JP6881002B2 - Power converter and power conversion system - Google Patents

Description

The present invention relates to a power conversion device and a power conversion system.

Conventionally, for the purpose of energy saving, a power conditioner, which is a power conversion device for converting DC power from a power generation device into AC power, has been developed.

For example, Patent Document 1 (Japanese Unexamined Patent Publication No. 2011-176155) discloses the following techniques. That is, the solar power generation device is a current collecting circuit for collecting electric power from a plurality of solar cell strings and the plurality of solar cell strings, and is a wiring material and an electron connected by the wiring material. An abnormality factor is determined by a current collecting circuit having a component and a plurality of temperature detecting means arranged at each of the plurality of merged portions of the wiring material and adjacent to the electronic component, and the result of the temperature detecting means. It is provided with an abnormality determination means for determining an electronic component that has become.

Japanese Unexamined Patent Publication No. 2011-176155 Japanese Unexamined Patent Publication No. 2014-27034 Japanese Unexamined Patent Publication No. 2014-27035 Japanese Patent No. 603501 Japanese Unexamined Patent Publication No. 2015-173262

"Environmental Business Online Environmental Glossary PID (Pontial Integrated Degradation) Phenomenon", [online], [Search on February 24, 2017], Internet <https: // www. Kankyo-business. jp / dictionary / 003723. php> "Fraunhofer CSP (Center for Silicon Photovoltaics) presents resets of potential integrated degradation (PID)", [online], [search on March 29, 2017], Internet <URL: tw. en. csp. Fraunhofer. de / news / data / id / 857 /> "Tokyo Institute of Technology Fujita Laboratory Laboratory Introduction # 45", [online], [Search on March 29, 2017], Internet <URL: http: // educ. tick. ac. jp / ee / news / 2016_11 / 052916. html>

For example, when the solar cell string described in Patent Document 1 has a potential with respect to the ground, the cell in the photovoltaic power generation device may deteriorate and the output of the photovoltaic power generation device may decrease.

Specifically, Non-Patent Document 1 (“Environmental Business Online Environmental Glossary PHP (Potential Induced Voltage) Phenomenon”, [online], [Search on February 24, 2017], Internet <https://www.kankyo -Busines.jp / voltage / 003723.php>), PID is generated in the solar cell module near the cathode where a larger potential difference from the metal frame is generated, and the output of the photovoltaic power generation device is reduced. To do. A technique for suppressing deterioration of such a photovoltaic power generation device such as a PID is required.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a power conversion device and a power conversion system capable of suppressing deterioration of a photovoltaic power generation device with a simple configuration. Is.

(1) In order to solve the above problems, the power conversion device according to a certain aspect of the present invention includes a power conversion unit that converts DC power received from a photovoltaic power generation unit into AC power, the photovoltaic power generation unit, and the above. The first switch connected between the power conversion unit, the second switch connected between the power conversion unit and the power system, and the photovoltaic power generation unit and the power conversion unit are electrically connected. A first connecting portion for grounding the negative side wire to be connected between the photovoltaic power generation unit and the first switch is provided.

(5) In order to solve the above problems, the power conversion system according to a certain aspect of the present invention includes a power conversion device and a control device, and the power conversion device receives DC power received from a photovoltaic power generation unit. A power conversion unit that converts AC power, a first switch connected between the photovoltaic power generation unit and the power conversion unit, and a second switch connected between the power conversion unit and the power system. The control device includes a switch and a connection portion for grounding a negative side line that electrically connects the photovoltaic power generation unit and the power conversion unit between the photovoltaic power generation unit and the first switch. , Controls the on and off of the first switch and the second switch.

The present invention can be realized not only as a power conversion device provided with such a characteristic processing unit, but also as a method of performing such a characteristic processing as a step, or for causing a computer to execute such a step. It can be realized as a program. Further, the present invention can be realized as a semiconductor integrated circuit that realizes a part or all of the power conversion device.

Further, the present invention can be realized not only as a power conversion system provided with such a characteristic processing unit, but also as a method of taking such a characteristic processing as a step. Further, the present invention can be realized as a semiconductor integrated circuit that realizes a part or all of the power conversion system.

According to the present invention, deterioration of the photovoltaic power generation device can be suppressed with a simple configuration.

FIG. 1 is a diagram showing a configuration of a comparative example of a power conversion device. FIG. 2 is a diagram showing a configuration of a comparative example of a power conversion device. FIG. 3 is a diagram showing a configuration of a grid interconnection system according to an embodiment of the present invention. FIG. 4 is a diagram showing a configuration of a power conversion device in the grid interconnection system according to the embodiment of the present invention. FIG. 5 is a diagram showing a detailed configuration of a terminal block 11 in the power conversion device according to the embodiment of the present invention. FIG. 6 is a diagram showing a configuration of a grid interconnection system according to an embodiment of the present invention. FIG. 7 is a diagram showing a configuration of a power conversion device in the grid interconnection system according to the embodiment of the present invention. FIG. 8 is a diagram showing a configuration of a modified example of the grid interconnection system according to the embodiment of the present invention. FIG. 9 is a diagram showing a configuration of a power conversion device in a modified example of the grid interconnection system according to the embodiment of the present invention. FIG. 10 is a diagram showing a configuration of an application example of a modification of the grid interconnection system shown in FIG. FIG. 11 is a diagram showing an example of each numerical value predicted by HEMS in the grid interconnection system according to the embodiment of the present invention. FIG. 12 is a diagram showing a configuration of a modified example of the grid interconnection system according to the embodiment of the present invention. FIG. 13 is a diagram showing a configuration of a power conversion device in a modified example of the grid interconnection system according to the embodiment of the present invention. FIG. 14 is a diagram showing a configuration of a modified example of the grid interconnection system according to the embodiment of the present invention. FIG. 15 is a diagram showing a configuration of a power conversion device in a modified example of the grid interconnection system according to the embodiment of the present invention. FIG. 16 is a diagram showing a configuration of a modified example of the grid interconnection system according to the embodiment of the present invention.

First, the contents of the embodiments of the present invention will be listed and described.

(1) The power conversion device according to the embodiment of the present invention is between a power conversion unit that converts DC power received from a photovoltaic power generation unit into AC power, and between the photovoltaic power generation unit and the power conversion unit. The sun is a negative side line that electrically connects the first switch to be connected, the second switch connected between the power conversion unit and the power system, and the photovoltaic power generation unit and the power conversion unit. A first connection for grounding between the photovoltaic unit and the first switch is provided.

In this way, due to the configuration in which the first connection portion for grounding the negative side wire is provided between the solar power generation unit and the first switch, the solar power generation unit can be operated regardless of the open / closed state of the first switch. The potential can be the same as the ground. Thereby, for example, it is possible to suppress the progress of PID for the solar cell module which deteriorates when it has a negative potential with respect to the grounded metal frame. Further, for example, even in a circuit configuration in which the power system and the power conversion device are not isolated and a ground fault current flows from the power system through the first connection portion, the second switch can be opened. Ground fault current can be prevented. Therefore, deterioration of the photovoltaic power generation device can be suppressed with a simple configuration.

(2) Preferably, the power conversion device further converts the output power of the photovoltaic power generation unit into energy and stores or consumes a second load for electrically connecting the power conversion unit. It has a connection part.

With such a configuration, for example, by connecting the load to the second connection portion, the output power of the photovoltaic power generation unit can be effectively used in the load while the first switch is closed. ..

(3) Preferably, the power conversion device further turns on the first switch and turns off the second switch, and turns off the first switch and turns off the second switch. A control unit for switching a second mode for turning on the switch is provided.

With such a configuration, for example, power conversion of either the power generated from the photovoltaic power generation unit or the power from the power system is performed while preventing a ground fault current when the power system and the power conversion device are not insulated. It can be supplied to the device.

(4) Preferably, the power conversion device further converts the output power of the photovoltaic power generation unit and the storage battery capable of storing the power from the power system, and the output power of the photovoltaic power generation unit into energy. The power consumption forecast information of the load to be stored or consumed and the power generation forecast information of the photovoltaic power generation unit are acquired, and based on the acquired power consumption forecast information and the power generation forecast information, the output power of the photovoltaic power generation unit and It is provided with a control unit that adjusts the remaining storage amount of the storage battery capable of storing power from the power system.

With such a configuration, for example, the remaining amount of electricity required to satisfy the power consumption of the load in the daytime of the next day can be calculated based on the power consumption prediction information and the power generation prediction information, so that the power system at night can be calculated. It is possible to prevent the amount of charge from the storage battery to be excessive or too small. This makes it possible to prevent an excessive amount of power generated by the photovoltaic power generation unit due to an excessive amount of charge to the storage battery and a shortage of power supply to the above load in the daytime of the next day due to an excessive amount of charge to the storage battery. it can.

(5) The power conversion system according to the embodiment of the present invention includes a power conversion device and a control device, and the power conversion device converts DC power received from a photovoltaic power generation unit into AC power. A first switch connected between the solar power generation unit and the power conversion unit, a second switch connected between the power conversion unit and the power system, and the photovoltaic power generation unit. The control device includes the photovoltaic power generation unit and a connection unit for grounding the negative side wire that electrically connects the unit and the power conversion unit between the photovoltaic power generation unit and the first switch, and the control device includes the first switch and the first switch. It controls the on and off of the second switch.

In this way, due to the configuration in which the first connection portion for grounding the negative side wire is provided between the solar power generation unit and the first switch, the solar power generation unit can be operated regardless of the open / closed state of the first switch. The potential can be the same as the ground. Thereby, for example, it is possible to suppress the progress of PID for the solar cell module which deteriorates when it has a negative potential with respect to the grounded metal frame. Further, for example, even in a circuit configuration in which the power system and the power conversion device are not isolated and a ground fault current flows from the power system through the first connection portion, the second switch can be opened. Ground fault current can be prevented. Therefore, deterioration of the photovoltaic power generation device can be suppressed with a simple configuration.

(6) More preferably, the control device turns on the first switch and turns off the second switch, and turns off the first switch and turns on the second switch. Toggle the second mode to turn on.

With such a configuration, for example, power conversion of either the power generated from the photovoltaic power generation unit or the power from the power system is performed while preventing a ground fault current when the power system and the power conversion device are not insulated. It can be supplied to the device.

(7) More preferably, the power conversion system further includes a storage battery capable of storing the output power of the photovoltaic power generation unit and the power from the power system, and the control device is the output of the photovoltaic power generation unit. The power consumption prediction information of the load that converts power into energy and stores or consumes, and the power generation prediction information of the photovoltaic power generation unit are acquired, and based on the acquired power consumption prediction information and the power generation prediction information, the storage battery Adjust the remaining charge.

With such a configuration, for example, the remaining amount of electricity required to satisfy the power consumption of the load in the daytime of the next day can be calculated based on the power consumption prediction information and the power generation prediction information, so that the power system at night can be calculated. It is possible to prevent the amount of charge from the storage battery to be excessive or too small. This makes it possible to prevent an excessive amount of power generated by the photovoltaic power generation unit due to an excessive amount of charge to the storage battery and a shortage of power supply to the above load in the daytime of the next day due to an excessive amount of charge to the storage battery. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated. In addition, at least a part of the embodiments described below may be arbitrarily combined.

[Configuration of comparative example of power converter]
FIG. 1 is a diagram showing a configuration of a comparative example of a power conversion device. FIG. 1 shows a comparative example of a single-phase three-wire power converter.

With reference to FIG. 1, the power conversion device 901, which is a comparative example, includes a capacitor 25, an inverter (power conversion unit) 26, an interconnection relay 32, and a control unit 91. The interconnection relay (second switch) 32 includes switches 32A, 32B, 32C.

When the photovoltaic power generation unit 1 receives sunlight, it converts the energy of the received solar power into DC power and outputs the converted DC power.

More specifically, the photovoltaic power generation unit 1 has a positive side terminal and a negative side terminal for outputting the converted DC power. In this example, the photovoltaic power generation unit 1 outputs DC power to the power conversion device 901 via the positive side terminal and the negative side terminal.

The capacitor 25 in the power conversion device 901 is provided to suppress fluctuations in the DC power received from the photovoltaic power generation unit 1, and is attached to the first end connected to the positive terminal of the photovoltaic power generation unit 1 and the negative terminal. It has a second end connected.

The inverter 26 has a first end connected to the first end of the capacitor 25, a second end connected to the second end of the capacitor 25, a third end, a fourth end, and a fifth end. ..

The interconnection relay 32 is connected between the inverter 26 and the power system. More specifically, the switch 32A in the interconnection relay 32 has a first end connected to a third end of the inverter 26 and a second end. The switch 32B has a first end and a second end connected to the fourth end of the inverter 26. The switch 32C has a first end and a second end connected to the fifth end of the inverter 26.

The transformer T1 is, for example, a pole transformer, and has a primary coil L1 and a secondary coil L2. The transformer T1 converts the 6.6 kilovolt AC voltage received from the AC power supply PS in the primary coil L1 into an AC voltage of 200 volts in the secondary coil L2.

Further, in the transformer T1, when the power conversion device 901 performs a reverse power flow, the AC power of 200 volts received from the power conversion device 901 in the secondary coil L2, that is, the AC voltage is 6.6 kilovolts in the primary coil L1. Convert to AC voltage.

More specifically, the secondary coil L2 in the transformer T1 is connected to the first end connected to the second end of the switch 32A in the interconnection relay 32 and to the second end of the switch 32B, and is grounded. It has a sex point and a second end connected to the second end of the switch 32C.

The primary coil L1 coupled to the secondary coil L2 by mutual inductance has a third end and a fourth end connected to the AC power supply PS.

The general loads 41A and 41B are loads that can be used with AC 100 volts such as microwave ovens, lighting fixtures, and televisions. The general load 41C is, for example, a load that can be used with an AC 200 volt such as an air conditioner. Hereinafter, each of the general loads 41A, 41B, and 41C is also referred to as a general load 41. The general load 41 is used, for example, intermittently by using the power from the power converter 901 and the power system.

The control unit 91 can switch the ON state and the OFF state of the interconnection relay 32 by outputting the control signal S2 to the interconnection relay 32.

The interconnection relay 32 electrically connects the inverter 26 with the power system and the general load 41 in the ON state by turning on or off its own switches 32A, 32B, 32C according to the control of the control unit 91. Electrically insulate in the off state.

Further, the control unit 91 controls a switch element (not shown) in the inverter 26 by outputting the control signal S3 to the inverter 26.

The inverter 26 converts the DC power received from the photovoltaic power generation unit 1 via the capacitor 25 into AC power according to the control of the control unit 91, and converts the converted AC power to the power system and the general load 41 by a single-phase three-wire system. Output.

FIG. 2 is a diagram showing a configuration of a comparative example of a power conversion device. FIG. 2 shows a comparative example of a single-phase two-wire power conversion device.

With reference to FIG. 2, the power conversion device 911, which is a modification of the power conversion device 901 shown in FIG. 1, includes a capacitor 25, an inverter (power conversion unit) 27, an interconnection relay 33, and a control unit 91. Be prepared. The interconnection relay 33 (second switch) includes switches 33A and 33B.

The configuration and operation of the capacitor 25, the general load 41, and the transformer T1 shown in FIG. 2 are the same as those of the capacitor 25, the general load 41, and the transformer T1 shown in FIG. 1, respectively.

The inverter 27 has a first end connected to the first end of the capacitor 25, a second end connected to the second end of the capacitor 25, a third end, and a fourth end.

The switch 33A in the interconnection relay 33 has a first end connected to the third end of the inverter 27 and a second end connected to the first end of the secondary coil L2 in the transformer T1. The switch 32B has a first end connected to the fourth end of the inverter 27 and a second end connected to the second end of the secondary coil L2 in the transformer T1.

The control unit 91 can switch the ON state and the OFF state of the interconnection relay 33 by outputting the control signal S2 to the interconnection relay 33.

The interconnection relay 33 electrically connects the inverter 27 and the power system in the on state and electrically in the off state by turning on or off the switches 33A and 33B of the interconnection relay 33 according to the control of the control unit 91. Insulate.

Further, the control unit 91 controls a switch element (not shown) in the inverter 27 by outputting the control signal S3 to the inverter 27.

Under the control of the control unit 91, the inverter 27 converts the DC power received from the photovoltaic power generation unit 1 via the capacitor 25 into AC power, and the converted AC power is transferred to the power system and the general load 41 by a single-phase two-wire system. Output.

[Task]
Non-Patent Document 1 and Non-Patent Document 2 (“Franhofer CSP presents of patents of patented degradation (PID)”, [online], [Search on March 29, 2017], Internet <URL: http: // www. As described in .csp.fraunhofer.de/news/details/id/857/>), solar panels have a problem of deterioration called PID.

Non-Patent Document 2 describes that the Fraunhofer CSP observed PID in 9 out of 13 panels under the conditions of temperature 50 ° C., humidity 50%, 1000 V and 48 hours.

Although the generation mechanism of PID has not been clarified, the possible generation mechanism will be described with reference to the power conversion devices 901 and 911 shown in FIGS. 1 and 2.

As shown in FIGS. 1 and 2, the power conversion device 901 and the power conversion device 911 and the power system are not insulated by using a transformer and are not insulated. Further, the neutral point is grounded in the pole transformer, that is, the transformer T1. In this case, the voltage between the first end and the second end of the capacitor 25 is approximately 340 volts, and the voltage to ground at the second end of the capacitor 25 is −170 volts.

The photovoltaic power generation unit 1 is composed of, for example, a photovoltaic power generation module including a plurality of power generation cells and a grounded frame. Since the second end of the capacitor 25 is connected to the negative terminal of the photovoltaic power generation unit 1, a negative voltage to ground is applied to the photovoltaic power generation module in the photovoltaic power generation unit 1.

In such a state, for example, it is said that PID is generated by an unexpected current flowing between some power generation cells to which a negative voltage is applied and a grounded frame. PID is likely to occur at high temperatures, high humidity and high voltages, but there is also information that it also occurs in low voltage interconnected home systems.

On the other hand, Patent Document 2 (Japanese Patent Laid-Open No. 2014-27034), Patent Document 3 (Japanese Patent Application Laid-Open No. 2014-27035), Patent Document 4 (Japanese Patent Application Laid-Open No. 603501) and Patent Document 5 (Japanese Patent Laid-Open No. 2015-173262). No.) describes the measures to be taken on the solar panel side using a sealing film, a sealing sheet, a sealing countermeasure film, and the like. Some panel makers find this measure unfavorable because it increases costs in materials and manufacturing.

Further, a method is conceivable in which a transformer is provided between the power converters 901 and 911 and the power system to insulate the power system, and the negative terminal of the solar power generation unit 1 is grounded to prevent PID. When the power converters 901 and 911 are for home use, for example, a configuration using a transformer for low frequency is not common.

In addition, as a countermeasure for the power converters 901 and 911, a configuration using a high-frequency insulation converter and Non-Patent Document 3 (“Tokyo Institute of Technology Fujita Laboratory Laboratory Introduction # 45”, [online], [March 29, 2017] Day search], the configuration using the Zig-Zag Connected Shopper (ZCC) converter described in the Internet <URL: http: //educ.titch.ac.jp/ee/news/2016_1/11/052916.html>). Has been devised by. However, in each of these configurations, the number of parts is large and the cost is high.

Therefore, in the power conversion device according to the embodiment of the present invention, such a problem is solved by the following configuration and operation.

[Basic example of single-phase two-wire]
FIG. 3 is a diagram showing a configuration of a grid interconnection system according to an embodiment of the present invention.

With reference to FIG. 3, the grid interconnection system (power conversion system) 311 includes a photovoltaic power generation unit 1, a power conversion device 111, and a specific load 51.

The configuration and operation of the photovoltaic power generation unit 1 and the general loads 41A, 41B, 41C shown in FIG. 3 are the same as those of the photovoltaic power generation unit 1 and the general loads 41A, 41B, 41C shown in FIG. 1, respectively.

The power converter 111 and the power system are non-isolated. The specific load 51 is, for example, a load that converts the output power of the photovoltaic power generation unit 1 into energy and stores or consumes it. In other words, the specific load 51 is a load that converts the amount of electric power based on the generated electric power of the photovoltaic power generation unit 1 into other energy and stores it.

Specifically, the specific load 51 is an electric water heater, a heat storage heater, a hydrogen generator, or the like. The specific load 51 may be used with an AC of 100 volts or may be used with an AC of 200 volts. In this example, the specific load 51 can be used with an alternating current of 100 volts.

In the grid interconnection system 311, one solar power generation unit 1 is provided, but the present invention is not limited to this, and a plurality of solar power generation units 1 may be provided.

[Configuration and basic operation]
FIG. 4 is a diagram showing a configuration of a power conversion device in the grid interconnection system according to the embodiment of the present invention.

With reference to FIG. 4, the power conversion device 111 includes terminal bases 11 and 12, terminal base (second connection part) 16, converter 21, capacitor 25, inverter (power conversion part) 27, and PV. A relay (first switch) 31 for use, an interconnection relay (second switch) 33, an independent relay 34, and a control unit (control device) 61 are provided.

The terminal block 11 includes terminals 11A and 11B. The terminal block 12 includes terminals 12A, 12B, 12C. The terminal block 16 includes terminals 16A and 16B.

The PV relay 31 includes switches 31A and 31B. The self-supporting relay 34 includes switches 34A and 34B. The PV relay 31 is connected between the photovoltaic power generation unit 1 and the inverter 27.

The configuration and operation of the capacitor 25, the inverter 27, and the interconnection relay 33 in the power conversion device 111 are the same as those of the capacitor 25, the inverter 27, and the interconnection relay 33 in the power conversion device 911 shown in FIG. 2, respectively.

FIG. 5 is a diagram showing a detailed configuration of a terminal block 11 in the power conversion device according to the embodiment of the present invention. FIG. 5 shows a plurality of terminal blocks 11 when a plurality of photovoltaic power generation units 1 are provided, unlike the configuration shown in FIG.

With reference to FIGS. 4 and 5, the positive lateral lines PLp1, Wp1 and the negative lateral lines PLm1, Wm1 electrically connect the photovoltaic power generation unit 1 and the inverter 27.

Specifically, the positive lateral line PLp1 and the negative lateral line PLm1 electrically connect the photovoltaic power generation unit 1 and the terminal block 11. The positive lateral line Wp1 and the negative lateral line Wm1 electrically connect the terminal block 11 and the inverter 27.

Inside the housing 70 of the power conversion device 111, a first connection portion for grounding the negative lateral lines PLm1 and Wm1 between the photovoltaic power generation unit 1 and the PV relay 31 is provided.

The terminal block 11, which is an example of the first connection unit, is provided corresponding to the solar power generation unit 1. The positive lateral line PLp1 has a first end connected to the positive terminal in the photovoltaic power generation unit 1 and a second end connected to the terminal 11A in the terminal block 11. The negative lateral line PLm1 has a first end connected to the negative terminal in the photovoltaic power generation unit 1 and a second end connected to the terminal 11B in the terminal block 11. The ground wire PLn1 has a grounded first end and a second end connected to the terminal 11C in the terminal block 11. The connection line CL1 has a first end connected to the terminal 11B in the terminal block 11 and a second end connected to the terminal 11C in the terminal block 11.

The positive lateral line Wp1 has a first end connected to the terminal 11A in the terminal block 11 and a second end connected to the first end of the switch 31A in the PV relay 31. The negative lateral line Wm1 has a first end connected to the terminal 11B in the terminal block 11 and a second end connected to the first end of the switch 31B in the PV relay 31.

At terminals 11A to 11C on the terminal block 11, each cable is connected using a screw and a conduction plate.

More specifically, at the terminal 11A, the second end of the positive lateral line PLp1 and the first end of the positive lateral line Wp1 are connected. At terminal 11B, the second end of the negative lateral line PLm1, the first end of the negative lateral line Wm1 and the first end of the connecting line CL1 are connected. At terminal 11C, the second end of the connection line CL1 and the second end of the connection line CL1 are connected.

The terminals 11A to 11C in the terminal block 11 are configured to connect each cable using screws and a conduction plate, but the present invention is not limited to this. For example, the terminals 11A to 11C may be configured to connect each cable by inserting the end of the cable into a dedicated insertion port.

Further, the connection between the photovoltaic power generation unit 1 and the terminal block 11 and the connection between the terminal block 11 and the PV relay 31 are not limited to the configuration using a cable, and may be a configuration using, for example, a metal plate.

With reference to FIG. 4 again, the converter 21 has a first end connected to the second end of the switch 31A in the PV relay 31, a second end connected to the second end of the switch 31B, and a third end. And a fourth end.

The capacitor 25 has a first end connected to the third end of the converter 21 and a second end connected to the fourth end of the converter 21.

The inverter 27 has a first end connected to the first end of the capacitor 25, a second end connected to the second end of the capacitor 25, a third end, and a fourth end.

The switch 33A in the interconnection relay 33 has a first end connected to a third end of the inverter 27 and a second end. The switch 33B has a first end and a second end connected to the fourth end of the inverter 27.

The terminal 12A in the terminal block 12 is connected to the second end of the switch 33A in the interconnection relay 33 and the first end of the secondary coil L2 in the transformer T1. The terminal 12B is connected to the neutral point in the transformer T1. The terminal 12C is connected to the second end of the switch 33B and the second end of the secondary coil L2.

The switch 34A in the self-supporting relay 34 has a first end connected to the third end of the inverter 27 and a second end connected to the terminal 16A in the terminal block 16. The switch 34B has a first end connected to the fourth end of the inverter 27 and a second end connected to the terminal 16B in the terminal block 16.

The terminal block 16 electrically connects, for example, the inverter 27 and the specific load 51. Specifically, the specific load 51 is connected to the terminals 16A and 16B in the terminal block 16.

The control unit 61 can switch the on state and the off state of the PV relay 31 by outputting the control signal S1 to the PV relay 31.

The PV relay 31 electrically connects the photovoltaic power generation unit 1 and the converter 21 in the on state by turning on or off its own switches 31A and 31B according to the control of the control unit 61, and in the off state. Electrically insulate.

Further, the control unit 61 can switch the ON state and the OFF state of the interconnection relay 33 by outputting the control signal S2 to the interconnection relay 33.

The interconnection relay 33 electrically connects the inverter 27 and the power system in the on state and electrically in the off state by turning on or off the switches 33A and 33B of the interconnection relay 33 according to the control of the control unit 61. Insulate.

Further, the control unit 61 can switch between the on state and the off state of the self-supporting relay 34 by outputting the control signal S7 to the self-supporting relay 34.

The self-supporting relay 34 electrically connects the inverter 27 and the specific load 51 in the on state and electrically in the off state by turning on or off the switches 34A and 34B of the self-supporting relay 34 according to the control of the control unit 61. Insulate.

Further, the control unit 61 controls a switch element (not shown) in the converter 21 by outputting the control signal S4 to the converter 21.

The converter 21 converts the voltage of the DC power received from the photovoltaic power generation unit 1 under the control of the control unit 61. Here, the converter 21 boosts the voltage of the DC power and outputs the boosted DC power to the capacitor 25.

Further, the control unit 61 controls a switch element (not shown) in the inverter 27 by outputting the control signal S3 to the inverter 27.

The inverter 27 converts the DC power received from the converter 21 via the capacitor 25 into AC power according to the control of the control unit 61, and outputs the converted AC power to the interconnection relay 33 and the self-supporting relay 34 with a single-phase two-wire system. To do.

Here, the voltage of the AC power output from the third end and the fourth end of the inverter 27 is 100 volts.

The control unit 61 operates its own power conversion device 111 in either the night mode or the day mode by switching between the night mode and the day mode. Specifically, the control unit 61 sets, for example, the period from sunrise to sunset in the day mode and the period from sunset to sunrise in the night mode.

Further, the control unit 61 can also set the night mode and the day mode according to a command from another device.

In the daytime mode, the control unit 61 sets the PV relay 31, the interconnection relay 33, and the self-supporting relay 34 to the on state, the off state, and the self-sustaining relay 34, respectively, and operates the converter 21 and the inverter 27 in the self-sustaining operation.

As described above, the power conversion device 111 receives the specific load 51 from the power conversion device 111 due to the configuration in which the power conversion device 111 operates independently during the period when the photovoltaic power generation unit 1 generates power and outputs 100 volt AC power to the specific load 51. The amount of power based on AC power can be converted to other energy and stored.

On the other hand, the control unit 61 sets the PV relay 31, the interconnection relay 33, and the self-supporting relay 34 to the off state, the on state, and the off state, respectively, in the night mode.

As described above, in each of the day mode and the night mode, both the PV relay 31 and the interconnection relay 33 are not set to the on state, and both of them are not set to the off state. The power of either one of the power systems can be input to the power conversion device 111, and simultaneous grounding of different voltage levels can be prevented.

Further, since the negative side lines PLm1 and Wm1 are grounded in the day mode and the night mode, it is possible to prevent a negative voltage to ground from being applied to the photovoltaic power generation module in the photovoltaic power generation unit 1, so that the power generation cell can be used. Deterioration due to PID can be prevented.

[Basic example of single-phase three-wire]
FIG. 6 is a diagram showing a configuration of a grid interconnection system according to an embodiment of the present invention.

With reference to FIG. 6, the grid interconnection system (power conversion system) 301 includes a photovoltaic power generation unit 1, a power conversion device 101, and specific loads 51C, 51D, and 51E which are specific loads 51.

The configuration and operation of the photovoltaic power generation unit 1 and the general loads 41A, 41B, 41C shown in FIG. 6 are the same as those of the photovoltaic power generation unit 1 and the general loads 41A, 41B, 41C shown in FIG. 1, respectively.

The power converter 101 and the power system are non-insulated. The specific loads 51C and 51D can be used with AC 100 volts. The specific load 51E can be used with an AC 200 volt.

In the grid interconnection system 301, one solar power generation unit 1 is provided, but the present invention is not limited to this, and a plurality of solar power generation units 1 may be provided.

[Configuration and basic operation]
FIG. 7 is a diagram showing a configuration of a power conversion device in the grid interconnection system according to the embodiment of the present invention.

With reference to FIG. 7, the power conversion device 101 includes terminal blocks 11 and 12, a terminal block (second connection portion) 13, a converter 21, a capacitor 25, an inverter 26, and a PV relay 31. It includes an interconnection relay 32 and a control unit 61. The terminal block 13 includes terminals 13A, 13B, 13C.

The configuration and operation of the terminal block 11, the terminal block 12, the converter 21 and the PV relay 31 in the power conversion device 101 are as follows: The terminal block 11, the terminal block 12, the converter 21 and the PV relay 31 in the power conversion device 111 shown in FIG. Is the same as each.

The configuration and operation of the capacitor 25, the inverter 26, and the interconnection relay 32 in the power conversion device 101 are the same as those of the capacitor 25, the inverter 26, and the interconnection relay 32 in the power conversion device 901 shown in FIG. 1, respectively.

The inverter 26 in the power conversion device 101 has a first end connected to the first end of the capacitor 25, a second end connected to the second end of the capacitor 25, a third end, a fourth end, and a first end. It has 5 ends.

The switch 32A in the interconnection relay 32 has a first end connected to a third end of the inverter 26 and a second end. The switch 32B has a first end and a second end connected to the fourth end of the inverter 26. The switch 32C has a first end and a second end connected to the fifth end of the inverter 26.

The terminal 12A in the terminal block 12 is connected to the second end of the switch 32A in the interconnection relay 32 and the first end of the secondary coil L2 in the transformer T1. The terminal 12B is connected to the second end of the switch 32B and the neutral point in the transformer T1. The terminal 12C is connected to the second end of the switch 32C and the second end of the secondary coil L2.

The terminal 13A in the terminal block 13 is connected to the third end of the inverter 26. The terminal 13B is connected to the fourth end of the inverter 26. The terminal 13C is connected to the fifth end of the inverter 26.

A specific load 51C is connected between the terminals 13A and 13B on the terminal block 13. A specific load 51D is connected between the terminals 13B and 13C. A specific load 51E is connected between the terminals 13C and 13A.

The control unit 61 can switch the ON state and the OFF state of the interconnection relay 32 by outputting the control signal S2 to the interconnection relay 32.

The interconnection relay 32 electrically connects the inverter 26 and the power system in the on state by turning on or off its own switches 32A, 32B, 32C according to the control of the control unit 61, and also electrically in the off state. Insulate.

Further, the control unit 61 controls a switch element (not shown) in the inverter 26 by outputting the control signal S3 to the inverter 26.

The inverter 26 converts the DC power received from the converter 21 via the capacitor 25 into AC power according to the control of the control unit 61, and outputs the converted AC power to the interconnection relay 33 and the self-sustaining relay 34.

Here, the voltage of the AC power output from the third end and the fifth end of the inverter 26 is 200 volts. The voltage of AC power output from the third and fourth ends and the fourth and fifth ends of the inverter 26 is 100 volts.

In the daytime mode, the control unit 61 sets the PV relay 31 and the interconnection relay 32 to the on state and the off state, respectively, and operates the converter 21 and the inverter 26 in an independent operation.

On the other hand, the control unit 61 sets the PV relay 31 and the interconnection relay 32 to the off state and the on state, respectively, in the night mode.

[Modification example 1 of single-phase three-wire]
FIG. 8 is a diagram showing a configuration of a modified example of the grid interconnection system according to the embodiment of the present invention.

With reference to FIG. 8, the grid interconnection system (power conversion system) 301A, which is a modification of the grid interconnection system 301, has power instead of the power conversion device 101 as compared with the grid interconnection system 301 shown in FIG. It is equipped with a conversion device 101A, and further includes a storage battery 6 and a HEMS (Home Energy Management System) (control device) 151.

HEMS 151 can acquire weather forecast information, for example. The HEMS 151 is connected to the Internet, for example, and acquires the weather forecast information via the Internet from a distribution server that distributes the weather forecast information.

Further, the HEMS 151 can acquire the remaining amount information indicating the remaining amount of electricity stored in the storage battery 6 by communicating with the storage battery 6, for example.

Further, the HEMS 151 can perform wireless communication with the power conversion device 101A. The HEMS 151 may have a configuration capable of performing wired communication with the power conversion device 101A.

The storage battery 6 can store, for example, the output power of the photovoltaic power generation unit 1 and the power from the power system. More specifically, the storage battery 6 can store the DC power received from the power conversion device 101A as chemical energy.

Further, the storage battery 6 can generate DC power by using the stored chemical energy and output the generated DC power to the power conversion device 101A. The input and output of DC power in the storage battery 6 is performed according to the control of the power conversion device 101A.

In the grid interconnection system 301A, one storage battery 6 is provided, but the present invention is not limited to this, and a plurality of storage batteries 6 may be provided.

FIG. 9 is a diagram showing a configuration of a power conversion device in a modified example of the grid interconnection system according to the embodiment of the present invention.

With reference to FIG. 9, the power conversion device 101A further includes a terminal block 14 and a converter 22 as compared with the power conversion device 101 shown in FIG. 7.

The configuration and operation of the terminal bases 11, 12, 13 in the power conversion device 101A, the converter 21, the capacitor 25, the inverter 26, the PV relay 31 and the interconnection relay 32 are as follows. The same applies to 12, 13, the converter 21, the capacitor 25, the inverter 26, the PV relay 31, and the interconnection relay 32, respectively.

The inverter 26 converts the DC power received from the photovoltaic power generation unit 1 via the capacitor 25 into AC power according to the control of the control unit 61, and converts the converted AC power into a single-phase three-wire interconnection relay 32 and a specific load. Output to 51.

Further, the inverter 26 converts the AC power received from the power system via the interconnection relay 32 into DC power according to the control of the control unit 61, and outputs the converted DC power to the converter 22.

The terminal block 14 includes a terminal 14A connected to the positive terminal of the storage battery 6 and a terminal 14B connected to the negative terminal of the storage battery 6.

The converter 22 includes a first end connected to the terminal 14A of the terminal block 14, a second end connected to the terminal 14B, a third end connected to the first end of the capacitor 25, and a second end of the capacitor 25. It has a fourth end connected to the end.

The control unit 61 controls a switch element (not shown) in the converter 22 by outputting the control signal S5 to the converter 22.

The converter 22 can convert the voltage of the DC power received from the storage battery 6 under the control of the control unit 61. Here, the converter 22 boosts the voltage of the DC power and outputs the boosted DC power to the inverter 26. In this case, the storage battery 6 discharges DC power to the power conversion device 101A.

Further, the converter 22 can convert the voltage of the DC power received from the converter 21 and the inverter 26 under the control of the control unit 61. Here, the converter 22 lowers the voltage of the DC power and outputs the reduced DC power to the storage battery 6. In this case, the storage battery 6 is charged with the DC power from the power conversion device 101A.

The power conversion device 101A is provided with one set of the terminal block 14 and the converter 22, but the present invention is not limited to this, and when a plurality of storage batteries 6 are provided, a plurality of storage batteries 6 are provided. The above set may be provided.

FIG. 10 is a diagram showing a configuration of an application example of a modification of the grid interconnection system shown in FIG.

With reference to FIG. 10, in the grid interconnection system (power conversion system) 301B, an electric water heater 51A is provided as a specific example of the specific load 51E shown in FIG.

The electric water heater 51A operates at an alternating current of 200 volts, and is specifically EcoCute (registered trademark). More specifically, the electric water heater 51A has a tank for storing water, and the temperature of the water stored in the tank is raised by operating the heat pump using the AC power received from the power converter 101A. Performs heat storage operation HSA.

The heat storage operation HSA in the electric water heater 51A can be turned on and off by, for example, HEMS 151.

FIG. 11 is a diagram showing an example of each numerical value predicted by HEMS in the grid interconnection system according to the embodiment of the present invention.

With reference to FIGS. 9 to 11, the operations of the HEMS 151 and the control unit 61 in the grid interconnection system 301B will be described here. Further, the power generated by the photovoltaic power generation unit 1 is 4 kW. Further, the fully charged amount of the storage battery 6 is 10 kilowatt hours.

The HEMS 151, for example, converts the output power of the photovoltaic power generation unit 1 into energy and acquires the power consumption prediction information of the load to be stored or consumed.

Specifically, the HEMS 151 calculates the planned power consumption of the electric water heater 51A as the power consumption prediction information.

More specifically, the HEMS 151 periodically acquires the measurement result of the power consumption of the electric water heater 51A, and calculates the daily power consumption based on the acquired measurement result.

The daily power consumption is not limited to the value calculated based on the measurement result, and may be the power consumption for filling the tank of the electric water heater 51A with hot water. It may be calculated based on the amount of hot water used in the past.

In this example, the HEMS 151 sets the calculated daily power consumption as the planned power consumption of 8 kilowatt hours (see FIG. 11).

Further, the HEMS 151 acquires, for example, the power generation prediction information of the photovoltaic power generation unit 1. Specifically, the HEMS 151 predicts the previous day's forecast value of the amount of power generated by the photovoltaic power generation unit 1, which is an example of the power generation prediction information.

More specifically, the HEMS 151 acquires weather forecast information from the distribution server via the Internet, and calculates the amount of power generated by the photovoltaic power generation unit 1 on the next day based on the acquired weather forecast information.

Specifically, for example, when the weather forecast for the next day is sunny in early summer, HEMS 151 predicts that the amount of power generated by the photovoltaic power generation unit 1 on the next day is 20 kilowatt hours. On the other hand, HEMS 151 predicts, for example, zero kilowatt hour when the weather forecast for the next day is rainy in early winter. In addition, the HEMS 151 predicts the amount of power generated according to the season and the weather in the case of other seasons and other weather.

Then, the HEMS 151 adjusts the remaining charge of the storage battery 6 based on the acquired consumption prediction information and power generation prediction information, for example.

Specifically, when the HEMS 151 predicts that the amount of power generated on the next day is zero kilowatt-hour, the power supply to the electric water heater 51A is only the storage battery 6, so the HEMS 151 calculates it as 10 kilowatt-hour as the preparation value on the previous day of the remaining charge. To do. The reason why the previous day's reserve value is 2 kilowatt hours higher than the planned power consumption of 8 kilowatt hours is because the reserve is included. Therefore, it is possible to calculate a slightly smaller value as the preparation value on the previous day of the remaining charge.

Further, when the HEMS 151 predicts that the amount of power generated on the next day is 5 kilowatt hours, it calculates 5.5 kilowatt hours as the preparation value on the previous day for the remaining amount of electricity stored. For example, even if the weather forecast is off and the amount of power generated the next day is only 2.5 kilowatt hours, the planned power consumption of 8 kilowatt hours can be covered. Further, even if the weather forecast is off and the amount of power generated on the next day reaches 10 kilowatt hours, the storage battery 6 can be charged with the remaining 2 kilowatt hours to cover the planned power consumption of 8 kilowatt hours.

Further, when the amount of power generated on the next day is predicted to be 20 kilowatt hours, HEMS 151 calculates it as 1 kilowatt hour as the preparation value on the previous day of the remaining storage amount. This is because the photovoltaic power generation unit 1 is a highly variable energy source in which the generated power decreases when the sunlight is blocked by clouds.

[Night mode in grid interconnection system 301B]
For example, at the timing of sunset, the HEMS 151 transmits the instruction information E1 indicating the setting command to the night mode and the charging command to the power conversion device 101A, and turns off the heat storage operation HSA of the electric water heater 51A.

The control unit 61 in the power conversion device 101A can communicate with the HEMS 151, and when it receives the instruction information E1 from the HEMS 151, it sets its own power conversion device 111 to the night mode according to the received instruction information E1.

At this time, the control unit 61 sets the PV relay 31 and the interconnection relay 32 to the off state and the on state, respectively.

Further, the control unit 61 interconnects the inverter 26 and the converter 22 according to the command information E1. As a result, the storage battery 6 is charged by the DC power received from the power conversion device 101A. On the other hand, the electric water heater 51A does not consume the AC power from the power conversion device 101A because the heat storage operation HSA is turned off.

For example, the HEMS 151 monitors the amount of electricity stored in the storage battery 6, and when the amount of electricity stored in the storage battery 6 reaches the preparation value on the previous day, the HEMS 151 transmits the instruction information H1 indicating the charge stop command to the power conversion device 101A.

When the control unit 61 receives the instruction information H1 from the HEMS 151, the control unit 61 stops the interconnection operation of the inverter 26 and the converter 22 according to the received instruction information H1.

[Daytime mode in grid interconnection system 301B]
For example, at the timing of sunrise, the HEMS 151 transmits the control information M1 indicating the day mode setting command and the discharge command to the power conversion device 101A, and turns on the heat storage operation HSA of the electric water heater 51A.

When the control unit 61 receives the instruction information M1 from the HEMS 151, the control unit 61 sets its own power conversion device 111 to the day mode according to the received instruction information M1.

At this time, the control unit 61 sets the PV relay 31 and the interconnection relay 32 to the on state and the off state, respectively.

Further, the control unit 61 causes the inverter 26, the converter 21 and the converter 22 to operate independently according to the instruction information M1. As a result, the electric power generated by the photovoltaic power generation unit 1 and the electric power discharged from the storage battery 6 are supplied to the electric water heater 51A.

With such a configuration, the electric water heater 51A can convert the amount of electric power based on the AC power received from the electric power converter 101A into heat and store it in the daytime.

[Modification example 1 of single-phase two-wire]
FIG. 12 is a diagram showing a configuration of a modified example of the grid interconnection system according to the embodiment of the present invention.

With reference to FIG. 12, the grid interconnection system (power conversion system) 311A, which is a modification of the grid interconnection system 311, has power instead of the power conversion device 111 as compared with the grid interconnection system 311 shown in FIG. A conversion device 111A is provided, and a storage battery 6 and a HEMS 151 are further provided.

The operations of the storage battery 6 and the HEMS 151 in the grid interconnection system 311A are the same as those of the storage battery 6 and the HEMS 151 in the grid interconnection system 301A shown in FIG. 10, respectively.

The electric water heater 51F operates at 100 volts AC, and is specifically EcoCute. The operation of the electric water heater 51F is the same as that of the electric water heater 51A shown in FIG.

FIG. 13 is a diagram showing a configuration of a power conversion device in a modified example of the grid interconnection system according to the embodiment of the present invention.

With reference to FIG. 13, the power conversion device 111A further includes a terminal block 14 and a converter 22 as compared with the power conversion device 111 shown in FIG.

The configuration and operation of the terminal block 14 and the converter 22 in the power conversion device 111A are the same as those of the terminal block 14 and the converter 22 in the power conversion device 101A shown in FIG. 9, respectively.

The inverter 27 converts the DC power received from the photovoltaic power generation unit 1 via the capacitor 25 into 100 volt AC power under the control of the control unit 61, and converts the converted AC power into a single-phase two-wire interconnection relay 33. And output to the self-supporting relay 34.

Further, the inverter 27 converts the AC power received from the power system via the interconnection relay 33 into DC power according to the control of the control unit 61, and outputs the converted DC power to the converter 22.

[Night mode in grid interconnection system 311A]
When the control unit 61 in the power conversion device 111A receives the instruction information E1 from the HEMS 151, the control unit 61 sets its own power conversion device 111A to the night mode according to the received instruction information E1.

At this time, the control unit 61 sets the PV relay 31, the interconnection relay 33, and the self-supporting relay 34 to the off state, the on state, and the off state, respectively.

Further, the control unit 61 interconnects the inverter 27 and the converter 22 according to the command information E1. As a result, the storage battery 6 is charged by the DC power received from the power conversion device 111A. On the other hand, the electric water heater 51F does not consume the AC power from the power conversion device 111A because the heat storage operation HSA is turned off by the control of the HEMS 151.

When the control unit 61 receives the instruction information H1 from the HEMS 151, the control unit 61 stops the interconnection operation of the inverter 27 and the converter 22 according to the received instruction information H1.

[Daytime mode in grid interconnection system 311A]
When the control unit 61 receives the instruction information M1 from the HEMS 151, the control unit 61 sets its own power conversion device 111A to the day mode according to the received instruction information M1.

At this time, the control unit 61 sets the PV relay 31, the interconnection relay 33, and the self-supporting relay 34 to the on state, the off state, and the on state, respectively.

Further, the control unit 61 causes the inverter 27, the converter 21 and the converter 22 to operate independently according to the instruction information M1. As a result, the electric power generated by the photovoltaic power generation unit 1 and the electric power discharged from the storage battery 6 are supplied to the electric water heater 51F.

With such a configuration, the electric water heater 51F can convert the amount of electric power based on the AC power received from the electric power converter 111A into heat and store it in the daytime.

[Modification example 2 of single-phase three-wire]
FIG. 14 is a diagram showing a configuration of a modified example of the grid interconnection system according to the embodiment of the present invention.

With reference to FIG. 14, the grid interconnection system (power conversion system) 301C, which is a modification of the grid interconnection system 301, has power instead of the power conversion device 101 as compared with the grid interconnection system 301 shown in FIG. A conversion device 101C is provided, and a storage battery 6 and a HEMS 151 are further provided.

The operations of the storage battery 6 and HEMS 151 in the grid interconnection system 301C are the same as those of the storage battery 6 and HEMS 151 in the grid interconnection system 301B shown in FIG. 10, respectively.

The electric water heater 51G operates on DC power, and is specifically EcoCute. The electric water heater 51G has a positive terminal and a negative terminal for receiving DC power from the power converter 101C. The operation of the electric water heater 51G is the same as that of the electric water heater 51A shown in FIG.

FIG. 15 is a diagram showing a configuration of a power conversion device in a modified example of the grid interconnection system according to the embodiment of the present invention.

With reference to FIG. 15, the power conversion device 101C has a terminal block 14, a terminal block (second connection portion) 15, and a converter, instead of the terminal block 13, as compared with the power conversion device 101 shown in FIG. 22 and 22 are provided.

The configurations and operations of the terminal bases 11 and 12, the converter 21, the capacitor 25, the inverter 26, the PV relay 31 and the interconnection relay 32 in the power conversion device 101C are as follows. The same applies to the converter 21, the capacitor 25, the inverter 26, the PV relay 31, and the interconnection relay 32, respectively.

The configuration and operation of the terminal block 14 and the converter 22 in the power conversion device 101C are the same as those of the terminal block 14 and the converter 22 in the power conversion device 101A shown in FIG. 9, respectively.

The terminal block 15 includes a terminal 15A connected to the positive terminal of the electric water heater 51G and a terminal 15B connected to the negative terminal.

The converter 23 includes a first end connected to the terminal 15A of the terminal block 15, a second end connected to the terminal 15B, a third end connected to the first end of the capacitor 25, and a second end of the capacitor 25. It has a fourth end connected to the end.

The control unit 61 controls a switch element (not shown) in the converter 23 by outputting the control signal S6 to the converter 23.

The converter 23 can convert the voltage of the DC power received from the converter 21, the converter 22, and the inverter 26 under the control of the control unit 61. Here, the converter 23 lowers the voltage of the DC power and outputs the reduced DC power to the electric water heater 51G. In this case, the electric water heater 51G is supplied with DC power from the power conversion device 101C.

[Night mode in power converter 101C]
When the control unit 61 in the power conversion device 101C receives the instruction information E1 from the HEMS 151, the control unit 61 sets its own power conversion device 101C to the night mode according to the received instruction information E1.

At this time, the control unit 61 sets the PV relay 31 and the interconnection relay 32 to the off state and the on state, respectively.

Further, the control unit 61 interconnects the inverter 26, the converter 22 and the converter 23 according to the instruction information E1. As a result, the storage battery 6 is charged by the DC power received from the power conversion device 101C. On the other hand, the electric water heater 51G does not consume the DC power from the power conversion device 101C because the heat storage operation HSA is turned off by the control of the HEMS 151.

By the configuration in which the control unit 61 does not connect the converter 23 in an interconnected manner, the supply of DC power from the power converter 101C to the electric water heater 51G may be stopped instead of the HEMS 151 turning off the heat storage operation HSA.

When the control unit 61 receives the instruction information H1 from the HEMS 151, the control unit 61 stops the interconnection operation of the inverter 26, the converter 22, and the converter 23 according to the received instruction information H1.

[Daytime mode in grid interconnection system 301C]
When the control unit 61 receives the instruction information M1 from the HEMS 151, the control unit 61 sets its own power conversion device 101C to the day mode according to the received instruction information M1.

At this time, the control unit 61 sets the PV relay 31 and the interconnection relay 32 to the on state and the off state.

Further, the control unit 61 causes the converter 21, the converter 22, and the converter 23 to operate independently according to the instruction information M1. As a result, the electric power generated by the photovoltaic power generation unit 1 and the electric power discharged from the storage battery 6 are supplied to the electric water heater 51G.

With such a configuration, the electric water heater 51G can convert the amount of electric power based on the DC electric power received from the electric power converter 101C into heat and store it in the daytime.

[Modification example 3 of single-phase three-wire]
FIG. 16 is a diagram showing a configuration of a modified example of the grid interconnection system according to the embodiment of the present invention.

With reference to FIG. 16, the grid interconnection system (power conversion system) 301D, which is a modification of the grid interconnection system 301, has power instead of the power conversion device 101 as compared with the grid interconnection system 301 shown in FIG. A conversion device 101A is provided, and a storage battery 6 and a HEMS 151 are further provided.

The operations of the storage battery 6, the power conversion device 101A, and the HEMS 151 in the grid interconnection system 301D are the same as those of the storage battery 6, the power conversion device 101A, and the HEMS 151 in the grid interconnection system 301B shown in FIG. 10, respectively.

In the grid interconnection system 301D, an electric water heater 51A and a heat storage heater 51B are provided as specific examples of the specific load 51E shown in FIG.

The operation of the electric water heater 51A in the grid interconnection system 301D is the same as that of the electric water heater 51A in the grid interconnection system 301B shown in FIG.

The heat storage heater 51B operates at 200 volts AC, and is specifically Mr. Onkichi (registered trademark). More specifically, the heat storage heater 51B has a heat storage body, and performs a heat storage operation HSB for raising the temperature of the heat storage body by using the AC power received from the power conversion device 101A.

The heat storage operation HSB in the heat storage heater 51B can be switched on and off by, for example, HEMS 151.

[Night mode in grid interconnection system 301D]
For example, the HEMS 151 transmits the command information E1 to the power converter 101A at the timing of sunset, and turns off both the heat storage operation HSA of the electric water heater 51A and the heat storage operation HSB of the heat storage heater 51B.

[Daytime mode in grid interconnection system 301D]
For example, the HEMS 151 transmits the control information M1 to the power converter 101A at the timing of sunrise, and turns on both the heat storage operation HSA of the electric water heater 51A and the heat storage operation HSB of the heat storage heater 51B.

The power conversion device 111 (see FIG. 4) according to the embodiment of the present invention is connected to the terminal bases 11, 12, 16 and the converter 21, the capacitor 25, the inverter 27, and the PV relay 31. The configuration includes a relay 33, an independent relay 34, and a control unit 61, but the present invention is not limited to this. The power conversion device 111 has a simple configuration and suppresses deterioration of the photovoltaic power generation device by a minimum component including a terminal block 11, a capacitor 25, an inverter 27, a PV relay 31, and an interconnection relay 33. It is possible to achieve the object of the present invention of Specifically, for example, when the voltage of the DC power from the photovoltaic power generation unit 1 is sufficiently large, the inverter 27 can generate an appropriate AC power without providing the converter 21 for boosting.

Similarly, the power conversion device 101 (see FIG. 7) according to the embodiment of the present invention includes terminal blocks 11, 12, 13 and a converter 21, a capacitor 25, an inverter 26, and a PV relay 31. The configuration is such that the system relay 32 and the control unit 61 are provided, but the present invention is not limited to this. The power conversion device 101 has a simple configuration and suppresses deterioration of the photovoltaic power generation device by a minimum component including a terminal block 11, a capacitor 25, an inverter 26, a PV relay 31, and an interconnection relay 32. It is possible to achieve the object of the present invention of

Further, the power conversion device according to the embodiment of the present invention has a configuration in which the terminal block 11 is provided, but the present invention is not limited to this. The power conversion device 101 may be configured so that the terminal block 11 is not provided. In this case, for example, the positive lateral lines PLp1 and PLm1 are directly connected to the PV relay 31, and are grounded at the connecting portion between the negative lateral line PLm1 and the PV relay 31.

Further, in the power conversion device according to the embodiment of the present invention, the control unit 61 is provided inside the power conversion devices 101 and 111, but the present invention is not limited to this. The control unit 61 may be provided outside the power converters 101 and 111.

Further, in the power conversion device according to the embodiment of the present invention, the power conversion devices 101 and 111 are configured to be connected to the specific load 51, but the present invention is not limited to this. The power conversion devices 101 and 111 may be configured not to be connected to the specific load 51.

Further, in the power conversion device according to the embodiment of the present invention, the control unit 61 is configured to control the PV relay 31 and the interconnection relays 32 and 33, but the present invention is not limited to this. For example, the user may manually operate the PV relay 31 and the interconnection relays 32 and 33.

Further, in the power conversion device according to the embodiment of the present invention, the HEMS 151 is configured to adjust the remaining charge of the storage battery 6, but the present invention is not limited to this. The control unit 61 may be configured to adjust the remaining charge of the storage battery 6.

Further, the grid interconnection system 311 (see FIG. 3) according to the embodiment of the present invention is configured to include a photovoltaic power generation unit 1, a power conversion device 111, and a specific load 51. It is not limited. The grid interconnection system 311 is simple due to a minimum component including a power conversion device including a terminal block 11, a capacitor 25, an inverter 27, a PV relay 31, an interconnection relay 33, and a control unit 61. With the configuration, it is possible to achieve the object of the present invention of suppressing deterioration of the photovoltaic power generation device.

Further, the grid interconnection system 301 (see FIG. 6) according to the embodiment of the present invention is configured to include a photovoltaic power generation unit 1, a power conversion device 101, and specific loads 51C, 51D, 51E. However, it is not limited to this. The grid interconnection system 301 is simple due to a minimum component including a power conversion device including a terminal block 11, a capacitor 25, an inverter 26, a PV relay 31, an interconnection relay 32, and a control unit 61. With the configuration, it is possible to achieve the object of the present invention of suppressing deterioration of the photovoltaic power generation device.

Further, in the power conversion system according to the embodiment of the present invention, the control unit 61 is configured to control the PV relay 31 and the interconnection relays 32 and 33, but the present invention is not limited to this. For example, the HEMS 151 may be configured to control the PV relay 31 and the interconnection relays 32 and 33.

Further, in the power conversion system according to the embodiment of the present invention, the HEMS 151 is configured to adjust the remaining charge of the storage battery 6 based on the consumption prediction information and the power generation prediction information, but the present invention is not limited to this. Absent. The HEMS 151 may have a configuration in which the remaining charge of the storage battery 6 is not adjusted. In this case, the HEMS 151 is charged, for example, every night so that the remaining charge of the storage battery 6 becomes a predetermined value.

By the way, for example, when the solar cell string described in Patent Document 1 has a potential with respect to the ground, the cell in the photovoltaic power generation device may deteriorate and the output of the photovoltaic power generation device may decrease.

Specifically, as described in Non-Patent Document 1, PID is generated in the solar cell module near the cathode where a larger potential difference from the metal frame is generated, and the output of the photovoltaic power generation device is reduced. A technique for suppressing deterioration of such a photovoltaic power generation device such as a PID is required.

On the other hand, in the power conversion device 111 according to the embodiment of the present invention, the inverter 27 converts the DC power received from the photovoltaic power generation unit 1 into AC power. The PV relay 31 is connected between the photovoltaic power generation unit 1 and the inverter 27. The interconnection relay 33 is connected between the inverter 27 and the power system. Then, the first connection portion grounds the negative side lines PLm1 and Wm1 negative side lines that electrically connect the solar power generation unit 1 and the inverter 27 between the solar power generation unit 1 and the PV relay 31.

In this way, with the configuration in which the first connection portion for grounding the negative side lines PLm1 and Wm1 is provided between the photovoltaic power generation unit 1 and the PV relay 31, the sun is provided regardless of the open / closed state of the PV relay 31. The potential of the photovoltaic power generation unit 1 can be set to the same potential as the ground. Thereby, for example, it is possible to suppress the progress of PID for the solar cell module which deteriorates when it has a negative potential with respect to the grounded metal frame. Further, for example, even in a circuit configuration in which the power system and the power conversion device 111 are not insulated and a ground fault current flows from the power system via the first connection portion, the interconnection relay 33 can be opened. , Ground fault current can be prevented. Therefore, deterioration of the photovoltaic power generation device can be suppressed with a simple configuration.

Further, in the power conversion device 111 according to the embodiment of the present invention, the terminal block 16 electrically converts the output power of the photovoltaic power generation unit 1 into energy and stores or consumes the specific load 51 and the inverter 27. Connecting.

With such a configuration, for example, by connecting the specific load 51 to the terminal block 16, the output power of the photovoltaic power generation unit 1 can be effectively used in the specific load 51 when the PV relay 31 is closed. it can.

Further, in the power conversion device 111 according to the embodiment of the present invention, the control unit 61 turns on the PV relay 31 and turns off the interconnection relay 33 in the daytime mode, and turns off the PV relay 31 and interconnects. Switch the night mode to turn on the relay 33.

With such a configuration, for example, while preventing a ground fault current in a state where the power system and the power conversion device 111 are not insulated, either the power generated from the photovoltaic power generation unit 1 or the power from the power system can be generated. It can be supplied to the power converter 111.

Further, in the power conversion device 111 according to the embodiment of the present invention, the control unit 61 converts the output power of the photovoltaic power generation unit 1 into energy and stores or consumes the power consumption prediction information of the specific load 51 and the sun. Acquires the power generation prediction information of the photovoltaic power generation unit 1. Then, the control unit 61 adjusts the output power of the photovoltaic power generation unit 1 and the remaining storage amount of the storage battery 6 capable of storing the power from the power system based on the acquired power consumption prediction information and power generation prediction information.

With such a configuration, for example, the remaining amount of electricity required to satisfy the power consumption of the specific load 51 in the daytime of the next day can be calculated based on the power consumption prediction information and the power generation prediction information, so that the power at night can be calculated. It is possible to prevent the amount of charge from the system to the storage battery 6 to be excessive or too small. As a result, the amount of power generated by the photovoltaic power generation unit 1 due to the excessive amount of charge to the storage battery 6 is excessive, and the amount of power supplied to the specific load 51 in the daytime of the next day is insufficient due to the excessive amount of charge to the storage battery 6. Can be prevented.

Further, the power conversion system 311 according to the embodiment of the present invention includes a power conversion device 111 and a HEMS 151. The power conversion device 111 includes an inverter 27 that converts DC power received from the photovoltaic power generation unit 1 into AC power, a PV relay 31 connected between the photovoltaic power generation unit 1 and the inverter 27, and an inverter 27. The interconnection relay 33 connected to the power system and the negative side lines PLm1 and Wm1 that electrically connect the photovoltaic power generation unit 1 and the inverter 27 are grounded between the photovoltaic power generation unit 1 and the PV relay 31. Includes a first connection for the purpose. Then, the HEMS 151 controls the ON / OFF of the PV relay 31 and the interconnection relay 33.

In this way, with the configuration in which the first connection portion for grounding the negative side lines PLm1 and Wm1 is provided between the photovoltaic power generation unit 1 and the PV relay 31, the sun is provided regardless of the open / closed state of the PV relay 31. The potential of the photovoltaic power generation unit 1 can be set to the same potential as the ground. Thereby, for example, it is possible to suppress the progress of PID for the solar cell module which deteriorates when it has a negative potential with respect to the grounded metal frame. Further, for example, even in a circuit configuration in which the power system and the power conversion device 111 are not insulated and a ground fault current flows from the power system via the first connection portion, the interconnection relay 33 can be opened. , Ground fault current can be prevented. Therefore, deterioration of the photovoltaic power generation device can be suppressed with a simple configuration.

Further, in the power conversion system 311 according to the embodiment of the present invention, the HEMS 151 has a day mode in which the PV relay 31 is turned on and the interconnection relay 33 is turned off, and a day mode in which the PV relay 31 is turned off and the interconnection relay 33 is turned off. Toggle the night mode to turn on.

With such a configuration, for example, while preventing a ground fault current in a state where the power system and the power conversion device 111 are not insulated, either the power generated from the photovoltaic power generation unit 1 or the power from the power system can be generated. It can be supplied to the power converter 111.

Further, the power conversion system 311 according to the embodiment of the present invention further includes a storage battery 6 capable of storing the output power of the photovoltaic power generation unit 1 and the power from the power system. Then, the HEMS 151 acquires the power consumption prediction information of the specific load 51 that converts the output power of the photovoltaic power generation unit 1 into energy and stores or consumes it, and the power generation prediction information of the photovoltaic power generation unit 1, and acquires the acquired power consumption. The remaining charge of the storage battery 6 is adjusted based on the prediction information and the power generation prediction information.

With such a configuration, for example, the remaining amount of electricity required to satisfy the power consumption of the specific load 51 in the daytime of the next day can be calculated based on the power consumption prediction information and the power generation prediction information, so that the power at night can be calculated. It is possible to prevent the amount of charge from the system to the storage battery 6 to be excessive or too small. As a result, the amount of power generated by the photovoltaic power generation unit 1 due to the excessive amount of charge to the storage battery 6 is excessive, and the amount of power supplied to the specific load 51 in the daytime of the next day is insufficient due to the excessive amount of charge to the storage battery 6. Can be prevented.

It should be considered that the above embodiments are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

The above description includes the features described below.

[Appendix 1]
It ’s a power converter,
A power conversion unit that converts DC power received from the photovoltaic power generation unit into AC power,
A first switch connected between the photovoltaic power generation unit and the power conversion unit,
A second switch connected between the power conversion unit and the power system,
A first connection portion for grounding the negative side line that electrically connects the solar power generation unit and the power conversion unit between the solar power generation unit and the first switch is provided.
In the power conversion device, a terminal block is provided as the first connection portion between the solar power generation unit and the first switch.
The terminal block includes a first terminal, a second terminal, and a third terminal.
The first terminal fixes a positive lateral line that electrically connects the photovoltaic power generation unit and the power conversion unit.
The second terminal fixes the negative lateral line and
The third terminal fixes a ground wire whose one end is grounded.
A power conversion device in which the second terminal and the third terminal are electrically connected.

[Appendix 2]
Power converter and
Equipped with a control device
The power converter
A power conversion unit that converts DC power received from the photovoltaic power generation unit into AC power,
A first switch connected between the photovoltaic power generation unit and the power conversion unit,
A second switch connected between the power conversion unit and the power system,
The negative side line for electrically connecting the photovoltaic power generation unit and the power conversion unit includes a connection unit for grounding between the photovoltaic power generation unit and the first switch.
The control device controls the on and off of the first switch and the second switch.
In the power conversion device, a terminal block is provided as the first connection portion between the solar power generation unit and the first switch.
The terminal block includes a first terminal, a second terminal, and a third terminal.
The first terminal fixes a positive lateral line that electrically connects the photovoltaic power generation unit and the power conversion unit.
The second terminal fixes the negative lateral line and
The third terminal fixes a ground wire whose one end is grounded.
A power conversion system in which the second terminal and the third terminal are electrically connected.

[Appendix 3]
The power conversion device according to Appendix 1 or Appendix 2, wherein the power conversion unit and the power system are non-insulated.

1 Solar power generation unit 6 Storage battery 11 Terminal block (first connection part)
12 terminal block 13 terminal block (second connection)
14 terminal block 15 terminal block (second connection)
16 terminal block (second connection)
21,22,23 Converter 25 Capacitor 26,27 Inverter (power converter)
31 PV relay (first switch)
32,33 interconnection relay (second switch)
34 Self-supporting relay 41 General load 51 Specific load 61 Control unit (control device)
70 Housing 91 Control unit 101 Power conversion device 111 Power conversion device 151 HEMS (Control device)
301,311 grid interconnection system (power conversion system)
901,901 power converter

Claims (7)

A power conversion unit that converts DC power received from the photovoltaic power generation unit into AC power,
A first switch connected between the photovoltaic power generation unit and the power conversion unit,
A second switch connected between the power conversion unit and the power system,
A first connection portion for grounding the negative side line that electrically connects the solar power generation unit and the power conversion unit between the solar power generation unit and the first switch ,
The first switch and the first switch and the state in which one of the first switch and the second switch is turned on and the other are turned off are maintained for a predetermined period longer than one AC cycle converted by the power conversion unit. A power conversion device including a control unit that controls the second switch. The power converter further
The power conversion device according to claim 1, further comprising a second connection unit for electrically connecting the load that converts the output power of the photovoltaic power generation unit into energy and stores or consumes the power conversion unit. .. The control unit sets a first mode in which the first switch is turned on and the second switch is turned off, and a second mode in which the first switch is turned off and the second switch is turned on. toggle its power conversion apparatus according to claim 1 or claim 2. The power converter further
The power consumption forecast information of the load stored or consumed by converting the output power of the photovoltaic power generation unit into energy, and the power generation forecast information of the photovoltaic power generation unit are acquired, and the acquired power consumption forecast information and the power generation forecast are obtained. The present invention according to any one of claims 1 to 3, further comprising a control unit for adjusting the output power of the photovoltaic power generation unit and the remaining storage amount of the storage battery capable of storing the power from the power system based on the information. The power converter described. Power converter and
Equipped with a control device
The power converter
A power conversion unit that converts DC power received from the photovoltaic power generation unit into AC power,
A first switch connected between the photovoltaic power generation unit and the power conversion unit,
A second switch connected between the power conversion unit and the power system,
The negative side line for electrically connecting the photovoltaic power generation unit and the power conversion unit includes a connection unit for grounding between the photovoltaic power generation unit and the first switch.
The control device maintains one of the first switch and the second switch on and off for a predetermined period longer than one AC cycle converted by the power conversion unit. A power conversion system that controls the on and off of a first switch and the second switch. The control device has a first mode in which the first switch is turned on and the second switch is turned off, and a second mode in which the first switch is turned off and the second switch is turned on. The power conversion system according to claim 5, which is switched. The power conversion system further
A storage battery capable of storing the output power of the photovoltaic power generation unit and the power from the power system , and
Power consumption prediction information before Symbol PV power generator output power loads that accumulate or consumed is converted into energy, and obtains the power generation prediction information of the photovoltaic unit, the acquired power consumption prediction information and the generator The power conversion system according to claim 5 or 6, further comprising a control device for adjusting the remaining charge of the storage battery based on the prediction information.

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