching means for switching whether or not one of the output terminal on the low potential side of the solar cell 10 and the output terminal on the high potential side of the solar cell 10 is connected to the reference potential point. It is.
　太陽電池１０は、太陽電池１０の中点である接続点１４に接続された太陽電池モジュール１２ａおよび太陽電池モジュール１２ｂを含む。太陽電池モジュール１２ａは、第１直流電源の一例であり、太陽電池モジュール１２ｂは、第２直流電源の一例である。接続点１４に接続された抵抗は、太陽電池１０全体の絶縁抵抗２００を疑似的に示している。なお、本実施形態では、太陽電池１０の中点に絶縁抵抗２００が接続されていると仮定している。しかし、太陽電池１０の電気特性に応じて、絶縁抵抗２００が接続されていると仮定する位置は、変更してよい。 The solar cell 10 includes a solar cell module 12a and a solar cell module 12b connected to a connection point 14 that is a midpoint of the solar cell 10. The solar cell module 12a is an example of a first DC power source, and the solar cell module 12b is an example of a second DC power source. The resistance connected to the connection point 14 indicates the insulation resistance 200 of the entire solar cell 10 in a pseudo manner. In the present embodiment, it is assumed that the insulation resistance 200 is connected to the midpoint of the solar cell 10. However, the position where the insulation resistance 200 is assumed to be connected may be changed according to the electrical characteristics of the solar cell 10.
　スイッチ３６の一端は、接続点１４に接続され、スイッチ３６の他端は、追加抵抗４２の一端に接続されている。スイッチ３６は、接続点１４を追加抵抗４２を介して基準電位点に接続するか否かを切り替える第１切り替え手段の一例である。追加抵抗４２の他端は、接地されている。追加抵抗４２は、予め定められた抵抗値を有する抵抗の一例である。追加抵抗４２は、既知の抵抗値Ｒｃを有する。本実施形態では、太陽電池１０の中点である接続点１４に追加抵抗４２を接続する例について説明する。しかし、追加抵抗４２は、太陽電池１０に含まれる他の太陽電池モジュール間の接続点に接続されてよい。 One end of the switch 36 is connected to the connection point 14, and the other end of the switch 36 is connected to one end of the additional resistor 42. The switch 36 is an example of a first switching unit that switches whether the connection point 14 is connected to the reference potential point via the additional resistor 42. The other end of the additional resistor 42 is grounded. The additional resistor 42 is an example of a resistor having a predetermined resistance value. The additional resistor 42 has a known resistance value Rc. In the present embodiment, an example in which the additional resistor 42 is connected to the connection point 14 that is the midpoint of the solar cell 10 will be described. However, the additional resistor 42 may be connected to a connection point between other solar cell modules included in the solar cell 10.
　電圧センサ４４は、太陽電池１０から出力される電圧の電圧値Ｖｏを検出する。電流センサ４６は、太陽電池１０の高電位側の出力端子または太陽電池１０の低電位側の出力端子がスイッチ３４またはスイッチ３５を介して接地点に接続されている場合に、太陽電池１０の高電位側の出力端子または太陽電池１０の低電位側の出力端子から出力されている電流の電流値を検出する。 The voltage sensor 44 detects the voltage value Vo of the voltage output from the solar cell 10. The current sensor 46 is configured so that the high potential output terminal of the solar cell 10 or the low potential output terminal of the solar cell 10 is connected to a ground point via the switch 34 or the switch 35. The current value of the current output from the output terminal on the potential side or the output terminal on the low potential side of the solar cell 10 is detected.
　制御部１００は、切断手段３２のリレー動作を制御する。制御部１００は、スイッチ３４、スイッチ３５、およびスイッチ３６のスイッチング動作を制御する。また、制御部１００は、電圧センサ４４により検出された電圧値Ｖｏおよび電流センサ４６により検出された電流値に基づいて、太陽電池１０の地絡抵抗値Ｒａを導出し、地絡抵抗値Ｒａに基づいて、太陽電池１０の地絡の有無を検出する。制御部１００は、地絡抵抗値Ｒａが基準地絡抵抗値より小さい場合、太陽電池１０の地絡が発生していると判断してよい。 The control unit 100 controls the relay operation of the cutting means 32. The control unit 100 controls the switching operations of the switch 34, the switch 35, and the switch 36. Further, the control unit 100 derives the ground fault resistance value Ra of the solar cell 10 based on the voltage value Vo detected by the voltage sensor 44 and the current value detected by the current sensor 46, and sets the ground fault resistance value Ra to the ground fault resistance value Ra. Based on this, the presence or absence of the ground fault of the solar cell 10 is detected. The control unit 100 may determine that a ground fault has occurred in the solar cell 10 when the ground fault resistance value Ra is smaller than the reference ground fault resistance value.
　図２は、制御部１００の機能ブロックの一例を示す図である。制御部１００は、リレー制御部１０２、スイッチ制御部１０４、電圧値取得部１０６、電流値取得部１０８、および地絡検出部１１０を備える。 FIG. 2 is a diagram illustrating an example of functional blocks of the control unit 100. The control unit 100 includes a relay control unit 102, a switch control unit 104, a voltage value acquisition unit 106, a current value acquisition unit 108, and a ground fault detection unit 110.
　制御部１００が備える各部は、コンピュータ読み取り可能な記録媒体に記憶され、太陽電池１０の地絡の検出に関する各種処理を行うプログラムをインストールし、このプログラムをコンピュータに実行させることで、構成してもよい。つまり、太陽電池１０の地絡の検出に関する各種処理を行うプログラムを実行させることにより、制御部１００が備える各部としてコンピュータを機能させることで、地絡検出装置３０を構成してもよい。 Each unit included in the control unit 100 is stored in a computer-readable recording medium, and can be configured by installing a program for performing various processes related to detection of a ground fault of the solar battery 10 and causing the computer to execute the program. Good. That is, the ground fault detection device 30 may be configured by causing a computer to function as each unit included in the control unit 100 by executing a program that performs various processes relating to detection of the ground fault of the solar cell 10.
　コンピュータは、ＣＰＵ、ＲＯＭ、ＲＡＭ、ＥＥＰＲＯＭ（登録商標）等の各種メモリ、通信バス及びインタフェースを有し、予めファームウェアとしてＲＯＭに格納された処理プログラムをＣＰＵが読み出して順次実行することで、地絡検出装置３０として機能する。 The computer has various memories such as a CPU, ROM, RAM, and EEPROM (registered trademark), a communication bus, and an interface. The CPU reads and sequentially executes a processing program stored in the ROM as firmware in advance, thereby causing a ground fault. It functions as the detection device 30.
　リレー制御部１０２は、太陽電池１０の地絡を検出すべき予め定められたタイミングで、切断手段３２に作動信号を出力して、太陽電池１０と電力変換装置２０との間を電気的に遮断する。例えば、リレー制御部１０２は、朝方、太陽電池１０からの電力が基準電力に達した後、電力変換装置２０が起動する前に、切断手段３２に作動信号を出力してよい。また、リレー制御部１０２は、夕方、太陽電池１０からの電力が基準電力を満たさなくなり、電力変換装置２０が停止した後に、切断手段３２に作動信号を出力してよい。 The relay control unit 102 outputs an operation signal to the cutting means 32 at a predetermined timing at which a ground fault of the solar cell 10 is to be detected, and electrically disconnects the solar cell 10 and the power conversion device 20 from each other. To do. For example, the relay control unit 102 may output an operation signal to the disconnecting unit 32 before the power conversion device 20 is started after the power from the solar cell 10 reaches the reference power in the morning. Moreover, the relay control part 102 may output an operation signal to the cutting | disconnection means 32 after the electric power from the solar cell 10 stops satisfy | filling reference | standard power and the power converter device 20 stops in the evening.
　スイッチ制御部１０４は、スイッチ３４、スイッチ３５、およびスイッチ３６のオンオフを制御する。スイッチ制御部１０４は、第１電流値検出条件において、スイッチ３４をオフ、スイッチ３５をオンし、かつスイッチ３６をオンする。スイッチ制御部１０４は、第２電流値検出条件において、スイッチ３４をオフ、スイッチ３６をオンし、かつスイッチ３６をオフする。スイッチ制御部１０４は、第３電流値検出条件において、スイッチ３４をオン、スイッチ３５をオフし、かつスイッチ３６をオンする。スイッチ制御部１０４は、第４電流値検出条件において、スイッチ３４をオン、スイッチ３５をオフし、かつスイッチ３６をオフする。 The switch control unit 104 controls on / off of the switch 34, the switch 35, and the switch 36. The switch control unit 104 turns off the switch 34, turns on the switch 35, and turns on the switch 36 under the first current value detection condition. The switch control unit 104 turns off the switch 34, turns on the switch 36, and turns off the switch 36 under the second current value detection condition. The switch control unit 104 turns on the switch 34, turns off the switch 35, and turns on the switch 36 under the third current value detection condition. The switch control unit 104 turns on the switch 34, turns off the switch 35, and turns off the switch 36 under the fourth current value detection condition.
　電圧値取得部１０６は、電圧センサ４４を介して太陽電池１０から出力される電圧の電圧値Ｖｏを取得する。電流値取得部１０８は、第１電流値検出条件においてスイッチ制御部１０４によりスイッチ３４がオフ、スイッチ３５がオン、かつスイッチ３６がオンした状態で、電流センサ４６を介して太陽電池１０の低電位側の出力端子から出力される電流を示す第１電流値ＩＡを取得する。電流値取得部１０８は、太陽電池モジュール１２ａと太陽電池モジュール１２ａに直列に接続された太陽電池モジュール１２ｂとの接続点１４を予め定められた抵抗値Ｒａの追加抵抗４２を介して基準電位点に接続し、かつ太陽電池１０の低電位側の出力端子を基準電位点に接続した状態で、太陽電池１０の低電位側の出力端子に流れる電流を示す第１電流値を取得する第１電流値取得部の一例である。 The voltage value acquisition unit 106 acquires the voltage value Vo of the voltage output from the solar cell 10 via the voltage sensor 44. The current value acquisition unit 108 is a low potential of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned off, the switch 35 is turned on, and the switch 36 is turned on by the switch control unit 104 under the first current value detection condition. The first current value IA indicating the current output from the output terminal on the side is acquired. The current value acquisition unit 108 sets the connection point 14 between the solar cell module 12a and the solar cell module 12b connected in series to the solar cell module 12a as a reference potential point via an additional resistor 42 having a predetermined resistance value Ra. A first current value for obtaining a first current value indicating a current flowing through the output terminal on the low potential side of the solar cell 10 in a state where the low potential side output terminal of the solar cell 10 is connected to the reference potential point. It is an example of an acquisition part.
　電流値取得部１０８は、第２電流値検出条件においてスイッチ制御部１０４によりスイッチ３４がオフ、スイッチ３５がオン、かつスイッチ３６がオフした状態で、電流センサ４６を介して太陽電池１０の低電位側の出力端子から出力される電流を示す第２電流値ＩＢを取得する。電流値取得部１０８は、接続点１４を追加抵抗４２を介して基準電位点に接続せず、かつ太陽電池１０の低電位側の出力端子を基準電位点に接続した状態で、低電位側の出力端子に流れる電流を示す第２電流値を取得する第２電流値取得部の一例である。 The current value acquisition unit 108 is connected to the low potential of the solar cell 10 via the current sensor 46 in a state where the switch 34 is turned off, the switch 35 is turned on, and the switch 36 is turned off by the switch control unit 104 under the second current value detection condition. The second current value IB indicating the current output from the output terminal on the side is acquired. The current value acquisition unit 108 does not connect the connection point 14 to the reference potential point via the additional resistor 42 and connects the output terminal on the low potential side of the solar cell 10 to the reference potential point. It is an example of the 2nd electric current value acquisition part which acquires the 2nd electric current value which shows the electric current which flows into an output terminal.
　電流値取得部１０８は、第３電流値検出条件においてスイッチ制御部１０４によりスイッチ３４がオン、スイッチ３５がオフ、かつスイッチ３６がオンした状態で、電流センサ４６を介して太陽電池１０の高電位側の出力端子から出力される電流を示す第３電流値ＩＣを取得する。電流値取得部１０８は、第４電流値検出条件においてスイッチ制御部１０４によりスイッチ３４がオン、スイッチ３５がオフ、かつスイッチ３６がオフした状態で、電流センサ４６を介して太陽電池１０の高電位側の出力端子から出力される電流を示す第４電流値ＩＤを取得する。電流値取得部１０８は、接続点１４を追加抵抗４２を介して基準電位点に接続し、または接続点１４を追加抵抗４２を介して基準電位点に接続せず、かつ太陽電池１０の高電位側の出力端子を基準電位点に接続した状態で、太陽電池１０の高電位側の出力端子に流れる電流を示す第３電流値を取得する第３電流値取得部の一例である。 The current value acquisition unit 108 has a high potential of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned on, the switch 35 is turned off, and the switch 36 is turned on by the switch control unit 104 under the third current value detection condition. The third current value IC indicating the current output from the output terminal on the side is acquired. The current value acquisition unit 108 has a high potential of the solar cell 10 via the current sensor 46 in a state where the switch 34 is turned on, the switch 35 is turned off, and the switch 36 is turned off by the switch control unit 104 under the fourth current value detection condition. The fourth current value ID indicating the current output from the output terminal on the side is acquired. The current value acquisition unit 108 connects the connection point 14 to the reference potential point via the additional resistor 42, or does not connect the connection point 14 to the reference potential point via the additional resistor 42, and the high potential of the solar cell 10. 4 is an example of a third current value acquisition unit that acquires a third current value indicating a current flowing through an output terminal on the high potential side of the solar cell 10 in a state where the output terminal on the side is connected to a reference potential point.
　地絡検出部１１０は、電圧値取得部１０６が取得した電圧値Ｖｏ、および電流値取得部１０８が取得した第１電流値ＩＡ、第２電流値ＩＢ、第３電流値ＩＣおよび第４電流値ＩＤの少なくとも３つの電流値に基づいて、太陽電池１０の地絡の有無を検出する。地絡検出部１１０は、電圧値Ｖｏ、および第１電流値ＩＡ、第２電流値ＩＢ、第３電流値ＩＣおよび第４電流値ＩＤの少なくとも３つの電流値に基づいて、太陽電池１０の地絡抵抗値を導出し、導出された地絡抵抗値が基準地絡抵抗値より小さい場合に、太陽電池１０の地絡が発生していると判断してよい。 The ground fault detection unit 110 includes the voltage value Vo acquired by the voltage value acquisition unit 106, the first current value IA, the second current value IB, the third current value IC, and the fourth current value acquired by the current value acquisition unit 108. Based on at least three current values of ID, the presence or absence of a ground fault of the solar cell 10 is detected. The ground fault detection unit 110 is connected to the ground of the solar cell 10 based on the voltage value Vo and at least three current values of the first current value IA, the second current value IB, the third current value IC, and the fourth current value ID. The fault resistance value is derived, and when the derived ground fault resistance value is smaller than the reference ground fault resistance value, it may be determined that the ground fault of the solar cell 10 has occurred.
　図３Ａ、図３Ｂ、図３Ｃ、図３Ｄは、最も低電位側の太陽電池モジュール１２ｃと２番目に低電位側の太陽電池モジュール１２ｄとの間の接続点において、地絡が生じている場合の太陽電池１０の回路構成を示す。 3A, 3B, 3C, and 3D show a case where a ground fault occurs at the connection point between the solar cell module 12c on the lowest potential side and the solar cell module 12d on the second lowest potential side. The circuit structure of the solar cell 10 is shown.
　図３Ａは、スイッチ制御部１０４が、第１電流値検出条件においてスイッチ３４がオフ、スイッチ３５がオン、かつスイッチ３６がオンした状態での太陽電池１０の回路構成を示す。図３Ａに示す回路構成において、太陽電池１０の低電位側の出力端子から出力された第１電流値ＩＡは、式（１）で示される追加抵抗４２と絶縁抵抗２００との合成抵抗を流れる電流を示す電流値Ｉ１ａと、式（２）で示される地絡抵抗３００を流れる電流を示す電流値Ｉ２ａとの合計である。 FIG. 3A shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned off, the switch 35 is turned on, and the switch 36 is turned on under the first current value detection condition. In the circuit configuration shown in FIG. 3A, the first current value IA output from the output terminal on the low potential side of the solar cell 10 is the current flowing through the combined resistance of the additional resistor 42 and the insulation resistor 200 represented by Expression (1). And a current value I2a indicating a current flowing through the ground fault resistance 300 represented by the equation (2).
　Ｉ１ａ＝５Ｖａ／Ｒ　　　・・・（１）
　Ｉ２ａ＝Ｖａ／Ｒａ　　　・・・（２）
　ＩＡ＝Ｉ１ａ＋Ｉ２ａ＝５Ｖａ／Ｒ＋Ｖａ／Ｒａ　　　・・・（３） I1a = 5Va / R (1)
I2a = Va / Ra (2)
IA = I1a + I2a = 5Va / R + Va / Ra (3)
　Ｖａは、１枚の太陽電池モジュール１２の両端の電圧の電圧値を示す。太陽電池１０を構成する太陽電池モジュール１２のそれぞれの電気的な特性は同一で、太陽電池１０を構成する太陽電池モジュール１２の枚数がＮ枚である場合、Ｖａ＝Ｖｏ／Ｎでよい。例えば、太陽電池モジュール１２の枚数が１０枚である場合、Ｖａ＝Ｖｏ／１０でよい。 Va represents the voltage value of the voltage at both ends of one solar cell module 12. When the electrical characteristics of the solar cell modules 12 constituting the solar cell 10 are the same and the number of the solar cell modules 12 constituting the solar cell 10 is N, Va = Vo / N may be satisfied. For example, when the number of solar cell modules 12 is 10, Va = Vo / 10.
　Ｒは、追加抵抗４２と絶縁抵抗２００との合成抵抗であり、追加抵抗４２の抵抗値Ｒｃ、絶縁抵抗２００の抵抗値Ｒｂとした場合、Ｒ＝Ｒｂ×Ｒｃ／（Ｒｂ＋Ｒｃ）である。Ｒａは、地絡抵抗３００の抵抗値を示す。 R is a combined resistance of the additional resistor 42 and the insulation resistor 200. When the resistance value Rc of the additional resistor 42 and the resistance value Rb of the insulation resistor 200 are R, R = Rb × Rc / (Rb + Rc). Ra represents the resistance value of the ground fault resistance 300.
　図３Ｂは、スイッチ制御部１０４が、第２電流値検出条件においてスイッチ３４がオフ、スイッチ３５がオン、かつスイッチ３６がオフした状態での太陽電池１０の回路構成を示す。図３Ｂに示す回路構成において、太陽電池１０の低電位側の出力端子から出力された第１電流値ＩＢは、式（４）で示される絶縁抵抗２００を流れる電流を示す電流値Ｉ１ｂと、式（５）で示される地絡抵抗３００を流れる電流を示す電流値Ｉ２ｂとの合計である。 FIG. 3B shows a circuit configuration of the solar cell 10 in a state where the switch controller 104 is turned off, the switch 35 is turned on, and the switch 36 is turned off under the second current value detection condition. In the circuit configuration shown in FIG. 3B, the first current value IB output from the output terminal on the low potential side of the solar cell 10 is the current value I1b indicating the current flowing through the insulation resistor 200 shown by the formula (4), and the formula This is the total of the current value I2b indicating the current flowing through the ground fault resistance 300 indicated by (5).
　Ｉ１ｂ＝５Ｖａ／Ｒｂ　　　・・・（４）
　Ｉ２ｂ＝Ｖａ／Ｒａ　　　・・・（５）
　ＩＢ＝Ｉ１ｂ＋Ｉ２ｂ＝５Ｖａ／Ｒｂ＋Ｖａ／Ｒａ　　　・・・（６） I1b = 5Va / Rb (4)
I2b = Va / Ra (5)
IB = I1b + I2b = 5Va / Rb + Va / Ra (6)
　図３Ｃは、スイッチ制御部１０４が、第３電流値検出条件においてスイッチ３４がオン、スイッチ３５がオフ、かつスイッチ３６がオンした状態での太陽電池１０の回路構成を示す。図３Ｃに示す回路構成において、太陽電池１０の高電位側の出力端子から出力された第３電流値ＩＣは、式（７）で示される地絡抵抗３００を流れる電流を示す電流値Ｉ１ｃと、式（８）で示される追加抵抗４２と絶縁抵抗２００との合成抵抗を流れる電流を示す電流値Ｉ３ｃとの合計である。 FIG. 3C shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is on, the switch 35 is off, and the switch 36 is on under the third current value detection condition. In the circuit configuration shown in FIG. 3C, the third current value IC output from the output terminal on the high potential side of the solar cell 10 is a current value I1c indicating a current flowing through the ground fault resistor 300 represented by Expression (7), This is the total of the current value I3c indicating the current flowing through the combined resistance of the additional resistance 42 and the insulation resistance 200 represented by Expression (8).
　Ｉ１ｃ＝９Ｖａ／Ｒａ　　　・・・（７）
　Ｉ３ｃ＝５Ｖａ／Ｒ　　　・・・（８）
　ＩＣ＝Ｉ１ｃ＋Ｉ３ｃ＝９Ｖａ／Ｒａ＋５Ｖａ／Ｒ　　　・・・（９） I1c = 9Va / Ra (7)
I3c = 5Va / R (8)
IC = I1c + I3c = 9Va / Ra + 5Va / R (9)
　図３Ｄは、スイッチ制御部１０４が、第４電流値検出条件においてスイッチ３４がオン、スイッチ３５がオフ、かつスイッチ３６がオフした状態での太陽電池１０の回路構成を示す。図３Ｄに示す回路構成において、太陽電池１０の高電位側の出力端子から出力された第４電流値ＩＤは、式（１０）で示される絶縁抵抗２００を流れる電流を示す電流値Ｉ１ｄと、式（１１）で示される地絡抵抗３００を流れる電流を示す電流値Ｉ３ｄとの合計である。 FIG. 3D shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned on, the switch 35 is turned off, and the switch 36 is turned off under the fourth current value detection condition. In the circuit configuration shown in FIG. 3D, the fourth current value ID output from the output terminal on the high potential side of the solar cell 10 is the current value I1d indicating the current flowing through the insulation resistance 200 shown by the equation (10), and the equation This is the total of the current value I3d indicating the current flowing through the ground fault resistance 300 indicated by (11).
　Ｉ１ｄ＝５Ｖａ／Ｒａ　　　・・・（１０）
　Ｉ３ｄ＝５Ｖａ／Ｒｂ　　　・・・（１１）
　ＩＤ＝Ｉ１ｄ＋Ｉ３ｄ＝５Ｖａ／Ｒａ＋５Ｖａ／Ｒｂ　　　・・・（１２） I1d = 5Va / Ra (10)
I3d = 5Va / Rb (11)
ID = I1d + I3d = 5Va / Ra + 5Va / Rb (12)
　地絡検出部１１０は、式（３）、式（６）、式（９）、および式（１２）を利用して、地絡抵抗３００の抵抗値Ｒａを導出する。ここで、太陽電池１０の地絡の位置が既知である場合、未知数はＲａおよびＲｂの２つなので、地絡検出部１１０は、式（３）、式（６）、式（９）、および式（１２）のいずれか２つの式を利用して、地絡抵抗３００の抵抗値Ｒａを導出できる。 The ground fault detection unit 110 derives the resistance value Ra of the ground fault resistance 300 using the formulas (3), (6), (9), and (12). Here, when the position of the ground fault of the solar cell 10 is known, since the unknowns are two, Ra and Rb, the ground fault detection unit 110 performs the expressions (3), (6), (9), and The resistance value Ra of the ground fault resistor 300 can be derived using any two of the equations (12).
　図４Ａ、図４Ｂ、図４Ｃ、図４Ｄは、地絡が最も低電位側からＸ（Ｘ＜５）枚目の太陽電池モジュールと（Ｘ＋１）枚目の太陽電池モジュールとの間の接続点において生じている場合の太陽電池１０の回路構成を示す。 FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D are the connection points between the X (X <5) th solar cell module and the (X + 1) th solar cell module from the lowest potential side of the ground fault. The circuit configuration of the solar cell 10 when it occurs is shown.
　図４Ａは、スイッチ制御部１０４が、第１電流値検出条件においてスイッチ３４がオフ、スイッチ３５がオン、かつスイッチ３６がオンした状態での太陽電池１０の回路構成を示す。図４Ａに示す回路構成において、太陽電池１０の低電位側の出力端子から出力された第１電流値ＩＡは、式（２０）で示される追加抵抗４２と絶縁抵抗２００との合成抵抗を流れる電流を示す電流値Ｉ１ａと、式（２１）で示される地絡抵抗３００を流れる電流を示す電流値Ｉ２ａとの合計である。 FIG. 4A shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned off, the switch 35 is turned on, and the switch 36 is turned on under the first current value detection condition. In the circuit configuration shown in FIG. 4A, the first current value IA output from the output terminal on the low potential side of the solar cell 10 is the current flowing through the combined resistance of the additional resistor 42 and the insulation resistor 200 represented by the equation (20). And a current value I2a indicating a current flowing through the ground fault resistance 300 represented by the equation (21).
　Ｉ１ａ＝５Ｖａ／Ｒ　　　・・・（２０）
　Ｉ２ａ＝Ｘ×Ｖａ／Ｒａ　　　・・・（２１）
　ＩＡ＝Ｉ１ａ＋Ｉ２ａ＝５Ｖａ／Ｒ＋Ｘ×Ｖａ／Ｒａ　　　・・・（２２） I1a = 5Va / R (20)
I2a = X × Va / Ra (21)
IA = I1a + I2a = 5Va / R + X × Va / Ra (22)
　図４Ｂは、スイッチ制御部１０４が、第２電流値検出条件においてスイッチ３４がオフ、スイッチ３５がオン、かつスイッチ３６がオフした状態での太陽電池１０の回路構成を示す。図４Ｂに示す回路構成において、太陽電池１０の低電位側の出力端子から出力された第１電流値ＩＢは、式（２３）で示される絶縁抵抗２００を流れる電流を示す電流値Ｉ１ｂと、式（２４）で示される地絡抵抗３００を流れる電流を示す電流値Ｉ２ｂとの合計である。 FIG. 4B shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned off, the switch 35 is turned on, and the switch 36 is turned off under the second current value detection condition. In the circuit configuration shown in FIG. 4B, the first current value IB output from the output terminal on the low potential side of the solar cell 10 is the current value I1b indicating the current flowing through the insulation resistor 200 shown by the equation (23), and the equation This is the total of the current value I2b indicating the current flowing through the ground fault resistance 300 indicated by (24).
　Ｉ１ｂ＝５Ｖａ／Ｒｂ　　　・・・（２３）
　Ｉ２ｂ＝Ｘ×Ｖａ／Ｒａ　　　・・・（２４）
　ＩＢ＝Ｉ１ｂ＋Ｉ２ｂ＝５Ｖａ／Ｒｂ＋Ｘ×Ｖａ／Ｒａ　　　・・・（２５） I1b = 5Va / Rb (23)
I2b = X × Va / Ra (24)
IB = I1b + I2b = 5Va / Rb + X × Va / Ra (25)
　図４Ｃは、スイッチ制御部１０４が、第３電流値検出条件においてスイッチ３４がオン、スイッチ３５がオフ、かつスイッチ３６がオンした状態での太陽電池１０の回路構成を示す。図４Ｃに示す回路構成において、太陽電池１０の高電位側の出力端子から出力された第３電流値ＩＣは、式（２６）で示される地絡抵抗３００を流れる電流を示す電流値Ｉ１ｃと、式（２７）で示される追加抵抗４２と絶縁抵抗２００との合成抵抗を流れる電流を示す電流値Ｉ３ｃとの合計である。 FIG. 4C shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned on, the switch 35 is turned off, and the switch 36 is turned on under the third current value detection condition. In the circuit configuration shown in FIG. 4C, the third current value IC output from the output terminal on the high potential side of the solar cell 10 is a current value I1c indicating the current flowing through the ground fault resistor 300 represented by the equation (26), This is the sum of the current value I3c indicating the current flowing through the combined resistance of the additional resistance 42 and the insulation resistance 200 represented by Expression (27).
　Ｉ１ｃ＝（５＋５－Ｘ）Ｖａ／Ｒａ　　　・・・（２６）
　Ｉ３ｃ＝５Ｖａ／Ｒ　　　・・・（２７）
　ＩＣ＝Ｉ１ｃ＋Ｉ３ｃ＝（１０－Ｘ）Ｖａ／Ｒａ＋５Ｖａ／Ｒ　　　・・・（２８） I1c = (5 + 5-X) Va / Ra (26)
I3c = 5Va / R (27)
IC = I1c + I3c = (10−X) Va / Ra + 5Va / R (28)
　図４Ｄは、スイッチ制御部１０４が、第４電流値検出条件においてスイッチ３４がオン、スイッチ３５がオフ、かつスイッチ３６がオフした状態での太陽電池１０の回路構成を示す。図４Ｄに示す回路構成において、太陽電池１０の高電位側の出力端子から出力された第４電流値ＩＤは、式（２９）で示される絶縁抵抗２００を流れる電流を示す電流値Ｉ１ｄと、式（３０）で示される地絡抵抗３００を流れる電流を示す電流値Ｉ３ｄとの合計である。 FIG. 4D shows a circuit configuration of the solar cell 10 in a state where the switch control unit 104 is turned on, the switch 35 is turned off, and the switch 36 is turned off under the fourth current value detection condition. In the circuit configuration shown in FIG. 4D, the fourth current value ID output from the output terminal on the high potential side of the solar cell 10 is the current value I1d indicating the current flowing through the insulation resistor 200 shown by the equation (29), and the equation This is the total of the current value I3d indicating the current flowing through the ground fault resistance 300 indicated by (30).
　Ｉ１ｄ＝（５＋５－Ｘ）Ｖａ／Ｒａ　　　・・・（２９）
　Ｉ３ｄ＝５Ｖａ／Ｒｂ　　　・・・（３０）
　ＩＤ＝Ｉ１ｄ＋Ｉ３ｄ＝（１０－Ｘ）Ｖａ／Ｒａ＋５Ｖａ／Ｒｂ　　　・・・（３１） I1d = (5 + 5-X) Va / Ra (29)
I3d = 5Va / Rb (30)
ID = I1d + I3d = (10−X) Va / Ra + 5Va / Rb (31)
　地絡検出部１１０は、式（２２）、式（２５）、式（２８）、および式（３１）を利用して、地絡抵抗３００の抵抗値Ｒａを導出する。ここで、太陽電池１０の地絡の位置が未知である場合、未知数はＲａ、Ｒｂ、Ｘの３つなので、地絡検出部１１０は、式（２２）、式（２５）、式（２８）、および式（３１）のいずれか３つの式を利用して、地絡抵抗３００の抵抗値Ｒａを導出できる。 The ground fault detection unit 110 derives the resistance value Ra of the ground fault resistance 300 using the formula (22), the formula (25), the formula (28), and the formula (31). Here, when the position of the ground fault of the solar cell 10 is unknown, since there are three unknowns Ra, Rb, and X, the ground fault detection unit 110 performs the expressions (22), (25), and (28). The resistance value Ra of the ground fault resistor 300 can be derived using any three of the equations (31) and (31).
　以上のように、太陽電池１０を構成するいずれか２つの太陽電池モジュール１２間の接続点を既知の抵抗値を有する抵抗を介して基準電位点である接地点に接続した状態、および接続していない状態のそれぞれについて、太陽電池１０の高電位側の出力端子を接地点に接続した場合、および太陽電池１０の低電位側の出力端子を接地点に接続した場合のそれぞれについて、接地点に接続した出力端子から出力される電流をそれぞれ検知する。これにより、地絡抵抗３００の抵抗値Ｒａ、絶縁抵抗２００の抵抗値Ｒｂ、および地絡の位置Ｘの３つの未知数を含む連立方程式を４つ導出できる。よって、地絡検出部１１０は、４つの連立方程式のいずれか３つの式を利用して、地絡抵抗３００の抵抗値Ｒａを導出できる。 As described above, the connection point between any two solar cell modules 12 constituting the solar cell 10 is connected to the ground point that is the reference potential point via the resistor having a known resistance value, and is connected. For each of the unconnected states, when the output terminal on the high potential side of the solar cell 10 is connected to the ground point, and when the output terminal on the low potential side of the solar cell 10 is connected to the ground point, each is connected to the ground point. The current output from each output terminal is detected. Accordingly, four simultaneous equations including three unknowns of the resistance value Ra of the ground fault resistance 300, the resistance value Rb of the insulation resistance 200, and the position X of the ground fault can be derived. Therefore, the ground fault detection unit 110 can derive the resistance value Ra of the ground fault resistance 300 using any three of the four simultaneous equations.
　ここで、地絡検出部１１０が、絶縁抵抗２００と地絡抵抗３００とを合成した合成抵抗を太陽電池１０の絶縁抵抗とみなして、その合成抵抗の抵抗値が基準抵抗値より小さい場合に、太陽電池１０の地絡が発生していると判断することも考えられる。しかし、絶縁抵抗２００の抵抗値は、気温などの環境の変化によって変動する。例えば、雨天の日の絶縁抵抗２００の抵抗値は、乾燥した晴天の日が続いた場合の絶縁抵抗２００の抵抗値より低くなる場合がある。そのため、地絡検出部１１０が、絶縁抵抗２００と地絡抵抗３００とを合成した合成抵抗に基づいて地絡の有無を判断する場合、地絡検出部１１０は、環境の変化に伴う絶縁抵抗２００の抵抗値の変化と、太陽電池１０の劣化の進行に伴う地絡抵抗３００の抵抗値の変化とを区別できない。したがって、地絡検出部１１０が絶縁抵抗２００と地絡抵抗３００とを合成した合成抵抗に基づいて地絡の有無を判断する場合、太陽電池１０の地絡の有無の判定の精度が低下する可能性がある。 Here, when the ground fault detection unit 110 regards the combined resistance obtained by combining the insulation resistance 200 and the ground fault resistance 300 as the insulation resistance of the solar cell 10, and the resistance value of the combined resistance is smaller than the reference resistance value, It may be determined that a ground fault of the solar cell 10 has occurred. However, the resistance value of the insulation resistance 200 varies depending on environmental changes such as temperature. For example, the resistance value of the insulation resistance 200 on a rainy day may be lower than the resistance value of the insulation resistance 200 when a dry sunny day continues. Therefore, when the ground fault detection unit 110 determines the presence or absence of a ground fault based on the combined resistance obtained by synthesizing the insulation resistance 200 and the ground fault resistance 300, the ground fault detection unit 110 includes the insulation resistance 200 according to the environmental change. The change in the resistance value of the solar cell 10 and the change in the resistance value of the ground fault resistor 300 as the deterioration of the solar cell 10 progresses cannot be distinguished. Therefore, when the ground fault detection unit 110 determines the presence / absence of a ground fault based on the combined resistance obtained by combining the insulation resistance 200 and the ground fault resistance 300, the accuracy of the determination of the presence / absence of the ground fault of the solar cell 10 may be reduced. There is sex.
　そこで、本実施形態に係る地絡検出部１１０は、絶縁抵抗２００と地絡抵抗３００とを区別して、地絡抵抗３００の抵抗値に基づいて、太陽電池１０の地絡の有無を判定している。したがって、本実施形態によれば、環境の変化に伴い絶縁抵抗２００の抵抗値が変化した場合でも、地絡検出部１１０による太陽電池１０の地絡の有無の判定の精度が低下することを防止できる。 Therefore, the ground fault detection unit 110 according to the present embodiment distinguishes between the insulation resistance 200 and the ground fault resistance 300, and determines the presence or absence of the ground fault of the solar cell 10 based on the resistance value of the ground fault resistance 300. Yes. Therefore, according to the present embodiment, even when the resistance value of the insulation resistance 200 changes due to a change in the environment, it is possible to prevent the accuracy of the determination of the presence or absence of the ground fault of the solar cell 10 by the ground fault detection unit 110 from being lowered. it can.
　図５は、地絡検出装置３０が太陽電池１０の地絡を検出する手順の一例を示すフローチャートである。 FIG. 5 is a flowchart illustrating an example of a procedure in which the ground fault detection device 30 detects a ground fault of the solar cell 10.
　リレー制御部１０２は、太陽電池１０の地絡を検出すべき予め定められたタイミングで、切断手段３２に作動信号を出力して、リレー３２ａおよびリレー３２ｂを作動させ、太陽電池１０と電力変換装置２０との間を電気的に遮断する（Ｓ１００）。 The relay control unit 102 outputs an operation signal to the cutting means 32 at a predetermined timing at which a ground fault of the solar cell 10 is to be detected, operates the relay 32a and the relay 32b, and the solar cell 10 and the power conversion device. Electrically cuts off from 20 (S100).
　電圧値取得部１０６は、電圧センサ４４を介して太陽電池１０から出力される電圧の電圧値Ｖｏを取得する（Ｓ１０２）。スイッチ制御部１０４は、スイッチ３４をオフ、スイッチ３５をオンして、太陽電池１０の低電位側の出力端子を基準電位点である接地点に接続する（Ｓ１０４）。また、スイッチ制御部１０４は、スイッチ３６をオンして、太陽電池１０の中点である接続点１４を追加抵抗４２を介して基準電位点に接続する（Ｓ１０６）。電流値取得部１０８は、スイッチ制御部１０４によりスイッチ３４がオフ、スイッチ３５がオン、かつスイッチ３６がオンした状態で、電流センサ４６を介して太陽電池１０の低電位側の出力端子から出力される電流を示す第１電流値ＩＡを取得する（Ｓ１０８）。 The voltage value acquisition unit 106 acquires the voltage value Vo of the voltage output from the solar cell 10 via the voltage sensor 44 (S102). The switch control unit 104 turns off the switch 34 and turns on the switch 35 to connect the output terminal on the low potential side of the solar cell 10 to the ground point that is the reference potential point (S104). In addition, the switch control unit 104 turns on the switch 36 to connect the connection point 14 that is the midpoint of the solar cell 10 to the reference potential point via the additional resistor 42 (S106). The current value acquisition unit 108 is output from the output terminal on the low potential side of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned off, the switch 35 is turned on, and the switch 36 is turned on by the switch control unit 104. The first current value IA indicating the current to be acquired is acquired (S108).
　次いで、スイッチ制御部１０４は、スイッチ３６をオフする（Ｓ１１０）。電流値取得部１０８は、スイッチ制御部１０４によりスイッチ３４がオフ、スイッチ３５がオン、かつスイッチ３６がオフした状態で、電流センサ４６を介して太陽電池１０の低電位側の出力端子から出力される電流を示す第２電流値ＩＢを取得する（Ｓ１１２）。 Next, the switch control unit 104 turns off the switch 36 (S110). The current value acquisition unit 108 is output from the output terminal on the low potential side of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned off, the switch 35 is turned on, and the switch 36 is turned off by the switch control unit 104. The second current value IB indicating the current to be acquired is acquired (S112).
　続いて、スイッチ制御部１０４は、スイッチ３４をオン、スイッチ３５をオフして、太陽電池１０の高電位側の出力端子を基準電位点である接地点に接続する（Ｓ１１４）。また、スイッチ制御部１０４は、スイッチ３６をオンして、太陽電池１０の中点である接続点１４を追加抵抗４２を介して基準電位点に接続する（Ｓ１１６）。電流値取得部１０８は、スイッチ制御部１０４によりスイッチ３４がオン、スイッチ３５がオフ、かつスイッチ３６がオンした状態で、電流センサ４６を介して太陽電池１０の高電位側の出力端子から出力される電流を示す第３電流値ＩＣを取得する（Ｓ１１８）。 Subsequently, the switch control unit 104 turns on the switch 34 and turns off the switch 35 to connect the output terminal on the high potential side of the solar cell 10 to the ground point that is the reference potential point (S114). Further, the switch control unit 104 turns on the switch 36 to connect the connection point 14 that is the midpoint of the solar cell 10 to the reference potential point via the additional resistor 42 (S116). The current value acquisition unit 108 is output from the output terminal on the high potential side of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned on, the switch 35 is turned off, and the switch 36 is turned on by the switch control unit 104. The third current value IC indicating the current to be acquired is acquired (S118).
　次いで、スイッチ制御部１０４は、スイッチ３６をオフする（Ｓ１２０）。電流値取得部１０８は、スイッチ制御部１０４によりスイッチ３４がオン、スイッチ３５がオフ、かつスイッチ３６がオフした状態で、電流センサ４６を介して太陽電池１０の高電位側の出力端子から出力される電流を示す第４電流値ＩＤを取得する（Ｓ１２２）。 Next, the switch control unit 104 turns off the switch 36 (S120). The current value acquisition unit 108 is output from the output terminal on the high potential side of the solar cell 10 through the current sensor 46 in a state where the switch 34 is turned on, the switch 35 is turned off, and the switch 36 is turned off by the switch control unit 104. The fourth current value ID indicating the current to be acquired is acquired (S122).
　地絡検出部１１０は、追加抵抗４２の既知の抵抗値Ｒｃ、電圧値Ｖｏ、並びに第１電流値ＩＡ、第２電流値ＩＢ、第３電流値ＩＣ、および第４電流値ＩＤの少なくとも３つの電流値に基づいて、式（２２）、式（２５）、式（２８）、および式（３１）の少なくとも３つの式を利用して、地絡抵抗値Ｒａを導出する（Ｓ１２４）。地絡検出部１１０は、導出された地絡抵抗値Ｒａと、予め定められた基準地絡抵抗値との比較により地絡の有無を判断する（Ｓ１２６）。 The ground fault detection unit 110 includes at least three of a known resistance value Rc, a voltage value Vo of the additional resistor 42, a first current value IA, a second current value IB, a third current value IC, and a fourth current value ID. Based on the current value, the ground fault resistance value Ra is derived using at least three formulas (22), (25), (28), and (31) (S124). The ground fault detection unit 110 determines the presence or absence of a ground fault by comparing the derived ground fault resistance value Ra with a predetermined reference ground fault resistance value (S126).
　以上、本実施形態によれば、地絡検出部１１０は、絶縁抵抗２００の抵抗値成分を含まない地絡抵抗３００の抵抗値に基づいて、太陽電池１０の地絡の有無を判定できる。したがって、本実施形態によれば、環境の変化に伴い絶縁抵抗２００の抵抗値が変化した場合でも、地絡検出部１１０による太陽電池１０の地絡の有無の判定の精度が低下することを防止できる。 As described above, according to the present embodiment, the ground fault detection unit 110 can determine the presence or absence of the ground fault of the solar cell 10 based on the resistance value of the ground fault resistor 300 that does not include the resistance component of the insulation resistance 200. Therefore, according to the present embodiment, even when the resistance value of the insulation resistance 200 changes due to a change in the environment, it is possible to prevent the accuracy of the determination of the presence or absence of the ground fault of the solar cell 10 by the ground fault detection unit 110 from being lowered. it can.
　なお、電流値取得部１０８は、第１電流値ＩＡ、第２電流値ＩＢ、第３電流値ＩＣ、および第４電流値ＩＤのいずれか３つのみを取得し、地絡検出部１１０は、取得された３つの電流値を用いて、地絡抵抗値を導出してもよい。 The current value acquisition unit 108 acquires only three of the first current value IA, the second current value IB, the third current value IC, and the fourth current value ID, and the ground fault detection unit 110 A ground fault resistance value may be derived using the three acquired current values.
　地絡検出部１１０は、第１時点における追加抵抗４２の既知の抵抗値Ｒｃ、並びに第１電流値ＩＡ、第２電流値ＩＢ、第３電流値ＩＣおよび第４電流値ＩＤの少なくとも３つの電流値に基づいて、太陽電池１０の第１時点における第１地絡抵抗値を導出してよい。さらに、地絡検出部１１０は、第１時点より後の第２時点における追加抵抗４２の既知の抵抗値Ｒｃ、並びに第１電流値ＩＡ、第２電流値ＩＢ、第３電流値ＩＣおよび第４電流値ＩＤの少なくとも３つの電流値に基づいて、太陽電池１０の第２時点における第２地絡抵抗値を導出してよい。そして、地絡検出部１１０は、第１地絡抵抗値と第２地絡抵抗値とに基づいて、太陽電池１０の地絡を検出してよい。地絡検出部１１０は、第２地絡抵抗値が第１地絡抵抗値に基づいて定められる基準地絡抵抗値より低い場合に、太陽電池１０の地絡が発生している、もしくは太陽電池１０の地絡が進行していると判断してよい。 The ground fault detection unit 110 has a known resistance value Rc of the additional resistor 42 at the first time point, and at least three currents of the first current value IA, the second current value IB, the third current value IC, and the fourth current value ID. The first ground fault resistance value at the first time point of the solar cell 10 may be derived based on the value. Further, the ground fault detection unit 110 includes the known resistance value Rc of the additional resistor 42 at the second time point after the first time point, the first current value IA, the second current value IB, the third current value IC, and the fourth current value. The second ground fault resistance value at the second time point of the solar cell 10 may be derived based on at least three current values of the current value ID. And the ground fault detection part 110 may detect the ground fault of the solar cell 10 based on a 1st ground fault resistance value and a 2nd ground fault resistance value. When the second ground fault resistance value is lower than the reference ground fault resistance value determined based on the first ground fault resistance value, the ground fault detection unit 110 has a ground fault in the solar cell 10 or the solar cell. It may be determined that ten ground faults are in progress.
　例えば、地絡検出部１１０は、太陽光発電システムに地絡検出装置３０が設置された時点などの第１時点で、地絡抵抗値を導出し、第１時点の地絡抵抗値に基づいて基準地絡抵抗値を決定する。地絡検出部１１０は、第１時点の地絡抵抗値を基準地絡抵抗値としてよい。地絡検出部１１０は、第１時点の地絡抵抗値から予め定められた値を減算した値を基準地絡抵抗値としてよい。地絡検出部１１０は、第１時点の地絡抵抗値に対して予め定められた割合を乗算した値を基準地絡抵抗値としてよい。そして、地絡検出部１１０は、第１時点より後の第２時点において導出した地絡抵抗値と第１時点の地絡抵抗値に基づく基準地絡抵抗値とを比較することにより、太陽電池１０の地絡の有無を判定してよい。 For example, the ground fault detection unit 110 derives a ground fault resistance value at a first time point such as a time point when the ground fault detection device 30 is installed in the solar power generation system, and based on the ground fault resistance value at the first time point. Determine the reference ground fault resistance value. The ground fault detection unit 110 may use the ground fault resistance value at the first time point as the reference ground fault resistance value. The ground fault detection unit 110 may use a value obtained by subtracting a predetermined value from the ground fault resistance value at the first time point as the reference ground fault resistance value. The ground fault detection unit 110 may set a value obtained by multiplying the ground fault resistance value at the first time point by a predetermined ratio as the reference ground fault resistance value. Then, the ground fault detection unit 110 compares the ground fault resistance value derived at the second time point after the first time point with the reference ground fault resistance value based on the ground fault resistance value at the first time point. The presence or absence of ten ground faults may be determined.
　太陽電池１０の地絡抵抗値は、太陽電池１０の電気的な特性に依存する。したがって、基準地絡抵抗値を、地絡検出部１１０が導出した地絡抵抗値に基づいて設定することで、太陽電池１０固有の基準地絡抵抗値を設定できる。よって、地絡検出部１１０が導出した地絡抵抗値に基づいて基準地絡抵抗値を設定することで、地絡検出部１１０は、より精度よく太陽電池１０の地絡の有無を判断できる。 The ground fault resistance value of the solar cell 10 depends on the electrical characteristics of the solar cell 10. Therefore, the reference ground fault resistance value unique to the solar cell 10 can be set by setting the reference ground fault resistance value based on the ground fault resistance value derived by the ground fault detection unit 110. Therefore, by setting the reference ground fault resistance value based on the ground fault resistance value derived by the ground fault detection unit 110, the ground fault detection unit 110 can determine the presence or absence of the ground fault of the solar cell 10 with higher accuracy.
　以上、本発明を実施の形態を用いて説明したが、本発明の技術的範囲は上記実施の形態に記載の範囲には限定されない。上記実施の形態に、多様な変更または改良を加えることが可能であることが当業者に明らかである。その様な変更または改良を加えた形態も本発明の技術的範囲に含まれ得ることが、請求の範囲の記載から明らかである。 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.
　請求の範囲、明細書、および図面中において示した装置、システム、プログラム、および方法における動作、手順、ステップ、および段階等の各処理の実行順序は、特段「より前に」、「先立って」等と明示しておらず、また、前の処理の出力を後の処理で用いるのでない限り、任意の順序で実現しうることに留意すべきである。請求の範囲、明細書、および図面中の動作フローに関して、便宜上「まず、」、「次に、」等を用いて説明したとしても、この順で実施することが必須であることを意味するものではない。 The execution order 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”. It should be noted that they can be implemented 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 the sake of convenience, it means that it is essential to carry out in this order. is not.
１０　太陽電池
１２　太陽電池モジュール
１４　接続点
２０　電力変換装置
３０　地絡検出装置
３２　切断手段
３２ａ，３２ｂ　リレー
３４，３５，３６　スイッチ
４０　検出抵抗
４２　追加抵抗
４４　電圧センサ
４６　電流センサ
１００　制御部
１０２　リレー制御部
１０４　スイッチ制御部
１０６　電圧値取得部
１０８　電流値取得部
１１０　地絡検出部
２００　絶縁抵抗
３００　地絡抵抗 DESCRIPTION OF SYMBOLS 10 Solar cell 12 Solar cell module 14 Connection point 20 Power converter 30 Ground fault detector 32 Cutting means 32a, 32b Relay 34, 35, 36 Switch 40 Detection resistor 42 Additional resistance 44 Voltage sensor 46 Current sensor 100 Control part 102 Relay control Unit 104 Switch control unit 106 Voltage value acquisition unit 108 Current value acquisition unit 110 Ground fault detection unit 200 Insulation resistance 300 Ground fault resistance

Claims (6)

  1. 　直列に接続された複数の直流電源の地絡を検出する地絡検出装置であって、
    　前記複数の直流電源に含まれる第１直流電源と前記第１直流電源に直列に接続された第２直流電源との接続点を予め定められた抵抗値の抵抗を介して基準電位点に接続し、かつ前記複数の直流電源の第１出力端を前記基準電位点に接続した状態で、前記第１出力端に流れる電流を示す第１電流値を取得する第１電流値取得部と、
    　前記接続点を前記抵抗を介して前記基準電位点に接続せず、かつ前記第１出力端を前記基準電位点に接続した状態で、前記第１出力端に流れる電流を示す第２電流値を取得する第２電流値取得部と、
    　前記接続点を前記抵抗を介して前記基準電位点に接続し、または前記接続点を前記抵抗を介して前記基準電位点に接続せず、かつ前記複数の直流電源の第２出力端を前記基準電位点に接続した状態で、前記第２出力端に流れる電流を示す第３電流値を取得する第３電流値取得部と、
    　前記抵抗値、前記第１電流値、前記第２電流値、および前記第３電流値に基づいて、前記複数の直流電源の地絡を検出する地絡検出部と
    を備える地絡検出装置。     A ground fault detection device for detecting a ground fault of a plurality of DC power supplies connected in series,
    A connection point between a first DC power source included in the plurality of DC power sources and a second DC power source connected in series to the first DC power source is connected to a reference potential point through a resistor having a predetermined resistance value. And a first current value acquisition unit for acquiring a first current value indicating a current flowing through the first output terminal in a state where the first output terminals of the plurality of DC power supplies are connected to the reference potential point;
    A second current value indicating a current flowing through the first output terminal in a state where the connection point is not connected to the reference potential point via the resistor and the first output terminal is connected to the reference potential point. A second current value acquisition unit to acquire;
    The connection point is connected to the reference potential point through the resistor, or the connection point is not connected to the reference potential point through the resistor, and second output terminals of the plurality of DC power supplies are connected to the reference potential point. A third current value acquisition unit that acquires a third current value indicating a current flowing through the second output terminal in a state of being connected to a potential point;
    A ground fault detection apparatus comprising: a ground fault detection unit that detects ground faults of the plurality of DC power sources based on the resistance value, the first current value, the second current value, and the third current value.
  2. 　前記接続点を前記抵抗を介して前記基準電位点に接続するか否かを切り替える第１切り替え手段と、
    　前記第１出力端および前記第２出力端のいずれか一方を前記基準電位点に接続するか否かを切り替える第２切り替え手段と
    をさらに備える、請求項１に記載の地絡検出装置。     First switching means for switching whether or not to connect the connection point to the reference potential point via the resistor;
    The ground fault detection device according to claim 1, further comprising second switching means for switching whether or not one of the first output terminal and the second output terminal is connected to the reference potential point.
  3. 　前記地絡検出部は、第１時点における前記抵抗値、前記第１電流値、前記第２電流値、および前記第３電流値に基づいて、前記複数の直流電源の前記第１時点における第１地絡抵抗値を導出し、前記第１時点より後の第２時点における前記抵抗値、前記第１電流値、前記第２電流値、および前記第３電流値に基づいて、前記複数の直流電源の前記第２時点における第２地絡抵抗値を導出し、前記第１地絡抵抗値と前記第２地絡抵抗値とに基づいて、前記複数の直流電源の地絡を検出する、請求項１または請求項２に記載の地絡検出装置。 The ground fault detection unit is configured to determine a first time at the first time point of the plurality of DC power sources based on the resistance value, the first current value, the second current value, and the third current value at a first time point. A plurality of DC power sources are derived based on the resistance value, the first current value, the second current value, and the third current value at a second time point after the first time point. A second ground fault resistance value at the second time point is derived, and ground faults of the plurality of DC power sources are detected based on the first ground fault resistance value and the second ground fault resistance value. The ground fault detection apparatus according to claim 1 or 2.
  4. 　前記複数の直流電源のそれぞれは、太陽電池である、請求項１から請求項３のいずれか１つに記載の地絡検出装置。 The ground fault detection device according to any one of claims 1 to 3, wherein each of the plurality of DC power supplies is a solar battery.
  5. 　請求項１から請求項４のいずれか１つに記載の地絡検出装置と、
    　前記複数の直流電源と、
    　前記複数の直流電源から供給される電力を消費または変換する負荷装置と
    を備え、
    　前記地絡検出装置は、
    　前記複数の直流電源と前記負荷装置との間を電気的に接続するか切断するかを切り替える第３切り替え手段をさらに備え、
    　前記第３切り替え手段により前記複数の直流電源と前記負荷装置との間を電気的に切断した状態で、前記第１電流値取得部は、前記第１出力端に流れる電流を示す前記第１電流値を取得し、前記第２電流値取得部は、前記第１出力端に流れる電流を示す前記第２電流値を取得し、前記第３電流値取得部は、前記第２出力端に流れる電流を示す前記第３電流値を取得する、電源システム。     A ground fault detection device according to any one of claims 1 to 4,
    The plurality of DC power supplies;
    A load device that consumes or converts power supplied from the plurality of DC power sources,
    The ground fault detection device is
    Further comprising third switching means for switching between electrically connecting or disconnecting between the plurality of DC power supplies and the load device;
    In the state where the plurality of DC power supplies and the load device are electrically disconnected by the third switching means, the first current value acquisition unit indicates the first current indicating a current flowing through the first output terminal. The second current value acquisition unit acquires the second current value indicating the current flowing through the first output terminal, and the third current value acquisition unit acquires the current flowing through the second output terminal. A power supply system that acquires the third current value indicating
  6. 　直列に接続された複数の直流電源の地絡を検出する地絡検出方法であって、
    　前記複数の直流電源に含まれる第１直流電源と前記第１直流電源に直列に接続された第２直流電源との接続点を予め定められた抵抗値の抵抗を介して基準電位点に接続し、かつ前記複数の直流電源の第１出力端を前記基準電位点に接続した状態で、前記第１出力端に流れる電流を示す第１電流値を取得する段階と、
    　前記接続点を前記抵抗を介して前記基準電位点に接続せず、かつ前記第１出力端を前記基準電位点に接続した状態で、前記第１出力端に流れる電流を示す第２電流値を取得する段階と、
    　前記接続点を前記抵抗を介して前記基準電位点に接続し、または前記接続点を前記抵抗を介して前記基準電位点に接続せず、かつ前記複数の直流電源の第２出力端を前記基準電位点に接続した状態で、前記第２出力端に流れる電流を示す第３電流値を取得する段階と、
    　前記抵抗値、前記第１電流値、前記第２電流値、および前記第３電流値に基づいて、前記複数の直流電源の地絡を検出する段階と
    を含む地絡検出方法。     A ground fault detection method for detecting ground faults of a plurality of DC power supplies connected in series,
    A connection point between a first DC power source included in the plurality of DC power sources and a second DC power source connected in series to the first DC power source is connected to a reference potential point through a resistor having a predetermined resistance value. And obtaining a first current value indicating a current flowing through the first output terminal in a state where the first output terminals of the plurality of DC power supplies are connected to the reference potential point;
    A second current value indicating a current flowing through the first output terminal in a state where the connection point is not connected to the reference potential point via the resistor and the first output terminal is connected to the reference potential point. The stage of acquiring,
    The connection point is connected to the reference potential point through the resistor, or the connection point is not connected to the reference potential point through the resistor, and second output terminals of the plurality of DC power supplies are connected to the reference potential point. Obtaining a third current value indicating a current flowing through the second output terminal in a state of being connected to a potential point;
    Detecting a ground fault of the plurality of DC power sources based on the resistance value, the first current value, the second current value, and the third current value.
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