Power System

Abstract

To provide an electrical power system capable of using a power conversion device more effectively.SOLUTION: The electrical power system includes: a DC power supply; a power conversion device that converts DC power supplied from the DC power supply into AC power according to the power system; and a high-frequency current supply unit that is placed between a DC circuit across the DC power supply and the power conversion device and the earth so as to flow a high-frequency current superimposed on the DC circuit to the earth. The power conversion device is configured to convert the AC power of the power system to DC power that includes high-frequency components according to the switching frequency of multiple switching elements by switching multiple switching elements and by supplying the converted DC power to the DC circuit to flow the high-frequency current via the high-frequency current supply unit to the earth.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE The present invention relates to a power supply system. [Background technology]

[0002] A power supply system including a DC power supply and a power conversion device is known. The DC power supply is, for example, a solar panel or a power storage device. The power conversion device has a plurality of switching elements, and converts DC power input from the DC power supply into AC power by switching the plurality of switching elements, and supplies the converted AC power to an AC power system. The power supply system supplies generated power to the power system and stabilizes the power system.

[0003] In a power supply system, under certain conditions, a power conversion device stops operating and goes into a standby state. For example, when the DC power supply is a solar panel, the power conversion device goes into a standby state when the solar radiation intensity is insufficient, such as at night. Also, when the DC power supply is a power storage device, the power conversion device goes into a standby state when the power of the power system is stable.

[0004] However, if the power conversion device is put into a standby state as described above, the utilization efficiency of the power conversion device is reduced. For example, in a power supply system in which a DC power supply is a solar panel, the power conversion device may be in a standby state for nearly half a day because the power supply system is in a standby state at night. In this way, in the power supply system, the power conversion device may be in a standby state for a relatively long time. For this reason, in the power supply system, there is a demand for a power conversion device that can be more effectively utilized by making the power conversion device perform a useful operation without stopping the operation of the power conversion device and putting it into a standby state even under the above-mentioned conditions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-107893 [Patent Document 2] JP 2017-85915 A Summary of the Invention [Problem to be solved by the invention]

[0006] An embodiment of the present invention provides a power supply system that can more effectively utilize a power conversion device. [Means for solving the problem]

[0007] According to an embodiment of the present invention, there is provided a power conversion device connected to the DC power supply for supplying DC power, the power conversion device being connected to an AC power system and for converting the DC power supplied from the DC power supply into AC power corresponding to the power system by switching a plurality of switching elements, and for supplying the converted AC power to the power system, and a high frequency current supply unit provided between a DC circuit between the DC power supply and the power conversion device and the ground, the high frequency current supply unit enabling a high frequency current superimposed on the DC circuit to flow to the ground. a rectifying element provided on the path of the DC current path; the power conversion device is capable of executing a first operation of converting DC power supplied from the DC power source into AC power corresponding to the power grid and supplying the AC power to the power grid, and a second operation of converting the AC power of the power grid into DC power and supplying the DC power to the DC electric circuit, and in the second operation, the power conversion device converts the AC power of the power grid into DC power including a high-frequency component corresponding to a switching frequency of the plurality of switching elements by switching the plurality of switching elements, and supplies the converted DC power to the DC electric circuit, thereby flowing a high-frequency current to the ground via the high-frequency current supply unit. The high frequency current supply unit is connected to the DC circuit at a portion closer to the power converter than the rectifier element. A power system is provided. Effect of the Invention

[0008] A power supply system capable of more effectively utilizing a power conversion device is provided. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram illustrating a power supply system according to an embodiment of the present invention.

[0010] Each embodiment will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as in reality. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same reference numerals and detailed descriptions thereof will be omitted as appropriate.

[0011] FIG. 1 is a block diagram that illustrates a power supply system according to an embodiment. As shown in Fig. 1, the power supply system 10 includes a DC power supply 12 and a power conversion device 14. The DC power supply 12 supplies DC power to the power conversion device 14. The power conversion device 14 is connected to the DC power supply 12 and also to an AC power system 2. Note that, for example, a transformer, a circuit breaker, and the like (not shown) may be further provided between the power conversion device 14 and the power system 2. The power conversion device 14 has a plurality of switching elements 14s. The power conversion device 14 converts the DC power supplied from the DC power supply 12 into AC power corresponding to the power system 2 by switching the plurality of switching elements 14s, and supplies the converted AC power to the power system 2.

[0012] The DC power supply 12 is, for example, a solar cell panel. The power conversion device 14 supplies power generated by the solar cell panel to the power grid 2. In other words, the power supply system 10 is a solar power generation system. In the following, the DC power supply 12 is assumed to be the solar cell panel 12, and a solar power generation system will be described as an example.

[0013] The solar panel 12 has, for example, a panel body 12a and a stand 12b. The panel body 12a has a plurality of cells. The panel body 12a also has a plurality of series-connected bodies (modules or strings) in which a plurality of cells are connected in series. The panel body 12a is composed of a plurality of series-connected bodies, and outputs DC power from each of the plurality of series-connected bodies. However, the configuration of the panel body 12a is not limited to the above. The panel body 12a may be configured to output one DC power, for example.

[0014] The mounting base 12b supports the panel body 12a. The panel body 12a is installed on the ground or on a building while being supported by the mounting base 12b. The mounting base 12b supports the panel body 12a at an optimal angle according to the solar altitude, etc. The mounting base 12b supports the panel body 12a at an orientation and angle that allows the optimal amount of power generation to be obtained.

[0015] Furthermore, the mounting base 12b installs the panel body 12a at a position higher than the ground, thereby preventing a decrease in the amount of power generated by the solar cell panel 12 due to, for example, dust, weeds, or the effects of snowfall.

[0016] Furthermore, the solar cell panel 12 may be installed on farmland. In this case, the mounting base 12b supports the panel body 12a while allowing crops to be grown on the farmland below the panel body 12a. The mounting base 12b, for example, installs the panel body 12a at a relatively high position to ensure space for crops and work machines, and supports the panel body 12a with gaps between the multiple cells or multiple serial connections of the panel body 12a, allowing light to enter the farmland below the panel body 12a, thereby allowing crops to be grown on the farmland below the panel body 12a. Such a solar power generation system is called, for example, agricultural solar power generation.

[0017] However, the configuration of the mount 12b is not limited to the above, and may be any configuration that can properly support the panel body 12a and properly install the panel body 12a on the ground, a building, or the like.

[0018] The power supply system 10 includes, for example, a plurality of solar cell panels 12. In FIG. 1, two solar cell panels 12 are illustrated. However, the number of solar cell panels 12 may be one, or three or more. The number of solar cell panels 12 may be any number. Also, for example, a plurality of panel bodies 12a may be installed on one mounting base 12b. The number of mounting bases 12b does not necessarily have to be the same as the number of panel bodies 12a.

[0019] The power supply system 10 further includes, for example, a junction box 16 and a current collecting box 18. For example, when the solar cell panel 12 has a plurality of series-connected bodies, the junction box 16 aggregates the outputs of the plurality of series-connected bodies into one and outputs the aggregated output. The junction box 16 aggregates the outputs of the plurality of series-connected bodies of the solar cell panel 12 into one output by connecting them in parallel. By thus aggregating the outputs of the plurality of series-connected bodies into one and outputting the aggregated output, the junction box 16 suppresses, for example, a voltage drop in the DC voltage between the solar cell panel 12 and the power conversion device 14.

[0020] The connection box 16 has, for example, a plurality of circuit breakers 16a and a plurality of rectifier elements 16b. The plurality of circuit breakers 16a are provided corresponding to each of the plurality of series-connected bodies. The connection box 16 can individually switch between connection and disconnection of the plurality of series-connected bodies by switching between on and off the plurality of circuit breakers 16a. As a result, even when a certain series-connected body fails, for example, it is possible to replace only the failed series-connected body by opening the corresponding circuit breaker 16a without stopping the operation of the solar panel 12 or the entire power supply system 10. Therefore, the maintainability of the power supply system 10 can be improved. The connection box 16 consolidates a plurality of outputs into one, thereby suppressing a voltage drop of the DC voltage and improving the maintainability of the power supply system 10.

[0021] The rectifying elements 16b are provided corresponding to the series connections, respectively. The rectifying elements 16b rectify the direction of the DC current flowing from the solar panel 12 toward the power converter 14, thereby suppressing the reverse flow of the DC current to the solar panel 12. The rectifying elements 16b are, for example, reverse current prevention diodes.

[0022] In this example, a plurality of rectifier elements 16b are provided corresponding to the plurality of series-connected bodies, respectively. However, without being limited thereto, for example, a configuration in which one rectifier element 16b is provided on a path after the outputs of the plurality of series-connected bodies are aggregated into one may be used. The rectifier element 16b may be provided separately from the connection box 16. The rectifier element 16b may be provided at any position on the path of the DC circuit between the solar cell panel 12 and the power conversion device 14. In other words, the power supply system 10 may include a rectifier element provided on the path of the DC circuit between the solar cell panel 12 and the power conversion device 14.

[0023] The power supply system 10 includes, for example, a plurality of junction boxes 16 corresponding to a plurality of solar cell panels 12. In this example, two junction boxes 16 corresponding to two solar cell panels 12, respectively, are included. The junction boxes 16 are attached, for example, to a space below the panel body 12a of the stand 12b. This shortens the path through which the outputs of the plurality of series-connected bodies are aggregated into one, and makes it possible to more appropriately suppress the voltage drop of the DC voltage. However, the junction boxes 16 may be installed in a location separate from the solar cell panels 12.

[0024] For example, if the number of input terminals (circuit breakers 16a) of the junction box 16 is greater than the number of series-connected solar cell panels 12, the output of multiple solar cell panels 12 may be input to one junction box 16. Conversely, if the number of input terminals of the junction box 16 is less than the number of series-connected solar cell panels 12, the output of one solar cell panel 12 may be input to multiple junction boxes 16. In this way, the number of junction boxes 16 does not necessarily have to be the same as the number of solar cell panels 12.

[0025] The current collecting box 18 is provided between the multiple junction boxes 16 and the power conversion device 14. The current collecting box 18 aggregates the outputs of the multiple junction boxes 16 into one and outputs the output to the power conversion device 14. The current collecting box 18 aggregates the outputs of the multiple junction boxes 16 into one output by connecting them in parallel. By aggregating the outputs of the multiple junction boxes 16 into one and outputting the output to the power conversion device 14 in this manner, the current collecting box 18 further suppresses a voltage drop in the DC voltage between, for example, the solar panel 12 and the power conversion device 14.

[0026] The current collecting box 18 has, for example, a plurality of circuit breakers 18a. The plurality of circuit breakers 18a are provided corresponding to the plurality of junction boxes 16, respectively. The current collecting box 18 allows the connection and disconnection of the plurality of junction boxes 16 to be individually switched by switching the connection and disconnection of the plurality of circuit breakers 18a on and off. As a result, for example, even when a malfunction or the like occurs in the system of a certain junction box 16, it is possible to stop only the system of the junction box 16 in which the malfunction has occurred by opening the corresponding circuit breaker 18a without stopping the operation of the entire power supply system 10. It is possible to continue the supply of power in the systems of the remaining junction boxes 16 by stopping the operation of only the system of the junction box 16 in which the malfunction has occurred. Therefore, it is possible to further improve the maintainability of the power supply system 10.

[0027] The junction box 16 and the current collecting box 18 are provided on the path of a DC electric circuit between the solar cell panel 12 (DC power source) and the power conversion device 14. In other words, the junction box 16 and the current collecting box 18 form part of the DC electric circuit between the solar cell panel 12 and the power conversion device 14.

[0028] The junction box 16 and the current collecting box 18 are provided as necessary and can be omitted. For example, when there is only one junction box 16, the current collecting box 18 is omitted. For example, there are cases where the power conversion device 14 has the function of the junction box 16. In this case, the junction box 16 and the current collecting box 18 are omitted.

[0029] The power supply system 10 further includes a plurality of high frequency current supply units 20, 30. The plurality of high frequency current supply units 20, 30 are provided between the ground and a DC current path between the solar cell panel 12 and the power conversion device 14, and enable the high frequency current superimposed on the DC current path to flow to the ground.

[0030] The high frequency current supply unit 20 is connected to the DC circuit at the junction box 16. The high frequency current supply unit 20 is connected to the DC circuit, for example, at a portion closer to the power conversion device 14 than the plurality of rectifier elements 16b. The high frequency current supply unit 20 is connected to the DC circuit, for example, at a portion after aggregating the plurality of outputs closer to the power conversion device 14 than the plurality of rectifier elements 16b.

[0031] The power supply system 10 includes, for example, a plurality of high frequency current supply units 20 corresponding to the respective plurality of junction boxes 16. However, the high frequency current supply unit 20 does not necessarily have to be provided in each of the plurality of junction boxes 16.

[0032] The high frequency current supply unit 30 is connected to a DC circuit in the current collection box 18. The high frequency current supply unit 30 is connected to a DC circuit, for example, in a portion of the current collection box 18 after aggregating a plurality of outputs.

[0033] However, the positions at which the high frequency current supply units 20, 30 are connected to the DC circuit are not limited to the above and may be any positions on the path of the DC circuit between the solar cell panel 12 and the power conversion device 14. In addition, the number of high frequency current supply units provided in the power supply system 10 is not limited to the above and may be any number.

[0034] The high frequency current supplying section 20 includes, for example, a ground electrode 21, a high frequency filter 22, and a switching circuit .

[0035] The ground electrode 21 is buried in the ground and thus electrically connected to the ground. The ground electrode 21 may be buried completely in the ground or may be partially exposed above the ground surface. The ground electrode 21 may be installed in any manner that allows electrical connection to the ground.

[0036] The high frequency filter 22 is provided between the DC circuit and the ground electrode 21. The high frequency filter 22 allows the high frequency current superimposed on the DC circuit to flow to the ground, and suppresses the DC current flowing in the DC circuit from flowing to the ground. In other words, the high frequency filter 22 allows only the components of the high frequency current superimposed on the DC circuit to flow to the ground. The high frequency filter 22 has, for example, a capacitor provided between the DC circuit and the ground electrode 21. The high frequency filter 22 is, for example, a high pass filter or a band pass filter. This allows only the components of the high frequency current to flow to the ground. The configuration of the high frequency filter 22 is not limited to this, and may be any configuration that allows only the high frequency current to flow to the ground.

[0037] The switching circuit 23 switches between a first state in which the flow of high-frequency current from the DC circuit to the ground is suppressed and a second state in which the flow of high-frequency current from the DC circuit to the ground is permitted. The first state is, for example, a state in which the DC circuit and the ground electrode 21 are electrically insulated, and the second state is, for example, a state in which the DC circuit and the ground electrode 21 are electrically connected. The switching circuit 23 has, for example, a switching element, and switches between the first state and the second state by switching between the on state and the off state of the switching element. The configuration of the switching circuit 23 is not limited to the above, and may be any configuration capable of appropriately switching between the first state and the second state.

[0038] The high frequency current supplying unit 30 has, for example, a ground electrode 31, a high frequency filter 32, and a switching circuit 33. The configuration of the high frequency current supplying unit 30 is substantially the same as the configuration of the high frequency current supplying unit 20, and therefore detailed description thereof will be omitted.

[0039] The power conversion device 14 is capable of performing a first operation of converting DC power supplied from the solar panel 12 into AC power corresponding to the power system 2 and supplying the AC power to the power system 2, and a second operation of converting the AC power of the power system 2 into DC power and supplying the DC power to a DC circuit.

[0040] The second operation is an operation in which the AC power of the power system 2 is converted into DC power containing high-frequency components according to the switching frequency of the multiple switching elements 14s by switching the multiple switching elements 14s, and the converted DC power is supplied to the DC circuit, thereby causing a high-frequency current to flow to the ground via the high-frequency current supply units 20, 30. The high-frequency current is a current that flows to the ground via the DC circuit and the high-frequency current supply units 20, 30, and returns to the power conversion device 14 via the ground. In other words, the high-frequency current is a leakage current (common mode current).

[0041] The power conversion device 14 is, for example, a two-level inverter in which a plurality of switching elements 14s are bridge-connected. The power conversion device 14 may be a multilevel inverter such as a three-level inverter. The power conversion device 14 may have any configuration that can perform the first operation and the second operation by switching the plurality of switching elements 14s.

[0042] The power conversion device 14 performs the first operation when the amount of power generated by the solar cell panel 12 is large, such as during the day, and performs the second operation when the amount of power generated by the solar cell panel 12 is small, such as at night.

[0043] For example, the power conversion device 14 executes a first operation when the magnitude of the DC voltage of the DC power supplied from each of the multiple solar cell panels 12 is equal to or greater than a predetermined voltage, and executes a second operation when the magnitude of the DC voltage is less than the predetermined voltage. In this way, the power conversion device 14 automatically switches between the first operation and the second operation based on the magnitude of the DC voltage of the DC power supplied from the solar cell panels 12, etc. However, without being limited thereto, the power conversion device 14 may switch between the first operation and the second operation based on, for example, a control signal input from an external device. The power conversion device 14 may switch between the first operation and the second operation based on, for example, a control signal input from a higher-level controller, etc.

[0044] For example, in the second operation, the power conversion device 14 sets the switching frequency of the multiple switching elements 14s to a frequency that repels harmful animals, thereby causing a high-frequency current of the frequency that repels harmful animals to flow to the ground. For example, cockroaches are thought to be repelled by electromagnetic waves with a frequency of about 15 kHz to 30 kHz. Also, for example, rats are thought to be repelled by electromagnetic waves with a frequency of about 20 kHz to 50 kHz. In the second operation, the power conversion device 14 sets the switching frequency of the multiple switching elements 14s to such a frequency.

[0045] For example, a high-frequency current supply unit 20 connected to the connection box 16 is installed around the solar panel 12, and a high-frequency current is passed around the solar panel 12, while a high-frequency current supply unit 30 connected to the current collection box 18 is installed around the power conversion device 14, and a high-frequency current is passed around the power conversion device 14.

[0046] This makes it possible to prevent harmful animals, such as vermin such as cockroaches and vermin such as rats, from approaching the solar panel 12 and the power conversion device 14. Therefore, it is possible to protect the solar panel 12 and the power conversion device 14 from harmful animals. For example, it is possible to prevent the occurrence of short circuit accidents caused by electric shock from harmful animals and wire breakage accidents caused by harmful animals gnawing on the wiring.

[0047] Furthermore, for example, when the power supply system 10 is an agricultural solar power generation system, the power conversion device 14 passes a high-frequency current with a frequency that repels harmful animals around the solar cell panel 12 (around the farmland below the panel body 12a). For example, harmful animals such as wild boars, deer, and monkeys may be repelled by electromagnetic waves with a frequency of about 20 kHz or more and 40 kHz or less. Harmful animals are not limited to harmful animals, and may also be pests such as mites. This makes it possible to suppress damage to agricultural crops caused by harmful animals.

[0048] The power conversion device 14 may, for example, pass a high-frequency current having a frequency that inhibits the growth of weeds around the solar panel 12. This can suppress a decrease in the amount of power generation caused by weeds and can save the effort of removing the weeds.

[0049] Furthermore, when the power supply system 10 is an agricultural solar power generation system, the power conversion device 14 may, for example, pass a high-frequency current having a frequency that promotes the growth of agricultural crops around the solar cell panel 12 (around the farmland below the panel body 12a).

[0050] The high-frequency current supply unit 20 switches the switching circuit 23 to a first state that suppresses the flow of high-frequency current when the power conversion device 14 is performing a first operation of supplying AC power to the power system 2, and switches the switching circuit 23 to a second state that allows the flow of high-frequency current when the power conversion device 14 is performing a second operation of supplying DC power to the DC circuit.

[0051] This makes it possible to prevent a high-frequency current corresponding to an unintended switching frequency from flowing to the ground when the power conversion device 14 is performing the first operation. Only a high-frequency current of a desired frequency can be caused to flow to the ground when the power conversion device 14 is performing the second operation.

[0052] The switching circuit 23 communicates with, for example, the power conversion device 14, and switches between the first state and the second state based on a control signal from the power conversion device 14. In other words, the power conversion device 14 transmits a control signal to the switching circuit 23, thereby switching the switching circuit 23 to the first state when the first operation is being performed, and switching the switching circuit 23 to the second state when the second operation is being performed.

[0053] However, the switching between the first state and the second state of the switching circuit 23 is not limited to the control signal from the power conversion device 14. The switching between the first state and the second state of the switching circuit 23 may be switched, for example, in response to a control signal from a higher-level controller. The method of switching between the first state and the second state of the switching circuit 23 may be any method that can appropriately switch between the first state and the second state of the switching circuit 23. Note that the operation of the switching circuit 33 of the high-frequency current supply unit 30 is similar to the operation of the switching circuit 23 of the high-frequency current supply unit 20, and therefore a detailed description thereof will be omitted.

[0054] Note that, even if a high-frequency current according to the switching frequency when the power conversion device 14 is performing the first operation flows to the ground, in cases where there is little impact on the surrounding environment, it is not necessarily necessary to provide the switching circuits 23, 33. The high-frequency current when the power conversion device 14 is performing the first operation may also be flowed to the ground via the high-frequency current supply units 20, 30.

[0055] As described above, the power supply system 10 according to this embodiment includes high-frequency current supply units 20 and 30 that allow the high-frequency current superimposed on the DC current circuit to flow to the ground, and the power conversion device 14 executes a first operation of supplying AC power to the power system 2 and a second operation of supplying DC power to the DC current circuit. In the second operation, the power conversion device 14 converts the AC power of the power system 2 into DC power containing high-frequency components according to the switching frequency of the multiple switching elements 14s by switching the multiple switching elements 14s, and supplies the converted DC power to the DC current circuit, thereby causing the high-frequency current to flow to the ground via the high-frequency current supply units 20 and 30.

[0056] This makes it possible to suppress the approach of harmful animals, suppress the growth of weeds, or promote the growth of agricultural crops, as described above, depending on the frequency of the high-frequency current passed through the ground. This also makes it possible to reduce the equipment costs, such as the installation of repellents and fences, required to implement the above-mentioned measures. The magnitude of the high-frequency current passed through the ground may be any magnitude that is sufficient to appropriately suppress the approach of harmful animals, suppress the growth of weeds, or promote the growth of agricultural crops.

[0057] In this way, in the power supply system 10 according to this embodiment, even under conditions where the operation of the power conversion device 14 would conventionally be stopped and put into a standby state, such as when the amount of power generated by the solar panel 12 is small, the power conversion device 14 can be made to perform useful operations. Therefore, the power conversion device 14 can be used more effectively.

[0058] The high-frequency current supply unit 20 passes a high-frequency current around the solar cell panel 12 (DC power source). This makes it possible to protect the solar cell panel 12 from harmful animals, suppress the effects of weeds, and promote the growth of agricultural crops, as described above. The power supply system 10 includes, for example, a plurality of high-frequency current supply units 20, and passes a high-frequency current around each of the plurality of solar cell panels 12 (DC power sources). This makes it possible to take the above-mentioned measures for each of the plurality of solar cell panels 12.

[0059] The high-frequency current supplying unit 30 supplies a high-frequency current to the periphery of the power conversion device 14. This makes it possible to protect the power conversion device 14 from harmful animals, as described above.

[0060] The power supply system 10 includes a plurality of high-frequency current supply units 20, 30, and supplies high-frequency current around the solar cell panel 12 and around the power conversion device 14. This makes it possible to appropriately protect the solar cell panel 12 and the power conversion device 14 from harmful animals, for example.

[0061] The high-frequency current may be passed only around the solar cell panel 12 (DC power source) or only around the power conversion device 14. The location where the high-frequency current is passed is not limited to this, and may be any location where it is necessary to suppress the approach of harmful animals, suppress the growth of weeds, or promote the growth of agricultural crops.

[0062] The power supply system 10 also includes a rectifier element 16b provided on the path of the DC circuit between the solar panel 12 and the power converter 14. The high-frequency current supply units 20 and 30 are connected to the DC circuit at a portion closer to the power converter 14 than the rectifier element 16b. This makes it possible to prevent DC current from flowing to the solar panel 12 when the power converter 14 performs the second operation. For example, in the second operation, only a DC voltage is applied to the DC circuit, and the DC current does not substantially flow through the DC circuit, and only the high-frequency current component flows to the ground. This makes it possible to reduce the power consumption associated with the execution of the second operation when the power converter 14 performs the second operation. It is possible to suppress the approach of harmful animals, suppress the growth of weeds, or promote the growth of agricultural crops with little power consumption.

[0063] The power conversion device 14 may change the switching frequency of the multiple switching elements 14s in the second operation, for example. This can, for example, suppress the approach of multiple types of harmful animals, or simultaneously suppress the approach of harmful animals and the growth of weeds. Furthermore, it is expected that the habituation of harmful animals to a high-frequency current of a specific frequency can be suppressed. Therefore, the power conversion device 14 can perform a beneficial operation. The change in the switching frequency may be a stepwise change or a continuous change.

[0064] In the above embodiment, the solar panel 12 is described as the DC power source. The DC power source is not limited to a solar panel, and may be, for example, a power storage device. When the DC power source is a power storage device, the power conversion device 14 performs the second operation, for example, when the AC power of the power system 2 is stable and there is no need to charge or discharge the power storage device. For example, when the DC power source is a power storage device, the operation during charging of the power storage device may be the second operation, and a high-frequency current may be passed to the ground.

[0065] The DC power supply may be configured by combining, for example, a generator that generates AC power, such as a wind power generator, and a converter that converts AC power into DC power. The DC power supply may be any power supply that can supply DC power to the power conversion device 14.

[0066] The timing when the power conversion device 14 performs the second operation may be any timing when AC power is not supplied to the power system 2. The timing when the power conversion device 14 performs the second operation may be appropriately set depending on the configuration of the DC power supply, etc.

[0067] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0068] 2...power system, 10...power supply system, 12...DC power supply (solar panel), 12a...panel body, 12b...mount, 14...power conversion device, 14s...switching element, 16...junction box, 16a...circuit breaker, 16b...rectifier element, 18...current collection box, 18a...circuit breaker, 20, 30...high frequency current supply section, 21, 31...ground electrode, 22, 32...high frequency filter, 23, 33...switching circuit

Claims

1. A DC power source for supplying DC power; a power conversion device connected to the DC power source and also connected to an AC power system, converting DC power supplied from the DC power source into AC power corresponding to the power system by switching a plurality of switching elements, and supplying the converted AC power to the power system; a high-frequency current supply unit provided between a DC circuit between the DC power source and the power conversion device and a ground, the high-frequency current supply unit enabling a high-frequency current superimposed on the DC circuit to flow to the ground; a rectifying element provided on the path of the DC current path; Equipped with the power conversion device is capable of executing a first operation of converting DC power supplied from the DC power source into AC power corresponding to the power grid and supplying the AC power to the power grid, and a second operation of converting the AC power of the power grid into DC power and supplying the DC power to the DC circuit, In the second operation, the power conversion device converts AC power of the power grid into DC power including a high-frequency component according to a switching frequency of the plurality of switching elements by switching the plurality of switching elements, and supplies the converted DC power to the DC circuit, thereby causing a high-frequency current to flow to the ground via the high-frequency current supply unit; The high frequency current supply unit is connected to the DC circuit at a portion closer to the power conversion device than the rectifier element.

2. A DC power source for supplying DC power; a power conversion device connected to the DC power source and also connected to an AC power system, converting DC power supplied from the DC power source into AC power corresponding to the power system by switching a plurality of switching elements, and supplying the converted AC power to the power system; a high-frequency current supply unit provided between a DC circuit between the DC power source and the power conversion device and a ground, the high-frequency current supply unit enabling a high-frequency current superimposed on the DC circuit to flow to the ground; Equipped with the power conversion device is capable of executing a first operation of converting DC power supplied from the DC power source into AC power corresponding to the power grid and supplying the AC power to the power grid, and a second operation of converting the AC power of the power grid into DC power and supplying the DC power to the DC circuit, In the second operation, the power conversion device converts AC power of the power grid into DC power including a high-frequency component according to a switching frequency of the plurality of switching elements by switching the plurality of switching elements, and supplies the converted DC power to the DC circuit, thereby causing a high-frequency current to flow to the ground via the high-frequency current supply unit; The high-frequency current supply unit has a switching circuit that switches between a first state that suppresses the flow of the high-frequency current from the DC circuit to the ground and a second state that allows the high-frequency current to flow from the DC circuit to the ground, and the power supply system switches the switching circuit to the first state when the power conversion device is performing the first operation, and switches the switching circuit to the second state when the power conversion device is performing the second operation.

3. 3. The power supply system according to claim 1, wherein the high frequency current supplying section supplies the high frequency current to a periphery of the DC power supply.

4. The power supply system according to claim 1 , wherein the high frequency current supplying section supplies the high frequency current to a periphery of the power conversion device.

5. A plurality of the high frequency current supply units are provided, 3 . The power supply system according to claim 1 , wherein the plurality of high-frequency current supplying units supply the high-frequency current around the DC power supply and around the power conversion device.

6. 6. The power supply system according to claim 1, wherein the power conversion device changes a switching frequency of the plurality of switching elements in the second operation.

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