Power management device, upper-level power management device, power management method, and power management program

Abstract

To increase power transmission efficiency.SOLUTION: A power management device 10 includes a control unit 13 that controls a converter which can bidirectionally convert between an external bus voltage supplied to an external DC bus and an internal bus voltage supplied to an internal DC bus in a power supply system. The control unit 13 transmits, when a power storage amount of the power supply system falls below a first power storage threshold, a first power transmission request to a host power management device, selects a first reception power target value according to a first transmission power value in the first power transmission request from among a plurality of reception power target values, sets a target value of the external bus voltage to the first reception power target value, selects, when the power storage amount of the power supply system exceeds a second power storage threshold and a second power transmission request is received from another power supply system, a first transmission power target value according to a second transmission power value in the second power transmission request from among a plurality of transmission power target values, and sets the target value of the external bus voltage to the first transmission power target value.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a power management device, an upper-level power management device, a power management method, and a power management program. [Background technology]

[0002] A power interchange system is known that interchanges power between power grids that supply power using distributed power sources. For example, Patent Document 1 describes a power interchange system that includes a plurality of power transmitting and receiving units and a virtual power transmission network construction device connected to the plurality of power transmitting and receiving units via a communication network. In this power interchange system, the virtual power transmission network construction device creates a power interchange plan between the power transmitting and receiving units, and the power transmitting and receiving unit on the power transmitting side transmits power specified in the power interchange plan over a specified route for a specified period of time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-177686 Summary of the Invention [Problem to be solved by the invention]

[0004] When transmitting power between power transmitting and receiving units (power supply systems), transmission loss occurs. In this technical field, it is desired to reduce the transmission loss and improve the transmission efficiency.

[0005] The present disclosure describes a power management device, an upper power management device, a power management method, and a power management program that can improve power transmission efficiency. [Means for solving the problem]

[0006] A power management device according to one aspect of the present disclosure includes: an acquisition unit that acquires a stored amount of power stored in a power supply system connected to another power supply system via an external DC bus; a control unit that switches an operation mode of the power supply system by controlling a converter that can bidirectionally convert between an external bus voltage supplied to the external DC bus and an internal bus voltage supplied to an internal DC bus that supplies DC power within the power supply system; and a storage unit that stores multiple power receiving target values ​​that are target values ​​of the external bus voltage of the converter when transmitting power from the other power supply system to the power supply system, and multiple power transmission target values ​​that are target values ​​of the external bus voltage of the converter when transmitting power from the power supply system to the other power supply system. The multiple power receiving target values ​​are target values ​​that minimize transmission loss at mutually different transmission power values. The multiple power transmission target values ​​are target values ​​that minimize transmission loss at mutually different transmission power values. When the amount of stored power falls below a first power storage threshold, the control unit transmits a first power transmission request to an upper power management device that manages power transmission and reception between the power supply system and another power supply system, and selects a first power reception target value corresponding to the first transmission power value in the first power transmission request from among a plurality of power reception target values, and sets a target value of the external bus voltage to the first power reception target value, thereby setting the power supply system to a power receiving mode.When the amount of stored power exceeds a second power storage threshold that is greater than the first power storage threshold, and the control unit receives a second power transmission request from the other power supply system via the upper power management device, the control unit selects a first power transmission target value corresponding to the second transmission power value in the second power transmission request from among the plurality of power transmission target values, and sets a target value of the external bus voltage to the first power transmission target value, thereby setting the power supply system to a power transmission mode.

[0007] A power management method according to another aspect of the present disclosure includes the steps of: acquiring an amount of stored power stored in a power supply system connected to another power supply system via an external DC bus; if the amount of stored power is below a first power storage threshold, sending a first power transmission request to an upper power management device that manages power transmission and reception between the power supply system and the other power supply system and setting the power supply system to a power receiving mode; and if the amount of stored power exceeds a second power storage threshold that is higher than the first power storage threshold and receiving a second power transmission request from the other power supply system via the upper power management device, setting the power supply system to the power transmitting mode. In the setting to the power receiving mode, the step of selecting a first power receiving target value from a plurality of power receiving target values ​​that corresponds to the first transmission power value in the first power transmission request, and setting a target value of an external bus voltage of a converter that can bidirectionally convert between an external bus voltage supplied to the external DC bus and an internal bus voltage supplied to an internal DC bus that supplies DC power within the power supply system to the first power receiving target value, thereby setting the power supply system to the power receiving mode. In the step of setting the power supply system to the power transmission mode, a first power transmission target value corresponding to the second transmission power value in the second power transmission request is selected from the plurality of power transmission target values, and a target value of the external bus voltage in the converter is set to the first power transmission target value, thereby setting the power supply system to the power transmission mode. The plurality of power reception target values ​​are target values ​​of the external bus voltage in the converter when transmitting power from another power supply system to the power supply system, and are target values ​​that minimize transmission loss at different transmission power values. The plurality of power transmission target values ​​are target values ​​of the external bus voltage in the converter when transmitting power from the power supply system to the other power supply system, and are target values ​​that minimize transmission loss at different transmission power values.

[0008] According to yet another aspect of the present disclosure, there is provided a power management program for causing a computer to execute the following steps: acquiring a stored amount of power stored in a power supply system connected to another power supply system via an external DC bus; if the stored amount is below a first storage threshold, transmitting a first power transmission request to an upper power management device that manages power transmission and reception between the power supply system and the other power supply system and setting the power supply system to a power receiving mode; and if the stored amount exceeds a second storage threshold that is higher than the first storage threshold and the second power transmission request is received from the other power supply system via the upper power management device, setting the power supply system to the power transmitting mode. In the setting to the power receiving mode, the program selects a first power receiving target value from multiple power receiving target values ​​that corresponds to the first transmission power value in the first power transmission request, and sets a target value of an external bus voltage of a converter that can bidirectionally convert between an external bus voltage supplied to the external DC bus and an internal bus voltage supplied to an internal DC bus that supplies DC power within the power supply system to the first power receiving target value, thereby setting the power supply system to the power receiving mode. In the step of setting the power supply system to the power transmission mode, a first power transmission target value corresponding to the second transmission power value in the second power transmission request is selected from the plurality of power transmission target values, and a target value of the external bus voltage in the converter is set to the first power transmission target value, thereby setting the power supply system to the power transmission mode. The plurality of power reception target values ​​are target values ​​of the external bus voltage in the converter when transmitting power from another power supply system to the power supply system, and are target values ​​that minimize transmission loss at different transmission power values. The plurality of power transmission target values ​​are target values ​​of the external bus voltage in the converter when transmitting power from the power supply system to the other power supply system, and are target values ​​that minimize transmission loss at different transmission power values.

[0009] In these power management devices, power management methods, and power management programs, the operating mode of the power supply system is switched based on the amount of stored power stored in the power supply system. When the amount of stored power stored in the power supply system is below a first power storage threshold, a first power receiving target value corresponding to the first transmission power value in the first power transmission request is selected from multiple power receiving target values, a target value of the external bus voltage in the converter of the power supply system is set to the first power receiving target value, and the power supply system is set to a power receiving mode. At this time, similar control is performed in other power supply systems, and if the other power supply systems are set to a power transmitting mode, a power transmission target value corresponding to the first transmission power value is selected from multiple power transmission target values ​​in the other power supply systems, and a target value of the external bus voltage in the converter of the other power supply systems is set to the selected power transmission target value. As a result, a power transmission target value that minimizes transmission loss at the first transmission power value is set in the converter of the other power supply system, and a first power receiving target value that minimizes transmission loss at the first transmission power value is set in the converter of the power supply system. Therefore, the transmission loss in power transmission from another power supply system to the power supply system is reduced. When the power supply system is in power transmission mode, similar control is performed so that the converter of the power supply system sets a first power transmission target value that minimizes the transmission loss at the second transmission power value, and the converter of the other power supply system sets a power receiving target value that minimizes the transmission loss at the second transmission power value. Therefore, the transmission loss in power transmission from the power supply system to another power supply system is reduced. As a result, the power transmission efficiency between the power supply system and another power supply system can be improved.

[0010] In some embodiments, when the power supply system is set to the power receiving mode, in response to a change request to change the first transmission power value to a third transmission power value, the control unit may select a second power receiving target value corresponding to the third transmission power value from among the plurality of power receiving target values ​​and set the target value of the external bus voltage to the second power receiving target value. With this configuration, even if the transmission power value is changed, the converter of the power supply system sets the second power receiving target value that minimizes the transmission loss at the changed transmission power value (third transmission power value). If similar control is performed in other power supply systems, the converter of the other power supply system sets a power transmission target value that minimizes the transmission loss at the changed transmission power value (third transmission power value). Therefore, even if the transmission power value is changed, the transmission loss in power transmission from other power supply systems to the power supply system is reduced, thereby improving power transmission efficiency.

[0011] In some embodiments, when the power supply system is set to the power transmission mode, in response to a change request to change the second transmission power value to a fourth transmission power value, the control unit may select a second transmission target value corresponding to the fourth transmission power value from among the plurality of power transmission target values ​​and set the target value of the external bus voltage to the second transmission target value. With this configuration, even if the transmission power value is changed, the converter of the power supply system sets the second transmission target value that minimizes the transmission loss at the changed transmission power value (fourth transmission power value). If similar control is performed in other power supply systems, the converter of the other power supply system sets a power receiving target value that minimizes the transmission loss at the changed transmission power value (fourth transmission power value). Therefore, even if the transmission power value is changed, the transmission loss in power transmission from the power supply system to the other power supply system is reduced, thereby improving power transmission efficiency.

[0012] In some embodiments, when the power supply system is set to the power receiving mode, the control unit may cancel the power receiving mode in response to the amount of stored power exceeding a first stop threshold that is smaller than the second power storage threshold and larger than the first power storage threshold. With this configuration, the power receiving mode can be canceled before the power supply system receives an excessive supply of power. Therefore, it is possible for the power supply system to receive power from another power supply system to the extent that the power supply system does not receive an excessive supply of power.

[0013] In some embodiments, when the power supply system is set to the power transmission mode, the control unit may cancel the power transmission mode in response to the stored power amount falling below a second stop threshold that is smaller than the second power storage threshold and larger than the first power storage threshold. With this configuration, the power transmission mode can be canceled before the stored power amount of the power supply system becomes insufficient. Therefore, it is possible to transmit power to other power supply systems to the extent that the stored power amount of the power supply system does not become insufficient.

[0014] According to yet another aspect of the present disclosure, there is provided an upper power management device for controlling power transmission and reception between a first power supply system and a second power supply system that transmit and receive power to and from each other via an external DC bus. The upper power management device includes: a determination unit that determines a first target value of an external bus voltage for a first converter that can bidirectionally convert an external bus voltage supplied to the external DC bus and a first internal bus voltage supplied to a first internal DC bus that supplies DC power in the first power supply system; and a second target value of an external bus voltage for a second converter that can bidirectionally convert the external bus voltage and a second internal bus voltage supplied to a second internal DC bus that supplies DC power in the second power supply system; an output unit that outputs a first setting command for setting the first target value in the first converter and a second setting command for setting the second target value in the second converter; and a storage unit that stores a first combination group that includes multiple combinations of power transmission target values ​​and power receiving target values ​​that minimize power transmission loss at different transmission power values. When the determination unit receives a first power transmission request from the first power supply system, it selects a first combination from the first combination group that corresponds to the first transmission power value in the first power transmission request, determines the power reception target value included in the first combination as the first target value, and determines the power transmission target value included in the first combination as the second target value.

[0015] The upper power management device selects a first combination from the first combination group according to the first transmission power value in the first power transmission request, determines the power reception target value included in the first combination as a first target value for the external bus voltage in the first converter of the first power supply system, and determines the power transmission target value included in the first combination as a second target value for the external bus voltage in the second converter of the second power supply system. As a result, the first converter sets the power reception target value of the first combination that minimizes the transmission loss at the first transmission power value, and the second converter sets the power transmission target value of the first combination that minimizes the transmission loss at the first transmission power value. This reduces the transmission loss in power transmission from the second power supply system to the first power supply system. As a result, the power transmission efficiency between the first power supply system and the second power supply system can be improved.

[0016] In some embodiments, when the determination unit receives a second power transmission request from the second power supply system, the determination unit may select a second combination from the first combination group according to the second transmission power value in the second power transmission request, may determine a power reception target value included in the second combination as the second target value, or may determine a power transmission target value included in the second combination as the first target value. According to this configuration, a common first combination group is used when transmitting power from the first power supply system to the second power supply system and when transmitting power from the second power supply system to the first power supply system. Therefore, it is sufficient to prepare one combination group, which simplifies the configuration of the upper power management device.

[0017] In some embodiments, the first combination group may be a plurality of combinations of power transmission target values ​​and power receiving target values ​​that minimize power transmission loss at different transmission power values ​​when transmitting power from the second power supply system to the first power supply system. The storage unit may further store a second combination group, which is a plurality of combinations of power transmission target values ​​and power receiving target values ​​that minimize power transmission loss at different transmission power values ​​when transmitting power from the first power supply system to the second power supply system. When receiving a second power transmission request from the second power supply system, the determination unit may select a second combination from the second combination group according to the second transmission power value in the second power transmission request, determine the power receiving target value included in the second combination as the second target value, or determine the power transmission target value included in the second combination as the first target value. According to this configuration, different combination groups are used when transmitting power from the first power supply system to the second power supply system and when transmitting power from the second power supply system to the first power supply system. Therefore, even if the characteristics of the converter in the first power supply system and the characteristics of the converter in the second power supply system are different, the power transmission loss can be reduced, and the power transmission efficiency can be improved. [Effects of the Invention]

[0018] According to each aspect and embodiment of the present disclosure, it is possible to improve power transmission efficiency. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a power interchange system including a higher-level power management device according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a configuration of the power supply system shown in FIG. [Figure 3] FIG. 3 is a hardware configuration diagram of the power management device shown in FIG. [Figure 4] FIG. 4 is a functional block diagram of the power management device shown in FIG. [Figure 5] FIG. 5 is a diagram showing an example of a plurality of combinations of power reception target values ​​and power transmission target values. [Figure 6] FIG. 6 is a flowchart showing a series of processes of a power management method performed by the power management apparatus shown in FIG. [Figure 7] FIG. 7 is a flowchart showing in detail the power receiving process shown in FIG. [Figure 8] FIG. 8 is a flowchart showing in detail the power transmission process shown in FIG. [Figure 9] FIG. 9 is a diagram showing the configuration of a power management program recorded on a recording medium. [Figure 10] FIG. 10 is a functional block diagram of an upper power management device according to another embodiment. [Figure 11] FIG. 11 is a flowchart showing a series of processes of the power management method performed by the upper power management apparatus shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0021] A power interchange system including an upper power management device according to one embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic configuration diagram of a power interchange system including an upper power management device according to one embodiment. The power interchange system 1 shown in Fig. 1 is a system for mutual supply of DC power (power interchange) between a power supply system 2A (power supply system) and a power supply system 2B (another power supply system). Hereinafter, supplying DC power will be referred to as "power transmission," and receiving a supply of DC power will be referred to as "power reception," and these may be collectively referred to as "power transmission and reception" or "power interchange." The power interchange system 1 includes a power supply system 2A, a power supply system 2B, an upper power management device 3, and an external DC bus B1.

[0022] The power supply system 2A and the power supply system 2B are connected to each other via an external DC bus B1. In this case, one of the power supply system 2A and the power supply system 2B supplies power to the other. For example, when the amount of stored power in the power supply system 2A (the amount of stored power will be described later) is surplus and the amount of stored power in the power supply system 2B is insufficient, the power supply system 2A supplies power to the power supply system 2B via the external DC bus B1. Details of the power supply systems 2A and 2B will be described later.

[0023] The external DC bus B1 is a bus that functions as a bus for supplying DC power between the power supply system 2A and the power supply system 2B. An external bus voltage Vbus1 is supplied to the external DC bus B1. The external bus voltage Vbus1 is a high-voltage DC voltage. The external bus voltage Vbus1 is, for example, a voltage of DC (Direct Current) 350V or more and DC 410V or less. The voltage value of the external bus voltage Vbus1 is set by the power supply system 2A or the power supply system 2B.

[0024] The upper power management device 3 is a device that controls power interchange between the power supply system 2A and the power supply system 2B. The upper power management device 3 is communicably connected to the power supply system 2A and the power supply system 2B via a communication network NW. The communication network NW may be configured as either a wired or wireless network. Examples of the communication network NW include the Internet, a wide area network (WAN), and a mobile communication network. The upper power management device 3 may be configured as a single computer 100 (see FIG. 3), similar to the power management device 10 described below. The upper power management device 3 may also be configured as a plurality of computers 100, as in cloud computing.

[0025] Next, power supply systems 2A and 2B will be described with reference to FIG. 2. FIG. 2 is a schematic diagram illustrating the configuration of the power supply system illustrated in FIG. 1. Since power supply system 2B has a configuration similar to that of power supply system 2A, only power supply system 2A will be described here. As illustrated in FIG. 2, power supply system 2A is a system that supplies load power WL (load voltage VL) to load device L. In this embodiment, power supply system 2A is a DC power supply system. Load device L may be a DC load device that operates on a DC voltage, or an AC load device that operates on an AC voltage. Examples of DC load devices include LED (Light Emission Diode) lighting fixtures, DC fans, televisions, and personal computers. Examples of AC load devices include washing machines, refrigerators, and air conditioners. Power supply system 2A mutually supplies power (power interchange) with power supply system 2B via an external DC bus B1.

[0026] The power supply system 2A includes an internal DC bus B2, a power supply device 5, an auxiliary power supply device 6, a converter 7, a power storage device 8, a bidirectional DC / DC converter 9, and a power management device 10.

[0027] The internal DC bus B2 functions as a bus for DC power supply that supplies DC power within the power supply system 2A. The internal DC bus B2 is laid across the installation locations of the power supply device 5, the auxiliary power supply device 6, the converter 7, and the power storage device 8. An internal bus voltage Vbus2 is supplied to the internal DC bus B2. The internal bus voltage Vbus2 is a high-voltage DC voltage. The internal bus voltage Vbus2 is set to be within the range of the input voltage of the converter 7. The internal bus voltage Vbus2 is, for example, a voltage of DC 240 V or more and DC 300 V or less. The value of the internal bus voltage Vbus2 may be fixed or variable. Note that the values ​​of the external bus voltage Vbus1 and the internal bus voltage Vbus2 are not limited to the above examples. The value of the external bus voltage Vbus1 and the value of the internal bus voltage Vbus2 may be the same value, or the value of the internal bus voltage Vbus2 may be greater than the value of the external bus voltage Vbus1.

[0028] The power supply device 5 is a device that supplies power to the internal DC bus B2. In this embodiment, the power supply system 2A includes one power supply device 5. The number of power supply devices 5 is not limited to one and can be changed appropriately as needed. The power supply device 5 includes a renewable energy power generation device 51 and a power conditioner 52.

[0029] The renewable energy power generation device 51 is a device that generates power Wre. Examples of the renewable energy power generation device 51 include a solar power generation device, a wind power generation device, a hydroelectric power generation device, and a geothermal power generation device. The renewable energy power generation device 51 is connected to the internal DC bus B2 via a power conditioner 52. The renewable energy power generation device 51 generates a power generation voltage Vre of a predetermined voltage value and outputs power generation Wre corresponding to the power generation voltage Vre. The power generation voltage Vre may be a DC voltage or an AC voltage.

[0030] The power conditioner 52 is connected to the internal DC bus B2 and is a device that converts the generated voltage Vre into the internal bus voltage Vbus2. The power conditioner 52 is provided between the renewable energy power generation device 51 and the internal DC bus B2. When the generated voltage Vre is a DC voltage, the power conditioner 52 includes a DC / DC converter. When the generated voltage Vre is an AC voltage, the power conditioner 52 includes an AC (Alternating Current) / DC converter. The power conditioner 52 operates, for example, with a DC voltage generated internally based on the internal bus voltage Vbus2. The power conditioner 52 controls the generated power Wre by controlling the power generation operation of the renewable energy power generation device 51 based on a command from the power management device 10.

[0031] When power conditioner 52 receives a start command from power management device 10, it converts generated power voltage Vre into internal bus voltage Vbus2 and supplies internal bus voltage Vbus2 to internal DC bus B2, thereby supplying generated power Wre to internal DC bus B2. When power conditioner 52 receives a stop command from power management device 10, it stops supplying generated power Wre.

[0032] The power conditioner 52 has a power measurement function of measuring the generated power Wre supplied from the renewable energy power generation device 51 to the internal DC bus B2. The power conditioner 52 measures the generated power Wre, for example, periodically. The power conditioner 52 transmits the measurement value of the generated power Wre to the power management device 10.

[0033] The auxiliary power supply 6 is a device that supplies power to the internal DC bus B2. The auxiliary power supply 6 includes a commercial power supply 61 and an AC / DC converter 62. The commercial power supply 61 supplies system power Ws including a system voltage Vs. The system voltage Vs is an AC voltage. The commercial power supply 61 is connected to the internal DC bus B2 via the AC / DC converter 62.

[0034] The AC / DC converter 62 is connected to the internal DC bus B2 and is a device that converts the system voltage Vs into an internal bus voltage Vbus2. The AC / DC converter 62 is provided between the commercial power supply 61 and the internal DC bus B2. The AC / DC converter 62 operates, for example, on a DC voltage that is internally generated based on the system voltage Vs. When a start command is received from the power management device 10, the AC / DC converter 62 converts the system voltage Vs into the internal bus voltage Vbus2 and supplies the internal bus voltage Vbus2 to the internal DC bus B2, thereby supplying system power Ws to the internal DC bus B2. When a stop command is received from the power management device 10, the AC / DC converter 62 stops supplying the system power Ws.

[0035] The AC / DC converter 62 has a power measurement function of measuring the grid power Ws supplied from the commercial power supply 61 to the internal DC bus B2. The AC / DC converter 62 measures the grid power Ws, for example, periodically. The AC / DC converter 62 transmits the measurement value of the grid power Ws to the power management device 10.

[0036] The auxiliary power supply device 6 is capable of supplying power stably, and is controlled to supply power when there is a power shortage in the entire power supply system 2A. In order to maintain the power supply system 2A, the grid power Ws is equal to or greater than the sum of the load power WL and the standby power in the power supply system 2A. The standby power includes the power consumption of the power management device 10 and the power consumption of auxiliary devices (relays, fans, small-capacity power supplies, etc., not shown).

[0037] The converter 7 is connected to the internal DC bus B2 and is a device that converts the internal bus voltage Vbus2 into a load voltage VL. The load voltage VL is a voltage supplied to the load device L. The load device L is connected to the internal DC bus B2 via the converter 7. The converter 7 operates on a DC voltage that is internally generated based on the internal bus voltage Vbus2, for example. In this embodiment, the power supply system 2A includes four converters 7. The number of converters 7 is not limited to four and can be changed depending on the number of load devices L.

[0038] When converter 7 receives a start command from power management apparatus 10, it converts internal bus voltage Vbus2 to load voltage VL and supplies load voltage VL (load power WL) to load device L. If load device L is a DC load device, the load voltage VL is a DC voltage and converter 7 is a DC / DC converter. Converter 7 converts, for example, internal bus voltage Vbus2 of 270 V DC to load voltage VL of 24 V DC. If load device L is an AC load device, the load voltage VL is an AC voltage and converter 7 is a DC / AC converter. When converter 7 receives a stop command from power management apparatus 10, it stops supplying load voltage VL (load power WL).

[0039] The converter 7 has a current limiting function that limits the current value of the load current supplied from the internal DC bus B2 to the load device L by an upper limit current value. The upper limit current value is set by the power management device 10. The converter 7 has a power measuring function that measures the load power WL supplied from the internal DC bus B2 to the load device L based on the load voltage VL and the load current. The converter 7 measures the load power WL, for example, periodically. The converter 7 transmits the measured value of the load power WL to the power management device 10.

[0040] The power storage device 8 is a device for storing surplus power generated in the power supply system 2A and supplying a power shortage generated in the power supply system 2A. When the differential power obtained by subtracting the sum of the load powers WL from the sum of the supplied powers is greater than 0, surplus power equal to the magnitude (power value) of the differential power is generated. The supplied power is power supplied to the internal DC bus B2. In this embodiment, the supplied power is generated power Wre and system power Ws. Each power storage device 8 is supplied with power Wc obtained by equally dividing the surplus power according to the number of power storage devices 8 from the internal DC bus B2. When the differential power is less than 0, a power shortage equal to the magnitude of the differential power is generated. Each power storage device 8 releases power Wc obtained by equally dividing the power shortage according to the number of power storage devices 8 to the internal DC bus B2.

[0041] The number of power storage devices 8 is not limited to three and can be changed appropriately as necessary. Each power storage device 8 includes a storage battery 81, a BMU (Battery Management Unit) 82, and a bidirectional DC / DC converter 83.

[0042] The storage battery 81 is a device that can be charged and discharged. The storage battery 81 is connected to the internal DC bus B2 via a bidirectional DC / DC converter 83. Examples of the storage battery 81 include a lithium ion battery, a sodium-sulfur (NAS) battery, a redox flow battery, a lead-acid battery, and a nickel-metal hydride battery. In this embodiment, the storage batteries 81 included in the multiple power storage devices 8 are of the same type and have the same storage capacity. The storage capacity is the maximum amount of electricity that can be stored. The storage batteries 81 included in the multiple power storage devices 8 may be of different types and may have different storage capacities. The storage battery 81 includes, for example, a plurality of battery cells.

[0043] The BMU 82 is a device that manages the storage battery 81. The BMU 82 has a function of measuring the battery voltage Vbat of the storage battery 81 and a function of measuring the current value of the charge / discharge current of the storage battery 81 to calculate the SOC (State of charge: remaining capacity). The BMU 82 may further have a function of measuring the cell voltages of multiple battery cells that make up the storage battery 81. The BMU 82 transmits battery information of the storage battery 81 to the power management device 10. The battery information includes the measured value of the battery voltage Vbat, the current value of the charge / discharge current, the temperature of the storage battery 81, the storage capacity of the storage battery 81, and the SOC. The BMU 82 periodically transmits the battery information to the power management device 10.

[0044] The bidirectional DC / DC converter 83 is connected to the internal DC bus B2 and is a device capable of bidirectionally converting between the internal bus voltage Vbus2 and the battery voltage Vbat. The bidirectional DC / DC converter 83 is provided between the storage battery 81 and the internal DC bus B2. The battery voltage Vbat is the voltage of the storage battery 81. A known bidirectional DC / DC converter can be used as the bidirectional DC / DC converter 83. The bidirectional DC / DC converter 83 operates, for example, on a DC voltage generated internally based on the internal bus voltage Vbus2.

[0045] The bidirectional DC / DC converter 83 is controlled by the power management device 10. Specifically, when the bidirectional DC / DC converter 83 receives a charge command from the power management device 10, it converts the internal bus voltage Vbus2 to the battery voltage Vbat and flows a charging current from the internal DC bus B2 to the storage battery 81. This charges the storage battery 81. When the bidirectional DC / DC converter 83 receives a discharge command from the power management device 10, it converts the battery voltage Vbat to the internal bus voltage Vbus2 and flows a discharging current from the storage battery 81 to the internal DC bus B2. This discharges the storage battery 81. The bidirectional DC / DC converter 83 may charge or discharge the storage battery 81 using a constant current method, or may charge or discharge the storage battery 81 using a constant voltage method.

[0046] When the bidirectional DC / DC converter 83 receives a stop command from the power management device 10, it stops operation and transitions to a sleep state in which power consumption is reduced. When the bidirectional DC / DC converter 83 receives a charge command or a discharge command while in the sleep state, it exits the sleep state and executes a charge process or a discharge process. The bidirectional DC / DC converter 83 has a current limiting function that limits the current values ​​of the charge current supplied to the storage battery 81 and the discharge current discharged from the storage battery 81 to equal to or less than a maximum current value. When the bidirectional DC / DC converter 83 receives a command to set the maximum current value from the power management device 10, it sets the maximum current values ​​of the charge current and the discharge current to the maximum current value specified by the setting command.

[0047] When bidirectional DC / DC converter 83 receives a command to set the target value of internal bus voltage Vbus2 from power management device 10, it sets the target value of internal bus voltage Vbus2 to the target value specified by the command. The target value is a voltage value for maintaining the voltage value of internal bus voltage Vbus2 constant. Bidirectional DC / DC converter 83 has a function of maintaining the voltage value of internal bus voltage Vbus2 at the target value even when power Wc is changed.

[0048] The bidirectional DC / DC converter 83 has a power measurement function for measuring the power Wc. The bidirectional DC / DC converter 83 measures the power Wc, for example, periodically. The bidirectional DC / DC converter 83 transmits the measurement value of the power Wc to the power management apparatus 10.

[0049] The bidirectional DC / DC converter 9 is provided between the external DC bus B1 and the internal DC bus B2 and is a device capable of bidirectionally converting between the external bus voltage Vbus1 and the internal bus voltage Vbus2. A known bidirectional DC / DC converter can be used as the bidirectional DC / DC converter 9. The bidirectional DC / DC converter 9 operates, for example, on a DC voltage generated internally based on the internal bus voltage Vbus2.

[0050] The bidirectional DC / DC converter 9 is controlled by the power management device 10. When the bidirectional DC / DC converter 9 receives a setting command for the target value of the external bus voltage Vbus1 from the power management device 10, it sets the target value of the external bus voltage Vbus1 to the target value specified by the setting command. The target value is a voltage value for keeping the voltage value of the external bus voltage Vbus1 constant.

[0051] When the bidirectional DC / DC converter 9 receives a stop command from the power management device 10, it stops operation and transitions to a sleep state in which power consumption is reduced. When the bidirectional DC / DC converter 9 receives a command to set the set value of the external bus voltage Vbus1 while in the sleep state, it exits the sleep state and executes power transmission and reception processing.

[0052] The power management device 10 is a device (controller) that manages the entire power supply system 2A. The power management device 10 is also referred to as an EMS (Energy Management System). The power management device 10 is connected to the power supply device 5, the auxiliary power supply device 6, the converter 7, the power storage device 8, and the bidirectional DC / DC converter 9 via communication lines so that they can communicate with each other. The communication lines may be wired or wireless. The power management device 10 is connected to the upper power management device 3 via a communication network NW so that they can communicate with each other. The power management device 10 may perform communication in accordance with standards such as RS-232C, RS-485, CAN (Controller Area Network), Ethernet (registered trademark), and Wi-Fi (registered trademark).

[0053] Power management apparatus 10 transmits a start command and a stop command to each of power conditioner 52, AC / DC converter 62, converter 7, bidirectional DC / DC converter 83, and bidirectional DC / DC converter 9. For example, power management apparatus 10 transmits a start command to converter 7 to cause converter 7 to supply load voltage VL. Power management apparatus 10 transmits a stop command to converter 7 to cause converter 7 to stop supplying load voltage VL. The same applies to the other converters.

[0054] The power management apparatus 10 controls the bidirectional DC / DC converter 83 to perform a charge / discharge process for charging / discharging the storage batteries 81. The power management apparatus 10 performs the charge / discharge process according to the differential power. When the total amount of supply power is greater than the total amount of load power WL (when the differential power is greater than 0), the power management apparatus 10 sends a charge command to the bidirectional DC / DC converter 83, causing the storage batteries 81 to store the surplus power, which is the differential power. For example, power obtained by equally dividing the surplus power among the number of storage batteries 81 is stored in each storage battery 81. When the total amount of supply power is less than the total amount of load power WL (when the differential power is less than 0), the power management apparatus 10 sends a discharge command to the bidirectional DC / DC converter 83, causing the storage batteries 81 to release the deficit power. For example, power obtained by equally dividing the deficit power among the number of storage batteries 81 is released from each storage battery 81.

[0055] The power management device 10 switches the operation mode of the power supply system 2A by controlling the bidirectional DC / DC converter 9. Details will be described later.

[0056] Next, the hardware configuration of the computer 100 that constitutes the power management apparatus 10 will be described with reference to Fig. 3. Fig. 3 is a hardware configuration diagram of the computer that constitutes the power management apparatus shown in Fig. 2. The power management apparatus 10 may be constituted by one computer 100. The power management apparatus 10 may also be constituted by multiple computers 100, as in cloud computing. As shown in Fig. 3, the computer 100 physically includes hardware such as a processor 101, a memory 102, and a communication interface 103.

[0057] An example of the processor 101 is a CPU (Central Processing Unit). The memory 102 can include a main storage device and an auxiliary storage device. The main storage device is composed of RAM (Random Access Memory) and ROM (Read Only Memory), etc. Examples of the auxiliary storage device are semiconductor memory and a hard disk drive. The communication interface 103 is a device that transmits and receives data to and from other devices. The communication interface 103 is composed of, for example, a communication module that complies with communication standards such as RS-232C, RS-485, and CAN, a network interface card (NIC), or a wireless communication module.

[0058] The processor 101 reads and executes the power management program PR (see FIG. 9) stored in the memory 102, causing each piece of hardware to operate under the control of the processor 101, and reading and writing data from and to the memory 102. This realizes each functional unit of the power management device 10 shown in FIG. 4. The power management device 10 and the upper power management device 3 of the power supply system 2B also have a similar hardware configuration.

[0059] Next, the functional configuration of the power management device 10 will be described with reference to Figures 4 and 5. Figure 4 is a functional block diagram of the power management device shown in Figure 2. Figure 5 is a diagram showing an example of multiple combinations of power receiving target values ​​and power transmission target values. Here, the functional configuration of the power management device 10 of the power supply system 2A will be described, but the power management device 10 of the power supply system 2B also has a similar functional configuration. As shown in Figure 4, the power management device 10 functionally comprises an acquisition unit 11, a storage unit 12, and a control unit 13.

[0060] The acquisition unit 11 is a functional unit that acquires the amount of stored power accumulated in the power supply system 2A. The acquisition unit 11 receives battery information from each BMU 82 and calculates the SOC of the entire power supply system 2A based on the SOC and power storage capacity included in each battery information. For example, the acquisition unit 11 calculates the amount of stored power of each storage battery 81 from the SOC and power storage capacity of each storage battery 81, and calculates the SOC of the entire power supply system 2A by dividing the sum of the stored power amounts of all the storage batteries 81 by the sum of the power storage capacities of all the storage batteries 81. The acquisition unit 11 then acquires the SOC of the entire power supply system 2A as the amount of stored power of the power supply system 2A. The acquisition unit 11 may acquire the smallest amount of stored power (SOC) of all the storage batteries 81 as the amount of stored power of the power supply system 2A.

[0061] The storage unit 12 is a functional unit that stores a plurality of power receiving target values ​​and a plurality of power transmission target values. Each power receiving target value is a target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 of the power supply system 2A when transmitting power from the power supply system 2B to the power supply system 2A. In other words, each power receiving target value is a target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 that receives power. The plurality of power receiving target values ​​are set so that transmission loss is minimized at different transmission power values. The power transmission loss here refers to the loss of power that occurs during transmission and reception of power between the power supply system 2A and the power supply system 2B. The power transmission loss includes, for example, loss caused by wiring resistance between the power supply system 2A and the power supply system 2B and internal loss in the bidirectional DC / DC converter 9.

[0062] Each power transmission target value is a target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 of the power supply system 2A when transmitting power from the power supply system 2A to the power supply system 2B. In other words, each power transmission target value is a target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 that transmits power. The multiple power transmission target values ​​are set so that the transmission loss is minimized at different transmission power values. Note that the transmission loss at the transmission power value can vary depending on the combination of the power transmission target value and the power receiving target value. As will be described later, combinations of the transmission power value and the power receiving target value that minimize the transmission loss at each transmission power value are measured in advance. The power receiving target value that minimizes the transmission loss at the transmission power value means the power receiving target value from the above combinations, and the power transmission target value that minimizes the transmission loss at the transmission power value means the power transmission target value from the above combinations.

[0063] 5, in this embodiment, the storage unit 12 stores a plurality of combinations of power receiving target values ​​and power transmission target values ​​that minimize the transmission loss for different transmission power values. That is, if the transmission power values ​​are the same when transmitting power from the power supply system 2A to the power supply system 2B and when transmitting power from the power supply system 2B to the power supply system 2A, the same combination is used. The storage unit 12 stores the plurality of combinations in, for example, a table format. The storage unit 12 of the power supply system 2A and the storage unit 12 of the power supply system 2B have the same table.

[0064] Combinations of the power receiving target value and the power transmission target value are set for several transmission power values ​​between the maximum power Wmax, which is the maximum value of power that the bidirectional DC / DC converter 9 can output, and 0 W. For example, if the maximum power Wmax is 2500 W, the combinations may be set in increments of 100 W, such as 2500 W, 2400 W, 2300 W, and so on. The power transmission target value corresponding to the maximum power Wmax is, for example, DC 380 V, and the power receiving target value is, for example, DC 340 V.

[0065] Each combination is measured and set in advance. For example, a plurality of combinations of target power receiving values ​​and target power transmission values ​​are prepared, and the combination that minimizes the transmission loss for each transmission power value is selected as the combination for that transmission power value.

[0066] The control unit 13 is a functional unit that switches the operation mode of the power supply system 2A by controlling the bidirectional DC / DC converter 9. The operation modes of the power supply system 2A include a power receiving mode, a power transmitting mode, and a normal mode. The power receiving mode is a mode in which the power supply system 2A receives DC power from another power supply system (in this embodiment, the power supply system 2B). The power transmitting mode is a mode in which the power supply system 2A supplies DC power to the other power supply system (in this embodiment, the power supply system 2B). The normal mode is a mode in which the power supply system 2A does not transmit or receive power to or from the other power supply system (in this embodiment, the power supply system 2B). The control unit 13 controls the bidirectional DC / DC converter 9 using a power storage threshold Bth1 (first power storage threshold), a power storage threshold Bth2 (second power storage threshold), a power storage threshold Bth3 (first stop threshold), a power storage threshold Bth4 (second stop threshold), a power storage threshold Bth5, and a power storage threshold Bth6.

[0067] The power storage threshold Bth1 is a threshold for determining whether the power supply system 2A has a shortage of stored power and needs to receive power from another power supply system (power supply system 2B in this embodiment). The power storage threshold Bth1 is expressed by, for example, SOC. The power storage threshold Bth1 is set to, for example, 20%. The power storage threshold Bth2 is a threshold for determining whether the power supply system 2A has a surplus of stored power and can transmit power to another power supply system (power supply system 2B in this embodiment). The power storage threshold Bth2 is greater than the power storage threshold Bth1. The power storage threshold Bth2 is expressed by, for example, SOC. The power storage threshold Bth2 is set to, for example, 70%.

[0068] The power storage threshold Bth3 is a threshold for determining whether the power supply system 2A has a sufficient amount of stored power. The power storage threshold Bth3 is a value greater than the power storage threshold Bth1 and less than the power storage threshold Bth2. The power storage threshold Bth3 is expressed by, for example, an SOC. The power storage threshold Bth3 is set to, for example, 50%. The power storage threshold Bth4 is a threshold for determining whether the power storage amount of the power supply system 2A has decreased and no more power can be transmitted to another power supply system (in this embodiment, the power supply system 2B). The power storage threshold Bth4 is a value greater than the power storage threshold Bth1 and less than the power storage threshold Bth2. The power storage threshold Bth4 may be the same value as the power storage threshold Bth3 or may be a different value. The power storage threshold Bth4 is expressed by, for example, an SOC. The power storage threshold Bth4 is set to, for example, 50%.

[0069] The power storage threshold Bth5 is a threshold for determining that the amount of stored power in the power supply system 2A is not sufficient but has accumulated to a certain extent. The power storage threshold Bth5 is a value greater than the power storage threshold Bth1 and less than the power storage threshold Bth3. The power storage threshold Bth5 is expressed by, for example, an SOC. The power storage threshold Bth5 is set to, for example, 35%. The power storage threshold Bth6 is a threshold for determining that power can be transmitted to another power supply system (in this embodiment, the power supply system 2B) but has decreased to a certain extent. The power storage threshold Bth6 is a value greater than the power storage threshold Bth4 and less than the power storage threshold Bth2. The power storage threshold Bth6 is expressed by, for example, an SOC. The power storage threshold Bth6 is set to, for example, 60%.

[0070] The control unit 13 transmits and receives power transmission requests and change requests to and from the upper power management device 3.

[0071] Next, a series of processes in the power management method performed by the power management apparatus 10 will be described with reference to Figures 6 to 8. Figure 6 is a flowchart showing a series of processes in the power management method performed by the power management apparatus shown in Figure 2. Figure 7 is a flowchart showing in detail the power reception process shown in Figure 6. Figure 8 is a flowchart showing in detail the power transmission process shown in Figure 6. The series of processes in Figure 6 are started a certain time after the power is turned on to the power management apparatus 10, and are repeated while the power management apparatus 10 is operating.

[0072] First, the acquisition unit 11 acquires the amount of stored power in the power supply system 2A (step S11). In step S11, the acquisition unit 11 receives, for example, battery information from each BMU 82, and calculates the SOC of the entire power supply system 2A based on the SOC and power storage capacity included in each piece of battery information. Then, the acquisition unit 11 acquires the SOC of the entire power supply system 2A as the amount of stored power in the power supply system 2A. The acquisition unit 11 may acquire the smallest amount of stored power among the amounts of stored power in all the storage batteries 81 as the amount of stored power in the power supply system 2A. Then, the acquisition unit 11 outputs the amount of stored power in the power supply system 2A to the control unit 13.

[0073] Next, when the control unit 13 receives the stored power amount of the power supply system 2A from the acquisition unit 11, the control unit 13 compares the stored power amount of the power supply system 2A with the power storage threshold Bth1 to determine whether the stored power amount of the power supply system 2A is smaller than the power storage threshold Bth1 (step S12). If it is determined in step S12 that the stored power amount of the power supply system 2A is smaller than the power storage threshold Bth1 (below the power storage threshold Bth1) (step S12; YES), the stored power amount of the power supply system 2A is insufficient and power needs to be received from the power supply system 2B. Therefore, the control unit 13 transmits a power transmission request (first power transmission request) to the upper-level power management device 3 (step S13) and performs power receiving processing (step S14). In this embodiment, it is agreed that the power supply system responding to the power transmission request will start transmitting power at the maximum power Wmax. The control unit 13 may transmit a transmission power value to the upper-level power management device 3 together with the power transmission request.

[0074] In the power receiving process of step S14, as shown in Fig. 7, first, the control unit 13 selects a power receiving target value Vt11 (first power receiving target value) corresponding to the maximum power Wmax from among a plurality of power receiving target values ​​stored in the storage unit 12. In the example shown in Fig. 5, DC 340 V is selected as the power receiving target value Vt11. Then, the control unit 13 sets the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 to the power receiving target value Vt11, thereby setting the power feeding system 2A to a power receiving mode (step S21).

[0075] On the other hand, when the control unit 13 of the power supply system 2B receives a power transmission request from the power supply system 2A via the upper-level power management device 3, the control unit 13 selects a power transmission target value Vt21 corresponding to the maximum power Wmax from among multiple power transmission target values ​​stored in the storage unit 12. In the example shown in FIG. 5, DC 380 V is selected as the power transmission target value Vt21. The control unit 13 of the power supply system 2B then sets the target value of the external bus voltage Vbus1 of the bidirectional DC / DC converter 9 to the power transmission target value Vt21, thereby placing the power supply system 2B in a power transmission mode. This starts power transmission (power interchange) from the power supply system 2B to the power supply system 2A. At this time, the target value of the external bus voltage Vbus1 of the bidirectional DC / DC converter 9 of the power supply system 2B is set to the power transmission target value Vt21, and the target value of the external bus voltage Vbus1 of the bidirectional DC / DC converter 9 of the power supply system 2A is set to the power reception target value Vt11. Therefore, power is transmitted at the maximum power Wmax while minimizing power transmission loss.

[0076] Next, similarly to step S11, the acquisition unit 11 acquires the amount of stored power in the power supply system 2A (step S22) and outputs the amount of stored power in the power supply system 2A to the control unit 13. Then, the control unit 13 determines whether or not a change request has occurred (step S23). The change request includes a change request occurring in the power supply system 2A and a change request occurring in the power supply system 2B.

[0077] For example, the control unit 13 compares the amount of stored power in the power supply system 2A with the power storage threshold Bth5, and if the amount of stored power in the power supply system 2A is greater than the power storage threshold Bth5 (exceeds the power storage threshold Bth5), determines that a change request has occurred in the power supply system 2A. At this time, the control unit 13 transmits the transmission power value together with the change request to the upper power management device 3, and the upper power management device 3 transmits the change request and the transmission power value to the power supply system 2B. In this embodiment, the intermediate power Wmid is used as the transmission power value transmitted together with the change request. The intermediate power Wmid is a value smaller than the maximum power Wmax. In other words, the change request is a request to change the maximum power Wmax (first transmission power value) to the intermediate power Wmid (third transmission power value).

[0078] When the control unit 13 receives a change request from the power supply system 2B via the upper power management device 3, the control unit 13 determines that a change request has occurred in the power supply system 2B. Specifically, the control unit 13 of the power supply system 2B compares, for example, the amount of stored power in the power supply system 2B with the power storage threshold Bth6, and if the amount of stored power in the power supply system 2B is smaller than the power storage threshold Bth6 (below the power storage threshold Bth6), transmits the change request together with the transmission power value to the upper power management device 3. Then, the upper power management device 3 transmits the change request and the transmission power value to the power supply system 2A. As a result, the control unit 13 of the power supply system 2A receives the change request from the power supply system 2B via the upper power management device 3.

[0079] If it is determined in step S23 that a change request has been made (step S23; YES), the control unit 13 selects a power receiving target value Vt12 (second power receiving target value) corresponding to the intermediate power Wmid from among the multiple power receiving target values ​​stored in the storage unit 12. In the example shown in Fig. 5, DC 290 V is selected as the power receiving target value Vt12. Then, the control unit 13 sets the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 to the power receiving target value Vt12 (step S24).

[0080] At this time, the control unit 13 of the power supply system 2B also determines that a change request has been made. Therefore, the control unit 13 of the power supply system 2B selects a power transmission target value Vt22 corresponding to the medium power Wmid from among the multiple power transmission target values ​​stored in the storage unit 12. In the example shown in FIG. 5, DC 330 V is selected as the power transmission target value Vt22. Then, the control unit 13 of the power supply system 2B sets the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 to the power transmission target value Vt22. As a result, power is transmitted at the medium power Wmid while minimizing transmission loss.

[0081] Next, the control unit 13 compares the amount of stored power in the power supply system 2A with the power storage threshold Bth3 to determine whether the amount of stored power in the power supply system 2A is greater than the power storage threshold Bth3 (step S25). If it is determined in step S23 that a change request has not been issued (step S23; NO), the target power receiving value is not changed and step S25 is performed. If it is determined in step S25 that the amount of stored power in the power supply system 2A is equal to or less than the power storage threshold Bth3 (step S25; NO), the amount of stored power in the power supply system 2A is not sufficient, and the power receiving mode is maintained.

[0082] Then, the control unit 13 determines whether or not a power transmission stop request has been received from the upper power management device 3 (step S26). The power transmission stop request is, for example, a signal transmitted by the power supply system 2B (control unit 13 thereof) when the power supply system 2B set to the power transmission mode can no longer maintain power transmission. Details of the power transmission stop request will be described later. In step S26, if the control unit 13 has not received the power transmission stop request (step S26; NO), the power receiving mode is maintained, and step S22 is performed again.

[0083] On the other hand, if it is determined in step S25 that the amount of stored power in the power supply system 2A is greater than the power storage threshold Bth3 (exceeds the power storage threshold Bth3) (step S25; YES), the control unit 13 transmits a power reception stop request to the upper power management device 3 (step S27). Then, the control unit 13 determines that the amount of stored power in the power supply system 2A is sufficiently accumulated, and cancels the power receiving mode of the power supply system 2A (step S28). Similarly, if the control unit 13 receives a power transmission stop request in step S26 (step S26; YES), the control unit 13 cancels the power receiving mode of the power supply system 2A (step S28). The control unit 13 cancels the power receiving mode of the power supply system 2A by, for example, stopping the bidirectional DC / DC converter 9, thereby canceling the power receiving mode of the power supply system 2A and setting the power supply system 2A to the normal mode. At this time, the bidirectional DC / DC converter 9 stops converting the external bus voltage Vbus1 into the internal bus voltage Vbus2, and stops flowing current from the external DC bus B1 to the internal DC bus B2.

[0084] This completes the power receiving process in step S14, and the series of processes shown in FIG. 6 ends.

[0085] On the other hand, if it is determined in step S12 that the amount of stored power in power supply system 2A is equal to or greater than power storage threshold Bth1 (step S12; NO), control unit 13 determines whether or not a power transmission request (second power transmission request) has been received from power supply system 2B via upper power management device 3 (step S15). For example, if the amount of stored power in power supply system 2B is smaller than power storage threshold Bth1 (below power storage threshold Bth1), control unit 13 of power supply system 2B transmits a power transmission request to upper power management device 3, and upper power management device 3 transmits the power transmission request to power supply system 2A. If control unit 13 has not received a power transmission request from upper power management device 3 in step S15 (step S15; NO), there is no need to transmit power to power supply system 2B. Therefore, power supply system 2A maintains the normal mode in which no power is transmitted or received between power supply system 2A and power supply system 2B, and the series of processes shown in FIG. 6 ends.

[0086] On the other hand, if the control unit 13 receives a power transmission request from the upper power management device 3 in step S15 (step S15; YES), the control unit 13 compares the amount of stored power in the power supply system 2A with the power storage threshold Bth2 to determine whether or not the amount of stored power in the power supply system 2A is greater than the power storage threshold Bth2 (step S16). If it is determined in step S16 that the amount of stored power in the power supply system 2A is equal to or less than the power storage threshold Bth2 (step S16; NO), the amount of stored power in the power supply system 2A is not insufficient but is not surplus either. In this case, the power supply system 2A maintains the normal mode in which it does not transmit or receive power to or from the power supply system 2B, and the series of processes shown in FIG. 6 ends.

[0087] On the other hand, if it is determined in step S16 that the amount of stored power in the power supply system 2A is greater than the power storage threshold Bth2 (exceeds the power storage threshold Bth2) (step S16; YES), the amount of stored power in the power supply system 2A is surplus, and therefore the power supply system 2A is in a state where it can transmit power to the power supply system 2B. In this case, the control unit 13 transmits a power transmission possible response to the upper power management device 3 (step S17) and performs power transmission processing (step S18). As described above, in this embodiment, it is agreed that the power supply system responding to the power transmission request will start transmitting power at the maximum power Wmax.

[0088] 8, in the power transmission process of step S18, first, the control unit 13 selects a power transmission target value Vt21 (first power transmission target value) corresponding to the maximum power Wmax from among a plurality of power transmission target values ​​stored in the storage unit 12. Then, the control unit 13 sets the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 to the power transmission target value Vt21, thereby setting the power supply system 2A to a power transmission mode (step S31).

[0089] Meanwhile, the control unit 13 of the power supply system 2B selects a power reception target value Vt11 corresponding to the maximum power Wmax from among the multiple power reception target values ​​stored in the storage unit 12. Then, the control unit 13 of the power supply system 2B sets the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 to the power reception target value Vt11, thereby setting the power supply system 2B to a power reception mode. This starts power transmission (power interchange) from the power supply system 2A to the power supply system 2B. At this time, the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 of the power supply system 2A is set to the power transmission target value Vt21, and the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 of the power supply system 2B is set to the power reception target value Vt11. Therefore, power is transmitted at the maximum power Wmax while minimizing power transmission loss.

[0090] Next, the acquisition unit 11 acquires the amount of stored power in the power supply system 2A in the same manner as in step S11 (step S32) and outputs the amount of stored power in the power supply system 2A to the control unit 13. Then, the control unit 13 determines whether a change request has occurred (step S33). For example, the control unit 13 compares the amount of stored power in the power supply system 2A with the power storage threshold Bth6, and if the amount of stored power in the power supply system 2A is smaller than the power storage threshold Bth6 (below the power storage threshold Bth6), determines that a change request has occurred in the power supply system 2A. At this time, the control unit 13 transmits the transmission power value together with the change request to the upper power management device 3, and the upper power management device 3 transmits the change request and the transmission power value to the power supply system 2B. As in step S23, the intermediate power Wmid is used as the transmission power value transmitted together with the change request. In other words, the change request is a request to change the maximum power Wmax (second transmission power value) to the intermediate power Wmid (fourth transmission power value).

[0091] When the control unit 13 receives a change request from the power supply system 2B via the upper power management device 3, the control unit 13 determines that a change request has occurred in the power supply system 2B. Specifically, the control unit 13 of the power supply system 2B, for example, compares the amount of stored power in the power supply system 2B with a power storage threshold Bth5, and if the amount of stored power in the power supply system 2B is greater than the power storage threshold Bth5 (exceeds the power storage threshold Bth5), transmits the change request together with the transmission power value to the upper power management device 3. Then, the upper power management device 3 transmits the change request and the transmission power value to the power supply system 2A. As a result, the control unit 13 of the power supply system 2A receives the change request from the power supply system 2B via the upper power management device 3.

[0092] If it is determined in step S33 that a change request has occurred (step S33; YES), the control unit 13 selects a power transmission target value Vt22 (second power transmission target value) corresponding to the medium power Wmid from among the multiple power transmission target values ​​stored in the storage unit 12. Then, the control unit 13 sets the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 to the power transmission target value Vt22 (step S34).

[0093] At this time, the control unit 13 of the power supply system 2B also determines that a change request has been made. Therefore, the control unit 13 of the power supply system 2B selects the power receiving target value Vt12 corresponding to the medium power Wmid from among the multiple power receiving target values ​​stored in the storage unit 12. Then, the control unit 13 of the power supply system 2B sets the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 to the power receiving target value Vt12. As a result, power is transmitted at the medium power Wmid while minimizing power transmission loss.

[0094] Next, the control unit 13 compares the amount of stored power in the power supply system 2A with the power storage threshold Bth4 to determine whether the amount of stored power in the power supply system 2A is smaller than the power storage threshold Bth4 (step S35). If it is determined in step S33 that a change request has not been generated (step S33; NO), the power transmission target value is not changed and step S35 is performed. If it is determined in step S35 that the amount of stored power in the power supply system 2A is equal to or greater than the power storage threshold Bth4 (step S35; NO), the power supply system 2A has a sufficient amount of stored power remaining to transmit power to the power supply system 2B, and therefore the power transmission mode is maintained.

[0095] Then, the control unit 13 determines whether or not a power reception stop request has been received from the upper power management device 3 (step S36). As described above, the power reception stop request is a signal transmitted by the power supply system 2B (control unit 13 thereof) when, for example, the power supply system 2B set to the power reception mode has stored a sufficient amount of power. In step S36, if the control unit 13 has not received the power reception stop request (step S36; NO), the power transmission mode is maintained, and step S32 is performed again.

[0096] On the other hand, if it is determined in step S35 that the amount of stored power in the power supply system 2A is smaller than the power storage threshold Bth4 (below the power storage threshold Bth4) (step S35; YES), the control unit 13 transmits a power transmission stop request to the upper power management device 3 (step S37). Then, the control unit 13 determines that the amount of stored power in the power supply system 2A is insufficient and that no more power can be transmitted, and cancels the power transmission mode of the power supply system 2A (step S38). Similarly, if the control unit 13 receives a power reception stop request in step S36 (step S36; YES), the control unit 13 cancels the power transmission mode of the power supply system 2A (step S38). The control unit 13 cancels the power transmission mode of the power supply system 2A by, for example, stopping the bidirectional DC / DC converter 9, thereby canceling the power transmission mode of the power supply system 2A and setting the power supply system 2A to the normal mode. At this time, the bidirectional DC / DC converter 9 stops converting the internal bus voltage Vbus2 into the external bus voltage Vbus1, and stops flowing current from the internal DC bus B2 to the external DC bus B1.

[0097] This completes the power transmission process in step S18, and the series of processes shown in FIG. 6 ends.

[0098] Note that step S15 may be performed before step S16 or in parallel with step S16. Step S25 may be performed before step S26 or in parallel with step S26. Step S35 may be performed before step S36 or in parallel with step S36.

[0099] In each determination, when a certain value is compared with a threshold, if the value is equal to the threshold, either determination result may be applied. For example, in step S12, the control unit 13 determines whether the amount of stored power is smaller than the power storage threshold Bth1, but may instead determine whether the amount of stored power is equal to or smaller than the power storage threshold Bth1. The same applies to the other determinations.

[0100] Next, a power management program PR for causing the computer 100 to function as the power management apparatus 10 and a recording medium MD on which the power management program PR is recorded will be described with reference to Fig. 9. Fig. 9 is a diagram showing the configuration of the power management program recorded on the recording medium.

[0101] 9, the power management program PR includes a main module P10, an acquisition module P11, and a control module P13. The main module P10 is a part that performs overall control of the processing related to the power management apparatus 10. The functions realized by executing the acquisition module P11 and the control module P13 are similar to the acquisition unit 11 and the control unit 13 in the above embodiment, respectively.

[0102] The power management program PR is recorded on a recording medium MD. The recording medium MD is a computer-readable non-transitory recording medium. Examples of the recording medium MD include a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), and a semiconductor memory. The power management program PR may be provided as a data signal via a communication network NW.

[0103] In the power management device 10, power management method, and power management program PR described above, the operating mode of the power supply system 2A is switched based on the amount of power stored in the power supply system 2A. When the amount of power stored in the power supply system 2A is below the power storage threshold Bth1, a power reception target value Vt11 corresponding to the maximum power Wmax in the power transmission request is selected from multiple power reception target values, the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 of the power supply system 2A is set to the power reception target value Vt11, and the power supply system 2A is set to the power reception mode. At this time, in the power supply system 2B, a power transmission target value Vt21 corresponding to the maximum power Wmax in the power transmission request is selected from multiple power transmission target values, and the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 of the power supply system 2B is set to the power transmission target value Vt21. As a result, the bidirectional DC / DC converter 9 of the power supply system 2B sets a power transmission target value V21 that minimizes the transmission loss at the maximum power Wmax, and the bidirectional DC / DC converter 9 of the power supply system 2A sets a power receiving target value Vt11 that minimizes the transmission loss at the maximum power Wmax. Therefore, the transmission loss in power transmission from the power supply system 2B to the power supply system 2A is reduced. When the power supply system 2A switches to the power transmission mode, the same control is performed, where the bidirectional DC / DC converter 9 of the power supply system 2A sets a power transmission target value Vt21 that minimizes the transmission loss at the maximum power Wmax, and the bidirectional DC / DC converter 9 of the power supply system 2B sets a power receiving target value Vt11 that minimizes the transmission loss at the maximum power Wmax. Therefore, the transmission loss in power transmission from the power supply system 2A to the power supply system 2B is reduced. From the above, it is possible to improve the power transmission efficiency between the power supply systems 2A and 2B.

[0104] When power supply system 2A is set to the power receiving mode, in response to a change request to change the transmission power value from maximum power Wmax to intermediate power Wmid, control unit 13 selects a power reception target value Vt12 corresponding to the intermediate power Wmid from among multiple power reception target values ​​and sets the target value of external bus voltage Vbus1 to power reception target value Vt12. At this time, in power supply system 2B, control unit 13 selects a power transmission target value Vt22 corresponding to the intermediate power Wmid from among multiple power transmission target values ​​and sets the target value of external bus voltage Vbus1 to power transmission target value Vt22. With this configuration, even if the transmission power value is changed, bidirectional DC / DC converter 9 of power supply system 2A sets the power reception target value Vt12 that minimizes the transmission loss at the changed transmission power value (intermediate power Wmid), and bidirectional DC / DC converter 9 of power supply system 2B sets the power transmission target value Vt22 that minimizes the transmission loss at the changed transmission power value (intermediate power Wmid). Therefore, even if the transmission power value is changed, the power transmission loss in the power transmission from the power supply system 2B to the power supply system 2A is reduced, and therefore the power transmission efficiency can be improved.

[0105] When power supply system 2A is set to the power transmission mode, in response to a change request to change the transmission power value from maximum power Wmax to medium power Wmid, control unit 13 selects a power transmission target value Vt22 corresponding to the medium power Wmid from among multiple power transmission target values ​​and sets the target value of external bus voltage Vbus1 to power transmission target value Vt22. At this time, in power supply system 2B, control unit 13 selects a power reception target value Vt12 corresponding to the medium power Wmid from among multiple power reception target values ​​and sets the target value of external bus voltage Vbus1 to power reception target value Vt12. With this configuration, even if the transmission power value is changed, bidirectional DC / DC converter 9 of power supply system 2A sets the power transmission target value Vt22 that minimizes the transmission loss at the changed transmission power value (medium power Wmid), and bidirectional DC / DC converter 9 of power supply system 2B sets the power reception target value Vt12 that minimizes the transmission loss at the changed transmission power value (medium power Wmid). Therefore, even if the transmission power value is changed, the transmission loss in the power transmission from the power supply system 2A to the power supply system 2B is reduced, and therefore the power transmission efficiency can be improved.

[0106] When the power supply system 2A is set to the power receiving mode, the control unit 13 cancels the power receiving mode in response to the amount of stored power in the power supply system 2A exceeding the power storage threshold Bth3. With this configuration, the power receiving mode can be canceled before the power supply system 2A receives an excessive supply of power. Therefore, the power supply system 2A can receive power from the power supply system 2B to an extent that the power supply system 2A does not receive an excessive supply of power.

[0107] When the power supply system 2A is set to the power transmission mode, the control unit 13 cancels the power transmission mode of the power supply system 2A in response to the amount of power stored in the power supply system 2A falling below the power storage threshold Bth4. With this configuration, the power transmission mode can be canceled before the amount of power stored in the power supply system 2A becomes insufficient. Therefore, it is possible to transmit power to the power supply system 2B to the extent that the amount of power stored in the power supply system 2A does not become insufficient.

[0108] Next, a power interchange system including an upper power management device according to another embodiment will be described with reference to Fig. 10. Fig. 10 is a functional block diagram of the upper power management device according to another embodiment. The power interchange system according to the another embodiment differs from power interchange system 1 mainly in that it includes an upper power management device 3A instead of the upper power management device 3, and in that the determination of each target value is performed by the upper power management device 3A instead of the power management devices 10 of power supply systems 2A and 2B. Other points are the same as those of power interchange system 1, so detailed description will be omitted.

[0109] 10 controls power transmission and reception (power interchange) between a power supply system 2A (first power supply system) and a power supply system 2B (second power supply system). Functionally, the upper power management device 3A includes a response unit 31, a storage unit 32, a determination unit 33, and an output unit 34.

[0110] The response unit 31 is a functional unit that responds to a power transmission request. When the response unit 31 receives a power transmission request from one of the power supply systems 2A, 2B, the response unit 31 transmits the power transmission request to the other power supply system. When the response unit 31 receives a power transmission possible response from the other power supply system in response to the power transmission request, the response unit 31 transmits a power transmission possible response to the power supply system that is making the power transmission request. When the response unit 31 receives a power transmission impossible response from the other power supply system in response to the power transmission request, the response unit 31 transmits a power transmission impossible response to the power supply system that is making the power transmission request.

[0111] The storage unit 32 is a functional unit that stores a combination group (first combination group) that is a plurality of combinations of power transmission target values ​​and power receiving target values ​​that minimize the transmission loss at different transmission power values. In this embodiment, the same combination group is used when transmitting power from the power supply system 2A to the power supply system 2B and when transmitting power from the power supply system 2B to the power supply system 2A. Therefore, the storage unit 32 is substantially the same as the storage unit 12.

[0112] The determiner 33 is a functional unit that determines a target value (hereinafter referred to as a "first target value") of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 (first converter) of the power supply system 2A and a target value (hereinafter referred to as a "second target value") of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 (second converter) of the power supply system 2B. Specifically, when a power transmission request is received from the power supply system 2A, the determiner 33 selects a combination from a group of combinations according to a transmission power value (for example, maximum power Wmax) in the power transmission request, determines a power reception target value included in the selected combination as the first target value, and determines a power transmission target value included in the selected combination as the second target value.

[0113] The output unit 34 is a functional unit that outputs a setting command (first setting command) for setting the first target value in the bidirectional DC / DC converter 9 of the power supply system 2A and a setting command (second setting command) for setting the second target value in the bidirectional DC / DC converter 9 of the power supply system 2B. The output unit 34 outputs (transmits) the setting commands to the power management devices 10 of the respective power supply systems.

[0114] Next, a series of processes of the power management method performed by the upper power management device 3A will be described with reference to Fig. 11. Fig. 11 is a flowchart showing a series of processes of the power management method performed by the upper power management device shown in Fig. 10. In this embodiment, as in the previous embodiment, it is agreed that a power supply system responding to a power transmission request will start transmitting power at maximum power Wmax. The series of processes in Fig. 11 are started when the upper power management device 3A receives a power transmission request. Here, a case where the power transmission request is transmitted by the power supply system 2A will be described.

[0115] 11, first, the response unit 31 transmits a power transmission request to the power supply system 2B (step S41). Then, the response unit 31 receives a power transmission possible response or a power transmission impossible response from (the power management device 10 of) the power supply system 2B as a response to the power transmission request.

[0116] Next, the response unit 31 determines whether the power supply system 2B is capable of transmitting power (step S42). Specifically, when the response unit 31 receives a power transmission possible response from the power supply system 2B, it determines that the power supply system 2B is capable of transmitting power. When the response unit 31 receives a power transmission impossible response from the power supply system 2B, it determines that the power supply system 2B is not capable of transmitting power. When it is determined in step S42 that the power supply system 2B is not capable of transmitting power (step S42; NO), the response unit 31 transmits a power transmission impossible response to the power supply system 2A (step S43), and the series of processes shown in FIG. 11 ends.

[0117] On the other hand, if it is determined in step S42 that the power supply system 2B is capable of transmitting power (step S42; YES), the determination unit 33 determines a first target value and a second target value (step S44). Specifically, the determination unit 33 selects a combination corresponding to the maximum power Wmax from the group of combinations in the storage unit 32. Then, the determination unit 33 determines the power reception target value included in the selected combination as the first target value, and determines the power transmission target value included in the selected combination as the second target value.

[0118] Next, the output unit 34 transmits a setting command to the power supply system 2A to set the first target value in the bidirectional DC / DC converter 9 of the power supply system 2A, and transmits a setting command to the power supply system 2B to set the second target value in the bidirectional DC / DC converter 9 of the power supply system 2B (step S45).

[0119] Then, when each power supply system (power management device 10 thereof) receives the setting command, the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 of the power supply system 2A is set to a first target value, and the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 of the power supply system 2B is set to a second target value. As a result, the power supply system 2A is set to the power receiving mode, and the power supply system 2B is set to the power transmitting mode. Therefore, power transmission from the power supply system 2B to the power supply system 2A starts at the maximum power Wmax while minimizing the power transmission loss. In other words, power interchange starts between the power supply systems 2A and 2B.

[0120] Next, the decision unit 33 determines whether a change request has been received (step S46). When a change request occurs in the power supply system 2A or the power supply system 2B, the power supply system 2A or the power supply system 2B (the power management device 10 thereof) transmits the transmission power value together with the change request to the upper power management device 3A. Here, the midpoint power Wmid is used as the transmission power value transmitted together with the change request.

[0121] When a change request is received from the power supply system 2A or the power supply system 2B (step S46; YES), the determination unit 33 determines a first target value and a second target value corresponding to the medium power Wmid (step S44). Specifically, the determination unit 33 selects a combination corresponding to the medium power Wmid from the group of combinations in the storage unit 32. Then, the determination unit 33 determines the power reception target value included in the selected combination as the first target value, and determines the power transmission target value included in the selected combination as the second target value.

[0122] Next, the output unit 34 transmits a setting command to the power supply system 2A to set the first target value in the bidirectional DC / DC converter 9 of the power supply system 2A, and transmits a setting command to the power supply system 2B to set the second target value in the bidirectional DC / DC converter 9 of the power supply system 2B (step S45).

[0123] Then, when each power supply system (power management device 10 thereof) receives the setting command, the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 of the power supply system 2A is set to a first target value, and the target value of the external bus voltage Vbus1 in the bidirectional DC / DC converter 9 of the power supply system 2B is set to a second target value. As a result, power is transmitted from the power supply system 2B to the power supply system 2A at the medium power Wmid while minimizing the power transmission loss. Thereafter, if the decision unit 33 receives another change request, steps S44 to S46 are performed again.

[0124] On the other hand, if the decision unit 33 has not received a change request (step S46; NO), the decision unit 33 determines whether or not a stop request has been received (step S47). The stop request may be transmitted from the power supply system 2A or the power supply system 2B. If the decision unit 33 has not received a stop request (step S47; NO), step S46 is performed again.

[0125] On the other hand, if the decision unit 33 receives a stop request (step S47; YES), the output unit 34 transmits a stop command to the power supply systems 2A and 2B (step S48). Then, upon receiving the stop command, the power management device 10 of the power supply system 2A stops the bidirectional DC / DC converter 9, thereby canceling the power receiving mode of the power supply system 2A and setting the power supply system 2A to the normal mode. Similarly, upon receiving the stop command, the power management device 10 of the power supply system 2B stops the bidirectional DC / DC converter 9, thereby canceling the power transmitting mode of the power supply system 2B and setting the power supply system 2B to the normal mode.

[0126] This completes the series of processes shown in FIG.

[0127] Similar processing is performed when the power supply system 2B transmits a power transmission request. Note that this case differs from the case when the power supply system 2A transmits a power transmission request in the following respects. In step S44, the determination unit 33 selects a combination corresponding to the maximum power Wmax from the group of combinations, determines the power transmission target value included in the selected combination as the first target value, and determines the power reception target value included in the selected combination as the second target value. If the determination unit 33 receives a change request in step S46, in step S44 the determination unit 33 selects a combination corresponding to the intermediate power Wmid from the group of combinations in the storage unit 32, determines the power transmission target value included in the selected combination as the first target value, and determines the power reception target value included in the selected combination as the second target value.

[0128] When the above-described upper power management device 3A receives a power transmission request from the power supply system 2A, it selects a combination from a group of combinations according to the maximum power Wmax in the power transmission request, determines the power reception target value included in the selected combination as the first target value, and determines the power transmission target value included in the selected combination as the second target value. As a result, the bidirectional DC / DC converter 9 of the power supply system 2A sets a power reception target value that minimizes the power transmission loss at the maximum power Wmax, and the bidirectional DC / DC converter 9 of the power supply system 2B sets a power transmission target value that minimizes the power transmission loss at the maximum power Wmax. Therefore, the power transmission loss in the power transmission from the power supply system 2B to the power supply system 2A is reduced. As a result, the power transmission efficiency between the power supply systems 2A and 2B can be improved.

[0129] When receiving a power transmission request from the power supply system 2B, the determination unit 33 selects a combination from the combination group according to the maximum power Wmax in the power transmission request, determines the power reception target value included in the selected combination as the second target value, and determines the power transmission target value included in the selected combination as the first target value. According to this configuration, a common combination group is used for transmitting power from the power supply system 2A to the power supply system 2B and for transmitting power from the power supply system 2B to the power supply system 2A. Therefore, it is sufficient to prepare one combination group, which simplifies the configuration of the upper power management device 3A.

[0130] The power management device, upper level power management device, power management method, and power management program according to the present disclosure are not limited to the above embodiments.

[0131] In the above embodiment, the same combination group (table) is used when transmitting power from the power supply system 2A to the power supply system 2B and when transmitting power from the power supply system 2B to the power supply system 2A. However, if the bidirectional DC / DC converter 9 of the power supply system 2A and the bidirectional DC / DC converter 9 of the power supply system 2B have different characteristics (input / output characteristics and input / output impedance), the combination that minimizes the transmission loss when transmitting power from the power supply system 2A to the power supply system 2B may differ from the combination that minimizes the transmission loss when transmitting power from the power supply system 2B to the power supply system 2B.

[0132] For example, in one embodiment, the storage unit 12 may further store another combination group (second combination group) different from the combination group. In this case, the combination group is a plurality of combinations of power transmission target values ​​and power receiving target values ​​that minimize the transmission loss at different transmission power values ​​when transmitting power from the power supply system 2B to the power supply system 2A. The other combination group is a plurality of combinations of power transmission target values ​​and power receiving target values ​​that minimize the transmission loss at different transmission power values ​​when transmitting power from the power supply system 2A to the power supply system 2B.

[0133] In this modification, when transmitting power from the power supply system 2B to the power supply system 2A, the control unit 13 selects a target value from a combination group. On the other hand, when transmitting power from the power supply system 2A to the power supply system 2B, the control unit 13 selects a target value from another combination group. For example, when a power transmission request is transmitted from the power supply system 2A, the control unit 13 of the power supply system 2A selects a power reception target value corresponding to the transmission power value (for example, maximum power Wmax) in the power transmission request from among a plurality of power reception target values ​​included in the combination group, and the control unit 13 of the power supply system 2B selects a power transmission target value corresponding to the transmission power value (for example, maximum power Wmax) in the power transmission request from among a plurality of power transmission target values ​​included in the combination group. On the other hand, when a power transmission request is sent from the power supply system 2B, the control unit 13 of the power supply system 2A selects a power transmission target value corresponding to the power transmission power value (e.g., maximum power Wmax) in the power transmission request from among a plurality of power transmission target values ​​included in another combination group, and the control unit 13 of the power supply system 2B selects a power reception target value corresponding to the power transmission power value (e.g., maximum power Wmax) in the power transmission request from among a plurality of power reception target values ​​included in another combination group.

[0134] Similarly, in another embodiment, the storage unit 32 may further store another combination group different from the combination group. In this case, the combination group is a plurality of combinations of power transmission target values ​​and power receiving target values ​​that minimize the transmission loss at different transmission power values ​​when transmitting power from the power supply system 2B to the power supply system 2A. The other combination group is a plurality of combinations of power transmission target values ​​and power receiving target values ​​that minimize the transmission loss at different transmission power values ​​when transmitting power from the power supply system 2A to the power supply system 2B.

[0135] In this modification, when power is transmitted from the power supply system 2B to the power supply system 2A, the determination unit 33 selects a target value from a combination group. On the other hand, when power is transmitted from the power supply system 2A to the power supply system 2B, the determination unit 33 selects a target value from another combination group. For example, when the determination unit 33 receives a power transmission request from the power supply system 2A, it selects a combination (first combination) according to a transmission power value (e.g., maximum power Wmax) in the power transmission request from the combination group, determines a power reception target value included in the selected combination as the first target value, and determines a power transmission target value included in the selected combination as the second target value. On the other hand, when the determination unit 33 receives a power transmission request from the power supply system 2B, it selects a combination (second combination) according to a transmission power value (e.g., maximum power Wmax) in the power transmission request from another combination group, determines a power reception target value included in the selected combination as the second target value, and determines a power transmission target value included in the selected combination as the first target value.

[0136] According to these configurations, different combination groups are used when transmitting power from power supply system 2A to power supply system 2B and when transmitting power from power supply system 2B to power supply system 2A. Therefore, even when the characteristics of the bidirectional DC / DC converter 9 of power supply system 2A and the characteristics of the bidirectional DC / DC converter 9 of power supply system 2B differ, for example, power transmission loss can be reduced, thereby improving power transmission efficiency.

[0137] In the above-described embodiments and their modified examples, the transmission power value in the power transmission request is not necessarily limited to the maximum power Wmax, and may be any value among the transmission power values ​​stored in the storage unit 12 or the storage unit 32. Similarly, the transmission power value in the change request is not necessarily limited to the intermediate power Wmid, and may be any value among the transmission power values ​​stored in the storage unit 12 or the storage unit 32. For example, the power management device 10 of each power supply system may transmit a desired transmission power value together with the power transmission request or the change request.

[0138] At least one of power conditioner 52, AC / DC converter 62, converter 7, bidirectional DC / DC converter 83, and bidirectional DC / DC converter 9 may not have a power measurement function. In this case, power management device 10 may obtain the measurement value of each power from the measurement value of the voltage measured by the voltage sensor and the measurement value of the current measured by the current sensor.

[0139] The power supply device 5 may include another power generation device instead of the renewable energy power generation device 51.

[0140] The auxiliary power supply 6 may include a power generation device instead of the commercial power supply 61. An example of a power generation device is a diesel generator. In this case, the number of auxiliary power supplies 6 is not limited to one and can be changed appropriately as needed. When the auxiliary power supply 6 does not include the commercial power supply 61, the power supply systems 2A and 2B are also referred to as independent DC power supply systems. The auxiliary power supply 6 may be used only when the power supply systems 2A and 2B are started up. For example, when a power shortage occurs in the power supply system 2A, the power supply system 2A may first receive power from the power supply system 2B, and if power cannot be supplied from the power supply system 2B, the power supply system 2A may receive power from the auxiliary power supply 6.

[0141] In the above-described embodiment and their modified examples, each of the power conditioner 52, AC / DC converter 62, converter 7, bidirectional DC / DC converter 83, and bidirectional DC / DC converter 9 operates on a DC voltage generated within the device. Alternatively, each of the power supply systems 2A and 2B may include a power supply unit, and the power supply unit may generate a DC voltage having a constant voltage value from the internal bus voltage Vbus2 (first internal bus voltage, second internal bus voltage) of the internal DC bus B2 (first internal DC bus, second internal DC bus), and supply the DC voltage (power) to each device.

[0142] The power supply system 2A does not have to include the renewable energy power generation device 51. In this case, the renewable energy power generation device 51 provided outside the power supply system 2A may be connected to the internal DC bus B2 via a power conditioner 52 included in the power supply system 2A.

[0143] The power supply system 2A does not necessarily have to include the commercial power supply 61. In this case, the commercial power supply 61 provided outside the power supply system 2A may be connected to the internal DC bus B2 via an AC / DC converter 62 included in the power supply system 2A.

[0144] (Addendum) [1] an acquisition unit that acquires the amount of stored power stored in a power supply system connected to another power supply system via an external DC bus; a control unit that switches an operation mode of the power supply system by controlling a converter that can bidirectionally convert an external bus voltage supplied to the external DC bus and an internal bus voltage supplied to an internal DC bus that supplies DC power within the power supply system; a storage unit configured to store a plurality of power receiving target values, which are target values ​​of the external bus voltage in the converter when power is transmitted from the other power supply system to the power supply system, and a plurality of power transmission target values, which are target values ​​of the external bus voltage in the converter when power is transmitted from the power supply system to the other power supply system; Equipped with the plurality of power receiving target values ​​are target values ​​that minimize power transmission loss among different power transmission power values, the plurality of power transmission target values ​​are target values ​​that minimize power transmission loss among different power transmission power values, The control unit when the amount of stored power falls below a first power storage threshold, transmitting a first power transmission request to an upper power management device that manages power transmission and reception between the power supply system and the other power supply system, selecting a first power reception target value corresponding to the first transmission power value in the first power transmission request from among the plurality of power reception target values, and setting a target value of the external bus voltage to the first power reception target value, thereby setting the power supply system to a power reception mode; and when the stored amount of power exceeds a second power storage threshold that is greater than the first power storage threshold and a second power transmission request is received from the other power supply system via the higher-level power management device, the power management device selects a first power transmission target value corresponding to a second transmission power value in the second power transmission request from among the plurality of power transmission target values, and sets a target value of the external bus voltage to the first power transmission target value, thereby setting the power supply system to a power transmission mode. [2] [1] The power management device described in [1], wherein when the power supply system is set to the power receiving mode, in response to a change request to change the first transmission power value to a third transmission power value, the control unit selects a second power receiving target value corresponding to the third transmission power value from among the plurality of power receiving target values, and sets the target value of the external bus voltage to the second power receiving target value. [3] [1] or [2]. The power management device according to [1] or [2], wherein when the power supply system is set to the power transmission mode, in response to a change request to change the second transmission power value to a fourth transmission power value, the control unit selects a second transmission target value corresponding to the fourth transmission power value from among the plurality of transmission target values, and sets the target value of the external bus voltage to the second transmission target value. [4] The power management device according to any one of [1] to [3], wherein when the power supply system is set to the power receiving mode, the control unit cancels the power receiving mode in response to the stored power amount exceeding a first stop threshold that is smaller than the second storage threshold and larger than the first storage threshold. [5] The power management device according to any one of [1] to [4], wherein when the power supply system is set to the power transmission mode, the control unit cancels the power transmission mode in response to the stored power amount falling below a second stop threshold that is smaller than the second storage threshold and larger than the first storage threshold. [Explanation of symbols]

[0145] 1...power interchange system, 10...power management device, 11...acquisition unit, 12...storage unit, 13...control unit, 100...computer, 2A...power supply system (first power supply system), 2B...power supply system (other power supply system, second power supply system), 3, 3A...upper power management device, 32...storage unit, 33...determination unit, 34...output unit, 9...bidirectional DC / DC converter (first converter, second converter), B1...external DC bus, B2...internal DC bus (first internal DC bus, second internal DC bus), Bth1...storage threshold (first storage threshold), Bth2...storage threshold (second power storage threshold), Bth3...power storage threshold (first stop threshold), Bth4...power storage threshold (second stop threshold), PR...power management program, Vbus1...external bus voltage, Vbus2...internal bus voltage (first internal bus voltage, second internal bus voltage), Vt11...power receiving target value (first power receiving target value), Vt12...power receiving target value (second power receiving target value), Vt21...power transmission target value (first power transmission target value), Vt22...power transmission target value (second power transmission target value), Wmax...maximum power (first transmission power value, second transmission power value), Wmid...intermediate power (third transmission power value, fourth transmission power value).

Claims

1. an acquisition unit that acquires the amount of stored power stored in a power supply system connected to another power supply system via an external DC bus; a control unit that switches an operation mode of the power supply system by controlling a converter that can bidirectionally convert an external bus voltage supplied to the external DC bus and an internal bus voltage supplied to an internal DC bus that supplies DC power within the power supply system; a storage unit configured to store a plurality of power receiving target values, which are target values ​​of the external bus voltage in the converter when power is transmitted from the other power supply system to the power supply system, and a plurality of power transmission target values, which are target values ​​of the external bus voltage in the converter when power is transmitted from the power supply system to the other power supply system; Equipped with the plurality of power receiving target values ​​are target values ​​that minimize power transmission loss among different power transmission power values, the plurality of power transmission target values ​​are target values ​​that minimize power transmission loss among different power transmission power values, The control unit when the stored power amount falls below a first power storage threshold, transmitting a first power transmission request to an upper power management device that manages power transmission and reception between the power supply system and the other power supply system, selecting a first power reception target value corresponding to a first transmission power value in the first power transmission request from among the plurality of power reception target values, and setting a target value of the external bus voltage to the first power reception target value, thereby setting the power supply system to a power reception mode; When the stored amount exceeds a second power storage threshold that is greater than the first power storage threshold and a second power transmission request is received from the other power supply system via the higher-level power management device, the power management device selects a first power transmission target value corresponding to a second transmission power value in the second power transmission request from the plurality of power transmission target values, and sets the target value of the external bus voltage to the first power transmission target value, thereby setting the power supply system to a power transmission mode.

2. 2. The power management device according to claim 1, wherein, when the power supply system is set to the power receiving mode, in response to a request to change the first transmission power value to a third transmission power value, the control unit selects a second power receiving target value corresponding to the third transmission power value from among the plurality of power receiving target values, and sets the target value of the external bus voltage to the second power receiving target value.

3. 3. The power management device according to claim 1, wherein when the power supply system is set to the power transmission mode, in response to a change request to change the second transmission power value to a fourth transmission power value, the control unit selects a second transmission target value corresponding to the fourth transmission power value from among the plurality of transmission target values, and sets the target value of the external bus voltage to the second transmission target value.

4. 3. The power management device according to claim 1, wherein when the power supply system is set to the power receiving mode, the control unit cancels the power receiving mode in response to the stored power amount exceeding a first stop threshold that is smaller than the second storage threshold and larger than the first storage threshold.

5. 3. The power management device according to claim 1, wherein when the power supply system is set to the power transmission mode, the control unit cancels the power transmission mode in response to the stored power amount falling below a second stop threshold that is smaller than the second storage threshold and larger than the first storage threshold.

6. An upper power management device that controls power transmission and reception between a first power supply system and a second power supply system that transmit and receive power to and from each other via an external DC bus, a determination unit that determines a first target value of an external bus voltage in a first converter that can bidirectionally convert an external bus voltage supplied to the external DC bus and a first internal bus voltage supplied to a first internal DC bus that supplies DC power in the first power supply system, and a second target value of the external bus voltage in a second converter that can bidirectionally convert the external bus voltage and a second internal bus voltage supplied to a second internal DC bus that supplies DC power in the second power supply system; an output unit that outputs a first setting command for setting the first target value in the first converter and a second setting command for setting the second target value in the second converter; a storage unit that stores a first combination group that is a plurality of combinations of power transmission target values ​​and power receiving target values ​​that minimize power transmission loss among different power transmission values; Equipped with When the determination unit receives a first power transmission request from the first power supply system, the upper power management device selects a first combination from the first combination group that corresponds to a first transmission power value in the first power transmission request, determines a power reception target value included in the first combination as the first target value, and determines a power transmission target value included in the first combination as the second target value.

7. 7. The upper power management device according to claim 6, wherein, when a second power transmission request is received from the second power supply system, the determination unit selects a second combination from the first combination group according to a second transmission power value in the second power transmission request, determines a power reception target value included in the second combination as the second target value, and determines a power transmission target value included in the second combination as the first target value.

8. the first combination group includes a plurality of combinations of a power transmission target value and a power receiving target value that minimize a power transmission loss at different power transmission power values ​​when transmitting power from the second power supply system to the first power supply system, the storage unit further stores a second combination group, which is a plurality of combinations of power transmission target values ​​and power receiving target values ​​that minimize power transmission loss at different transmission power values ​​when transmitting power from the first power supply system to the second power supply system; 7. The upper power management device according to claim 6, wherein, when a second power transmission request is received from the second power supply system, the determination unit selects a second combination from the second combination group according to a second transmission power value in the second power transmission request, determines a power reception target value included in the second combination as the second target value, and determines a power transmission target value included in the second combination as the first target value.

9. acquiring a stored amount of power stored in a power supply system connected to another power supply system via an external DC bus; When the amount of stored power is less than a first power storage threshold, transmitting a first power transmission request to an upper power management device that manages power transmission and reception between the power supply system and the other power supply system, and setting the power supply system to a power receiving mode; and when the stored power amount exceeds a second power storage threshold value that is greater than the first power storage threshold value and a second power transmission request is received from the other power supply system via the higher-level power management device, setting the power supply system to a power transmission mode; the step of setting the power supply system to the power receiving mode includes selecting a first power receiving target value corresponding to a first transmission power value in the first power transmission request from a plurality of power receiving target values, and setting a target value of the external bus voltage of a converter capable of bidirectionally converting between an external bus voltage supplied to the external DC bus and an internal bus voltage supplied to an internal DC bus that supplies DC power within the power supply system to the first power receiving target value, thereby setting the power supply system to the power receiving mode; in the step of setting the power transmission mode, a first power transmission target value corresponding to a second power transmission value in the second power transmission request is selected from a plurality of power transmission target values, and a target value of the external bus voltage in the converter is set to the first power transmission target value, thereby setting the power supply system to the power transmission mode; the plurality of power receiving target values ​​are target values ​​of the external bus voltage in the converter when transmitting power from the other power supply system to the power supply system, and are target values ​​that minimize power transmission loss at mutually different transmission power values; the plurality of power transmission target values ​​are target values ​​of the external bus voltage in the converter when transmitting power from the power supply system to the other power supply system, and are target values ​​that minimize transmission loss at mutually different transmission power values.

10. acquiring a stored amount of power stored in a power supply system connected to another power supply system via an external DC bus; When the amount of stored power is less than a first power storage threshold, transmitting a first power transmission request to an upper power management device that manages power transmission and reception between the power supply system and the other power supply system, and setting the power supply system to a power receiving mode; a step of setting the power supply system to a power transmission mode when the stored power amount exceeds a second power storage threshold value that is greater than the first power storage threshold value and a second power transmission request is received from the other power supply system via the higher-level power management device, the step of setting the power supply system to the power receiving mode includes selecting a first power receiving target value corresponding to a first transmission power value in the first power transmission request from a plurality of power receiving target values, and setting a target value of the external bus voltage of a converter capable of bidirectionally converting between an external bus voltage supplied to the external DC bus and an internal bus voltage supplied to an internal DC bus that supplies DC power within the power supply system to the first power receiving target value, thereby setting the power supply system to the power receiving mode; in the step of setting the power transmission mode, a first power transmission target value corresponding to a second power transmission value in the second power transmission request is selected from a plurality of power transmission target values, and a target value of the external bus voltage in the converter is set to the first power transmission target value, thereby setting the power supply system to the power transmission mode; the plurality of power receiving target values ​​are target values ​​of the external bus voltage in the converter when transmitting power from the other power supply system to the power supply system, and are target values ​​that minimize power transmission loss at mutually different transmission power values; the plurality of power transmission target values ​​are target values ​​of the external bus voltage in the converter when transmitting power from the power supply system to the other power supply system, and are target values ​​that minimize transmission loss at different transmission power values.

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