Power supply system

Abstract

To provide a power supply system capable of supplying stable AC power to a load without being affected by the fluctuation of the voltage or frequency of a commercial power system or the switching noise of an AC switch.SOLUTION: The uninterruptible power supply 2 includes the converter 21 that converts AC power from the AC power supply AC into DC power and supplies the DC power to the DC connection bus DC, the inverter 22 that mutually converts DC power from the DC connection bus DC and AC power from the power supply line 40 to which the load L is connected, and the power storage device 23 that is connected to the DC connection bus DC. And an AC switch 24 for breaking the connection between the AC power supply AC and the converter 21 when the AC power supply AC is abnormal, and the distributed power supply 3 supplies the generated power to the power supply line 40 in cooperation with the inverter 22.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, a power supply system using a distributed power source such as a solar cell and an uninterruptible power supply has been proposed (see, for example, Patent Document 1). The uninterruptible power supply in such a power supply system has one end connected to a commercial power system, connects the commercial power system to a load, and includes an AC switch that cuts off the connection between the commercial power system and the load in the event of a power outage in the commercial power system, 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 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional technology, AC power from a commercial power system is supplied directly to a load via an AC switch, which causes a problem in that fluctuations in voltage and frequency (momentary interruptions, momentary drops, surges, noise, etc.) in the commercial power system and switching noise from the AC switch can make the AC power supplied to the load by the distributed power source connected to the commercial power system unstable.

[0005] An 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 voltage and frequency of the commercial power system or by switching noise of the AC switch. [Means for solving the problem]

[0006] 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 in a system separate from the AC power source, wherein the uninterruptible power supply comprises: a converter that converts AC power from the AC power source into DC power and supplies the DC power to a DC connection bus; a bidirectional inverter that converts the DC power of the DC connection bus into AC power of a power supply line to which the load is connected, and vice versa; 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 normal and cuts off the connection between the AC power source and the converter when the AC power source is abnormal, and the distributed power source is interconnected with the bidirectional inverter to supply the generated power to the power supply line. Moreover, a 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 in a system separate from the AC power source, wherein the uninterruptible power supply comprises: a converter that converts AC power from the AC power source into DC power and supplies the DC power to a DC connection bus; a bidirectional inverter that converts the DC power of the DC connection bus into AC power of a power supply line to which the load is connected, and vice versa; 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 normal and cuts off the connection between the AC power source and the converter when the AC power source is abnormal, and the distributed power source is interconnected with the AC power source and supplies generated power to a connection point between the AC switch and the converter. [Effects of the Invention]

[0007] According to the present invention, AC power from an AC power supply is supplied to a power supply line through a converter and a bidirectional inverter, and therefore the uninterruptible power supply and distributed power supplies are interconnected to supply stable AC power to a load without being affected by fluctuations in voltage and frequency of the commercial power system or by switching noise from AC switches. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a configuration diagram showing a configuration example of a first embodiment of a power supply system according to the present invention. [Figure 2] FIG. 2 is an explanatory diagram illustrating the operation of the power supply system shown in FIG. [Figure 3] FIG. 4 is a configuration diagram showing a configuration example of a second embodiment of a power supply system according to the present invention. [Figure 4] FIG. 4 is an explanatory diagram illustrating the operation of the power supply system shown in FIG. [Figure 5] FIG. 10 is a configuration diagram showing a configuration example of a third embodiment of a power supply system according to the present invention. [Figure 6] FIG. 6 is an explanatory diagram illustrating the operation of the power supply system shown in FIG. [Figure 7] FIG. 10 is a configuration diagram showing a configuration example of a fourth embodiment of a power supply system according to the present invention. [Figure 8] FIG. 8 is an explanatory diagram illustrating the operation of the power supply system shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, components having similar functions will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0010] (First embodiment) Referring to FIG. 1, a power supply system 1 according to the first embodiment includes an uninterruptible power supply (UPS) 2 that supplies power from an alternating current power source AC such as a commercial power system to a load L, and a distributed power source 3 that supplies power generated in a system separate from the alternating current power source AC to the load L.

[0011] The uninterruptible power supply 2 includes a converter 21, an inverter 22, a power storage device 23, an AC switch 24, and a control unit 25. AC AC power is connected to the load connection terminal T LA power supply line 40, to which a load L is connected, is connected to each of the components. Note that the control unit 25 has the function of controlling the converter 21, the inverter 22, and the AC switch 24, but these functions may be distributed among the converter 21, the inverter 22, and the AC switch 24. In Fig. 1, the solid lines connecting the components are power lines that supply power, and the dashed lines connecting the components are control lines.

[0012] The converter 21 is a power conversion device that converts AC to DC. The input terminal of the converter 21 is connected to the AC connection terminal T AC The output terminals are connected to the DC connection bus DC.

[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 to.

[0014] The power storage device 23 is configured by a secondary battery such as a lithium ion battery, a lead battery, or a nickel-metal hydride battery, or a capacitor. The power storage device 23 is connected to the DC connection bus DC, and is charged with DC power converted by the converter 21 and the inverter 22, and discharges the DC power that the inverter 22 converts into AC power to supply the DC power.

[0015] The AC switch 24 is an AC power supply disconnecting switch that connects and cuts off AC power from the AC power supply AC. One end of the AC switch 24 is connected to the AC power supply 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 of a microcomputer, etc. The control unit 25 controls the converter 21, the inverter 22, and the AC switch 24 in accordance with the current and voltage of each part of the uninterruptible power supply 2 detected by current and voltage sensors (not shown).

[0017] The control unit 25 is connected to the AC connection terminal T AC By monitoring the voltage and current, the control unit 25 determines whether the AC power supply AC is normal or abnormal (power outage) and if the determination is that the power supply is normal, the control unit 25 connects the AC switch 24, and if the determination is that the power supply is abnormal, the control unit 25 disconnects the AC switch 24 and disconnects the uninterruptible power supply 2 from the AC power supply AC.

[0018] The control unit 25 operates the converter 21 when the AC power supply AC is normal, and controls the operation of the converter 21 so that the DC connection bus DC has a preset set voltage.

[0019] The control unit 25 operates the inverter 22 regardless of the state of the AC power supply AC. When the AC power supplied to the power supply line 40 is insufficient, that is, when the AC power supplied from the distributed power source 3 is insufficient relative to the load power of the load L, the control unit 25 converts the DC power of the DC connection bus DC by the inverter 22 and supplies the AC power to the power supply line 40 to make up for the shortage.

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

[0021] The control unit 25 also has a function of detecting the amount of electricity stored in the electricity storage device 23 and determining whether the electricity storage device 23 is fully charged. For example, the control unit 25 integrates the charging current and discharging current of the electricity storage device 23 and detects the amount of electricity stored in the electricity storage device 23 based on the difference between the integrated currents. The amount of electricity stored in the electricity storage device 23 may also be detected based on the terminal voltage of the electricity storage device 23, etc.

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

[0023] The power generation device 31 is a small-scale generator such as a solar cell, wind power generation, hydroelectric power generation, diesel power generation, or fuel cell power generation, 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 when the power supply is normal will be described with reference to FIG. 2(a). When the power supply is normal, the control unit 25 of the uninterruptible power supply 2 connects the AC switch 24 and operates the converter 21 and the inverter 22. As a result, the AC power of the AC power supply AC is converted into DC power by the converter 21 as shown by arrow A1 and supplied to the DC connection bus DC, where it charges the power storage device 23.

[0025] The power conditioner 32 converts the power generated by the power generation device 31 into AC power that is connected to the inverter 22, i.e., synchronizes the frequency, voltage, and phase of the AC power output by the inverter 22, and supplies it to the power supply line 40 as shown by arrow A2.

[0026] When the power generated by the power generation device 31 is insufficient for the load power of the load L, the shortage is supplied from the DC connection bus DC to the power supply line 40 via the inverter 22 as shown by arrow A3.

[0027] When the power generated by the power generation device 31 exceeds the load power of the load L, the surplus power is supplied from the power supply line 40 through the inverter 22 to the DC connection bus DC as shown by arrow A4, and is charged into the power storage device 23. When the power 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, reduces or stops the power generation of the power generation device 31.

[0028] Next, the operation of the power supply system 1 when a power supply abnormality occurs will be described with reference to FIG. 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 converts the power generated by the power generation device 31 into AC power that is connected to the inverter 22, i.e., synchronizes the frequency, voltage, and phase of the AC power output by the inverter 22, and supplies it to the power supply line 40 as shown by arrow B1.

[0030] When the power generated by the power generation device 31 is insufficient for the load power of the load L, the shortage is supplied from the power storage device 23 to the power supply line 40 via the inverter 22 as shown by arrow B2.

[0031] When the power generated by the power generation device 31 exceeds the load power of the load L, the surplus power is charged from the power supply line 40 through the inverter 22 to the power storage device 23 as shown by arrow B3. When the power 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, reduces or stops the power generation of the power generation device 31.

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

[0033] The bypass line 26 is connected to the AC connection terminal T AC and load connection terminal T L The bypass switch 27 is a switch that connects and disconnects the bypass line 26. The inverter switch 28 is a wiring that directly connects the inverter 22 and the load connection terminal T L This is a switch that connects and disconnects the power supply line 40.

[0034] The control unit 25a accepts the setting of either an indirect supply mode or a direct supply mode. The indirect supply mode is a mode in which, when the power supply is normal, AC power from the AC power source AC 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 is a mode in which priority is given to self-consumption of power generated by the power generation device 31. The direct supply mode is a mode in which, when the power supply is normal, AC power from the AC power source AC is supplied directly to the power supply line 40 (supplied without passing through the uninterruptible power supply 2a), and is a mode in which priority is given to reverse flow of power generated by the power generation device 31 to the AC power source AC.

[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 always off and the inverter switch 28 always on.

[0036] When the direct supply mode is set, the control unit 25a connects the AC switch 24 and the bypass switch 27 and cuts off the inverter switch 28 when the power supply is normal, and cuts 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 the direct supply mode when the power supply is normal will be described with reference to FIG. 4(a). When the power supply is normal, 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 AC is converted into DC power by the converter 21 as shown by arrow C1, and is supplied to the DC connection bus DC and charged into the power storage device 23.

[0038] The power conditioner 32 converts the power generated by the power generation device 31 into AC power that is connected to the AC power source AC, i.e., AC power that is synchronized in frequency, voltage, and phase with the AC power source AC, and supplies the converted power to the power supply line 40 as shown by arrow C2.

[0039] When the power generated by the power generation device 31 is insufficient for the load power of the load L, the shortage is supplied from the AC power source AC to the power supply line 40 through the bypass line 26 as shown by arrow C3.

[0040] When the power generated by the power generation device 31 exceeds the load power of the load L, the surplus power flows back from the power supply line 40 to the AC power supply AC through the bypass line 26 as shown by arrow C4. In this way, the excess or deficiency of the power consumption and generated power of the load L is adjusted by the AC power supply AC. Note that if the AC power supply AC is a generator rather than a commercial power supply, reverse power flow is not possible, and the voltage on the power supply line 40 rises. Detecting this, the power conditioner 32 suppresses the power generation of the power generation device 31.

[0041] Next, the operation of the power supply system 1a in the direct supply mode when a power supply abnormality occurs will be described with reference to FIG. 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 converts the power generated by the power generation device 31 into AC power that is connected to the inverter 22, i.e., synchronizes the frequency, voltage, and phase of the AC power output by the inverter 22, and supplies it to the power supply line 40 as shown by arrow D1.

[0043] When the power generated by the power generation device 31 is insufficient for the load power of the load L, the shortage is supplied from the power storage device 23 to the power supply line 40 via the inverter 22 as shown by arrow D2.

[0044] When the power generated by the power generation device 31 exceeds the load power of the load L, the surplus power is charged from the power supply line 40 through the inverter 22 to the power storage device 23 as shown by arrow D3. When the power 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, reduces or stops the power generation of the power generation device 31.

[0045] (Third embodiment) Referring to FIG. 5, the power supply system 1b of the third embodiment differs from the first embodiment in that the distributed power source 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 when the power supply is normal will be described with reference to FIG. 6(a). When the power supply is normal, the control unit 25 of the uninterruptible power supply 2 connects the AC switch 24 and operates the converter 21 and the inverter 22.

[0047] The power conditioner 32 converts the power generated by the power generation device 31 into AC power that is interconnected with the AC power source AC, i.e., synchronizes the frequency, voltage, and phase of the AC power output by the AC power source AC, and supplies the converted power to the converter 21 as shown by arrow E1. The power generated by the power generation device 31 is converted into DC power by the converter 21 as shown by arrow E2 and supplied to the DC connection bus DC, and 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 via the inverter 22 as shown by arrow E3.

[0048] When the power generated by the power generation device 31 is insufficient for the load power of the load L, the shortage is made up by AC power from the AC power supply AC passing through the converter 21 to the DC connection bus DC, as shown by arrow E4.

[0049] When the power generated by the power generation device 31 exceeds the load power of the load L, the surplus is charged to the power storage device 23 as shown by arrow E5. In this way, the excess or deficiency of the power consumption and generated power of the load L is adjusted by the converter 21 that supplies DC power to the DC connection bus DC. Then, when the power storage device 23 cannot be fully charged, the surplus power is reversely flowed to the AC power supply AC.

[0050] Next, the operation of the power supply system 1b when a power supply abnormality occurs will be described with reference to FIG. 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 the inverter 22. The converter 21 operates as an inverter rather than a rectifier, and controls 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 be connected to the grid.

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

[0052] The power generated by the power generation device 31 is converted into DC power by the converter 21 as shown by arrow F2 and supplied to the DC connection bus DC, and 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 F3.

[0053] When the power generated by the power generation device 31 is insufficient for the load power of the load L, the shortage is supplied from the power storage device 23 via the inverter 22 as shown by the arrow F4.

[0054] When the power generated by the power generation device 31 exceeds the load power of the load L, the surplus power is charged to the power storage device 23 as shown by arrow F5. When the power 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, reduces or stops the power generation of the power generation device 31.

[0055] (Fourth embodiment) Referring to FIG. 7, the power supply system 1c of the fourth embodiment differs from the second embodiment in that the distributed power source 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 of either the indirect supply mode or the direct supply mode. When the indirect supply mode is selected, the control unit 25a performs the same control as in the third embodiment by keeping the bypass switch 27 constantly OFF and the inverter switch 28 constantly ON.

[0057] When the direct supply mode is set, the control unit 25a connects the AC switch 24 and the bypass switch 27 and cuts off the inverter switch 28 when the power supply is normal, and cuts 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 the direct supply mode when the power supply is normal will be described with reference to FIG. 8(a). When the power supply is normal, the control unit 25a of the uninterruptible power supply 2a connects the AC switch 24 and the bypass switch 27, and also cuts off the inverter switch 28, thereby operating the converter 21.

[0059] The power conditioner 32 converts the power generated by the power generation device 31 into AC power that is connected to the AC power source AC, i.e., AC power that is synchronized in frequency, voltage, and phase with the AC power source AC, and supplies the AC power to the power supply line 40 through the bypass line 26 as shown by arrow G1.

[0060] When the power generated by the power generation device 31 is insufficient for the load power of the load L, the shortage is supplied from the AC power source AC to the power supply line 40 through the bypass line 26 as shown by arrow G2.

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

[0062] Next, the operation of the power supply system 1c in the direct supply mode when a power supply abnormality occurs will be described with reference to FIG. 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, and also connects the inverter switch 28 to operate the converter 21 and the inverter 22. The converter 21 performs inverter operation instead of rectification operation, and controls 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 be connected to the grid.

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

[0064] The power generated by the power generation device 31 is converted into DC power by the converter 21 as shown by arrow H2 and supplied to the DC connection bus DC, and 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 H3.

[0065] When the power generated by the power generation device 31 is insufficient for the load power of the load L, the shortage is supplied from the power storage device 23 via the inverter 22 as shown by the arrow H4.

[0066] When the power generated by the power generation device 31 exceeds the load power of the load L, the surplus power is charged to the power storage device 23 as shown by arrow H5. When the power 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, reduces or stops the power generation of the power generation device 31.

[0067] As described above, according to the first embodiment, there is provided a power supply system 1 that supplies power to a load L using an uninterruptible power supply 2 connected to an AC power supply AC and a distributed power supply 3 that generates power in a system separate from the AC power supply AC, wherein the uninterruptible power supply 2 includes a converter 21 that converts AC power from the AC power supply AC into DC power and supplies the DC power to a DC connection bus DC, an inverter 22 that is a bidirectional inverter that converts the DC power from the DC connection bus DC into AC power from a 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 supply AC and the converter 21 when the AC power supply AC is operating normally and disconnects the connection between the AC power supply AC and the converter 21 when the AC power supply AC has a power abnormality, and the distributed power supply 3 is interconnected with the inverter 22 and supplies the generated power to the power supply line 40. With this configuration, AC power from the AC power source AC is supplied to the power supply line 40 through the converter 21 and the inverter 22, so that the uninterruptible power supply 2 and the distributed power source 3 are interconnected and stable AC power can be supplied to the load L without being affected by fluctuations in voltage and frequency of the commercial power system or by switching noise from the AC switch 24.

[0068] Furthermore, according to the first embodiment, when the AC power supplied to the power supply line 40 is insufficient, the inverter 22 converts the DC power of the DC connection bus DC into AC power to make up the shortage and supplies it to the power supply line 40, and when the AC power supplied to the power supply line 40 is surplus, the inverter 22 converts the surplus AC power into DC power and supplies it to the DC connection bus DC. This configuration makes it possible to adjust the excess or deficiency of AC power supplied by the inverter 22 to the power supply line 40 .

[0069] As described above, according to the second embodiment, the uninterruptible power supply 2a includes the bypass line 26 that directly supplies AC power from the AC power supply AC to the power supply line 40, the bypass switch 27 that connects and disconnects the bypass line 26, and the inverter switch 28 that connects and disconnects the inverter 22 and the power supply line 40, and accepts setting of either an indirect supply mode in which AC power from the AC power supply AC is supplied to the power supply line 40 via the converter 21 and the inverter 22, or a direct supply mode in which AC power from the AC power supply AC is directly supplied 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 makes it possible to set an indirect supply mode in which AC power from the AC power source AC is supplied to the power supply line 40 through the converter 21 and the inverter 22.

[0070] As described above, according to the third embodiment, there is provided a power supply system 1b that supplies power to a load L using an uninterruptible power supply 2 connected to an AC power supply AC and a distributed power supply 3 that generates power in a system separate from the AC power supply AC, wherein the uninterruptible power supply 2 includes a converter 21 that converts AC power from the AC power supply AC into DC power and supplies the DC power to a DC connection bus DC, an inverter 22 that converts the DC power from the DC connection bus DC into AC power from a power supply line 40 to which the load L is connected, and vice versa, a power storage device 23 connected to the DC connection bus DC, and an AC switch 24 that connects the AC power supply AC and the converter 21 when the AC power supply AC is operating normally and disconnects the connection between the AC power supply AC and the converter 21 when the AC power supply AC has a power abnormality, and the distributed power supply 3 is interconnected with the AC power supply AC and supplies generated power to a connection point between the AC switch 24 and the converter 21. With this configuration, AC power from the AC power source AC is supplied to the power supply line 40 through the converter 21 and the inverter 22, so that the uninterruptible power supply 2 and the distributed power source 3 are interconnected and stable AC power can be supplied to the load L without being affected by fluctuations in voltage and frequency of the commercial power system or by switching noise from the AC switch 24.

[0071] As described above, according to the fourth embodiment, the uninterruptible power supply 2a includes the bypass line 26 that directly supplies AC power from the AC power supply AC to the power supply line 40, the bypass switch 27 that connects and disconnects the bypass line 26, and the inverter switch 28 that connects and disconnects the inverter 22 and the power supply line 40, and accepts setting of either an indirect supply mode in which AC power from the AC power supply AC is supplied to the power supply line 40 via the converter 21 and the inverter 22, or a direct supply mode in which AC power from the AC power supply AC is directly supplied 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 makes it possible to set an indirect supply mode in which AC power from the AC power source AC is supplied to the power supply line 40 through the converter 21 and the inverter 22.

[0072] Although the present invention has been described above with reference to specific embodiments, it goes without saying that the above embodiments are merely examples and can be modified and implemented without departing from the spirit of the present invention. [Explanation of symbols]

[0073] 1, 1a, 1b, 1c Power Supply System 2, 2a uninterruptible power supply 3 Distributed power generation 21 Converter 22 Inverter 23 Energy storage devices 24 AC switch 25, 25a Control section 26 Bypass Line 27 Bypass switch 28 Inverter switch 31 Power generating equipment 32 Power conditioner 40 Power Supply Line AC alternating current power supply DC direct current 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 in a system separate from the AC power source, The uninterruptible power supply is a converter that converts AC power from the AC power source into DC power and supplies the DC power to a DC connection bus; a bidirectional inverter that converts DC power from the DC connection bus into AC power from a power supply line to which the load is connected, and vice versa; an electric storage device connected to the DC connection bus; an AC switch that connects the AC power supply and the converter when the AC power supply is normal and disconnects the AC power supply and the converter when the AC power supply is abnormal; The power supply system is characterized in that the distributed power source is interconnected with the bidirectional inverter and supplies generated power to the power supply line.

2. 2. The power supply system according to claim 1, wherein, when AC power supplied to the power supply line is insufficient, the bidirectional inverter converts DC power of the DC connection bus into AC power to compensate for the shortage and supplies the AC power to the power supply line, and when AC power supplied to the power supply line is surplus, the bidirectional inverter converts the surplus AC power into DC power and supplies the DC power to the DC connection bus.

3. The uninterruptible power supply is a bypass line that directly supplies AC power from the AC power supply to the power supply line; a bypass switch that connects and disconnects the bypass line; an inverter switch that connects and disconnects the bidirectional inverter and the power supply line, accepts a setting of either an indirect supply mode in which the AC power of the AC power supply 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 supply is directly supplied to the power supply line; In the indirect supply mode, the bypass switch is always disconnected and the inverter switch is always connected; 3. The power supply system according to claim 1, wherein in the direct supply mode, when the power supply is normal, the bypass switch is connected and the inverter switch is disconnected, and when the power supply is abnormal, the bypass switch is disconnected and the inverter switch is connected.

4. 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 in a system separate from the AC power source, The uninterruptible power supply is a converter that converts AC power from the AC power source into DC power and supplies the DC power to a DC connection bus; a bidirectional inverter that converts DC power from the DC connection bus into AC power from a power supply line to which the load is connected, and vice versa; an electric storage device connected to the DC connection bus; an AC switch that connects the AC power supply and the converter when the AC power supply is normal and disconnects the AC power supply and the converter when the AC power supply is abnormal; The distributed power supply system is characterized in that the distributed power supply is interconnected with the AC power supply and supplies generated power to a connection point between the AC switch and the converter.

5. The uninterruptible power supply is a bypass line that directly supplies AC power from the AC power supply to the power supply line; a bypass switch that connects and disconnects the bypass line; an inverter switch that connects and disconnects the bidirectional inverter and the power supply line, accepts a setting of either an indirect supply mode in which the AC power of the AC power supply 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 supply is directly supplied to the power supply line; In the indirect supply mode, the bypass switch is always disconnected and the inverter switch is always connected; 5. The power supply system according to claim 4, wherein in the direct supply mode, when the power supply is normal, the bypass switch is connected and the inverter switch is disconnected, and when the power supply is abnormal, the bypass switch is disconnected and the inverter switch is connected.

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