JP2013078190A - Power distribution system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for suppressing lowering of power selling price to an electric power company even when a storage battery is provided.SOLUTION: A storage battery 22 is charged by electric power generated using a regenerable energy source or electric power from a commercial power supply 20. A control section 32 controls charge and discharge of the storage battery 22. Particularly, the control section 32 switches the storage battery 22 from a charge state to a discharge state when it is detected that generated power amount has transited from a higher state than power consumption amount to a lower state than the power consumption amount.

Description

  The present invention relates to power distribution technology, and more particularly to a power distribution system that controls power from a commercial power source and power from renewable energy.

  2. Description of the Related Art As a power distribution system using solar cells, a system in which a solar cell is connected in parallel with a commercial power system and a grid-connected operation for supplying power from both the commercial power source and the solar cell to a load is known. In this type of power distribution system, in the daytime when sufficient power is generated by the solar cell, when the generated power of the solar cell exceeds the power consumption, surplus, that is, when surplus power is generated, Surplus power can flow back to the commercial power system and be sold to the power company. Further, a power source other than a solar cell such as a fuel cell or a secondary battery is added to the power distribution system, and the use of a commercial power source is suppressed even at night when the power generation amount of the solar cell is reduced. ing.

  However, in Japan, in consideration of the influence on the commercial power system, etc., currently, power sale is permitted only for solar cells, and power sale is permitted for fuel cells and secondary batteries other than solar cells. Absent. Therefore, the fuel cell and secondary battery are stipulated in the “Guidelines for grid interconnection technical requirements for ensuring power quality” so that there is no reverse power flow to the commercial power system even if surplus power is generated. The battery and the secondary battery are provided with a reverse power prevention device for preventing a reverse power flow (see, for example, Patent Document 1).

JP 2011-15501 A

  A power distribution system including a fuel cell and a secondary battery in addition to a solar cell is also called “double power generation”. In the case of double power generation, power consumption is reduced by supplying power from a fuel cell or secondary battery to a load even during the daytime. If the power consumption is reduced, the surplus power increases, so the power that can be sold increases. That is, even if the power generated by the solar cell is similar, the amount of power that can be sold in the case of double power generation is larger than the amount of power that can be sold in the case of non-double power generation. In order to cope with this, the electric power company sets the power selling price in the case of double power generation lower than the power selling price in the case of non-double power generation. On the other hand, even for the case of double power generation, it is desirable for the user of the power distribution system to set the power selling price as in the case of not double power generation. In addition, below, the case where the storage battery is added to the solar cell as double electric power generation is made into the object of description.

  This invention is made | formed in view of such a condition, and the objective is to provide the technique which suppresses the fall of the electric power selling price to an electric power company, even when it is a case where the storage battery is provided.

  In order to solve the above-described problems, a power distribution system according to an aspect of the present invention controls a storage battery charged with power generated from a renewable energy source or power from a commercial power source, and charging and discharging of the storage battery. A control unit. The control unit switches the storage battery from the charged state to the discharged state when detecting a transition from a state where the generated power amount is higher than the consumed power amount to a state where the generated power amount is lower than the consumed power amount.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where a storage battery is provided, the fall of the power sale price to an electric power company can be suppressed.

It is a figure which shows the structure of the power distribution system which concerns on the Example of this invention. FIGS. 2A and 2B are diagrams showing an outline of the operation of the power distribution system of FIG. FIGS. 3A to 3B are diagrams showing the data structure of the table stored in the control unit of FIG. It is a figure which shows the data structure of another table memorize | stored in the control part of FIG. It is a figure which shows the data structure of the table by which operation | movement of the emergency switch of FIG. 1 was prescribed | regulated. It is a flowchart which shows the procedure of charging / discharging by the power distribution system of FIG. It is a figure which shows the structure of the power distribution system which concerns on the modification of this invention.

  Before describing the present invention in detail, an outline will be described. Embodiments of the present invention relate to a power distribution system that connects a solar cell in parallel with a commercial power system, supplies power from both the commercial power source and the solar cell to a household load, and charges the storage battery. Such a power distribution system is installed in a home, for example. Here, double power generation is constituted by the solar battery and the storage battery. When the electric power company adopts a time-based electricity rate system, the electricity rate for the night time zone is set lower than the electricity rate for the daytime time zone. Further, as an example, the daytime time zone is defined as from 7:00 to 23:00, and the nighttime zone is defined as from 23:00 to 7:00 on the next day. In order to effectively use such a low electricity bill, the power distribution system charges the storage battery with electric power from the commercial power source over the night time zone.

  On the other hand, if electric power is supplied to the household load by discharging the storage battery during the daytime, the consumption of electric power from a commercial power source with a high electric charge is reduced. However, as described above, when the power consumption is reduced in this way, the power selling price when selling the power generated by the solar cell is lowered. For this reason, it is desired to suppress a decrease in the selling price of power while effectively using the power stored in the storage battery during the daytime. In order to cope with this, the power distribution system according to the present embodiment executes the following processing.

  Even during the daytime, the relationship between the amount of power generated by the solar cell and the amount of power consumed changes with the passage of time. For example, since the amount of generated power is small for a while after the start of the daytime time zone (hereinafter referred to as “first period time zone”), the generated power amount is smaller than the consumed power amount. In the subsequent period (hereinafter referred to as “medium-term time zone”), the amount of generated power becomes larger than the amount of consumed power as the amount of generated power increases. Furthermore, since the amount of generated power decreases for a while until the daytime period ends (hereinafter referred to as “late period”), the amount of generated power is smaller than the amount of consumed power.

  If the storage battery is discharged in the middle period, the above-described state occurs, and the selling price of the generated power decreases. On the other hand, since there is no surplus power in the first and second time zones, the generated power is not sold. Therefore, even if the storage battery is discharged during these times, the selling price of the generated power does not decrease. Therefore, the power distribution system detects the first period and the second period, and discharges the storage battery during these periods.

  FIG. 1 shows a configuration of a power distribution system 100 according to an embodiment of the present invention. The power distribution system 100 includes a solar cell 10, an emergency switch 12, a first inverter 14, a distribution board 16, a reverse power flow sensor 18, a commercial power supply 20, a storage battery 22, a charge / discharge execution unit 24, a first diode 26, and a charger 28. , Second diode 30, control unit 32, first type load 34, and second type load 36. Further, the charge / discharge execution unit 24 includes a second inverter 38 and a selector 40. Further, the emergency switch 12 includes a first terminal 42, a second terminal 44, and a third terminal 46, and the selector 40 includes a first terminal 48, a second terminal 50, and a third terminal 52.

  The commercial power source 20 is an AC power source for supplying power from an electric power company. As described above, the electricity charge of the commercial power from the commercial power source 20 is in accordance with the hourly electricity charge system, and for example, daytime hours and nighttime hours are defined. The reverse power flow sensor 18 is provided between one end of a distribution board 16 described later and the commercial power source 20. The reverse power flow sensor 18 detects the direction of power between one end of the distribution board 16 and the commercial power supply 20. More specifically, the reverse power flow sensor 18 detects forward power from the commercial power supply 20 toward one end of the distribution board 16 or reverse power from one end of the distribution board 16 toward the commercial power supply 20. Since a known technique may be used for the detection processing in the reverse power flow sensor 18, the description thereof is omitted here.

  The distribution board 16 is connected to the reverse power flow sensor 18 at one end and to the first inverter 14 at the other end. The distribution board 16 receives supply of AC power from one end side or the other end side, and supplies AC power to the first type load 34 installed at a predetermined location in the house. The first type load 34 is an AC drive type electric device. The distribution board 16 outputs AC power received at one end from the other end, which corresponds to the forward power described above. In addition, the distribution board 16 outputs AC power received at the other end from one end, and outputs it to the aforementioned reverse power.

  The solar cell 10 is a power device that uses the photovoltaic effect to directly convert light energy into electric power. As the solar cell 10, a silicon solar cell, a solar cell made of various compound semiconductors, a dye-sensitized type (organic solar cell), or the like is used. The solar cell 10 outputs the generated power to the emergency switch 12.

  The emergency switch 12 includes a first terminal 42, a second terminal 44, and a third terminal 46, and connects the first terminal 42 to the solar cell 10 and connects the second terminal 44 to the first inverter 14. The third terminal 46 is connected to the storage battery 22. The emergency switch 12 connects the first terminal 42 and the second terminal 44 or connects the first terminal 42 and the third terminal 46. Although details of the connection of the emergency switch 12 will be described later, the first terminal 42 and the second terminal 44 are usually connected.

  The first inverter 14 is provided between the other end of the distribution board 16 and the solar cell 10. In particular, the first inverter 14 is connected to the solar cell 10 by connecting to the second terminal 44 of the emergency switch 12. The 1st inverter 14 inputs the electric power generated with the power generator. The power is DC power, and the first inverter 14 electrically generates AC power from the DC power. The first inverter 14 outputs AC power to the other end of the distribution board 16. As described above, the AC power corresponds to power in the reverse direction.

  The first diode 26, the charger 28, and the second diode 30 are arranged in series on a path branched from between the first inverter 14 and the other end of the distribution board 16. The first diode 26 and the second diode 30 are electronic elements having a function of flowing a current only in a certain direction, that is, a rectifying function. The first diode 26, the charger 28, The second diode 30 is passed in this order. The charger 28 has one end connected to the path via the first diode 26 and the other end connected to the storage battery 22 via the second diode 30. The charger 28 charges the storage battery 22 with forward power or reverse power. At that time, the charger 28 converts AC power into DC power.

  The storage battery 22 is a secondary battery that can be used repeatedly by storing electricity and being used as a battery. The storage battery 22 is charged with power generated based on a renewable energy source, that is, power in the reverse direction, or power from a commercial power source, that is, power in the forward direction. The second inverter 38 has one end connected to the storage battery 22 and the other end connected to a selector 40 described later. The second inverter 38 receives power from the storage battery 22. Similar to the first inverter 14, the second inverter 38 electrically generates AC power from the DC power and outputs the AC power to the selector 40. The operation or non-operation of the second inverter 38 is instructed by the control unit 32.

  The selector 40 includes a first terminal 48, a second terminal 50, and a third terminal 52, and the charger 28 is connected to a path branched from between the first inverter 14 and the other end of the distribution board 16. Connects the first terminal 48 in parallel. The selector 40 connects the second terminal 50 to the other end of the second inverter 38 and connects the third terminal 52 to the second type load 36. The selector 40 switches the connection between the first terminal 48 and the third terminal 52 or the connection between the second terminal 50 and the third terminal 52 in accordance with an instruction from the control unit 32.

  Note that the switching in the selector 40 is linked to the operation or non-operation of the second inverter 38. That is, the selector 40 connects the first terminal 48 and the third terminal 52 when the second inverter 38 is not operating. As a result, forward power or reverse power input at the first terminal 48 is output from the third terminal 52. On the other hand, the selector 40 connects the second terminal 50 and the third terminal 52 when the second inverter 38 is operating. As a result, the electric power from the second inverter 38 input at the second terminal 50 is output from the third terminal 52.

  Similar to the first type load 34, the second type load 36 is an AC drive type electric device. The first type load 34 is driven by forward power or reverse power. On the other hand, the second type load 36 is driven by power in the forward direction or power in the reverse direction, and is also driven by power charged in the storage battery 22. Therefore, when the forward power or the reverse power is not supplied, the first type load 34 stops, but the second type load 36 continues to operate with the power charged in the storage battery 22. Therefore, it can be said that the second type load 36 is an electric device to be driven even when forward power or reverse power is not supplied.

  The control unit 32 controls charging and discharging of the storage battery 22 by controlling the operations of the second inverter 38 and the selector 40. 2A to 2B show an outline of the operation of the power distribution system 100. FIG. FIG. 2A shows the time change between the amount of power generated in the solar cell 10 and the amount of power consumed. The horizontal axis indicates time. When the electricity rate system by time zone is adopted as the electricity rate for commercial power, the time period from time T1 to T4 is defined as the daytime period, and the period from time T4 to T1 of the next day is defined as the nighttime period. Furthermore, the price for selling power from a commercial power supply is specified to be higher in the daytime period than in the nighttime period. In the above example, time T1 is 7:00 and time T4 is 23:00.

  The amount of power generation 300 corresponds to the amount of power generated by the solar cell 10, and the amount of consumption 302 corresponds to the amount of power consumption. The power generation amount 300 increases during the daytime period and decreases during the nighttime period. On the other hand, the consumption amount 302 changes between the daytime zone and the nighttime zone, and increases in the morning and night and decreases in the daytime and midnight. Therefore, the power generation amount 300 and the consumption amount 302 intersect at P1 and P2. In addition, the time of P1 is T2, and the time of P2 is T3. Since the times T2 and T3 are both included in the daytime time zone, they arrive in the order of the times T1, T2, T3, and T4.

  In the daytime time zone, the power generation amount 300 is smaller than the consumption amount 302 during the period from the time T1 to the time T2, and this corresponds to the previous time zone. In addition, since the amount of power generation 300 is greater than or equal to the consumption amount 302 between times T2 and T3, this corresponds to the above-described medium-term time zone. Further, since the power generation amount 300 is smaller than the consumption amount 302 between the times T3 and T4, this corresponds to the above-described latter period. The operation of the storage battery 22 corresponding to this is shown in FIG. As shown in the figure, charging is performed in the night time zone, discharging is performed in the previous time zone, charging is performed in the middle time zone, and discharging is performed in the later time zone. Returning to FIG.

  The control unit 32 acquires time information and determines whether it is a daytime time zone or a nighttime zone based on the time. The time information may be input from the outside via a network or the like, or may be generated by a clock provided inside the control unit 32. The control part 32 selects the control according to a daytime time slot | zone or a night time slot | zone. FIGS. 3A to 3B show the data structure of the table stored in the control unit 32. FIG. In particular, FIG. 3A shows the data structure of a table for executing control according to the time zone. As shown, a time zone column 200 and a control column 202 are included. While referring to the table, the control unit 32 fixes the storage battery 22 in a charged state in the night time zone. On the other hand, the control part 32 performs condition determination according to the detection result in the reverse power flow sensor 18 in the daytime time zone. Returning to FIG.

  The control unit 32 receives the detection result of the reverse power flow sensor 18 in the daytime time zone. The detection result indicates forward power or reverse power. The forward power corresponds to a case where the power generation amount 300 is smaller than the consumption amount 302, and the reverse power corresponds to a case where the power generation amount 300 is equal to or greater than the consumption amount 302. The control unit 32 switches the storage battery 22 between a charged state and a discharged state depending on whether the electric power is in the forward direction or the reverse direction. FIG. 3B shows a data structure of a table for determining control according to the direction of power. As shown, a condition column 204 and a control column 206 are included. With reference to the table, the control unit 32 determines discharging if the power is in the forward direction, and determines charging if the power is in the reverse direction. Returning to FIG.

  By such processing, the control unit 32 switches the storage battery 22 from the charged state to the discharged state at time T1 when the night time zone is switched to the daytime time zone. Thereafter, the control unit 32 charges the storage battery 22 from the discharged state at a time T2 when a transition from a state where the generated power amount is lower than the consumed power amount to a state where the generated power amount is higher than the consumed power amount is detected. Switch to state. Thereafter, the control unit 32 discharges the storage battery 22 from the charged state at a time T3 when a transition from a state in which the generated power amount is higher than the consumed power amount to a state in which the generated power amount is lower than the consumed power amount is detected. Switch to state. Further, the control unit 32 switches the storage battery 22 from the discharged state to the charged state at time T4 when the daytime time zone is switched to the night time zone.

  Next, the process of the control part 32 according to a charge condition and a discharge condition is demonstrated. FIG. 4 shows the data structure of another table stored in the control unit 32. As shown, a control column 208, a second inverter column 210, and a selector column 212 are included. While referring to the table, the control unit 32 operates the second inverter 38 and connects the second terminal 50 to the third terminal 52 in the selector column 212 in the discharging state. On the other hand, in the charged state, the control unit 32 deactivates the second inverter 38 and connects the first terminal 48 to the third terminal 52 with respect to the selector column 212. Returning to FIG.

  The emergency switch 12 detects whether it is a normal time or an emergency time. Note that an emergency corresponds to a case where power is no longer supplied from the commercial power supply 20, such as during a power failure. Further, the emergency may be a case where the capacity of the storage battery 22 is reduced for some reason, that is, a case where the storage battery 22 is to be charged with the power generated by the solar battery 10. Since a known technique may be used for detecting whether it is a normal time or an emergency, the description is omitted here. FIG. 5 shows a data structure of a table in which the operation of the emergency switch 12 is defined. As shown, a status column 220, an output destination column 222, and an instruction content column 224 are included. With reference to the table, the emergency switch 12 connects the first terminal 42 and the second terminal 44 in order to set the output destination to the first inverter 14 in a normal state. As a result, the electric power generated in the solar cell 10 is output to the first inverter 14.

  On the other hand, the emergency switch 12 connects the first terminal 42 and the third terminal 46 in order to set the output destination to the storage battery 22 in an emergency. As a result, the electric power generated in the solar battery 10 is output to the storage battery 22. The emergency switch 12 instructs the control unit 32 to control discharge. As a result, power is supplied from the solar cell 10 or the storage battery 22 to the second type load 36.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of any computer, and in terms of software, it can be realized by a program loaded in the memory, but here it is realized by their cooperation. Draw functional blocks. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms only by hardware, or by a combination of hardware and software.

  The operation of the power distribution system 100 configured as above will be described. FIG. 6 is a flowchart illustrating a charging / discharging procedure by the power distribution system 100. When it is determined that the emergency switch 12 is normal (Y in S10), if it is a night time zone (Y in S12), the control unit 32 performs a discharge (S16). If it is not a night time zone (N of S12) and it is electric power of a forward direction (Y of S14), the control part 32 will perform charge (S18). If the electric power is not forward (N in S14), the control unit 32 performs discharging (S16). When the emergency switch 12 is not determined to be normal (N in S10), the emergency switch 12 outputs the generated electric power to the storage battery 22, and the control unit 32 performs discharge (S20).

  Next, a modified example will be described. Similarly to the embodiment, the modified example relates to a power distribution system including a solar battery connected in parallel with the commercial power system and a storage battery. In the embodiment, in order to prevent the power charged in the storage battery from being output to the commercial power source, the power is output to the second type load using a combination of the second inverter and the selector. Moreover, although 1st type load and 2nd type load are connected as load, these are all AC drive type electric equipment. On the other hand, in addition to the AC drive type electric device, a DC drive type electric device is connected to the power distribution system according to the modification. Even under such circumstances, the purpose of the modified example is to prevent the power charged in the storage battery from being output to the commercial power supply more reliably than in the embodiment.

  FIG. 7 shows a configuration of a power distribution system 110 according to a modification of the present invention. In addition to the power distribution system 100 shown in FIG. 1, the power distribution system 110 includes a discharge switch 60, a direct power supply switch 62, a converter 64, and a third type load 66. Below, it demonstrates focusing on the difference with the power distribution system 100. FIG.

  The discharge switch 60 is provided between the storage battery 22 and the second inverter 38. The discharge switch 60 is opened and closed according to an instruction from the control unit 32. When the discharge switch 60 is disconnected, the storage battery 22 is not discharged. Converter 64 is connected to distribution board 16. The converter 64 inputs forward power or reverse power. Converter 64 converts the input AC power into DC power. Converter 64 outputs DC power to third type load 66. The third type load 66 is a DC drive type electric device, for example, illumination. The third type load 66 is driven by DC power from the converter 64.

  The direct power supply switch 62 is provided between the storage battery 22 and the third type load 66. The direct power supply switch 62 opens and closes according to an instruction from the control unit 32. When the direct power supply switch 62 is connected, the power from the storage battery 22 is supplied to the third type load 66. Therefore, even if the power from the converter 64 is not supplied to the third type load 66 due to a power failure, the third type load 66 is driven by the power from the storage battery 22. When the direct power supply switch 62 is disconnected, the storage battery 22 is not discharged.

  The control unit 32 disconnects at least one of the discharge switch 60 and the direct power supply switch 62 when the detection result of the reverse flow sensor 18 is power in the reverse direction. For example, when power in the reverse direction is detected in the daytime period, the control unit 32 causes the charge / discharge execution unit 24 to perform charging. If power in the reverse direction is still detected after that, the control unit 32 disconnects at least one of the discharge switch 60 and the direct power supply switch 62. Both may be cut.

  According to the embodiment of the present invention, since the second inverter and the selector are interlocked, charging or discharging of the storage battery can be controlled. Moreover, since electric power is supplied only to the second type load when discharging the storage battery, the electric power charged in the storage battery cannot be output to the commercial power source. Moreover, since the electric power charged in the storage battery is not output to the commercial power source, it is possible to avoid returning the electric power supplied from the commercial power source to the commercial power source again. Further, since charging or discharging of the storage battery is controlled based on the detection result of the reverse power flow sensor, charging or discharging can be controlled in detail not only during daytime hours and nighttime hours but also during daytime hours.

  In addition, since the discharge is executed in the first period and the second period, the amount of power supplied from the commercial power source can be reduced. Moreover, since the discharge is not executed in the middle period, it is possible to suppress a decrease in the power selling price. Moreover, since the switch for discharge is cut | disconnected when the electric power of a reverse direction is detected, the discharge from a storage battery can be suppressed. In addition, when power in the reverse direction is detected, the power feeding switch is directly disconnected, so that discharge from the storage battery can be suppressed. Moreover, since the electric power generated in the solar cell is output to the storage battery in an emergency, the second type load can be continuously used.

  In addition, when a transition from a state where the amount of generated power is higher than the amount of consumed power to a state where the amount of generated power is lower than the amount of consumed power is detected, the storage battery is switched from the charged state to the discharged state. The amount of power provided from a commercial power source can be reduced without reducing the price. In addition, when a transition from a state where the amount of generated power is lower than the amount of consumed power to a state where the amount of generated power is higher than the amount of consumed power is detected, the storage battery is switched from the discharged state to the charged state. The price can be maintained. In addition, since the storage battery is fixed in the charged state during the nighttime period, the storage battery is switched between the charged state and the discharged state based on the comparison between the generated electric energy and the consumed electric energy during the daytime period. Electricity charges can be reduced without lowering the electricity sales price.

  In the above, this invention was demonstrated based on the Example. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

  In an embodiment of the present invention, a solar cell 10 is provided to generate power. However, the present invention is not limited thereto, and for example, a device for generating electric power based on a renewable energy source may be provided in addition to the solar battery 10. For example, a wind power generator. At that time, the time characteristic of the power generation amount 300 in FIG. 2 is adjusted. According to this modification, the degree of freedom of the configuration of the power distribution system 100 can be improved.

  In the embodiment of the present invention, it is assumed that the power distribution system 100 is provided at home. However, the present invention is not limited thereto, and for example, the power distribution system 100 may be provided outside the home. At that time, the time characteristic of the consumption amount 302 in FIG. 2 is adjusted. According to this modification, the power distribution system 100 can be applied to various situations.

  DESCRIPTION OF SYMBOLS 10 Solar cell, 12 Emergency switch, 14 1st inverter, 16 Distribution board, 18 Reverse power flow sensor, 20 Commercial power supply, 22 Storage battery, 24 Charging / discharging execution part, 26 1st diode, 28 Charger, 30 2nd diode , 32 control unit, 34 first type load, 36 second type load, 38 second inverter, 40 selector, 42 first terminal, 44 second terminal, 46 third terminal, 48 first terminal, 50 second terminal , 52 third terminal, 100 power distribution system.

Claims (3)

A storage battery charged with electric power generated from a renewable energy source or from commercial power;
A controller for controlling charging and discharging of the storage battery,
The control unit switches the storage battery from a charged state to a discharged state when detecting a transition from a state where the generated power amount is higher than the consumed power amount to a state where the generated power amount is lower than the consumed power amount. Power distribution system characterized by that.   The control unit switches the storage battery from a discharged state to a charged state when detecting a transition from a state where the generated power amount is lower than the consumed power amount to a state where the generated power amount is higher than the consumed power amount. The power distribution system according to claim 1. The power selling price from the commercial power source is defined to be higher in the second time zone than in the first time zone,
The controller fixes the storage battery in a charged state in a first time zone, and charges the storage battery in a second time zone based on a comparison between the amount of power generated and the amount of power consumed. The power distribution system according to claim 1, wherein switching between a discharge state and a discharge state is executed.

Images