Power Supply System and Charge / Discharge System

Abstract

To provide a power supply system capable of linking an operation of a power generation device to an operation of a charge / discharge device.SOLUTION: In a power supply system, a charge / discharge device 20, in an abnormal state where a power supply from a power system 1 is not performed properly, operates in an autonomous operation mode of adjusting charge power or discharge power so that voltage and a frequency of power at an autonomous connection path may be kept to target voltage and a target frequency, in which the target voltage is determined by a relationship in which the voltage becomes higher as a remaining quantity of stored power of the charge / discharge device 20 becomes larger. A power generation device 30, when a high voltage condition is not satisfied, operates in a normal output mode of adjusting supply power to a value determined by a supply power determination rule, and when the high voltage condition is satisfied, operates in an output suppression mode of adjusting the supply power to a value smaller than the value determined by the supply power determination rule.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power supply system including a charging and discharging device, a power generation device, and a connection switching unit that switches a connection path between the charging and discharging device and the power generation device, and a charging and discharging system including the charging and discharging device and the switching unit.

Background Art

[0002] Patent Document 1 (Japanese Patent Application Laid-Open No. 2015-35893) describes a power supply system including a storage battery (23), a fuel cell (24), and a connection switching unit (switch 34, switches 55 and 56) that switches a connection path between the storage battery (23) and the fuel cell (24). In this power supply system, in a normal state where power supply from the power grid is being performed normally, the storage battery (23) and the fuel cell (24) are connected to each other and connected to the power grid by the operation of the connection switching unit. On the other hand, in an abnormal state where power supply from the power grid is not being performed normally, the storage battery (23) and the fuel cell (24) are connected to each other and electrically disconnected from the power grid by the operation of the connection switching unit.

[0003] Also, in the power supply system described in Patent Document 1, a current sensor (37) is provided upstream of a branch breaker (32) to which the fuel cell (24) and a load (60) are connected. Then, in a normal state where power supply from the power grid is being performed normally, the fuel cell (24) determines whether all the power output from the fuel cell (24) is consumed by the load (60), that is, whether reverse power flow to the power grid is occurring, based on the measurement result of the current sensor (37), and controls the output power so that reverse power flow to the power grid does not occur.

[0004] In addition, Patent Document 1 also describes that by communication between a power conversion device (50) connected to the storage battery (23) and the fuel cell (24), the output of the current sensor (37) is invalidated and power supply from the fuel cell (24) to the storage battery (23) is permitted.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In Patent Document 1, if necessary, for example, when the storage battery (23) needs to be charged, it is considered possible to communicate with the fuel cell (24) and charge the storage battery (23) with the power supplied from the fuel cell (24).

[0007] However, when communicating between the power conversion device (50) connected to the storage battery (23) and the fuel cell (24), if the communication quality deteriorates or communication becomes impossible, the operation of charging the storage battery (23) with the power supplied from the fuel cell (24) also becomes impossible.

[0008] The present invention has been made in view of the above problems, and an object thereof is to provide a power system and a charge / discharge system capable of interlocking the operation of a power supply device such as a power generation device with the operation of a charge / discharge device.

Means for Solving the Problems

[0009] A characteristic configuration of a power system according to the present invention for achieving the above object is a connection switching unit that switches between a connection path between a charge / discharge device, a power generation device, and the charge / discharge device and the power generation device, and a connection path that connects the charge / discharge device and the power generation device to each other in a state where the charge / discharge device and the power generation device are electrically connected to a power system, and a self-supporting connection path that connects the charge / discharge device and the power generation device to each other in a state where the charge / discharge device and the power generation device are electrically disconnected from the power system. A power system comprising When the power supply from the power grid is in a normal state, the connection switching unit switches the connection path between the charge-discharge device and the power generation device to the system connection path. When the power supply from the power grid is in an abnormal state where the power supply is not being carried out normally, the connection path between the charge-discharge device and the power generation device is configured to be switched to the self-sufficient connection path. When in the abnormal state, the charge-discharge device operates in a self-sufficient operation mode in which it adjusts the charging power or discharging power so as to maintain the voltage and frequency of the power in the self-sufficient connection path at the target voltage and target frequency. The target voltage is determined in such a relationship that the voltage becomes higher as the remaining charge amount of the charge-discharge device is larger. While the power generation device does not satisfy a predetermined high voltage condition including that the voltage of the power in the connection path between the charge-discharge device and the power generation device is equal to or higher than a set voltage, it operates in a normal output mode in which it adjusts the power supplied to the connection path to a value determined by a predetermined power supply determination rule. While satisfying the high voltage condition, it operates in an output suppression mode in which it adjusts the power supplied to the connection path to a value smaller than the value determined by the power supply determination rule.

[0010] According to the above characteristic configuration, when the charge-discharge device operates in the self-sufficient operation mode and adjusts the charging power or discharging power so as to maintain the voltage and frequency of the power in the self-sufficient connection path at the target voltage and target frequency, the higher the remaining charge amount of the charge-discharge device itself, the higher the target voltage. That is, the higher the remaining charge amount of the charge-discharge device, the higher the voltage of the power in the connection path between the charge-discharge device and the power generation device. Also, while the power generation device satisfies a predetermined high voltage condition including that the voltage of the power in the connection path between the charge-discharge device and the power generation device is equal to or higher than a set voltage, it operates in an output suppression mode in which it adjusts the power supplied to the connection path to a value smaller than the value determined by the power supply determination rule for determining the power supply when the high voltage condition is not satisfied. That is, the power generation device reduces the power supply as the remaining charge amount of the charge-discharge device increases, and increases the power supply as the remaining charge amount of the charge-discharge device decreases. As a result, it is possible to prevent the remaining charge amount of the energy storage unit from becoming too low and from becoming too high. As described above, in this characteristic configuration, even though the charge / discharge device and the power generation device do not communicate with each other, the operation of the power generation device can be linked to the operation of the charge / discharge device, such that the greater the remaining charge amount of the charge / discharge device, the smaller the power supply of the power generation device.

[0011] Another characteristic configuration of the power supply system according to the present invention is that the charge / discharge device is connected to a first connection point of a power line connected to the power grid, the power generation device is connected to a second connection point of the power line, a power load device is connected to the second connection point of the power line, the first connection point and the second connection point are provided in that order as seen from the connection point of the power grid to the power line downstream, the charge / discharge device, the power generation device, and the power load device are connected to the connection path and the power grid is connected thereto, and the first connection point and the second connection point are included in the connection path, the charge / discharge device, the power generation device, and the power load device are connected to the self - contained connection path and the power grid is not connected thereto.

[0012] According to the above characteristic configuration, in the normal state where the power supply from the power grid is being performed normally, power can be supplied from at least one of the power grid, the charge / discharge device, and the power generation device to the power load device. Also, in the abnormal state where the power supply from the power grid is not being performed normally, power can be supplied from at least one of the charge / discharge device and the power generation device to the power load device.

[0013] Yet another characteristic configuration of the power supply system according to the present invention includes a connection device that switches between a first state in which the electrical resistance for the current flowing between the power generation device and the second connection point is relatively low and a second state in which the electrical resistance for the current flowing between the power generation device and the second connection point is relatively high, the connection device is configured to switch the connection state between the power generation device and the second connection point to the second state while in the abnormal state and satisfying the high - voltage condition.

[0014] According to the above characteristic configuration, in an abnormal state where power supply from the power system is not being carried out normally and while high voltage conditions are satisfied (i.e., while the remaining charge amount of the charge-discharge device is large), in the connection device, the electrical resistance for the current supplied by the power generation device becomes relatively high. That is, among the power supplied by the power generation device, the power consumed by the connection device becomes relatively large. As a result, the degree of increase in the remaining charge amount of the charge-discharge device can be reduced.

[0015] Another characteristic configuration of the power supply system according to the present invention includes an isolation transformer provided in the middle of the independent connection path between the charge-discharge device and the power generation device. The charge-discharge device is provided with a voltage measurement unit that measures the voltage of the power in the independent connection path on the side of the power generation device rather than the isolation transformer.

[0016] According to the above characteristic configuration, even if an isolation transformer is provided in the middle of the independent connection path, when the charge-discharge device operates in the independent operation mode, based on the measurement result of the voltage measurement unit that measures the voltage of the power in the independent connection path on the side of the power generation device rather than the isolation transformer, the charging power or the discharging power can be adjusted so as to maintain the voltage of the power in the independent connection path at the target voltage.

[0017] Another characteristic configuration of the power supply system according to the present invention is that the charge-discharge device includes a power storage unit and a power conversion unit. The connection path between the charge-discharge device and the power generation device is configured using a single-phase three-wire wiring having a first voltage line, a second voltage line, and a neutral line. The power conversion unit operates in the grid-connected operation mode when in the normal state and operates in the independent operation mode when in the abnormal state. When the power conversion unit is operating in the grid-connected operation mode, while the remaining charge amount of the power storage unit is equal to or higher than a first set amount lower than a predetermined upper limit remaining charge amount, it operates by prohibiting the acceptance of current from one or both of the first voltage line and the second voltage line of the connection path. When operating in the self - operating mode, the power conversion unit operates while allowing the acceptance of current from one or both of the first voltage line and the second voltage line of the connection path, regardless of the remaining charge amount of the power storage unit.

[0018] As described above, the power generation device operates in the output suppression mode while satisfying a predetermined high - voltage condition including that the voltage of the power in the connection path between the power generation device and the power storage / discharge device is equal to or higher than a set voltage. However, there may also be a timing when such operation in the output suppression mode is not executed. For example, it may be set that such operation is not performed for, for example, several minutes after starting the output of power from the power generation device to the connection path. Therefore, even when the power conversion unit is operating in the self - operating mode in an abnormal state and the remaining charge amount of the power storage unit is large, the supply power from the power generation device may not be reduced, and the increase in the remaining charge amount of the power storage / discharge device may progress quickly. And if the power storage / discharge device continues to be supplied with power from the power generation device even when it is fully charged, it may stop operating. However, in this characteristic configuration, when the power conversion unit is operating in the coordinated operation mode, while the remaining charge amount of the power storage unit is equal to or higher than a first set amount lower than a predetermined upper limit remaining charge amount, it operates by prohibiting the acceptance of current from one or both of the first voltage line and the second voltage line of the connection path. When operating in the self - operating mode, it operates while allowing the acceptance of current from one or both of the first voltage line and the second voltage line of the connection path, regardless of the remaining charge amount of the power storage unit. That is, even if the power generation device does not operate in the output suppression mode immediately after being connected to the connection path and power is supplied from the power generation device to the power storage / discharge device, the power storage unit can charge the power with a margin. As a result, the problem of the power storage / discharge device stopping operation can be avoided.

[0019] Another characteristic configuration of the power supply system according to the present invention is that the power storage / discharge device includes a power storage unit and a power conversion unit. The power storage / discharge device includes a solar cell device connected in parallel with the power storage unit to the power conversion unit of the power storage / discharge device. When the charging / discharging device operates in the self-operating mode, while the remaining charge amount of the power storage unit is equal to or more than a second set remaining amount and power is being supplied from the self-operating connection path to the power conversion unit, the power supplied from the solar cell device is not received by the power conversion unit.

[0020] As described above, the power generation device operates in the output suppression mode while a predetermined high voltage condition including that the voltage of the power in the connection path between the charging / discharging device and the power generation device is equal to or more than a set voltage is satisfied. However, there may also be a timing when such operation in the output suppression mode is not executed. For example, it may be set that such operation is not performed for, for example, several minutes after starting the output of power from the power generation device to the connection path. Therefore, even when the power conversion unit is operating in the self-operating mode in an abnormal state and the remaining charge amount of the power storage unit is large, the power supplied from the power generation device may not be reduced, and the increase in the remaining charge amount of the charging / discharging device may progress quickly. And when the charging / discharging device is fully charged and power continues to be supplied from the power generation device, the operation may stop. However, in this characteristic configuration, when the charging / discharging device operates in the self-operating mode, while the remaining charge amount of the power storage unit is equal to or more than a second set remaining amount and power is being supplied from the self-operating connection path to the power conversion unit, the power supplied from the solar cell device is not received by the power conversion unit. That is, even if it is necessary to charge the power storage unit with the power supplied from the power generation device in a situation where the remaining charge amount of the power storage unit is equal to or more than a second set remaining amount, it becomes unnecessary to charge the power storage unit with the power supplied from the solar cell device. As a result, compared with the case of charging the power storage unit with the power supplied from both the power generation device and the solar cell device, the progress of the increase in the remaining charge amount of the charging / discharging device can be moderated.

Brief Description of the Drawings

[0023]

Figure 1

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Embodiments for Carrying Out the Invention

[0024] <First Embodiment> The power supply system of the first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of the power supply system according to the first embodiment. As shown in the figure, the power supply system includes a charge / discharge device 20, a power generation device 30, and a connection switching unit 12. Specifically, a power line 2 is connected to a power grid 1. The charge / discharge device 20 is connected to a first connection point P1 of the power line 2 via a first switching unit 13. The power generation device 30 and a power load device 3 are connected to a second connection point P2 of the power line 2. The first connection point P1 and the second connection point P2 are provided in this order from the connection point of the power grid 1 to the power line 2, looking downstream. The power line 2 is configured using a single-phase three-wire wiring having a first voltage line, a second voltage line, and a neutral line. That is, the connection path, the associated connection path, and the self-supporting connection path described later are also configured using a single-phase three-wire wiring having a first voltage line, a second voltage line, and a neutral line.

[0025] The charge / discharge device 20 includes a power storage unit 21, a power conversion unit 22, and a charge / discharge control unit 23. The power storage unit 21 can be configured using a secondary battery such as a lithium-ion battery. The power conversion unit 22 can convert the power stored in the power storage unit 21 into power with a desired voltage, frequency, and phase and output it. The charge / discharge control unit 23 controls the operation of the power conversion unit 22 to control the output power (discharge power) from the power storage unit 21 and the input power (charge power) to the power storage unit 21. Also, the power conversion unit 22 can detect the voltage and current of the line to which the charge / discharge device 20 is connected.

[0026] The measurement result of a voltage measurement unit 9 that measures the voltage of the power on the power line 2 and the measurement result of a current measurement unit 10 that measures the current of the power on the power line 2, both upstream of the first connection point P1, i.e., on the power grid 1 side, are transmitted to the charge / discharge device 20.

[0027] The voltage measurement unit 9 is configured using, for example, an instrument transformer used to measure the voltage value of electric power. Then, the charge and discharge control unit 23 of the charge and discharge device 20 refers to the measurement result of the voltage measurement unit 9 to determine whether it is a normal state in which power supply from the power grid 1 is being performed normally, or an abnormal state in which power supply from the power grid 1 is not being performed normally. The charge and discharge control unit 23 can determine whether power supply from the power grid 1 is being performed normally based on the voltage value of the electric power transmitted from the voltage measurement unit 9, the frequency of the voltage, and the like. For example, if the voltage value transmitted from the voltage measurement unit 9 is equal to or greater than a predetermined value, the charge and discharge control unit 23 determines that it is a normal state in which power supply from the power grid 1 is being performed normally. If the voltage value transmitted from the voltage measurement unit 9 is less than the predetermined value, it can be determined that it is an abnormal state in which power supply from the power grid 1 is not being performed normally.

[0028] The current measurement unit 10 is configured using, for example, a current transformer (instrument current transformer) used to detect the current value of electric power. Then, the charge and discharge control unit 23 of the charge and discharge device 20 refers to the measurement result of the current measurement unit 10 to measure the power flowing from the power grid 1 toward the first connection point P1. The charge and discharge control unit 23 can derive the power value from the product of the current value transmitted from the current measurement unit 10 and the measurement result of the voltage measurement unit 9 or a predetermined voltage value (for example, 100V, 200V, etc.).

[0029] When the charging and discharging device 20 is in a normal state where power supply from the power system 1 is being carried out normally, it operates in the grid-connected operation mode. When it is in an abnormal state where power supply from the power system 1 is not being carried out normally, it operates in the self-sufficient operation mode. In the grid-connected operation mode, the charging and discharging device 20 controls the charging power or discharging power, for example, with reference to the measurement result of the current measurement unit 10 so that the power flowing from the power system 1 toward the first connection point P1 becomes zero or a predetermined power value. In the self-sufficient operation mode, the charging and discharging device 20 controls the charging power or discharging power, for example, so as to maintain the voltage and frequency of the power in the self-sufficient connection path described later at predetermined target voltage and target frequency. In the present embodiment, the above-mentioned target voltage is determined in such a relationship that the higher the state of charge (SOC) of the power storage unit 21 of the charging and discharging device 20, the higher the voltage.

[0030] The power generation device 30 includes a power generation unit 31, a power conversion unit 32, and a power generation control unit 33. The power generation unit 31 is configured by using, for example, a device including a fuel cell, or a device including an engine and a generator driven by the engine. The power conversion unit 32 can supply the power generated by the power generation device 30 as generated power converted into power with a desired voltage, frequency, and phase. Further, the power conversion unit 32 can detect the voltage and current of the line to which the power generation device 30 is connected.

[0031] To the power generation device 30, the measurement result of the current measurement unit 11 that measures the current of the power on the power line 2 between the second switching unit 14 and the second connection point P2, and the measurement result of the voltage measurement unit 15 that measures the voltage of the power on the power line 2 between the second switching unit 14 and the second connection point P2 are transmitted. Note that in FIG. 1, a form is depicted in which the voltage measurement unit 15 measures the voltage between the second connection point P2 and the power generation device 30, but that voltage is the same as the voltage at the second connection point P2 of the power line 2 (that is, the voltage of the power in the connection path between the charging and discharging device 20 and the power generation device 30, and the voltage between the second switching unit 14 and the second connection point P2).

[0032] The current measurement unit 11 is configured using, for example, a current transformer (instrument current transformer) used to detect the current value of electric power. Then, the power generation control unit 33 of the power generation device 30 refers to the measurement result of the current measurement unit 11 and measures the power from the first connection point P1 to the second connection point P2. For example, the power generation control unit 33 can derive the power value from the product of the current value transmitted from the current measurement unit 11 and a predetermined voltage value (e.g., 100V, 200V, etc.). And the power generation control unit 33 refers to the measurement result of the current measurement unit 11 and controls the generated power supplied from the power generation device 30.

[0033] The power generation control unit 33 of the power generation device 30 refers to the measurement result of the current measurement unit 11 and measures the power from the second switching unit 14 to the second connection point P2. For example, the power generation control unit 33 can derive the power value from the product of the current value transmitted from the current measurement unit 11 and a predetermined voltage value (e.g., 100V, 200V, etc.). And the power generation control unit 33 refers to the measurement result of the current measurement unit 11 and controls the generated power supplied from the power generation device 30.

[0034] The power generation control unit 33 of the power generation device 30 determines the operation mode to the normal output mode or the output suppression mode described later according to the voltage of the power in the connection path between the charge and discharge device 20 and the power generation device 30 measured by the voltage measurement unit 15.

[0035] The reason why the power generation control unit 33 of the power generation device 30 determines the operation mode according to the voltage of the power in the connection path between the charge and discharge device 20 and the power generation device 30 measured by the voltage measurement unit 15 is due to the voltage suppression function installed in the power generation device 30. According to this voltage suppression function, when the voltage of the power in the connection path between the charge and discharge device 20 and the power generation device 30 becomes too high, the power generation control unit 33 performs control to reduce the power supplied to the connection path between the charge and discharge device 20 and the power generation device 30. When this control is performed, it is expected that the voltage of the power in the connection path between the charge and discharge device 20 and the power generation device 30 measured by the voltage measurement unit 15 will decrease.

[0036] Specifically, while the power voltage in the connection path between the power storage and discharge device 20 and the power generation device 30 does not satisfy a predetermined high voltage condition including that the voltage is equal to or higher than a set voltage, the power generation control unit 33 operates in a normal output mode in which the power supplied to the connection path is adjusted to a value determined by a predetermined power supply determination rule. While the high voltage condition is satisfied, the power generation control unit 33 operates in an output suppression mode in which the power supplied to the connection path is adjusted to a value smaller than the value determined by the power supply determination rule.

[0037] In the case of the normal output mode, for example, the power generation device 30 refers to the measurement result of the current measurement unit 11 and determines the power supplied to the connection path between the power storage and discharge device 20 and the power generation device 30 according to a power supply determination rule such that the power from the second switching unit 14 toward the second connection point P2 becomes a predetermined negative value (that is, power of a predetermined value is supplied from the second connection point P2 to the second switching unit 14). Alternatively, in the case of the normal output mode, for example, the power generation device 30 may be set to determine the power supplied to the connection path between the power storage and discharge device 20 and the power generation device 30 according to a power supply determination rule such that the power from the second switching unit 14 toward the second connection point P2 becomes zero (that is, reverse power flow does not occur) by referring to the measurement result of the current measurement unit 11.

[0038] In the case of the output suppression mode, the power generation device 30 determines the power supplied to the connection path between the power storage and discharge device 20 and the power generation device 30 to be a value smaller than the generated power supplied in the case of operating in the normal output mode (that is, the value determined by the power supply determination rule). For example, the power supplied to the connection path between the power storage and discharge device 20 and the power generation device 30 is determined to be a power smaller than the value determined by the power supply determination rule by a predetermined value such as 100 W or 200 W. When the power generation control unit 33 outputs the power supplied in this output suppression mode to the connection path between the power storage and discharge device 20 and the power generation device 30 while the above high voltage condition is satisfied, the discharge power of the power storage and discharge device 20 becomes larger or the charging power becomes smaller than when the power supplied in the normal output mode is output. Therefore, the degree of decrease in the remaining power storage amount of the power storage unit 21 of the power storage and discharge device 20 becomes larger or the degree of increase becomes smaller.

[0039] Thus, in this embodiment, the power generation device 30 switches between the normal output mode and the output suppression mode according to whether or not the above high voltage condition is satisfied, and the charge / discharge device 20 determines the target voltage (that is, the voltage of the connection path between the charge / discharge device 20 and the power generation device 30). In this embodiment, as described above, the target voltage is determined such that the higher the remaining charge amount (SOC: state of charge) of the power storage unit 21 of the charge / discharge device 20, the higher the voltage.

[0040] In order to ensure the remaining discharge capacity from the charge / discharge device 20, it is preferable to prevent the remaining charge amount of the power storage unit 21 from becoming too low. In order to ensure the remaining charge capacity to the charge / discharge device 20, it is preferable to prevent the remaining charge amount of the power storage unit 21 from becoming too high. Therefore, when it is desired to increase the remaining charge amount of the power storage unit 21 of the charge / discharge device 20 or to reduce the degree of its decrease, the target voltage is lowered so that the power generation device 30 outputs a large supply power in the normal output mode. On the contrary, when it is desired to decrease the remaining charge amount of the power storage unit 21 of the charge / discharge device 20 or to reduce the degree of its increase, the target voltage is raised so that the power generation device 30 outputs a small supply power in the output suppression mode.

[0041] The connection switching unit 12 switches the connection path between the charge / discharge device 20 and the power generation device 30 to either the linked connection path in a state where the charge / discharge device 20 and the power generation device 30 are connected to each other and connected to the power grid 1 or the self-sustaining connection path in a state where the charge / discharge device 20 and the power generation device 30 are connected to each other and electrically disconnected from the power grid 1. Further, the connection switching unit 12 switches the connection path between the charge / discharge device 20 and the power generation device 30 so that the power load device 3 is connected to the above linked connection path in the normal state and the power load device 3 is connected to the above self-sustaining connection path in the abnormal state.

[0042] The connection switching unit 12 of this embodiment includes a first switching unit 13 and a second switching unit 14. The first switching unit 13 is provided between the charge and discharge device 20 and the first connection point P1 of the power line 2. The second switching unit 14 is provided between the first connection point P1 and the second connection point P2 in the middle of the power line 2.

[0043] The first switching unit 13 has a contact point a connected to the charge and discharge device 20, a contact point b connected to the first connection point P1 of the power line 2, and a contact point c connected to the second switching unit 14 via the connection line 4. And the first switching unit 13 is switched to either a state where the contact point a and the contact point b are connected or a state where the contact point a and the contact point c are connected. Both the first switching unit 13 and the second switching unit 14 or the first switching unit 13 correspond to the "switching unit for switching the connection destination of the charge and discharge device 20" of the present invention. And a charge and discharge system including the charge and discharge device 20 and the first switching unit 13, or a charge and discharge system including the charge and discharge device 20, the first switching unit 13, and the second switching unit 14 is realized.

[0044] The second switching unit 14 has a contact point a connected to the second connection point P2 of the power line 2, that is, connected to the power load device 3 and the power generation device 30, a contact point b connected to the first switching unit 13 via the connection line 4, and a contact point c connected to the first connection point P1 of the power line 2. And the second switching unit 14 is switched to either a state where the contact point a and the contact point b are connected or a state where the contact point a and the contact point c are connected.

[0045] The operation of the connection switching unit 12 is controlled by the charge and discharge control unit 23 of the charge and discharge device 20. Specifically, when the power supply from the power grid 1 is in a normal state, the charge and discharge control unit 23 switches the connection path between the charge and discharge device 20 and the power generation device 30 to a series connection path by the connection switching unit 12. When the power supply from the power grid 1 is in an abnormal state where the power supply is not normally performed, the connection path between the charge and discharge device 20 and the power generation device 30 is switched to a self - contained connection path.

[0046] FIG. 2 is a diagram showing an example when the power grid 1 is in a normal state in the power supply system. As shown in the figure, when the charge / discharge control unit 23 determines that the power grid 1 is in a normal state with reference to the measurement result of the voltage measurement unit 9, the first switching unit 13 is switched to a state where the contact point a and the contact point b are connected, and the second switching unit 14 is switched to a state where the contact point a and the contact point c are connected. As a result, the connection path between the charge / discharge device 20 and the power generation device 30 is switched to a linked connection path in a state where the charge / discharge device 20 and the power generation device 30 are connected to each other and connected to the power grid 1. That is, in the power supply system shown in FIGS. 1 and 2, the linked connection path is set to a path connecting the charge / discharge device 20, the first switching unit 13, the first connection point P1, the second switching unit 14, the second connection point P2, and the power generation device 30.

[0047] FIG. 3 is a diagram showing an example when the power grid 1 is in an abnormal state in the power supply system. As shown in the figure, when the charge / discharge control unit 23 determines that the power grid 1 is in an abnormal state with reference to the measurement result of the voltage measurement unit 9, the first switching unit 13 is switched to a state where the contact point a and the contact point c are connected, and the second switching unit 14 is switched to a state where the contact point a and the contact point b are connected. As a result, the connection path between the charge / discharge device 20 and the power generation device 30 is switched to a self-sustaining connection path in a state where the charge / discharge device 20 and the power generation device 30 are connected to each other and electrically disconnected from the power grid 1. That is, in the power supply system shown in FIGS. 1 and 3, the self-sustaining connection path is set to a path connecting the charge / discharge device 20, the first switching unit 13, the connection line 4, the second switching unit 14, the second connection point P2, and the power generation device 30.

[0048] As described above, both the first switching unit 13 and the second switching unit 14 or the first switching unit 13 connect the charge / discharge device 20 to a linked connection path that is electrically connected to the power grid 1 in the case of a normal state where the power supply from the power grid 1 is normally performed, and connect the charge / discharge device 20 to a self-sustaining connection path that is electrically disconnected from the power grid 1 in the case of an abnormal state where the power supply from the power grid 1 is not normally performed.

[0049] Next, the operation control of the charge / discharge device 20 in the power supply system of the first embodiment will be described. FIG. 4 is a flowchart for explaining the operation control of the charge / discharge device 20. In step #10, the charge / discharge control unit 23 determines whether the power grid 1 is in a normal state with reference to the measurement result of the voltage measurement unit 9. Then, when the power grid 1 is in a normal state, the charge / discharge control unit 23 proceeds to step #17 and operates the charge / discharge device 20 in the grid-connected operation mode. When the power grid 1 is in an abnormal state, the charge / discharge control unit 23 proceeds to step #11 and operates the charge / discharge device 20 in the self-operated mode.

[0050] In step #12, the charge / discharge control unit 23 determines whether the remaining charge amount of the power storage unit 21 is equal to or greater than a first stored charge amount (for example, SOC = 80%) stored in advance. Then, when the remaining charge amount is less than the first stored charge amount, the charge / discharge control unit 23 proceeds to step #16, sets the target voltage to an initial value (for example, 107V, etc.), and performs control to maintain the voltage and frequency of the self-connected path.

[0051] On the other hand, when the charge / discharge control unit 23 determines in step #12 that the remaining charge amount is equal to or greater than the first stored charge amount, it proceeds to step #13. In step #13, the charge / discharge control unit 23 determines whether the remaining charge amount is equal to or greater than a second stored charge amount (for example, SOC = 90%) that is greater than the first stored charge amount. When the remaining charge amount is equal to or greater than the second stored charge amount, it proceeds to step #15. When the remaining charge amount is less than the second stored charge amount (and equal to or greater than the first stored charge amount), it proceeds to step #14.

[0052] In step #14, the charge / discharge control unit 23 sets the target voltage to a first voltage (for example, 109V, etc.) that is higher than the initial value and performs control to maintain the voltage and frequency of the self-connected path.

[0053] In step #15, the charge / discharge control unit 23 sets the target voltage to a second voltage (for example, 110V, etc.) that is higher than the initial value and higher than the first voltage and performs control to maintain the voltage and frequency of the self-connected path.

[0054] As described above, when the charging / discharging device 20 operates in the self-operating mode and adjusts the charging power or the discharging power so as to maintain the voltage and frequency of the power in the self-connecting path at the target voltage and the target frequency, the higher the remaining battery level of the charging / discharging device 20 itself is, the higher the target voltage is set. That is, the higher the remaining battery level of the charging / discharging device 20 is, the higher the voltage of the power in the connection path between the charging / discharging device 20 and the power generation device 30 becomes. Further, while the power generation device 30 satisfies a predetermined high voltage condition including that the voltage of the power in the connection path between the charging / discharging device 20 and the power generation device 30 is equal to or higher than a set voltage, the power supply to the connection path is adjusted to a value smaller than the value determined by the power supply determination rule that determines the power supply when the high voltage condition is not satisfied, and the power generation device 30 operates in an output suppression mode. That is, the power generation device 30 reduces the power supply as the remaining battery level of the charging / discharging device 20 increases, and increases the power supply as the remaining battery level of the charging / discharging device 20 decreases. As a result, it is possible to prevent the remaining battery level of the charging / discharging device 20 from becoming too low and from becoming too high.

[0055] <Second Embodiment> The power supply system of the second embodiment is different from the above-described embodiment in that it includes a connection device 6 that connects the power generation device 30 to the second connection point P2 of the power line 2. The power supply system of the second embodiment will be described below, but the description of the same configuration as the above-described embodiment will be omitted.

[0056] FIG. 5 is a diagram showing the configuration of the power supply system of the second embodiment. As shown in the figure, in the power supply system, a connection device 6 is provided between the power generation device 30 and the second connection point P2 of the power line 2. The connection device 6 switches between a first state in which the electrical resistance for the current flowing between the power generation device 30 and the second connection point P2 is relatively low and a second state in which the electrical resistance for the current flowing between the power generation device 30 and the second connection point P2 is relatively high. The connection device 6 has a switch 7 and a power consumption unit 8 in parallel. The power consumption unit 8 is realized using, for example, an electrical resistor. The operation of the connection device 6 is controlled by the charge / discharge control unit 23 of the charge / discharge device 20.

[0057] The first state of the connection device 6 is when the switch 7 is in the closed state (i.e., when the switch 7 is connected). Since the electrical resistance of the switch 7 when current flows through it is smaller than that of the power consumption unit 8, more current flows through the switch 7 with a smaller electrical resistance than through the power consumption unit 8. Therefore, the electrical resistance for the current flowing between the power generation device 30 and the second connection point P2 becomes relatively low.

[0058] In contrast, the second state of the connection device 6 is when the switch 7 is in the open state (i.e., when the switch 7 is not connected), and all the current flows through the power consumption unit 8 with a large electrical resistance. Therefore, the electrical resistance for the current flowing between the power generation device 30 and the second connection point P2 becomes relatively high.

[0059] Based on the command from the charge and discharge control unit 23, the connection device 6 switches the connection state between the power generation device 30 and the second connection point P2 to the second state while in an abnormal state and satisfying the high voltage condition.

[0060] FIG. 6 is a diagram showing an example when the power grid 1 is in a normal state in the power supply system and the connection device 6 is in the first state (i.e., the switch 7 of the connection device 6 is in the closed state). As shown in the figure, when the charge and discharge control unit 23 refers to the measurement result of the voltage measurement unit 9 and determines that the power grid 1 is in a normal state, the first switching unit 13 is switched to a state where the contact point a and the contact point b are connected, and the second switching unit 14 is switched to a state where the contact point a and the contact point c are connected. As a result, the connection path between the charge and discharge device 20 and the power generation device 30 is switched to a linked connection path in a state where the charge and discharge device 20 and the power generation device 30 are connected to each other and connected to the power grid 1. That is, in the power supply system shown in FIGS. 5 and 6, the linked connection path is set to a path connecting the charge and discharge device 20, the first switching unit 13, the first connection point P1, the second switching unit 14, the second connection point P2, and the power generation device 30.

[0061] FIG. 7 is a diagram showing an example in the case where the power grid 1 is in an abnormal state and the connection device 6 is in the first state (i.e., the switch 7 of the connection device 6 is in the closed state) in the power supply system. As shown in the figure, when the charge / discharge control unit 23 determines that the power grid 1 is in an abnormal state with reference to the measurement result of the voltage measurement unit 9, the first switching unit 13 is switched to a state where the contact point a and the contact point c are connected, and the second switching unit 14 is switched to a state where the contact point a and the contact point b are connected. As a result, the connection path between the charge / discharge device 20 and the power generation device 30 is switched to a self - contained connection path in a state where the charge / discharge device 20 and the power generation device 30 are connected to each other and electrically disconnected from the power grid 1. That is, in the power supply system shown in FIGS. 5 and 7, the self - contained connection path is set to a path connecting the charge / discharge device 20, the first switching unit 13, the connection line 4, the second switching unit 14, the second connection point P2, and the power generation device 30.

[0062] FIG. 8 is a diagram showing an example in the case where the power grid 1 is in an abnormal state and the connection device 6 is in the second state (i.e., the switch 7 of the connection device 6 is in the open state) in the power supply system. As shown in the figure, when the charge / discharge control unit 23 determines that the power grid 1 is in an abnormal state with reference to the measurement result of the voltage measurement unit 9, the first switching unit 13 is switched to a state where the contact point a and the contact point c are connected, and the second switching unit 14 is switched to a state where the contact point a and the contact point b are connected. As a result, the connection path between the charge / discharge device 20 and the power generation device 30 is switched to a self - contained connection path in a state where the charge / discharge device 20 and the power generation device 30 are connected to each other and electrically disconnected from the power grid 1. That is, in the power supply system shown in FIGS. 5 and 8, the self - contained connection path is set to a path connecting the charge / discharge device 20, the first switching unit 13, the connection line 4, the second switching unit 14, the second connection point P2, and the power generation device 30.

[0063] Next, the operation control of the charge / discharge device 20 in the power supply system of the second embodiment will be described. FIG. 9 is a flowchart for explaining the operation control of the charge / discharge device 20. In Step #20, the charge / discharge control unit 23 determines whether the power grid 1 is in a normal state by referring to the measurement result of the voltage measurement unit 9. Then, when the power grid 1 is in a normal state, the charge / discharge control unit 23 proceeds to Step #27 and operates the charge / discharge device 20 in the grid-connected operation mode. When the power grid 1 is in an abnormal state, the charge / discharge control unit 23 proceeds to Step #21 and operates the charge / discharge device 20 in the self-sustained operation mode. When operating the charge / discharge device 20 in the grid-connected mode, as shown in FIG. 6, the switch 7 of the connection device 6 is switched to the closed state (the first state).

[0064] In Step #22, the charge / discharge control unit 23 determines whether the remaining charge amount of the power storage unit 21 is equal to or greater than a pre-stored first charge amount (for example, SOC = 80% or the like). Then, when the remaining charge amount is less than the first charge amount, the charge / discharge control unit 23 proceeds to Step #26, sets the target voltage to an initial value (for example, 107 V or the like), and performs control to maintain the voltage and frequency of the self-sustained connection path. In addition, as shown in FIG. 7, the charge / discharge control unit 23 switches the switch 7 of the connection device 6 to the closed state (the first state).

[0065] On the other hand, when the charge / discharge control unit 23 determines in Step #22 that the remaining charge amount is equal to or greater than the first charge amount, it proceeds to Step #23. In Step #23, the charge / discharge control unit 23 determines whether the remaining charge amount is equal to or greater than a second charge amount (for example, SOC = 90% or the like) that is greater than the first charge amount. When the remaining charge amount is equal to or greater than the second charge amount, it proceeds to Step #25. When the remaining charge amount is less than the second charge amount (and equal to or greater than the first charge amount), it proceeds to Step #24.

[0066] In Step #24, the charge / discharge control unit 23 sets the target voltage to a first voltage (for example, 109 V or the like) that is higher than the initial value, and performs control to maintain the voltage and frequency of the self-sustained connection path. In addition, as shown in FIG. 8, the charge / discharge control unit 23 switches the switch 7 of the connection device 6 to the open state (the second state).

[0067] In Process #25, the charge / discharge control unit 23 sets the target voltage to a second voltage (e.g., 110 V, etc.) that is higher than the initial value and higher than the first voltage, and performs control to maintain the voltage and frequency of the self - supporting connection path. In addition, as shown in FIG. 8, the charge / discharge control unit 23 switches the switch 7 of the connection device 6 to the open state (second state).

[0068] As described above, since the power system of the present embodiment includes the connection device 6, in an abnormal state where the power supply from the power grid 1 is not being performed normally, and while the high - voltage condition is satisfied (i.e., while the remaining charge of the charge / discharge device 20 is large), in the connection device 6, the electrical resistance for the current supplied by the power generation device 30 becomes relatively high. That is, among the power supplied by the power generation device 30, the power consumed by the connection device 6 becomes relatively large. As a result, it is possible to reduce the degree to which the remaining charge of the charge / discharge device 20 increases.

[0069] <Third Embodiment> The power system of the third embodiment is different from the above - described embodiment in that the control of charging the storage unit 21 is made different depending on whether the power conversion unit 22 of the charge / discharge device 20 is operating in the grid - connected operation mode or the self - supporting operation mode. The power system of the third embodiment will be described below, but the description of the same configuration as the above - described embodiment will be omitted. Note that the following description is made as a modification of the first embodiment, but the features of the present embodiment can also be applied to the second embodiment described above.

[0070] Also in the present embodiment, the power conversion unit 22 of the charge / discharge device 20 operates in the grid - connected operation mode when the power supply from the power grid 1 is in a normal state where the power supply is being performed normally under the control of the charge / discharge control unit 23, and operates in the self - supporting operation mode when the power supply from the power grid 1 is in an abnormal state where the power supply is not being performed normally. In addition, the above - described connection path, grid - connected connection path, and self - supporting connection path are configured using a single - phase three - wire wiring having a first voltage line, a second voltage line, and a neutral line. For example, the wiring connecting the power conversion unit 22 of the charge / discharge device 20 and the first switching unit 13 is configured using a single - phase three - wire wiring having a first voltage line, a second voltage line, and a neutral line.

[0071] As described above, while the power generation device 30 operates in the output suppression mode while satisfying a predetermined high voltage condition including that the voltage of the power in the connection path between the power storage and discharge device 20 and the power generation device 30 is equal to or higher than a set voltage, there may also be a timing when such operation in the output suppression mode is not executed. For example, it may be set that such operation is not performed for, for example, several minutes after starting the output of power from the power generation device 30 to the connection path. Therefore, even if the power conversion unit 22 is operating in the self-sustaining operation mode in an abnormal state and the remaining power storage amount of the power storage unit 21 is large, the supply power from the power generation device 30 is not reduced, and the increase in the remaining power storage amount of the power storage and discharge device 20 may proceed quickly. And when the power storage and discharge device 20 is fully charged and power is continuously supplied from the power generation device 30, it may stop operating.

[0072] In order to avoid such problems, in the power supply system of the present embodiment, when the power conversion unit 22 is operating in the linked operation mode under the control of the power storage and discharge control unit 23, while the remaining power storage amount of the power storage unit 21 is equal to or higher than a first set amount lower than a predetermined upper limit remaining power storage amount, it operates by prohibiting the acceptance of current from one or both of the first voltage line and the second voltage line of the connection path, and when operating in the self-sustaining operation mode, regardless of the remaining power storage amount of the power storage unit 21, it operates by allowing the acceptance of current from one or both of the first voltage line and the second voltage line of the connection path.

[0073] Specifically, when the upper limit of the remaining charge amount (upper limit SOC) is 100%, the first set remaining amount is set to a value such as 95%. When the power conversion unit 22 is operating in the linked operation mode, while the remaining charge amount of the power storage unit 21 is equal to or greater than the first set remaining amount, the power conversion unit 22 prohibits the acceptance of current from one or both of the first voltage line and the second voltage line that constitute the wiring between the power conversion unit 22 and the first switching unit 13 and operates. That is, while the remaining charge amount of the power storage unit 21 is equal to or greater than the first set remaining amount, the power conversion unit 22 prohibits the inflow of current from one phase of the wiring between the power conversion unit 22 and the first switching unit 13. Note that while the remaining charge amount of the power storage unit 21 is less than the first set remaining amount, the inflow of current into the power conversion unit 22 is allowed. When the power conversion unit 22 is operating in the self - operating mode under the control of the charge - discharge control unit 23, regardless of the remaining charge amount of the power storage unit 21, the power conversion unit 22 allows the acceptance of current from one or both of the first voltage line and the second voltage line of the above - mentioned connection path and operates.

[0074] That is, when the charge - discharge device 20 is operating in the linked operation mode, while the remaining charge amount of the power storage unit 21 is less than the first set remaining amount, charging of the power storage unit 21 is performed, but while the remaining charge amount of the power storage unit 21 is equal to or greater than the first set remaining amount, only discharge from the power storage unit 21 is performed. As a result, it is expected that the remaining charge amount of the power storage unit 21 while the charge - discharge device 20 is operating in the linked operation mode will be at most about the first remaining charge amount. Therefore, when the charge - discharge device 20 switches from the linked operation mode to the self - operating mode, it is expected that the power storage unit 21 has a remaining capacity to be charged from the first remaining charge amount to the upper limit of the remaining charge amount. Thus, for example, even if the power generation device 30 supplies power to the charge - discharge device 20 immediately after the power generation device 30 is connected to the above - mentioned connection path in an abnormal state such as a power outage and the power generation device 30 does not operate in the output suppression mode, the power storage unit 21 can charge the power with a margin. As a result, the problem of the charge - discharge device 20 stopping its operation can be avoided.

[0075] <Fourth Embodiment> The power supply system of the fourth embodiment differs from the above-described embodiments in that the charging control of the power storage unit 21 is different between the case where the power conversion unit 22 of the charge / discharge device 20 is operating in the grid-connected operation mode and the case where it is operating in the self-operating mode. The power supply system of the fourth embodiment will be described below, but the description of the same configuration as the above-described embodiments will be omitted. Note that the following description is made as a modification of the first embodiment, but the features of the present embodiment can also be applied to the above-described second embodiment and the above-described third embodiment.

[0076] FIG. 10 is a diagram showing the configuration of the power supply system of the fourth embodiment. As shown in the figure, the power supply system includes a solar cell device PV connected in parallel to the power storage unit 21 with respect to the power conversion unit 22 of the charge / discharge device 20. Specifically, the power conversion unit 22 includes an AC / DC conversion unit 22a connected to the first switching unit 13, and a DC / DC conversion unit 22b and a DC / DC conversion unit 22c connected in parallel to the DC part of the AC / DC conversion unit 22a. The power storage unit 21 is connected to the DC / DC conversion unit 22b, and the solar cell device PV is connected to the DC / DC conversion unit 22c. Then, the power conversion unit 22 adjusts the charging power to the power storage unit 21, the discharging power from the power storage unit 21, and the generated power received from the solar cell device PV under the control of the charge / discharge control unit 23.

[0077] Also in this embodiment, the charge / discharge device 20 operates in the grid-connected operation mode when the power supply from the power grid 1 is in a normal state where the power supply is performed normally, and operates in the self-operating mode when the power supply from the power grid 1 is in an abnormal state where the power supply is not performed normally.

[0078] In the case of the grid-connected operation mode, the charge / discharge device 20, for example, while receiving the power supplied from the solar cell device PV by the power conversion unit 22, performs operations such as an operation in which at least a part of the power supplied from the solar cell device PV flows back to the power grid 1, an operation in which at least a part of the power supplied from the solar cell device PV is consumed by the power load device 3, and an operation in which at least a part of the power supplied from the solar cell device PV is charged to the power storage unit 21.

[0079] In the case of the self-operating mode, the charge / discharge device 20 controls the charging power or the discharging power so as to maintain the voltage and frequency of the power in the self-connection path, for example, at predetermined target voltage and target frequency, which will be described later. In addition, when operating in the self-operating mode, if the remaining charge amount of the power storage unit 21 is equal to or greater than the second set remaining amount and power is being supplied from the self-connection path to the power conversion unit 22, the charge / discharge device 20 does not receive the power supplied from the solar cell device PV by the power conversion unit 22. In the following description, the case where the second set remaining amount is the same as the above-mentioned second charge amount, i.e., SOC = 90%, will be described, but the second set remaining amount may be a value different from the above-mentioned second charge amount.

[0080] FIG. 11 is a flowchart for explaining the operation control of the charge / discharge device 20 in the present embodiment. In step #30, the charge / discharge control unit 23 determines whether or not the power grid 1 is in a normal state with reference to the measurement result of the voltage measurement unit 9. Then, if the power grid 1 is in a normal state, the charge / discharge control unit 23 proceeds to step #37 to operate the charge / discharge device 20 in the grid-connected operation mode, and if the power grid 1 is in an abnormal state, the charge / discharge control unit 23 proceeds to step #31 to operate the charge / discharge device 20 in the self-operating mode.

[0081] In step #32, the charge / discharge control unit 23 determines whether or not the remaining charge amount of the power storage unit 21 is equal to or greater than a pre-stored first charge amount (for example, SOC = 80%, etc.). Then, if the remaining charge amount is less than the first charge amount, the charge / discharge control unit 23 proceeds to step #36 to set the target voltage to an initial value (for example, 100 V, etc.) and perform control to maintain the voltage and frequency of the self-connection path.

[0082] On the other hand, if the charge / discharge control unit 23 determines in step #32 that the remaining charge amount is equal to or greater than the first charge amount, it proceeds to step #33. In step #33, the charge / discharge control unit 23 determines whether or not the remaining charge amount is equal to or greater than a second charge amount (for example, SOC = 90%, etc.) that is greater than the first charge amount. If the remaining charge amount is equal to or greater than the second charge amount, it proceeds to step #35, and if the remaining charge amount is less than the second charge amount (and equal to or greater than the first charge amount), it proceeds to step #34.

[0083] In Step #34, the charge / discharge control unit 23 sets the target voltage to a first voltage (e.g., 107 V, etc.) higher than the initial value and performs control to maintain the voltage and frequency of the self-sustaining connection path.

[0084] In Step #35, the charge / discharge control unit 23 sets the target voltage to a second voltage (e.g., 109 V, etc.) higher than the initial value and higher than the first voltage and performs control to maintain the voltage and frequency of the self-sustaining connection path.

[0085] Next, in Step #38, the charge / discharge control unit 23 determines whether the power conversion unit 22 is receiving power from the self-sustaining connection path. That is, the charge / discharge control unit 23 determines whether power is being supplied from the power generation device 30 to the charge / discharge device 20. And when the power conversion unit 22 is receiving power from the self-sustaining connection path, the charge / discharge control unit 23 proceeds to Step #39 and operates so that the power conversion unit 22 does not receive the power supplied from the solar cell device PV. On the other hand, when the power conversion unit 22 is not receiving power from the self-sustaining connection path, the charge / discharge control unit 23 does not perform such an operation and the power conversion unit 22 receives the power supplied from the solar cell device PV.

[0086] Thus, when the charge / discharge device 20 operates in the self-sustaining operation mode, while the remaining charge amount of the power storage unit 21 is equal to or greater than the second set remaining amount (i.e., the second stored charge amount) and power is being supplied from the self-sustaining connection path to the power conversion unit 22, the power conversion unit 22 does not receive the power supplied from the solar cell device PV. That is, even if it is necessary to charge the power storage unit 21 with the power supplied from the power generation device 30 in a situation where the remaining charge amount of the power storage unit 21 is equal to or greater than the second set remaining amount, there is no need to charge the power storage unit 21 with the power supplied from the solar cell device PV. As a result, compared with the case of charging the power storage unit 21 with the power supplied from both the power generation device 30 and the solar cell device PV, the progress of the increase in the remaining charge amount of the charge / discharge device 20 can be slowed down.

[0087] <Another Embodiment> <1> In the above-described embodiment, specific examples were given for the configurations of the power supply system and the charge / discharge system, but those configurations can be changed as appropriate. In the above-described embodiment, a state in which the first switching unit 13 is configured separately from the charge / discharge device 20 is illustrated, but for example, the first switching unit 13 may be configured integrally with the charge / discharge device 20.

[0088] <2> In the above embodiment, the power supply system may include an isolation transformer 16 provided in the middle of the independent connection path between the charge / discharge device 20 and the power generation device 30. FIG. 12 is a diagram showing the configuration of a power supply system according to another embodiment, and is described as a modification of FIG. 1. As shown, the power supply system includes an isolation transformer 16 in the middle of the connection line 4 between the first switching unit 13 and the second switching unit 14 in the independent connection path. In addition, the charge / discharge device 20 includes a voltage measurement unit 24 that measures the voltage of the power on the connection line 4 as the independent connection path on the side of the power generation device 30 rather than the isolation transformer 16. By adopting such a configuration, even if an isolation transformer 16 is provided in the middle of the independent connection path, when the charge / discharge device 20 operates in the independent operation mode, based on the measurement result of the voltage measurement unit 24 that measures the voltage of the power on the independent connection path on the side of the power generation device 30 rather than the isolation transformer 16, the charging power or the discharging power can be adjusted to maintain the voltage of the power on the independent connection path at the target voltage.

[0089] <3> In the above-described embodiment, specific numerical values were given for the remaining charge amount and the voltage value, but those values are described for illustrative purposes and can be changed as appropriate.

[0090] <4> In the above-described embodiment, an example in which the voltage measurement unit 15 measures the voltage between the second switching unit 14 and the second connection point P2 (that is, the voltage at the second connection point P2 of the power line 2) was described, but the voltage measurement unit 15 may not be provided. For example, instead of the voltage measurement unit 15, the power generation device 30 may refer to the voltage measured by the power conversion unit 32 as the voltage between the second switching unit 14 and the second connection point P2 (the voltage at the second connection point P2 of the power line 2).

[0091] <5> The configurations disclosed in the above embodiments (including alternative embodiments) can be applied in combination with the configurations disclosed in other embodiments as long as there is no contradiction. Also, the embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope not departing from the object of the present invention.

Industrial Applicability

[0092] The present invention can be used in a power system and a charge / discharge system that can interlock the operation of a power supply device such as a power generation device with the operation of a charge / discharge device.

Explanation of Reference Numerals

[0093] 1 Power grid 2 Power line 3 Power load device 4 Connection line 6 Connection device 7 Switch 8 Power consumption section 9 Voltage measurement section 10 Current measurement section 11 Current measurement section 12 Connection switching section 13 First switching section (switching section) 14 Second switching section (switching section) 15 Voltage measurement section 16 Insulation transformer 20 Charge / discharge device 21 Energy storage section 22 Power conversion section 23 Charge / discharge control section 24 Voltage measurement section 30 Power generation device 31 Power generation section 32 Power conversion section 33 Power generation control section P1 First connection point P2 Second connection point

Claims

1. A power system comprising a connection switching unit that switches a connection path between a charge-discharge device, a power generation device, and a connection path between the charge-discharge device and the power generation device to either a connection connection path that connects the charge-discharge device and the power generation device to each other in a state where the charge-discharge device and the power generation device are electrically connected to a power system, or a self-supporting connection path that connects the charge-discharge device and the power generation device to each other in a state where the charge-discharge device and the power generation device are electrically disconnected from the power system, wherein the connection switching unit is configured to switch the connection path between the charge-discharge device and the power generation device to the connection connection path in a normal state where power supply from the power system is being performed normally, and to switch the connection path between the charge-discharge device and the power generation device to the self-supporting connection path in an abnormal state where power supply from the power system is not being performed normally, wherein the charge-discharge device operates in a self-operating mode in which, in the abnormal state, the charging power or the discharging power is adjusted so as to maintain the voltage and frequency of the power in the self-supporting connection path at a target voltage and a target frequency, and the target voltage is determined in such a relationship that the voltage becomes higher as the remaining charge amount of the charge-discharge device is larger, wherein the power generation device operates in a normal output mode in which, while a predetermined high voltage condition including that the voltage of the power in the connection path between the charge-discharge device and the power generation device is not less than a set voltage is not satisfied, the supply power to the connection path is adjusted to a value determined by a predetermined supply power determination rule, and operates in an output suppression mode in which, while the high voltage condition is satisfied, the supply power to the connection path is adjusted to a value smaller than the value determined by the supply power determination rule.

2. The charge-discharge device is connected to a first connection point of a power line connected to the power system, the power generation device is connected to a second connection point of the power line, a power load device is connected to the second connection point of the power line, the first connection point and the second connection point are provided in that order as seen from the connection point of the power system to the power line toward the downstream side, the connection connection path is connected to the charge-discharge device, the power generation device, and the power load device and is connected to the power system, and the first connection point and the second connection point are included in the connection connection path, The power system according to claim 1, wherein the self-supporting connection path is connected to the charge-discharge device, the power generation device, and the power load device and is not connected to the power system.

3. A connection device is provided for switching between a first state in which the electrical resistance for the current flowing between the power generation device and the second connection point is relatively low, and a second state in which the electrical resistance for the current flowing between the power generation device and the second connection point is relatively high. The power supply system according to claim 2, wherein the connection device switches the connection state between the power generation device and the second connection point to the second state while in the abnormal state and satisfying the high voltage condition.

4. An insulating transformer is provided in the middle of the independent connection path between the charge / discharge device and the power generation device. The power supply system according to any one of claims 1 to 3, wherein the charge / discharge device includes a voltage measurement unit that measures the voltage of the power in the independent connection path on the side of the power generation device with respect to the insulating transformer.

5. The charge / discharge device includes a power storage unit and a power conversion unit. The connection path between the charge / discharge device and the power generation device is configured using a single-phase three-wire wiring having a first voltage line, a second voltage line, and a neutral line. The power conversion unit operates in a grid-connected operation mode when in the normal state, and operates in the independent operation mode when in the abnormal state. When the power conversion unit is operating in the grid-connected operation mode, while the remaining charge amount of the power storage unit is equal to or higher than a first set remaining amount lower than a predetermined upper remaining charge amount, the power conversion unit prohibits accepting current from one or both of the first voltage line and the second voltage line constituting the connection path between the charge / discharge device and the power generation device and operates. The power supply system according to any one of claims 1 to 4, wherein when operating in the independent operation mode, regardless of the remaining charge amount of the power storage unit, the power conversion unit allows accepting current from one or both of the first voltage line and the second voltage line constituting the connection path between the charge / discharge device and the power generation device and operates.

6. The charge / discharge device includes a power storage unit and a power conversion unit. The charge / discharge device includes a solar cell device connected in parallel with the power storage unit to the power conversion unit of the charge / discharge device. The power supply system according to any one of claims 1 to 5, wherein when the charge / discharge device is operating in the independent operation mode, while the remaining charge amount of the power storage unit is equal to or higher than a second set remaining amount, when power is being supplied from the independent connection path to the power conversion unit, the power conversion unit does not receive the power supplied from the solar cell device.

Images