Power supply system

Abstract

To provide a power supply system capable of supplying stable AC power to a load without being affected by fluctuations in the voltage or frequency of a commercial power system or switching noise on an AC switch.SOLUTION: An uninterruptible power supply device 2 includes a converter 21 that converts AC power from an AC power source AC to DC power and supplies it to a DC connection bus DC, an inverter 22 that mutually converts the DC power on the DC connection bus DC and the AC power on a power supply line 40 to which a load L is connected, a power storage device 23 connected to the DC connection bus DC, and an AC switch 24 that sets the connection between the AC power supply AC and the converter 21 in a connected state when the AC power supply AC is in a normal state and sets the connection between the AC power supply AC and the converter 21 in a disconnected state when the AC power supply AC is in an abnormal state. A distributed power supply 3 is interconnected with the inverter 22 to supply the generated power to the power supply line 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a power supply system using distributed power sources and an uninterruptible power supply. [Background technology]

[0002] In recent years, power supply systems using distributed power sources such as solar cells and uninterruptible power supplies have been proposed (see, for example, Patent Document 1). The uninterruptible power supply in such a power supply system has one end connected to the commercial power grid, connecting the commercial power grid to the load, and is equipped with an AC switch that cuts off the connection between the commercial power grid and the load in the event of a commercial power grid failure, and the distributed power source is connected to the connection line between the AC switch and the load. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 6458891 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, in conventional technology, AC power from the commercial power grid is supplied directly to the load via an AC switch. This has the problem that fluctuations in the voltage and frequency of the commercial power grid (momentary power outages, momentary dips, surges, noise, etc.) and switching noise from the AC switch can make the AC power supplied to the load by distributed power sources connected to the commercial power grid unstable.

[0005] The object of the present invention is to solve the above-mentioned problems of the prior art and to provide a power supply system that can supply stable AC power to a load without being affected by fluctuations in the voltage and frequency of the commercial power grid or switching noise of AC switches. [Means for solving the problem]

[0006] Also The power supply system of the present invention is a power supply system that supplies power to a load using an uninterruptible power supply connected to an AC power source and a distributed power source that generates power on a separate system from the AC power source, wherein the uninterruptible power supply includes a converter that converts the AC power of the AC power source into DC power and supplies it to a DC connection bus, a bidirectional inverter that converts the DC power of the DC connection bus and the AC power of the power supply line to which the load is connected to each other, an energy storage device connected to the DC connection bus, and an AC switch that connects the AC power source and the converter when the AC power source is functioning normally and disconnects the AC power source and the converter when the AC power source is malfunctioning, and the distributed power source is connected to the AC power source and supplies generated power to the connection point between the AC switch and the converter. [Effects of the Invention]

[0007] According to the present invention, since AC power from an AC power source is supplied to the power supply line through a converter and a bidirectional inverter, the uninterruptible power supply and distributed power sources can be linked together to supply stable AC power to the load without being affected by fluctuations in the voltage and frequency of the commercial power grid or switching noise from AC switches. [Brief explanation of the drawing]

[0008] [Figure 1] This is a configuration diagram showing an example of the configuration of a first embodiment of the power supply system according to the present invention. [Figure 2] Figure 1 is an explanatory diagram illustrating the operation of the power supply system shown. [Figure 3] This is a configuration diagram showing an example of the configuration of a second embodiment of the power supply system according to the present invention. [Figure 4] Figure 3 is an explanatory diagram illustrating the operation of the power supply system shown. [Figure 5] This is a configuration diagram showing an example of the configuration of a third embodiment of the power supply system according to the present invention. [Figure 6] Figure 5 is an explanatory diagram illustrating the operation of the power supply system shown. [Figure 7] This is a configuration diagram showing an example of the configuration of a fourth embodiment of the power supply system according to the present invention. [Figure 8] Figure 7 is an explanatory diagram illustrating the operation of the power supply system shown. [Modes for carrying out the invention]

[0009] The embodiments of the present invention will be described in detail below with reference to the figures. In the following embodiments, components that perform similar functions are denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0010] (First Embodiment) The power supply system 1 of the first embodiment, as shown in Figure 1, includes an uninterruptible power supply (UPS) 2 that supplies power to a load L from an AC power source such as a commercial power grid, and a distributed power source 3 that supplies power to the load L generated on a separate system from the AC power source.

[0011] The uninterruptible power supply (UPS) 2 comprises a converter 21, an inverter 22, an energy storage device 23, an AC switch 24, and a control unit 25, and has an AC connection terminal T AC AC power supply to load connection terminal T L A power supply line 40 to which a load L is connected is connected to each of these. The control unit 25 has the function of controlling the converter 21, inverter 22, and AC switch 24, but these functions may be configured to be distributed among the converter 21, inverter 22, and AC switch 24. Also, in Figure 1, the solid lines connecting each component are power lines that supply power, and the dashed lines connecting each component are control lines.

[0012] Converter 21 is a power conversion device that converts alternating current to direct current. Converter 21 has an input terminal which is connected to an AC connection terminal T via an AC switch 24. AC The output terminals are connected to the DC connection bus.

[0013] The inverter 22 is a bidirectional power conversion device that converts power bidirectionally between AC and DC. One input / output terminal of the inverter 22 is connected to the DC connection bus DC, and the other input / output terminal is connected to the load connection terminal T L is connected.

[0014] The power storage device 23 is composed of a secondary battery such as a lithium-ion battery, a lead battery, or a nickel-hydrogen battery, or a capacitor. The power storage device 23 is connected to the DC connection bus DC, charges the DC power converted by the converter 21 and the inverter 22, and supplies the DC power converted by the inverter 22 into AC power by discharging.

[0015] The AC switch 24 is an AC power disconnect switch that connects and disconnects the AC power of the AC power source AC. One end of the AC switch 24 is connected to the AC power source AC, and the other end is connected to the input terminal of the converter 21.

[0016] The control unit 25 is an information processing unit that operates under program control such as a microcomputer. The control unit 25 controls the converter 21, the inverter 22, and the AC switch 24 according to the currents and voltages of each part of the uninterruptible power supply device 2 detected by current and voltage sensors (not shown).

[0017] The control unit 25 monitors the voltage and current of the AC connection terminal T AC to determine whether the AC power source AC is normal (power-on) or abnormal (power failure). When the determination is that the power source is normal, the control unit 25 connects the AC switch 24. When the determination is that the power source is abnormal, the control unit 25 disconnects the AC switch 24 to disconnect the uninterruptible power supply device 2 from the AC power source AC.

[0018] When the AC power source AC is normal, the control unit 25 operates the converter 21 and controls the operation of the converter 21 so that the DC connection bus DC reaches a preset voltage.

[0019] The control unit 25 operates the inverter 22 regardless of the state of the AC power supply. Furthermore, if the AC power supplied to the power supply line 40 is insufficient, that is, if the AC power supplied from the distributed power supply 3 is insufficient for the load power of the load L, the control unit 25 has the inverter 22 convert the DC power from the DC connection bus DC and supply the insufficient AC power to the power supply line 40.

[0020] The control unit 25, when there is a surplus of AC power supplied to the power supply line 40, that is, when the AC power supplied from the distributed power source 3 exceeds the load power of the load L, converts the surplus AC power into DC power using the inverter 22 and supplies it to the DC connection bus DC.

[0021] Furthermore, the control unit 25 has a function to detect the amount of charge stored in the energy storage device 23 and to determine whether the energy storage device 23 is fully charged or not. For example, the control unit 25 integrates the charging current and the discharge current of the energy storage device 23 and detects the amount of charge stored in the energy storage device 23 based on the difference between them. Alternatively, the amount of charge stored in the energy storage device 23 may be detected based on the terminal voltage of the energy storage device 23 or the like.

[0022] The distributed power source 3 is a small-scale power generation facility that generates electricity on a separate system from the AC power source, and is equipped with a power generation device 31 and a power conditioner (RCS) 32.

[0023] The power generation device 31 is a small-scale generator such as a solar cell, wind power generator, hydroelectric power generator, diesel power generator, or fuel cell, and the power conditioner 32 converts the power generated by the power generation device 31 into AC power that can be supplied to the load L and outputs it to the power supply line 40.

[0024] Next, the operation of the power supply system 1 under normal power conditions will be explained with reference to Figure 2(a). When the power supply is functioning normally, the control unit 25 of the uninterruptible power supply 2 connects the AC switch 24 and operates the converter 21 and inverter 22. As a result, the AC power of the AC power supply is converted to DC power by the converter 21, as shown by arrow A1, and supplied to the DC connection bus DC to charge the energy storage device 23.

[0025] The power conditioner 32 connects the power generated by the power generator 31 to the inverter 22, that is, it converts the AC power output by the inverter 22 into AC power with synchronized frequency, voltage, and phase, and supplies it to the power supply line 40 as shown by arrow A2.

[0026] If the power generated by the power generator 31 is insufficient for the load power of the load L, the deficit is supplied to the power supply line 40 from the DC connection bus DC through the inverter 22, as indicated by arrow A3.

[0027] If the power generated by the power generator 31 exceeds the load power of the load L, the surplus is supplied from the power supply line 40 to the DC connection bus DC via the inverter 22, as shown by arrow A4, and charges the energy storage device 23. If the energy storage device 23 is not fully charged, the control unit 25 sends a command to the power conditioner 32, and the power conditioner 32, upon detecting this, suppresses or stops the power generation of the power generator 31.

[0028] Next, the operation of the power supply system 1 in the event of a power supply abnormality will be explained with reference to Figure 2(b). In the event of a power supply abnormality, the control unit 25 of the uninterruptible power supply 2 shuts off the AC switch 24, stops the converter 21, and operates the inverter 22.

[0029] The power conditioner 32 connects the power generated by the power generator 31 to the inverter 22, that is, it converts the AC power output by the inverter 22 into AC power with synchronized frequency, voltage, and phase, and supplies it to the power supply line 40 as indicated by arrow B1.

[0030] If the power generated by the power generator 31 is insufficient to meet the load power of the load L, the deficit is supplied from the energy storage device 23 to the power supply line 40 via the inverter 22, as indicated by arrow B2.

[0031] If the power generated by the power generator 31 exceeds the load power of the load L, the surplus is charged to the energy storage device 23 from the power supply line 40 via the inverter 22, as indicated by arrow B3. If the energy storage device 23 is not fully charged, the control unit 25 sends a command to the power conditioner 32, and the power conditioner 32, upon detecting this, suppresses or stops the power generation of the power generator 31.

[0032] (Second Embodiment) Referring to Figure 3, the power supply system 1a of the second embodiment includes, in addition to the configuration of the first embodiment, an uninterruptible power supply 2a which is equipped with a bypass line 26, a bypass switch 27, and an inverter switch 28.

[0033] Bypass line 26 has AC connection terminal T AC and load connection terminal T L This wiring directly connects the inverter 22 and the load connection terminal T, supplying AC power from the AC power supply directly to the power supply line 40. The bypass switch 27 is a switch that connects and disconnects the bypass line 26. The inverter switch 28 connects the inverter 22 and the load connection terminal T. L This is a switch for connecting and disconnecting (power supply line 40).

[0034] The control unit 25a accepts a setting for either indirect supply mode or direct supply mode. In indirect supply mode, when the power supply is functioning normally, AC power from the AC power supply is supplied to the power supply line 40 via the converter 21 and inverter 22 of the uninterruptible power supply 2a, as in the first embodiment, and this mode prioritizes the self-consumption of the power generated by the power generator 31. In direct supply mode, when the power supply is functioning normally, AC power from the AC power supply is supplied directly to the power supply line 40 (without going through the uninterruptible power supply 2a), and this mode prioritizes the reverse power flow of the power generated by the power generator 31 to the AC power supply.

[0035] When the indirect supply mode is set, the control unit 25a performs the same control as in the first embodiment by keeping the bypass switch 27 permanently off and the inverter switch 28 permanently connected.

[0036] When set to direct supply mode, the control unit 25a connects the AC switch 24 and the bypass switch 27 and shuts off the inverter switch 28 when the power supply is normal, and shuts off the AC switch 24 and the bypass switch 27 and connects the inverter switch 28 when the power supply is abnormal.

[0037] Next, the operation of the power supply system 1a in direct supply mode under normal power conditions will be explained with reference to Figure 4(a). When the power supply is functioning normally, the control unit 25a of the uninterruptible power supply 2 operates the converter 21. As a result, the AC power of the AC power supply is converted to DC power by the converter 21, as shown by arrow C1, and supplied to the DC connection bus DC to charge the energy storage device 23.

[0038] The power conditioner 32 connects the power generated by the power generator 31 to the AC power supply, that is, it converts it into AC power with synchronized frequency, voltage, and phase, and supplies it to the power supply line 40 as shown by arrow C2.

[0039] If the power generated by the power generator 31 is insufficient for the load power of the load L, the deficit is supplied from the AC power source AC to the power supply line 40 through the bypass line 26, as indicated by arrow C3.

[0040] If the power generated by the power generator 31 exceeds the load power of the load L, the surplus is reverse-flowed from the power supply line 40 to the AC power source AC through the bypass line 26, as shown by arrow C4. In this way, the surplus or deficit of the power consumed by the load L and the power generated is adjusted by the AC power source AC. However, if the AC power source AC is a generator and not commercial power, reverse power flow is not possible, causing the voltage of the power supply line 40 to rise. The power conditioner 32, detecting this, suppresses the power generation of the power generator 31.

[0041] Next, the operation of the power supply system 1a in the event of a power supply abnormality in direct supply mode will be explained with reference to Figure 4(b). In the event of a power supply abnormality, the control unit 25a of the uninterruptible power supply 2a stops the converter 21 and operates the inverter 22.

[0042] The power conditioner 32 connects the power generated by the power generator 31 to the inverter 22, that is, it converts the AC power output by the inverter 22 into AC power with synchronized frequency, voltage, and phase, and supplies it to the power supply line 40 as indicated by arrow D1.

[0043] If the power generated by the power generator 31 is insufficient to meet the load power of the load L, the deficit is supplied from the energy storage device 23 to the power supply line 40 via the inverter 22, as indicated by arrow D2.

[0044] If the power generated by the power generator 31 exceeds the load power of the load L, the surplus is charged to the energy storage device 23 from the power supply line 40 via the inverter 22, as indicated by arrow D3. If the energy storage device 23 cannot be fully charged, the control unit 25a sends a command to the power conditioner 32, and the power conditioner 32, upon detecting this, suppresses or stops the power generation of the power generator 31.

[0045] (Third embodiment) Referring to Figure 5, the power supply system 1b of the third embodiment differs from the first embodiment in that the distributed power supply 3 is connected to the connection point between the AC switch 24 and the input terminal of the converter 21, rather than to the power supply line 40.

[0046] Next, the operation of the power supply system 1b under normal power conditions will be explained with reference to Figure 6(a). When the power supply is functioning normally, the control unit 25 of the uninterruptible power supply 2 connects the AC switch 24 and operates the converter 21 and inverter 22.

[0047] The power conditioner 32 connects the power generated by the power generator 31 to the AC power supply AC, that is, it converts the AC power output by the AC power supply AC into AC power with synchronized frequency, voltage, and phase, and supplies it to the converter 21 as shown by arrow E1. The power generated by the power generator 31 is converted to DC power by the converter 21 as shown by arrow E2 and supplied to the DC connection bus DC, and the AC power equivalent to the load power of the load L is supplied from the DC connection bus DC to the power supply line 40 through the inverter 22 as shown by arrow E3.

[0048] If the power generated by the power generator 31 is insufficient for the load power of the load L, the deficit is compensated for by supplying AC power from the AC power source AC to the DC connection bus DC via the converter 21, as indicated by arrow E4.

[0049] If the power generated by the power generator 31 exceeds the load power of the load L, the surplus is charged into the energy storage device 23, as indicated by arrow E5. In this way, the surplus or deficit between the power consumption of the load L and the power generated is adjusted by the converter 21, which supplies DC power to the DC connection bus DC. If the energy storage device 23 cannot be fully charged, the surplus is returned to the AC power supply.

[0050] Next, the operation of the power supply system 1b in the event of a power supply abnormality will be explained with reference to Figure 6(b). In the event of a power supply abnormality, the control unit 25 of the uninterruptible power supply 2 shuts off the AC switch 24 and operates the converter 21 and inverter 22. The converter 21 operates as an inverter rather than a rectifier, controlling the voltage at the connection point between the power conditioner 32 and the switch 24 to a voltage that allows the power conditioner 32 to connect to the grid.

[0051] The power conditioner 32 connects the power generated by the power generator 31 to the converter 21, that is, converts it into AC power of a frequency, voltage, and phase that the converter 21 can input, and supplies it to the converter 21 as shown by arrow F1.

[0052] The power generated by the power generator 31 is converted to DC power by the converter 21 as indicated by arrow F2 and supplied to the DC connection bus DC, and the AC power equivalent to the load power of the load L is supplied from the DC connection bus DC to the power supply line 40 through the inverter 22 as indicated by arrow F3.

[0053] If the power generated by the power generator 31 is insufficient for the load power of the load L, the deficit is supplied from the energy storage device 23 through the inverter 22, as indicated by arrow F4.

[0054] If the power generated by the power generator 31 exceeds the load power of the load L, the surplus is charged to the energy storage device 23 as indicated by arrow F5. If the energy storage device 23 cannot be fully charged, the control unit 25 sends a command to the power conditioner 32, and the power conditioner 32, upon detecting this, suppresses or stops the power generation of the power generator 31.

[0055] (Fourth embodiment) Referring to Figure 7, the power supply system 1c of the fourth embodiment differs from the second embodiment in that the distributed power supply 3 is connected to the connection point between the AC switch 24 and the input terminal of the converter 21, rather than to the power supply line 40.

[0056] The control unit 25a accepts a setting for either indirect supply mode or direct supply mode. When set to indirect supply mode, the control unit 25a performs the same control as in the third embodiment by keeping the bypass switch 27 permanently off and the inverter switch 28 permanently connected.

[0057] When set to direct supply mode, the control unit 25a connects the AC switch 24 and the bypass switch 27 and shuts off the inverter switch 28 when the power supply is normal, and shuts off the AC switch 24 and the bypass switch 27 and connects the inverter switch 28 when the power supply is abnormal.

[0058] Next, the operation of the power supply system 1c in direct supply mode under normal power conditions will be explained with reference to Figure 8(a). When the power supply is functioning normally, the control unit 25a of the uninterruptible power supply 2a connects the AC switch 24 and the bypass switch 27, shuts off the inverter switch 28, and operates the converter 21.

[0059] The power conditioner 32 connects the power generated by the power generator 31 to the AC power supply, that is, it converts it into AC power with synchronized frequency, voltage, and phase, and supplies it to the power supply line 40 through the bypass line 26 as shown by arrow G1.

[0060] If the power generated by the power generator 31 is insufficient for the load power of the load L, the deficit is supplied from the AC power source AC to the power supply line 40 through the bypass line 26, as indicated by arrow G2.

[0061] If the power generated by the power generator 31 exceeds the load power of the load L, the surplus is converted to DC power by the converter 21, as shown by arrow G3, and supplied to the DC connection bus DC to charge the energy storage device 23. If the energy storage device 23 cannot be fully charged, the surplus is returned to the AC power supply AC.

[0062] Next, the operation of the power supply system 1c in the event of a power supply abnormality in direct supply mode will be explained with reference to Figure 8(b). In the event of a power supply abnormality, the control unit 25a of the uninterruptible power supply 2a shuts off the AC switch 24 and the bypass switch 27, connects the inverter switch 28, and operates the converter 21 and the inverter 22. The converter 21 operates as an inverter rather than a rectifier, controlling the voltage at the connection point between the power conditioner 32 and the switch 24 to a voltage that allows the power conditioner 32 to connect to the grid.

[0063] The power conditioner 32 connects the power generated by the power generator 31 to the converter 21, that is, converts it into AC power of a frequency, voltage, and phase that the converter 21 can input, and supplies it to the converter 21 as shown by arrow H1.

[0064] The power generated by the power generator 31 is converted to DC power by the converter 21 as indicated by arrow H2 and supplied to the DC connection bus DC, and the AC power equivalent to the load power of the load L is supplied from the DC connection bus DC to the power supply line 40 through the inverter 22 as indicated by arrow H3.

[0065] If the power generated by the power generator 31 is insufficient for the load power of the load L, the deficit is supplied from the energy storage device 23 through the inverter 22, as indicated by arrow H4.

[0066] If the power generated by the power generator 31 exceeds the load power of the load L, the surplus is charged to the energy storage device 23 as indicated by arrow H5. If the energy storage device 23 cannot be fully charged, the control unit 25a sends a command to the power conditioner 32, and the power conditioner 32, upon detecting this, suppresses or stops the power generation of the power generator 31.

[0067] As described above, according to the first embodiment, the power supply system 1 supplies power to a load L using an uninterruptible power supply 2 connected to an AC power source AC and a distributed power source 3 that generates power on a separate system from the AC power source AC. The uninterruptible power supply 2 comprises a converter 21 that converts the AC power of the AC power source AC into DC power and supplies it to a DC connection bus DC, an inverter 22 which is a bidirectional inverter that mutually converts the DC power of the DC connection bus DC and the AC power of the power supply line 40 to which the load L is connected, an energy storage device 23 connected to the DC connection bus DC, and an AC switch 24 that connects the AC power source AC and the converter 21 when the AC power source AC is functioning normally and disconnects the AC power source AC and the converter 21 when the AC power source AC is malfunctioning. The distributed power source 3 is linked with the inverter 22 and supplies generated power to the power supply line 40. With this configuration, AC power from the AC power supply is supplied to the power supply line 40 through the converter 21 and inverter 22. As a result, the uninterruptible power supply 2 and the distributed power supply 3 can connect and supply stable AC power to the load L without being affected by fluctuations in the voltage and frequency of the commercial power grid or switching noise from the AC switch 24.

[0068] Furthermore, according to the first embodiment, if the AC power supplied to the power supply line 40 is insufficient, the inverter 22 converts the DC power from the DC connection bus DC to the insufficient AC power and supplies it to the power supply line 40, and if the AC power supplied to the power supply line 40 is in excess, it converts the excess AC power to DC power and supplies it to the DC connection bus DC. This configuration allows the inverter 22 to adjust for any excess or deficiency of AC power supplied to the power supply line 40.

[0069] As described above, according to the second embodiment, the uninterruptible power supply 2a comprises a bypass line 26 that directly supplies AC power from an AC power source to a power supply line 40, a bypass switch 27 that connects and disconnects the bypass line 26, and an inverter switch 28 that connects and disconnects the inverter 22 to the power supply line 40. The system accepts a setting of either an indirect supply mode, in which AC power from an AC power source is supplied to the power supply line 40 via a converter 21 and an inverter 22, or a direct supply mode, in which AC power from an AC power source is supplied directly to the power supply line 40. In the indirect supply mode, the bypass switch 27 is always disconnected and the inverter switch 28 is always connected. In the direct supply mode, when the power supply is normal, the bypass switch 27 is connected and the inverter switch 28 is disconnected, and when the power supply is abnormal, the bypass switch 27 is disconnected and the inverter switch 28 is connected. This configuration allows for setting an indirect supply mode in which AC power from an AC power source is supplied to the power supply line 40 through the converter 21 and inverter 22.

[0070] As described above, according to the third embodiment, the power supply system 1b supplies power to a load L using an uninterruptible power supply 2 connected to an AC power source AC and a distributed power source 3 that generates power on a separate system from the AC power source AC. The uninterruptible power supply 2 comprises a converter 21 that converts the AC power of the AC power source AC into DC power and supplies it to a DC connection bus DC, an inverter 22 that converts the DC power of the DC connection bus DC and the AC power of the power supply line 40 to which the load L is connected to each other, an energy storage device 23 connected to the DC connection bus DC, and an AC switch 24 that connects the AC power source AC and the converter 21 when the AC power source AC is functioning normally and disconnects the AC power source AC and the converter 21 when the AC power source AC is malfunctioning. The distributed power source 3 is connected to the AC power source AC and supplies generated power to the connection point between the AC switch 24 and the converter 21. With this configuration, AC power from the AC power supply is supplied to the power supply line 40 through the converter 21 and inverter 22. As a result, the uninterruptible power supply 2 and the distributed power supply 3 can connect and supply stable AC power to the load L without being affected by fluctuations in the voltage and frequency of the commercial power grid or switching noise from the AC switch 24.

[0071] As described above, according to the fourth embodiment, the uninterruptible power supply 2a comprises a bypass line 26 that directly supplies AC power from an AC power source to a power supply line 40, a bypass switch 27 that connects and disconnects the bypass line 26, and an inverter switch 28 that connects and disconnects the inverter 22 to the power supply line 40. The system accepts a setting of either an indirect supply mode, in which AC power from an AC power source is supplied to the power supply line 40 via a converter 21 and an inverter 22, or a direct supply mode, in which AC power from an AC power source is supplied directly to the power supply line 40. In the indirect supply mode, the bypass switch 27 is always disconnected and the inverter switch 28 is always connected. In the direct supply mode, when the power supply is normal, the bypass switch 27 is connected and the inverter switch 28 is disconnected, and when the power supply is abnormal, the bypass switch 27 is disconnected and the inverter switch 28 is connected. With this configuration, an indirect supply mode can be set in which AC power from the AC power supply AC is supplied to the power supply line 40 through the converter 21 and the inverter 22.

[0072] As described above, the present invention has been described with specific embodiments, but it is needless to say that the above embodiments are merely examples and can be implemented with modifications without departing from the gist of the present invention.

Explanation of Reference Numerals

[0073] 1, 1a, 1b, 1c Power supply system 2, 2a Uninterruptible power supply 3 Distributed power source 21 Converter 22 Inverter 23 Energy storage device 24 AC switch 25, 25a Control unit 26 Bypass line 27 Bypass switch 28 Inverter switch 31 Power generation device 32 Power conditioner 40 Power supply line AC AC power supply DC DC connection bus L Load T AC AC connection terminal T L Load connection terminal

Claims

1. A power supply system that supplies power to a load using an uninterruptible power supply connected to an AC power source and a distributed power source that generates power on a separate system from the AC power source, The aforementioned uninterruptible power supply device is A converter that converts the AC power of the aforementioned AC power source into DC power and supplies it to a DC connection bus, A bidirectional inverter that converts between the DC power of the DC connection bus and the AC power of the power supply line to which the load is connected, A power storage device connected to the aforementioned DC connection bus, The AC power supply comprises an AC switch that connects the AC power supply and the converter when the AC power supply is functioning normally, and disconnects the AC power supply and the converter when the AC power supply is malfunctioning. The distributed power source connects with the bidirectional inverter to supply generated power to the power supply line. The bidirectional inverter is characterized in that, when the AC power supplied to the power supply line is insufficient, it converts the DC power of the DC connection bus into AC power to compensate for the shortage and supplies it to the power supply line, and when the AC power supplied to the power supply line is in excess, it converts the excess AC power into DC power and supplies it to the DC connection bus.

2. The aforementioned uninterruptible power supply device is A bypass line that directly supplies AC power from the aforementioned AC power source to the power supply line, A bypass switch for connecting and disconnecting the aforementioned bypass line, The system comprises an inverter switch for connecting and disconnecting the bidirectional inverter and the power supply line, The system accepts a setting for either an indirect supply mode, in which the AC power of the AC power source is supplied to the power supply line via the converter and the bidirectional inverter, or a direct supply mode, in which the AC power of the AC power source is supplied directly to the power supply line. In the aforementioned indirect supply mode, the bypass switch is kept off at all times, and the inverter switch is kept on at all times. The power supply system according to claim 1, characterized in that, in the direct supply mode, the bypass switch is connected and the inverter switch is shut off when the power supply is normal, and the bypass switch is shut off and the inverter switch is connected when the power supply is abnormal.

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