JP6375042B1 - Connection circuit and power conditioner - Google Patents

Abstract

[PROBLEMS] To suppress a factor that causes a PID phenomenon during a period when a photovoltaic power generation system is not operated, such as at night. A connection circuit is provided between a solar panel and a power conditioner. In the connection circuit 30, the power lines 31 and 32 are provided with high impedance portions 41 and 51 having high impedance when the solar panel 10 stops outputting, and the power lines 31 and 32 on the solar panel 10 side are connected to the resistance elements 42. , 52 are grounded. Even if the difference between the potential of the power lines 31 and 32 on the power conditioner 20 side and the ground potential is large, the difference between the potential of the power lines 31 and 32 on the solar panel 10 side and the ground potential can be kept small. [Selection] Figure 1

Description

  The present invention relates to a photovoltaic power generation system, for example, a countermeasure against a PID phenomenon.

  In the photovoltaic power generation system, a PID (Potential Induced Degradation) phenomenon is a problem. The PID phenomenon refers to a phenomenon in which the performance of a solar panel deteriorates due to the influence of ground voltage and the amount of power generation decreases. That is, when a DC voltage is applied between the frame (earth) and the electrode of the solar panel, the resin layer between them is deteriorated and the panel output is lowered.

  Patent Document 1 discloses a configuration in which a negative electrode side or a positive electrode side of a solar cell string is grounded as an example of a countermeasure method against the PID phenomenon.

Japanese Patent Laying-Open No. 2015-32601 (FIG. 10)

  Conventionally, some measures against the PID phenomenon have been taken on the solar panel side during the daytime when the photovoltaic power generation system is operating. On the other hand, in recent years, the number of non-insulating systems has been increasing in order to increase the efficiency of power conditioners used in photovoltaic power generation systems. In addition to solar panels, hybrid type power conditioners to which a storage battery, an electric vehicle (EV), or the like is connected are also beginning to spread.

  Among them, when the hybrid type power conditioner is used in a non-insulated system, the inventors of the present application may cause a PID phenomenon even during a period in which the photovoltaic power generation system is not operated, such as at night. I understood.

  In view of the above problems, an object of the present invention is to suppress a factor that causes a PID phenomenon during a period in which a photovoltaic power generation system does not operate, such as at night.

  The connection circuit according to the present invention provides a high-impedance part having a high impedance in the power line when the solar panel stops outputting, and grounds the power line on the solar panel side via a resistance element. Thereby, even if the difference between the potential of the power line on the power conditioner side and the ground potential is large, the difference between the potential of the power line on the solar panel side and the ground potential can be kept small. Therefore, it is possible to suppress a factor that causes the PID phenomenon during a period when the photovoltaic power generation system is not operated, such as at night.

  That is, in the aspect of the present invention, the connection circuit provided between the output of the solar panel and the input of the power conditioner includes the first power line connecting the positive electrode of the solar panel and the positive electrode of the power conditioner, High impedance when inserted into one of the second power line connecting the negative electrode of the solar panel and the negative electrode of the power conditioner, and the first and second power lines, and the solar panel stops outputting A high-impedance part, and a resistor element having one end connected to the solar panel side of the one power line and the other end grounded.

  According to this aspect, in the connection circuit, a high impedance part having a high impedance is inserted into one of the first and second power lines when the solar panel stops outputting. And the solar panel side rather than the high impedance part of the said one electric power line is earth | grounded via the resistive element. Thereby, even if the difference between the potential of the power line on the power conditioner side and the ground potential is large, the difference between the potential of the power line on the solar panel side and the ground potential can be kept small. Therefore, it is possible to suppress a factor that causes the PID phenomenon during a period when the photovoltaic power generation system is not operated, such as at night.

  And the said aspect WHEREIN: The said high impedance part is good also as including the diode which is inserted in said one electric power line and makes the direction which goes to the said solar panel from the said power conditioner forward.

  Further, in the above aspect, the high impedance section controls the FET (Field Effect Transistor) inserted in the one power line and the FET, and the solar panel stops the output. And a control circuit for turning off the FET.

  Moreover, in the said aspect, the said high impedance part controls the said relay and the relay inserted in said one electric power line, and turns off the said relay when the said solar panel has stopped the output And a control circuit.

  In the above aspect, the resistance element may have a resistance value of 1 MΩ or more.

  Moreover, the said aspect WHEREIN: It is good also as providing the 2nd high impedance part which is inserted in the other among the said 1st and 2nd electric power lines, and has a high impedance when the said solar panel has stopped the output. .

  According to this aspect, even in the other power line, even if the difference between the potential on the power conditioner side and the ground potential is large, the difference between the potential on the solar panel side and the ground potential can be suppressed small.

  And the said aspect WHEREIN: The said 2nd high impedance part is good also as including the diode which is inserted in said other power line, and makes the direction which goes to the said power conditioner from the said solar panel forward.

  In the above aspect, the second high-impedance unit controls the FET inserted in the other power line and the FET, and turns off the FET when the solar panel stops outputting. And a control circuit.

  In the above aspect, the second high impedance unit controls the relay inserted into the other power line, and turns off the relay when the solar panel stops outputting. And a control circuit.

  And in the said aspect, the said power conditioner is good also as being comprised so that a storage battery can be connected by a non-insulation system.

  Further, in another aspect of the present invention, a power conditioner that receives the output of the solar panel includes an inverter unit, and a connection circuit provided between the output of the solar panel and the input of the inverter unit, The connection circuit includes a first power line that connects a positive electrode of the solar panel and a positive electrode of the inverter unit, a second power line that connects a negative electrode of the solar panel and a negative electrode of the inverter unit, and the first The second solar power line is inserted into one of the second power lines, and the solar panel has a high impedance when the output is stopped, and the solar power is higher than the high impedance part of the one power line. A resistor element having one end connected to the panel side and the other end grounded.

  According to this aspect, in the connection circuit built in the power conditioner, a high impedance portion having a high impedance is inserted into one of the first and second power lines when the solar panel stops outputting. And the solar panel side rather than the high impedance part of the said one electric power line is earth | grounded via the resistive element. Thereby, even if the difference between the power line potential on the inverter side and the ground potential is large, the difference between the power line potential on the solar panel side and the ground potential can be kept small. Therefore, it is possible to suppress a factor that causes the PID phenomenon during a period when the photovoltaic power generation system is not operated, such as at night.

  And in the said aspect, the said power conditioner is good also as being comprised so that a storage battery can be connected by a non-insulation system.

  According to the present invention, it is possible to suppress a factor that causes a PID phenomenon during a period when the photovoltaic power generation system does not operate, such as at night.

Configuration of a photovoltaic power generation system including a connection circuit according to the first embodiment It is a figure which shows operation | movement of the connection circuit of FIG. 1, (a) is an output change of a solar panel, (b) is a voltage change of the negative electrode side power line. Configuration of a photovoltaic power generation system including a connection circuit according to the second embodiment Configuration of a photovoltaic power generation system including a connection circuit according to the third embodiment Schematic configuration of power conditioner with built-in connection circuit

  Hereinafter, embodiments will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a configuration of a photovoltaic power generation system including a connection circuit according to the first embodiment. The solar power generation system 1 of FIG. 1 includes a solar panel 10 that generates power using solar energy, and a power conditioner 20 that receives DC power output from the solar panel 10. In the solar panel 10, the three solar cell strings 12a, 12b, and 12c are configured by a plurality of solar cell modules 11 that are electrically connected in series. The solar cell strings 12a, 12b, and 12c are electrically connected in parallel. And the positive electrode (+) of each solar cell string 12a, 12b, 12c is connected in common, and the negative electrode (-) of each solar cell string 12a, 12b, 12c is connected in common.

  In the configuration of FIG. 1, each solar cell string 12a, 12b, 12c is configured by three solar cell modules 11 connected in series, but the number of solar cell modules connected in series is as follows. It is not limited to three. In the configuration of FIG. 1, three solar cell strings 12a, 12b, and 12c are connected in parallel. However, the number of solar cell strings connected in parallel is not limited to three.

  Here, the power conditioner 20 is a non-insulating type and is a so-called hybrid type to which a storage battery 25, an electric vehicle (EV) 26, and the like are connected. The power conditioner 20 includes an inverter unit 21 that converts DC power output from the solar panel 10 into AC power for a commercial system.

  In this embodiment, a connection circuit 30 is provided between the output of the solar panel 10 and the input of the power conditioner 20. The connection circuit 30 includes a first power line 31 that connects the positive electrode of the solar panel 10 and the positive electrode of the power conditioner 20, and a second power line 32 that connects the negative electrode of the solar panel 10 and the negative electrode of the power conditioner 20. . A diode 41 having a forward direction from the power conditioner 20 toward the solar panel 10 is inserted into the second power line 32. In the present embodiment, the diode 41 constitutes a high impedance portion having a high impedance when the solar panel 10 stops outputting. The impedance in the reverse direction of the diode 41 is, for example, about 100 MΩ. In addition, the connection circuit 30 includes a resistance element 42 having one end connected to the solar panel 10 side of the second power line 32 with respect to the diode 41 and the other end grounded. The resistance value of the resistance element 42 is 1 MΩ or more. The impedance in the reverse direction of the diode 41 is preferably sufficiently higher than the resistance value of the resistance element 42.

  Further, in the connection circuit 30, a diode 51 having a forward direction from the solar panel 10 toward the power conditioner 20 is inserted in the first power line 31. The diode 51 forms a second high impedance portion having a high impedance when the solar panel 10 stops outputting. The impedance of the diode 51 in the reverse direction is, for example, about 100 MΩ. In addition, the connection circuit 30 includes a resistance element 52 having one end connected to the solar panel 10 side of the first power line 31 with respect to the diode 51 and the other end grounded. The resistance value of the resistance element 52 is 1 MΩ or more. The impedance in the reverse direction of the diode 51 is preferably sufficiently higher than the resistance value of the resistance element 52.

  FIG. 2 is a diagram illustrating the operation of the connection circuit 30 according to the present embodiment, and illustrates an example of a voltage change of the power line when the output of the solar panel 10 is stopped. 2A shows the output change of the solar panel 10, and FIG. 2B shows the voltage change of the second power line 32. As shown in FIG.

  When the solar panel 10 is operating, it outputs, for example, 300 V as its output. At this time, the voltage on the solar panel 10 side of the second power line 32 is about −150V. Further, the voltage on the power conditioner 20 side of the second power line 32 is slightly higher than that. For example, assume that at night, the output of the solar panel 10 decreases, and eventually the output stops. At this time, the voltage on the solar panel 10 side of the second power line 32 gradually approaches 0V, and after gradually reaching 0V over several tens of volts, gradually decreases. The voltage on the solar panel 10 side of the second power line 32 finally approaches a voltage obtained by dividing the voltage on the power conditioner 20 side of the second power line 32 by the impedance of the diode 41 and the resistance value of the resistance element 42. To go.

  On the other hand, when the diode 41 and the resistance element 42 are not provided in the second power line 32, when the output of the solar panel 10 is stopped, the voltage on the solar panel 10 side of the second power line 32 is The voltage is almost the same as the voltage on the power conditioner 20 side of the second power line 32. On the other hand, when the storage battery 25 or the like is connected to the non-insulated power conditioner 20, a large voltage may be output to the second power line 32. In this case, even if the output of the solar panel 10 is stopped, a DC voltage is applied between the ground and the negative electrode of the solar panel 10, so that the resin layer between them is Deteriorated and panel output decreases. That is, a so-called PID (Potential Induced Degradation) phenomenon is caused. Therefore, by providing the diode 41 and the resistance element 42 in the second power line 32, it is possible to suppress a factor that causes the PID phenomenon in a period in which the solar power generation system 1 is not operated such as at night.

  Similarly, by providing the first power line 31 with the diode 51 and the resistance element 52, it is possible to suppress a factor that causes the PID phenomenon during a period in which the solar power generation system 1 does not operate, such as at night.

  As described above, according to the present embodiment, the first and second power lines 31 and 32 are provided with the diodes 41 and 51 having high impedance when the solar panel 10 stops outputting, and the solar panel 10 side power line. 31 and 32 are grounded via resistance elements 42 and 52. Thereby, even if the difference between the potential of the power lines 31 and 32 on the power conditioner 20 side and the ground potential is large, the difference between the potential of the power lines 31 and 32 on the solar panel 10 side and the ground potential is suppressed to a small level. Therefore, it is possible to suppress a factor that causes the PID phenomenon during a period when the photovoltaic power generation system is not operated, such as at night.

(Second Embodiment)
FIG. 3 is a diagram illustrating a configuration of a photovoltaic power generation system including a connection circuit according to the second embodiment. In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and detailed description thereof is omitted here. In the configuration of FIG. 3, the connection circuit 30 </ b> A includes a field effect transistor (FET) 53 inserted into the first power line 31 and a control circuit 54 that controls the FET 53. The control circuit 54 turns off the FET 53 when the solar panel 10 stops outputting. Here, the control circuit 54 monitors the voltage of the first power line 31 and detects the stop of the output of the solar panel 10. In the present embodiment, the FET 53 and the control circuit 54 constitute a second high impedance part. The impedance of the FET 53 at the off time is, for example, about 10 MΩ. The configuration related to the second power line 32 is the same as that of the first embodiment.

  Also in this embodiment, the same effect as the first embodiment can be obtained. That is, the first power line 31 is provided with an FET 53 that is turned off when the output of the solar panel 10 is stopped. Thereby, even if the difference between the potential of the power line 31 on the power conditioner 20 side and the ground potential is large, the difference between the potential of the power line 31 on the solar panel 10 side and the ground potential is suppressed to a small level. Therefore, it is possible to suppress a factor that causes the PID phenomenon during a period when the photovoltaic power generation system is not operated, such as at night.

(Third embodiment)
FIG. 4 is a diagram illustrating a configuration of a photovoltaic power generation system including a connection circuit according to the third embodiment. In FIG. 4, the same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and detailed description thereof is omitted here. In the configuration of FIG. 4, the connection circuit 30 </ b> B includes a latching relay 55 inserted into the first power line 31 and a control circuit 56 that controls the latching relay 55. Here, the latching relay 55 is an example of a relay. The control circuit 56 turns off the latching relay 55 when the solar panel 10 stops outputting. Here, the control circuit 56 includes a rise detection circuit 56 a that detects the rise of the voltage of the second power line 32 and a fall detection circuit 56 b that detects the fall of the voltage of the second power line 32. When the rising detection circuit 56a detects the rising of the voltage of the second power line 32, the rising detection circuit 56a turns off the latching relay 55. The fall detection circuit 56b turns on the latching relay 55 when detecting the fall of the voltage of the second power line 32. In the present embodiment, the latching relay 55 and the control circuit 56 constitute a second high impedance unit. The impedance of the latching relay 55 at the off time is, for example, 5000 MΩ or more. The configuration related to the second power line 32 is the same as that of the first embodiment.

  Also in this embodiment, the same effect as the first and second embodiments can be obtained. That is, the first power line 31 is provided with a latching relay 55 that is turned off when the solar panel 10 stops outputting. Thereby, even if the difference between the potential of the power line 31 on the power conditioner 20 side and the ground potential is large, the difference between the potential of the power line 31 on the solar panel 10 side and the ground potential is suppressed to a small level. Therefore, it is possible to suppress a factor that causes the PID phenomenon during a period when the photovoltaic power generation system is not operated, such as at night.

  Instead of the latching relay 55, another mechanical relay (contact relay) may be applied.

(Modification of connection circuit)
(Part 1)
In the connection circuit 30 of FIG. 1, the diode 51 and the resistance element 52 provided in the first power line 31 may be omitted. Alternatively, the diode 41 and the resistance element 42 provided on the second power line 32 may be omitted.

(Part 2)
The power conditioner 20 includes a booster circuit in front of the inverter unit 21, and the booster circuit may have a diode inserted in a power line connected to the first power line 31. In this case, the diode 51 provided in the first power line 31 in the connection circuit 30 in FIG. 1 may be omitted.

(Part 3)
Instead of the diode 41 provided on the second power line 32, an FET 53 and a control circuit 54 as shown in FIG. 3 may be provided. In this case, the FET 53 and the control circuit 54 constitute a high impedance part. Alternatively, a latching relay 55 and a control circuit 56 as shown in FIG. 4 may be provided in place of the diode 41 provided on the second power line 32. In this case, the latching relay 55 and the control circuit 56 constitute a high impedance unit.

(Part 4)
The second power line 32 may be provided with the FET 53 and the control circuit 54 as shown in FIG. 3 in addition to the diode 41. In this case, the diode 41, the FET 53, and the control circuit 54 constitute a high impedance unit. Alternatively, the second power line 32 may be provided with a latching relay 55 and a control circuit 56 as shown in FIG. 4 in addition to the diode 41. In this case, the diode 41, the latching relay 55, and the control circuit 56 constitute a high impedance unit.

<Other configuration examples>
The connection circuit described above may be built in the power conditioner. FIG. 5 is a schematic configuration of a power conditioner 20A incorporating the connection circuit 30 described above. The power conditioner 20A is a non-insulating type and is a so-called hybrid type, and is configured so that the storage battery 25, the EV 26, and the like can be connected thereto.

  As shown in FIG. 5, the power conditioner 20 </ b> A includes an inverter unit 21 and a connection circuit 30 provided between the output of the solar panel 10 and the input of the inverter unit 21. The configuration of the connection circuit 30 is the same as that in the first embodiment. That is, the connection circuit 30 includes a first power line 31 that connects the positive electrode of the solar panel 10 and the positive electrode of the inverter unit 21, and a second power line 32 that connects the negative electrode of the solar panel 10 and the negative electrode of the inverter unit 21. Is provided. A diode 41 and a resistance element 42 are provided on the second power line 32, and a diode 51 and a resistance element 52 are provided on the first power line 31.

  Note that it is needless to say that the connection circuit 30 in FIG. 5 may apply the configuration as in the second and third embodiments described above, and may apply the above-described modification.

  In this invention, since the factor which causes a PID phenomenon in a photovoltaic power generation system can be suppressed, for example, it is useful for extending the lifetime of a solar panel.

DESCRIPTION OF SYMBOLS 10 Solar panel 20, 20A Power conditioner 30, 30A, 30B Connection circuit 31 1st power line 32 2nd power line 41 Diode 42 Resistance element 51 Diode 52 Resistance element 53 FET
54 Control Circuit 55 Latching Relay (Relay)
56 Control circuit

Claims (14)

A connection circuit provided between the output of the solar panel and the input of the power conditioner,
A first power line connecting the positive electrode of the solar panel and the positive electrode of the power conditioner;
A second power line connecting the negative electrode of the solar panel and the negative electrode of the power conditioner;
FET (Field Effect Transistor) inserted into one of the first and second power lines;
It is to control the pre-Symbol FET, and a control circuit for turning off the FET when the solar panel is stopped the output,
Of the one power line, wherein one end is connected to the solar panel side than the FET, the other end is grounded, the connecting circuit, characterized in that it comprises a resistive element. A connection circuit provided between the output of the solar panel and the input of the power conditioner,
A first power line connecting the positive electrode of the solar panel and the positive electrode of the power conditioner;
A second power line connecting the negative electrode of the solar panel and the negative electrode of the power conditioner;
A relay inserted into one of the first and second power lines;
A control circuit for controlling the relay, and for turning off the relay when the solar panel stops outputting;
A connection circuit comprising: a resistance element having one end connected to the solar panel side of the one power line with respect to the solar panel and the other end grounded. The connection circuit according to claim 1 or 2 ,
The connection circuit, wherein the resistance element has a resistance value of 1 MΩ or more. A connection circuit provided between the output of the solar panel and the input of the power conditioner,
A first power line connecting the positive electrode of the solar panel and the positive electrode of the power conditioner;
A second power line connecting the negative electrode of the solar panel and the negative electrode of the power conditioner;
A resistance element having one end connected to one of the first and second power lines and the other end grounded;
A high-impedance portion that is inserted on the power conditioner side of the one of the power lines with respect to the resistance element, and has a higher impedance than the resistance element when the solar panel stops outputting;
A second high impedance part that is inserted into the other of the first and second power lines and has a higher impedance than the resistance element when the solar panel stops outputting. A connection circuit characterized by that. The connection circuit according to claim 4 , wherein
The high impedance part is
A connection circuit including a diode inserted in the one power line and having a forward direction from the power conditioner toward the solar panel. The connection circuit according to claim 4 , wherein
The high impedance part is
FET (Field Effect Transistor) inserted in the one power line,
A connection circuit that controls the FET and includes a control circuit that turns off the FET when the solar panel stops output. The connection circuit according to claim 4 , wherein
The high impedance part is
A relay inserted into the one power line;
A connection circuit that controls the relay and includes a control circuit that turns off the relay when the solar panel stops output. The connection circuit according to claim 4 , wherein
The connection circuit, wherein the resistance element has a resistance value of 1 MΩ or more. The connection circuit according to any one of claims 4 to 8 ,
The second high impedance part is:
A connection circuit comprising a diode inserted in the other power line and having a forward direction from the solar panel toward the power conditioner. The connection circuit according to any one of claims 4 to 8 ,
The second high impedance part is:
An FET inserted in the other power line;
A connection circuit that controls the FET and includes a control circuit that turns off the FET when the solar panel stops output. The connection circuit according to any one of claims 4 to 8 ,
The second high impedance part is:
A relay inserted in the other power line;
A connection circuit that controls the relay and includes a control circuit that turns off the relay when the solar panel stops output. The connection circuit according to any one of claims 1 to 11 ,
The power conditioner is a non-insulating system and is configured so that a storage battery can be connected. A power conditioner that receives the output of a solar panel,
An inverter section;
A connection circuit provided between the output of the solar panel and the input of the inverter unit;
The connection circuit is
A first power line connecting the positive electrode of the solar panel and the positive electrode of the inverter unit;
A second power line connecting the negative electrode of the solar panel and the negative electrode of the inverter unit;
A resistance element having one end connected to one of the first and second power lines and the other end grounded;
Of the one power line, it is inserted into the power conditioner side of the resistive element, when the solar panel is stopped the output has a higher impedance than the resistor element, and a high impedance section Power conditioner characterized by that. The power conditioner according to claim 13 , wherein the power conditioner is a non-insulating type and configured to be connectable to a storage battery.

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