JP7529428B2 - Power Supply System - Google Patents

Description

The present invention relates to a power supply system.

In recent years, there has been progress in the development of microgrids, which supply electricity by combining multiple distributed power sources, including natural gas cogeneration generators and photovoltaic (PV) power generation devices, with power storage devices.

When applying a microgrid to a building for long-term operation, a storage device with sufficient capacity is required. However, due to the high installation costs of stationary storage devices, the stationary storage capacity of a building is inevitably limited.

In order to compensate for the lack of capacity of stationary power storage devices, a method has been proposed in which storage batteries from electric vehicles (hereinafter sometimes referred to as EVs), which are expected to become more widespread in the future, are utilized (for example, Patent Documents 1 and 2).
Patent Document 1 describes a method of supplying power to an EV by installing a charging/discharging device in an ordinary house and connecting the EV to the charging/discharging device during a power outage.
Furthermore, Patent Document 2 describes a method for stably supplying power to a plurality of EVs during a power outage by connecting each of the EVs to a separate charging/discharging device.

Japanese Patent Application Publication No. 11-178234 JP 2018-182925 A

However, in power supply systems such as microgrids that operate autonomously during power outages, as in Patent Document 1, typically only one EV can be connected to a charging/discharging device, and sufficient power may not be obtained during a power outage. Furthermore, as in Patent Document 2, when multiple charging/discharging devices are used, power cannot be exchanged between the multiple charging/discharging devices, and so stable power may not be obtained during a power outage. Thus, with the conventional technology described above, it was difficult to stably supply power from multiple EVs to important loads during a power outage.

The present invention was made in consideration of these circumstances, and its purpose is to provide a power supply system that can stably supply PV power and EV power to important loads during a power outage.

In order to solve the above-mentioned problems, one aspect of the present invention is a power supply system that, when there is no power supply from a commercial grid, utilizes a power generation device and storage batteries of a plurality of electric vehicles to supply power from the power generation device and power from the electric vehicles to an important load connected to a power grid in an independent operation range, the power supply system including a charging/discharging device that detects the charging rate of the storage battery of the connected electric vehicle and switches between charging and discharging the storage battery, a changeover switch that switches and connects the charging/discharging device to one of the plurality of electric vehicles and detects identification information from the connected electric vehicle, and when there is no power supply from the commercial grid, instructs the charging/discharging device to switch between charging and discharging of the storage battery of the connected electric vehicle via the changeover switch based on the generated power of the power generation device and the power consumption of the important load, and and a control device that controls the connection of the change-over switch based on the identification information, the control device having a memory unit that stores a charging rate table that corresponds the identification information with the charging rate, and when instructing the charge/discharge device to switch charging, the control device refers to the charging rate table stored in the memory unit based on the identification information detected by the change-over switch to determine whether or not the change-over switch is connected to a chargeable electric vehicle, and if it is determined that the electric vehicle is connected, controls the change-over switch to charge the storage battery of the electric vehicle, and if it is determined that the electric vehicle is not connected, controls the connection to be switched to one of the chargeable electric vehicles, and the control device determines whether or not there is a chargeable electric vehicle based on the charging rate table stored in the memory unit, and if there is no chargeable electric vehicle, switches to discharging of the storage battery by stopping power generation of the power generation device .

According to the present invention, during a power outage, by switching to an electric vehicle suitable for charging and discharging, it is possible to stably supply power from a power generation device and power from an electric vehicle to important loads.

1 is a diagram illustrating an example of a power supply system according to an embodiment of the present invention. FIG. 2 is a functional block diagram showing a configuration of a control device according to the present embodiment. FIG. 2 is a functional block diagram showing the configuration of a storage unit according to the embodiment. FIG. 4 is a diagram showing an example of an EV identification table according to the embodiment. FIG. 4 is a diagram showing an example of a charging rate table according to the embodiment; 5 is a flowchart showing the flow of a power supply process according to the embodiment.

The power supply system according to one embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an example of a power supply system 1 according to the present embodiment.
As shown in FIG. 1, the power supply system 1 includes a changeover switch 10, a plurality of electric vehicles (hereinafter referred to as EVs) (20a, 20b, 20c), an important load 30, a power meter 40, a PV device 50 (an example of a power generation device), a charge/discharge device 60, and a control device 70.

In the event of an abnormality such as a power outage, power from the commercial grid is not supplied to load 80 and important load 30, as indicated by the crosses.

The changeover switch 10 switches between the charge/discharge device 60 and one of a plurality of EVs (20a to 20c). Specifically, the changeover switch 10 receives a connection instruction to connect a specified EV 20 from the control device 70 (a changeover switch control unit 74, described later), and connects the specified EV.
The changeover switch 10 also detects identification information for identifying the connected EV 20 from the EV, and transmits the information to the control device 70 (a changeover switch control unit 74, which will be described later). For example, in this embodiment, it is assumed that EV 20a is assigned with identification information EV1, EV 20b is assigned with identification information EV2, and EV 20c is assigned with identification information EV3.

Any one of the multiple EVs (20a to 20c) is connected to a charging/discharging device 60 via a changeover switch 10. In this embodiment, when referring to any EV included in the power supply system 1 or when no particular distinction is made, the EV will be described as EV 20.
The EVs 20a, 20b, and 20c include storage batteries 21a, 21b, and 21c, respectively. In the present embodiment, when referring to the storage batteries of any EV included in the power supply system 1 or when no particular distinction is made, the storage batteries will be described as storage battery 21.

The EV 20 also has a function of detecting the charging rate of the storage battery 21, and for example, transmits the charging rate detected by a battery level gauge IC (Integrated Circuit) to the charging/discharging device 60. Here, when the charging rate is 100%, the storage battery 21 is fully charged, and when it is 0%, the storage battery 21 is empty.

The important load 30 is connected to the PV device 50 and the charge/discharge device 60 via the power meter 40, and is further connected to the EV 20 via the charge/discharge device 60. During a power outage in the commercial grid, the important load 30 is supplied with PV power, which is the output power of the PV device 50, or EV power, which is the power of the storage battery 21 of the EV 20.

The power meter 40 is connected to the important load 30 and measures the power consumption of the load (hereinafter sometimes referred to as load power consumption).

The PV device 50 is a solar power generation device that is connected to the charge/discharge device 60 and supplies PV power, which is the output power of the PV device 50, to at least one of the EV 20 and the important load 30.

The charging/discharging device 60 is connected to the EV 20 via a changeover switch 10 provided at the tip of the EV connection terminal, and receives the charging rate of the storage battery 21 detected by the EV 20. Furthermore, the charging/discharging device 60 connects the important load 30, the power meter 40, and the PV device 50.

The charging/discharging device 60 also switches between charging and discharging the storage battery 21 of the EV 20 connected to the changeover switch 10. In this embodiment, the charging/discharging device 60 charges the storage battery 21 when it receives a charging instruction from the control device 70 (the charging/discharging device control unit 75 described later) to charge the storage battery 21, and discharges the storage battery 21 when it receives a discharging instruction from the control device 70 (the charging/discharging device control unit 75 described later).

The control device 70 includes, for example, a CPU (Central Processing Unit) and controls the changeover switch 10, the PV device 50, and the charge/discharge device 60 wirelessly or via wires.

The configuration of the control device 70 will be described in detail with reference to FIG.
FIG. 2 is a functional block diagram showing the configuration of the control device 70 according to the present embodiment.
As shown in FIG. 2 , the control device 70 includes a storage unit 71 , an EV management unit 72 , a PV device control unit 73 , a changeover switch control unit 74 , and a charge/discharge device control unit 75 .

The storage unit 71 stores various data used by the control device 70 .
The storage unit 71 is configured by a storage medium such as a hard disk drive (HDD), a flash memory, an electrically erasable programmable read only memory (EEPROM), a random access read/write memory (RAM), a read only memory (ROM), or any combination of these storage media. Also, the storage unit 71 can be configured by a non-volatile memory, for example.

Here, the configuration of the storage unit 71 will be described with reference to FIGS.
FIG. 3 is a functional block diagram showing the configuration of the storage unit 71 according to the present embodiment.
As shown in FIG. 3 , the storage unit 71 stores an EV identification table 711 and a charging rate table 712 .

The storage unit 71 stores, as an EV identification table 711, identification information and a vehicle name (for example, EV 20a, EV 20b, EV 20c) in association with each other.
4 is a diagram showing an example of the EV identification table 711 in this embodiment. For example, as shown in Fig. 4, the identification information EV1 indicates EV 20a, EV2 indicates EV 20b, and EV1 indicates EV 20a.

The storage unit 71 stores the identification information, the vehicle name, and the charging rate in association with each other as a charging rate table 712 .
5 is a diagram showing an example of the charging rate table 712 in this embodiment. For example, as shown in FIG. 5, the identification information indicates that the charging rate of EV1 (vehicle name EV20a) is 100%, the charging rate of EV2 (vehicle name EV20b) is 20%, and the charging rate of EV3 (vehicle name EV20c) is 80%.

Returning to FIG. 2, the configuration of the control device 70 will be further described.
The EV management unit 72 acquires the charging rate of the storage battery 21 detected by the charging/discharging device 60 and stores it in the memory unit 71 (charging rate table 712). For example, if the identification information received from the selector switch 10 is EV2 and the acquired charging rate is 20 percent, the EV management unit 72 associates the identification information EV2 (EV 20b) with the charging rate of 20 percent and stores it, as shown in Fig. 5. Note that the charging rate of an EV 20 not connected to the selector switch 10 is a value acquired immediately before the EV was disconnected.

Furthermore, the EV management unit 72 determines, based on the charging rate table 712, whether or not the storage batteries (21a to 21c) of each of the multiple EVs (20a to 20c) are chargeable or dischargeable.
In addition, the EV management unit 72 determines that charging is not possible when the charging rate is 100%, and determines that charging is possible in other cases. For example, as shown in Fig. 5, when the charging rate of the EV 20a is 100%, the charging rate of the EV 20b is 20%, and the charging rate of the EV 20c is 80%, the EV management unit 72 determines that the EV 20a is not possible to charge, and determines that the EVs 20b and 20c are possible to charge.

The EV management unit 72 also determines that discharge is not possible when the charge rate is 0 percent, and determines that discharge is possible in other cases. For example, as shown in FIG. 5, when the charge rate of EV 20a is 100 percent, the charge rate of EV 20b is 20 percent, and the charge rate of EV 20c is 80 percent, the EV management unit 72 determines that all of EVs 20a to 20c are dischargeable.

When it is determined that all of the storage batteries (21a to 21c) are not chargeable, the EV management unit 72 transmits a PV stop instruction to the PV device control unit 73 to stop the PV.
When the PV device control unit 73 receives the PV stop instruction from the EV management unit 72, it stops the solar power generation of the PV device 50.

The changeover switch control unit 74 refers to the charging rate table 712 based on the identification information detected by the changeover switch 10 and determines whether the changeover switch 10 is connected to a chargeable EV 20. If it is determined that the changeover switch 10 is not connected, the changeover switch control unit 74 transmits a connection instruction to the changeover switch 10 to switch to and connect one of the chargeable EVs 20. On the other hand, if it is determined that the changeover switch 10 is connected, the charging/discharging device control unit 75 (described later) transmits a charging instruction to the charging/discharging device 60 to charge the EV.

The changeover switch control unit 74 also refers to the charging rate table 712 based on the identification information detected by the changeover switch 10 to determine whether the changeover switch 10 is connected to a dischargeable EV 20. If it is determined that the changeover switch 10 is not connected, the changeover switch control unit 74 transmits a connection instruction to the changeover switch 10 to switch to and connect one of the dischargeable EVs 20. On the other hand, if it is determined that the changeover switch 10 is connected, the charge/discharge device control unit 75, which will be described later, transmits a charge instruction to the charge/discharge device 60, which is an instruction to discharge the EV.

The charge/discharge device control unit 75 determines switching between charging and discharging the storage battery 21 based on the PV power, which is the output power of the PV device 50, and the load power consumption, which is the power consumption of the important load 30. The charge/discharge device control unit 75 determines to perform charging when the PV power is greater than the load power consumption, and determines to perform discharging when the PV power is less than the load power consumption.
Furthermore, when the changeover switch control unit 74 determines that the changeover switch 10 is connected to a chargeable EV 20, the charging/discharging device control unit 75 transmits a charge instruction to charge the EV to the charging/discharging device 60. On the other hand, when the changeover switch 10 is determined to be connected to a dischargeable EV 20, the charging/discharging device control unit 75 transmits a discharge instruction to the charging/discharging device 60 to discharge the EV.

Next, the charging and discharging process of the storage battery 21 of the EV 20 will be described with reference to FIG.
FIG. 6 is a flowchart illustrating an example of a charge/discharge process according to the present embodiment.

When a power outage occurs, the charge/discharge device control unit 75 obtains the PV power, which is the output power of the PV device 50, from the PV device 50, and obtains the load power consumption, which is the power consumption of the important load 30, from the power meter 40 (step S101).

The charge/discharge device control unit 75 determines whether to switch between charging and discharging the storage battery 21 based on the PV power and the load power consumption (step S102). If the PV power is greater than the load power consumption (step S102-YES), the charge/discharge device control unit 75 determines that charging is to be performed and proceeds to the charging process from step S103 onwards. If the PV power is less than the load power consumption (step S102-NO), the charge/discharge device control unit 75 determines that charging is to be performed and proceeds to the charging process from step S103 onwards.

First, the charging process from step S103 onwards will be described.
In step S<b>103 , the EV management unit 72 determines whether or not there is an EV 20 that can be charged, based on the charging rate table 712 in the storage unit 71 .

If it is determined in step S103 that there is no EV 20 that can be charged (step S103-NO), the EV management unit 72 transmits a PV stop instruction to the PV device control unit 73 to stop the PV. The PV device control unit 73 stops the power generation of the PV device 50 in accordance with this PV stop instruction (step S107).

After step S107, the control device 70 returns the process to step S101 and repeats the same process. Because the PV power is zero, the charge/discharge device control unit 75 determines that the PV power is smaller than the load power consumption (step S102-NO), and switches from charging to discharging.

On the other hand, if it is determined in step S103 that there is one or more chargeable EVs 20 (step S103-YES), the changeover switch control unit 74 refers to the charging rate table 712 based on the identification information and determines whether the changeover switch 10 is connected to a chargeable EV 20 (step S104).

If the changeover switch control unit 74 determines that the changeover switch 10 is not connected to a chargeable EV 20 (step S104-NO), the process proceeds to step S105. If the changeover switch control unit 74 determines that the changeover switch 10 is connected (step S104-YES), the process proceeds to step S106.

In step S105, the changeover switch control unit 74 transmits a connection instruction to the changeover switch 10 to switch and connect to one of the chargeable EVs 20. In this case, for example, the chargeable EV 20 with the smallest charging rate may be specified. The changeover switch 10 connects the specified EV 20 in accordance with this connection instruction. After processing in step S105, the control device 70 advances the process to step S106.

In step S106, the charge/discharge device control unit 75 transmits a charge instruction to the charge/discharge device 60, which is an instruction to charge the chargeable EV 20 connected to the changeover switch 10. In accordance with this charge instruction, the charge/discharge device 60 starts charging the storage battery 21 of the connected EV 20. In this case, the PV power is supplied to the important load 30, and surplus PV power is charged to the storage battery 21.

After step S106, the control device 70 returns the process to step S101 and repeats the same process.

Next, the discharge process from step S108 onwards will be described.
In step S108, the EV management unit 72 determines whether or not there is an EV 20 that can discharge, based on the charging rate table 712 in the storage unit 71.

If it is determined in step S108 that there are no EVs 20 that are capable of discharging (step S108-NO), EV power is not supplied to the important loads 30 and a power outage occurs (step S112).

On the other hand, if it is determined in step S108 that there is one or more EVs 20 that can discharge (step S108-YES), the changeover switch control unit 74 refers to the charging rate table 712 based on the identification information and determines whether the changeover switch 10 is connected to an EV 20 that can discharge (step S109).

If the changeover switch control unit 74 determines that the changeover switch 10 is not connected to a dischargeable EV 20 (step S109-NO), the process proceeds to step S110. If the changeover switch control unit 74 determines that the changeover switch 10 is connected (step S109-YES), the process proceeds to step S111.

In step S110, the changeover switch control unit 74 transmits a connection instruction to the changeover switch 10 to switch and connect to one of the dischargeable EVs 20. In this case, for example, the EV 20 that is capable of discharging may be specified as the one with the highest charging rate. The changeover switch 10 connects the specified EV 20 in accordance with this connection instruction. After processing in step S110, the control device 70 advances the processing to step S111.

In step S111, the charge/discharge device control unit 75 transmits a discharge instruction to the charge/discharge device 60, which is an instruction to charge the dischargeable EV 20 connected to the changeover switch 10. In accordance with this discharge instruction, the charge/discharge device 60 starts discharging the storage battery 21 of the connected EV 20. In this case, PV power and EV power are supplied to the important load 30.

After step S111, the control device 70 returns the process to step S101 and repeats the same process.

As described above, the power supply system 1 according to this embodiment is a power supply system that utilizes the PV device 50 and the storage batteries of multiple EVs (20a-20c) to supply power from the PV device 50 and the power from the EV 20 to important loads 30 connected to a power grid in an independent operation range when there is no power supply from the commercial grid, and includes a charge/discharge device 60, a changeover switch 10, and a control device 70. The charge/discharge device 60 detects the charge rate of the storage battery 21 of the connected EV 20, and switches between charging and discharging the storage battery 21. The changeover switch 10 switches between and connects the charge/discharge device 60 to one of the multiple EVs (20a-20c), and detects identification information from the connected EV 20 that identifies the EV. When there is no power supply from the commercial grid, the control device 70 instructs the charge/discharge device 60 to switch between charging and discharging the storage battery 21 of the EV 20 connected via the changeover switch 10 based on the power generated by the PV device 50 and the power consumption of the important load 30, and controls the connection of the changeover switch 10 based on the charging rate detected by the charge/discharge device 60 and the identification information detected by the changeover switch 10.

As a result, the power supply system 1 according to this embodiment can stably supply PV power and EV power to the important load 30 by utilizing the PV device 50 and the storage batteries of multiple EVs (20a to 20c) when there is no power supply from the commercial grid.

The control device 70 in the above embodiment may determine whether there are any chargeable EVs 20, and if it determines that there are two or more chargeable EVs 20, may set charging priorities based on the charging rate table 712 and connect to the changeover switch 10 in descending order of priority. For example, by setting a higher priority for EVs with a lower charging rate during charging, EVs with the lowest charging rate (longest charging time) are charged first, and the number of times the changeover switch 10 is switched can be minimized.

The control device 70 in the above embodiment may determine whether there are any EVs 20 that can be discharged, and if it determines that there are two or more EVs 20 that can be discharged, may set the priority of discharge based on the charging rate table 712 and connect to the changeover switch 10 in descending order of priority. For example, by setting a higher priority for a higher charging rate during discharging, the EVs with the highest charging rates (longest discharge times) are discharged in descending order, thereby minimizing the number of times the changeover switch 10 is switched.

In addition, in the above embodiment, an example was described in which the power generation device was a PV device 50, but this is not limited to this, and the power generation device may be another type of power generation device, such as a natural gas cogeneration generator or a wind power generation device.

In addition, the changeover switch 10 in the above embodiment may be a high-speed switch such as a semiconductor switch. In this case, the EV 20 can be switched without interruption.

The charging and discharging process in the above-mentioned embodiment may be realized by a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to realize the function. The term "computer system" here includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. The term "computer-readable recording medium" may also include a medium that dynamically holds a program for a short period of time, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, and a medium that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or client in such a case. The above-mentioned program may be a program for realizing a part of the above-mentioned function, or may be a program that can realize the above-mentioned function in combination with a program already recorded in the computer system, or may be a program that is realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

The above describes an embodiment of the present invention in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and includes designs that do not deviate from the gist of the present invention.

1...power supply system, 10...changeover switch, 20...electric vehicle, 21...storage battery, 30...important load, 40...power meter, 50...PV device, 60...charging/discharging device, 70...control device, 71...storage unit, 72...EV management unit, 73...PV device control unit, 74...changeover switch control unit, 75...charging/discharging device control unit, 80...load, 711...EV identification table, 712...charging rate table

Claims (6)

A power supply system that utilizes a power generation device and storage batteries of a plurality of electric vehicles to supply power from the power generation device and power from the electric vehicles to important loads connected to a power system within an independent operation range when there is no power supply from a commercial grid,
a charging/discharging device that detects a charging rate of the storage battery of the connected electric vehicle and switches between charging and discharging of the storage battery;
a changeover switch that selectively connects the charging/discharging device to any one of the plurality of electric vehicles and detects, from the electric vehicle, identification information that identifies the connected electric vehicle;
a control device that, when there is no power supply from a commercial grid, instructs the charging/discharging device to switch between charging and discharging of the storage battery of the electric vehicle connected via the change-over switch based on the power generated by the power generation device and the power consumption of the important load, and controls the connection of the change-over switch based on the charging rate detected by the charging/discharging device and the identification information detected by the change-over switch;
Equipped with
the control device includes a storage unit configured to store a charging rate table in which the identification information is associated with the charging rate;
when instructing the charging/discharging device to switch charging, referring to the charging rate table stored in the storage unit based on the identification information detected by the changeover switch, determining whether the changeover switch is connected to a chargeable electric vehicle, and if it is determined that the changeover switch is connected, controlling the changeover switch to charge the storage battery of the electric vehicle, and if it is determined that the changeover switch is not connected, controlling the changeover switch to switch the connection to one of the chargeable electric vehicles;
The control device determines whether or not there is an electric vehicle that can be charged based on the charging rate table stored in the memory unit, and if there is no electric vehicle that can be charged, switches to discharging of the storage battery by stopping power generation of the power generation device . the control device determines whether the generated power is greater than the consumed power, and when it is determined that the generated power is greater than the consumed power, switches to charging of the storage battery and controls so as to charge the storage battery of the electric vehicle that is capable of being charged;
2. The power supply system according to claim 1, the control device determines whether the generated power is greater than the consumed power, and when it is determined that the generated power is smaller, switches to discharging of the storage battery and controls the storage battery of the electric vehicle capable of discharging to be discharged;
3. The power supply system according to claim 1 or 2, wherein: when instructing the charging/discharging device to switch discharging, the control device refers to the charging rate table stored in the storage unit based on the identification information detected by the changeover switch to determine whether the changeover switch is connected to one of the electric vehicles capable of discharging, and when it is determined that the changeover switch is connected, controls the storage battery of the electric vehicle to be discharged, and when it is determined that the changeover switch is not connected, controls the connection to be switched to one of the electric vehicles capable of discharging;
The power supply system according to any one of claims 1 to 3, characterized in that the control device determines whether or not there are any electric vehicles that can be charged based on the charging rate table stored in the storage unit, and when it is determined that there are two or more electric vehicles that can be charged, sets a priority order for charging based on the charging rate, and connects the electric vehicles with the highest priority to the selector switch first;
The power supply system according to any one of claims 1 to 4, characterized in that the control device determines whether or not there is an electric vehicle that can be discharged based on the charging rate table stored in the storage unit, and when it is determined that there are two or more electric vehicles that can be discharged, sets a priority order for discharging based on the charging rate and connects the electric vehicles with the highest priority to the changeover switch in that order;
The power supply system according to any one of claims 1 to 5 , characterized in that

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