JP5584491B2 - Uninterruptible power supply system - Google Patents

Description

  The present invention relates to an uninterruptible power supply system capable of continuing to supply stable power to a load even when a commercial power supply becomes abnormal.

  A normal uninterruptible power supply always converts AC power supplied from a commercial power source into the same voltage and the same frequency as the commercial power source by a converter (converter that converts AC to DC) and an inverter (converter that converts DC to AC). When the AC power is converted into AC power and supplied to the load facility and the AC power supply fails, the load facility is supplied with power from the storage battery provided on the output side of the converter. A bypass circuit is provided for supplying power to the load equipment from the bypass commercial power supply when an abnormality occurs in the converter or the inverter, and can be switched between the output of the inverter by the uninterruptible switching circuit. ing.

  In recent years, when a failure occurs in one uninterruptible power supply unit for a plurality of uninterruptible power supply units each having a load facility as described above, the uninterruptible power supply unit failed due to another uninterruptible power supply unit An uninterruptible power supply system has been adopted in which an overlap-type switching device is provided on the load side so that power can be supplied to a corresponding load facility and power supply switching between the uninterruptible power supply devices can be performed. (For example, see Patent Document 1.)

JP-A-4-58738 (Overall)

  The inverter of each uninterruptible power supply in the uninterruptible power supply system configured in Patent Document 1 normally outputs a constant voltage that matches the output of its own bypass power supply. For example, when the uninterruptible power supply system is configured by two uninterruptible power supplies, if one inverter fails, the failed uninterruptible power supply is automatically switched to bypass power feeding. And, when trying to switch the power supply from one bypass power supply on the failed side to the other uninterruptible power supply by the overlap type switching device, the voltage of both does not always match, so the other uninterruptible power supply An excessive cross current may flow through the inverter.

  For this reason, after switching the output of the healthy uninterruptible power supply to the power supply from its own bypass power supply and switching the power supply between the bypass power supplies with the overlap type switching device, the healthy uninterruptible power supply apparatus Must be switched from its own bypass power supply to the inverter power supply by an uninterruptible switching circuit. By performing such complicated switching, power supply reliability to the load facility is lowered.

  The present invention has been made in order to solve the above-described problems, and in an uninterruptible power supply system in which two uninterruptible power supply units are abutted by an overlap type switching device, one uninterruptible power supply unit It is an object of the present invention to provide an uninterruptible power supply system that can be switched to a sound uninterruptible power supply switching device without deteriorating the power supply reliability to the load facility when an abnormality occurs.

In order to achieve the above object, an uninterruptible power supply system according to the present invention converts an AC of a commercial power source into a DC by a converter, converts this DC again into an AC by an inverter, and bypasses the output by an uninterruptible switching circuit. The outputs of the first and second uninterruptible power supply devices configured to be switched to bypass power supply from the input commercial power supply and the outputs of the first and second uninterruptible power supply devices are respectively connected via switches. First and second output branch circuits branching into two systems, one branch output of the first output branch circuit and one branch output of the second output branch circuit as inputs, and a first load A first overlap switching device that switches power supply to the facility without interruption, and the other branch output of the first output branch circuit and the other branch output of the second output branch circuit are input, Supply to load equipment of 2 A second overlap switching device for switching without interruption, and
Voltage / frequency command means for providing at least one of an output voltage command and an output frequency command for each inverter, and the voltage / frequency command means is provided with a switching preparation command from the overlap switching device; and When any of the uninterruptible power supply devices fails, the output voltage command given to the sound uninterruptible power supply device is switched from a predetermined constant voltage to the voltage of the commercial power supply for bypass input of the failed uninterruptible power supply device. And by obtaining the voltage of the commercial power supply for bypass input of the failed uninterruptible power supply from the output side of the switch that is supplying power to the load facility by the output branch circuit, When the overlap switching device is switched from bypass power supply to healthy uninterruptible power supply power supply, the first and second two sets of It is characterized in that so as to prevent lateral flow between Power Supplies.

  According to the present invention, in an uninterruptible power supply system in which two uninterruptible power supplies are abutting in an overlap type switching device, when an abnormality occurs in one uninterruptible power supply, power is supplied to a load facility. It is possible to provide an uninterruptible power supply system that can be switched to a sound uninterruptible power supply switching device without lowering reliability.

The circuit block diagram of the uninterruptible power supply system which concerns on Example 1 of this invention. The circuit block diagram of the uninterruptible power supply system which concerns on Example 2 of this invention. The circuit block diagram of the uninterruptible power supply system which concerns on Example 3 of this invention. FIG. 6 is a block configuration diagram of an output voltage / frequency command circuit used in the third embodiment. The circuit block diagram of the uninterruptible power supply system which concerns on Example 4 of this invention. FIG. 6 is a block configuration diagram of an output voltage / frequency command circuit used in the fourth embodiment. The circuit block diagram of the uninterruptible power supply system which concerns on Example 5 of this invention. The circuit block diagram of the uninterruptible power supply system which concerns on Example 6 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 is a circuit configuration diagram of an uninterruptible power supply system according to Embodiment 1 of the present invention.

  In FIG. 1, AC power is supplied from commercial power sources 1 and 2 to uninterruptible power supply devices 11 and 21, respectively. Converters 11a and 21a of uninterruptible power supply devices 11 and 21 respectively convert this alternating current into direct current and supply power to inverters 11b and 21b. Storage batteries 31 and 41 for supplying DC power when the commercial power sources 1 and 2 are cut off are connected to the respective inputs of the inverters 11b and 21b. Outputs of the inverters 11b and 21b are connected to output branch circuits 71 and 72 via uninterruptible switching circuits 11c and 21c, respectively. The commercial power supply 5 for bypass input is connected to the uninterruptible switching circuits 11c and 21c, and bypass power is supplied from the commercial power supply 5 for bypass input when an abnormality occurs in the converters 11a to 11b and the converters 21a to 21b. In addition, power supply to the load facilities 91 and 92 can be continued through the output branch circuits 71 and 72 and the overlap type switching devices 81 and 82, respectively.

  The switch 71a and the switch 71b in the output branch circuit 71 are provided to branch the output of the uninterruptible power supply 11 to the overlap switching devices 81 and 82. The switch 72a and the switch in the output branch circuit 72 are provided. 72 b is provided to branch the output of the uninterruptible power supply 21 to the overlap switching devices 81 and 82.

  The voltage / frequency command circuit 101 is a part of the entire control circuit of the inverter 11b (not shown), and its internal configuration will be described below.

  A switching preparation command is given from the overlap switching device 82 as one input of the AND circuit 102. A failure signal from the uninterruptible power supply 21 is given as the other input of the AND circuit 102. The failure signal in this case is a signal meaning that the uninterruptible switching circuit 21c is on the bypass power supply side due to the failure of the converter 21a or the inverter 21b. The output of the switch 103 gives an output voltage command of the inverter 11b. According to the output of the AND circuit 102, the output of the switch 103 is switched from the fixed voltage reference 104 side to the voltage side detected by the voltage detector 105 from the switch 72b.

  Hereinafter, the operation of the uninterruptible power supply system of FIG. 1 will be described.

  During normal operation, power is supplied from the uninterruptible power supply 11 to the load equipment 91 via the switch 71a of the output branch circuit 71 and the overlap switching device 81. Similarly, power is supplied from the uninterruptible power supply 21 to the load facility 92 via the switch 72b of the output branch circuit 72 and the overlap switching device 82.

  In this state, for example, a case where an abnormality has occurred in the converter 21a or the inverter 21b of the uninterruptible power supply 21 will be considered. At this time, the uninterruptible switching circuit 21c is operated by an automatic sequence in the uninterruptible power supply 21, and the power supply to the load facility 92 is switched to the bypass power supply from the commercial power supply 5 for bypass input. That is, power is supplied from the commercial power source for bypass input through the uninterruptible switching circuit 21c, the switch 72b of the output branch circuit 72, and the overlap switching device 82.

  At this time, since a failure signal is given from the uninterruptible power supply 21 to the AND circuit 102 of the voltage / frequency command circuit 101, if the overlap-type switching device 82 gives a switching preparation command to the AND circuit 102 in advance. The switch 103 selects the output voltage of the switch 72b, that is, the bypass power supply voltage of the failed uninterruptible power supply as the output voltage command of the inverter 11b.

  In this way, the uninterruptible power supply apparatus in which the output voltage command value of the sound uninterruptible power supply apparatus 11 has failed in response to the failure signal from the failed uninterruptible power supply apparatus 21 and the switching preparation command from the overlap type switching apparatus 82. 21, the voltage applied from the uninterruptible power supply 11 to the overlap type switching device 82 via the switch 71b of the output branch circuit 71 and the output branch from the uninterruptible power supply 21. The voltage applied to the overlap type switching device 82 via the switch 72b of the circuit 72 matches. Under this condition, the overlap type switching device 82 supplies power to the load facility 92 from bypass power supply from the switch 72b of the output branch circuit 72, and from the sound uninterruptible power supply 11 to the switch 71b of the output branch circuit 71. When the power supply is switched, the cross current does not flow between the uninterruptible power supply 11 and the uninterruptible power supply 21. Therefore, it is possible to easily switch without changing the power supply state from the sound uninterruptible power supply 11.

  In the case of FIG. 1, since the commercial power supply 5 for bypass input is common to the uninterruptible power supply devices 11 and 21, the input voltage of the voltage detector 105 is obtained from the bypass power supply bus in the uninterruptible power supply device 11. However, considering the influence of the voltage drop due to the wiring, it is desirable to detect at a position as close to the input of the overlap type switching device 82 as possible. Therefore, in the present embodiment, it is obtained from the output side of the switch 72b of the output branch circuit 72 in consideration of practicality and the like. In addition, since it is possible to obtain the frequency of the commercial power supply 5 for bypass input within the uninterruptible power supply 11 with respect to the frequency, in the case of the first embodiment, it is not necessary to switch the frequency command.

  In FIG. 1, only the voltage / frequency command circuit 101 for the uninterruptible power supply 11 is shown, and the voltage / frequency command circuit for the uninterruptible power supply 21 is not shown. Similarly, illustration of other embodiments shown below is also omitted. These voltage / frequency command circuits are usually installed in each uninterruptible power supply or can be installed separately from individual uninterruptible power supplies as a common control unit.

  As described above, in response to the failure signal from the failed uninterruptible power supply and the switch preparation command from the overlap type switching device, the output voltage command value of the healthy uninterruptible power supply is changed from the rated voltage (constant voltage). In an uninterruptible power supply system in which two uninterruptible power supply units are matched by an overlap type switching device by providing a voltage / frequency command circuit that performs selective switching to the bypass voltage on the failed uninterruptible power supply side. When an abnormality occurs in one uninterruptible power supply, a healthy uninterruptible power supply power supply state is maintained, and the sound unreliable power supply from the uninterruptible power supply to the load facility is maintained. It is possible to switch the power supply to the power failure power supply.

  FIG. 2 is a circuit configuration diagram of the uninterruptible power supply system according to the second embodiment of the present invention. In the second embodiment, the same parts as those in the circuit configuration diagram of the uninterruptible power supply system according to the first embodiment of the present invention shown in FIG. The second embodiment is different from the first embodiment in that the bypass input commercial power supply 5 is dedicated to the uninterruptible power supply 11 and the bypass input commercial power supply 6 is provided for the uninterruptible power supply 21, and a voltage / frequency command is provided. A switching device 106 is provided in the circuit 101A, and a frequency command given to the inverter 11b based on the output of the AND circuit 102 is detected from the frequency detector 107 side that detects the frequency of the bypass power source 5, and the frequency detector 108 side that detects the bypass power source 6 frequency. It is the point which was set as the structure switched to.

  In the first embodiment, the case where the two uninterruptible power supply units that are matched in the overlap type switching device have the same bypass power supply is described. However, as shown in FIG. In order to apply the present invention when different bypass power supplies are used, it is necessary to match not only the voltage but also the phase. Therefore, a failure signal from the failed uninterruptible power supply and a switch preparation command from the overlap type switching device are issued. In addition to the circuit that selectively switches the output voltage command from the rated voltage (constant voltage) to the bypass voltage on the uninterruptible power supply side, the frequency command that is the synchronous control reference value has failed from the bypass power source side of the own unit. It is also necessary to provide a circuit for selective switching on the bypass power supply side of the uninterruptible power supply. The frequency command serving as the synchronization control reference value means a frequency command including a phase command. Based on this frequency command, control such as a phase locked loop is used in the entire control circuit of the inverter 11b (not shown). The output frequency and phase of the inverter 11b are made to coincide with this frequency command.

  According to the circuit configuration of FIG. 2, for example, a frequency signal that becomes a synchronous control reference value in response to a failure signal from the uninterruptible uninterruptible power supply 21 and a switching preparation command from the overlap type switching device 82 is sent to the bypass power supply of the own machine. The switch 106 selectively switches from the 5 side to the bypass power source 6 side of the uninterruptible uninterruptible power supply 21.

  In this way, the failure signal from the failed uninterruptible power supply and the switching preparation command from the overlap type switching device are received, and the output voltage command value of the sound uninterruptible power supply is failed from the rated voltage (constant voltage). In addition to performing selective switching to the bypass voltage on the uninterruptible power supply side, the uninterruptible power supply apparatus that has failed from the bypass power supply side of its own machine in response to the above failure notification and switching preparation command By selectively switching to the bypass power source side, the same effect as in the first embodiment can be obtained even in the case of an uninterruptible power system in which the bypass power sources of the two uninterruptible power supply devices are different.

  Hereinafter, an uninterruptible power supply system according to Embodiment 3 of the present invention will be described with reference to FIGS. 3 and 4.

  FIG. 3 is a circuit configuration diagram of an uninterruptible power supply system according to Embodiment 3 of the present invention. In the third embodiment, the same parts as those of the circuit configuration diagram of the uninterruptible power supply system according to the first embodiment of the present invention shown in FIG. The third embodiment differs from the first embodiment in that an uninterruptible power supply 12 fed from the commercial power supply 3 is provided in parallel with the uninterruptible power supply 11 and is operated in parallel by the switches 51a and 51b in the parallel connection circuit 51. Similarly, the uninterruptible power supply 22 fed from the commercial power source 4 is provided in parallel with the uninterruptible power supply 21 and can be operated in parallel by the switches 52a and 52b in the parallel connection circuit 52. The point is that the failure signal of the uninterruptible power supply 21 and the uninterruptible power supply 22 is given to the voltage / frequency command circuit 101A.

  FIG. 4 shows the internal configuration of the voltage / frequency command circuit 101B. As shown in FIG. 4, failure signals of the uninterruptible power supply 21 and the uninterruptible power supply 22 are given to the OR circuit 109, and the output of the OR circuit 109 is used as one input of the AND circuit 102. The other circuits are basically the same as the voltage / frequency command circuit 101 of the first embodiment. In FIG. 3, the voltage command which is the output of the voltage / frequency command circuit 101B is given to the inverter 11b and the inverter 12b in parallel, but the voltage / frequency command circuit is used for the uninterruptible power supply 11 and the uninterruptible power supply. It is good also as a structure provided for 12 each.

  Further, since the uninterruptible power supply 21 and the uninterruptible power supply 22 are basically operated in parallel, a configuration in which a failure signal as a parallel system is given to the voltage / frequency command circuit 101B instead of the individual failure signals described above. Also good. In that case, the OR circuit 109 becomes unnecessary.

  The operation in FIG. 3 is basically the same as that in the first embodiment.

  That is, in the normal state, the uninterruptible power supply units 11 and 12 are operated in parallel with the switches 51 a and 51 b in the parallel connection circuit 51 being closed, and are connected via the switch 71 a and the overlap switching device 81 of the output branch circuit 71. Power is supplied to the load facility 91. Similarly, the uninterruptible power supply devices 21 and 22 operate in parallel with the switches 52a and 52b in the parallel connection circuit 52 being closed, and load equipment is installed via the switch 72b and the overlap switching device 82 in the output branch circuit 72. Power is supplied to 92.

  In this state, consideration will be given to a case where an abnormality has occurred in the converter 21a or inverter 21b of the uninterruptible power supply 21 or the converter 22a or inverter 22b of the uninterruptible power supply 22. At this time, the uninterruptible switching circuit 21c and the uninterruptible switching circuit 22c are operated by an automatic sequence in the uninterruptible power supply 21 or the uninterruptible power supply 22, and power supply to the load facility 92 is supplied from the commercial power supply 5 for bypass input. Switch to bypass power supply. That is, power is supplied from the bypass input commercial power source via the uninterruptible switching circuit 21c, the uninterruptible switching circuit 22c, the switch 72b of the output branch circuit 72, and the overlap switching device 82.

  At this time, since the failure signal is given from the uninterruptible power supply 21 or the uninterruptible power supply 22 to the AND circuit 102 via the OR circuit 109 of the voltage / frequency command circuit 101B, the overlap type switching device 82 preliminarily instructs the switching preparation command. Is applied to the AND circuit 102, the switch 103 selects the output voltage of the switch 72b, that is, the bypass power supply voltage of the failed uninterruptible power supply as the output voltage command of the inverters 11b and 12b.

  In this way, in response to the failure signal from the failed uninterruptible power supply 21 or the uninterruptible power supply 22 and the switching preparation command from the overlap type switching device 82, the output voltage command of the sound uninterruptible power supply 11 and 12 is sound. When the value is selectively switched to the bypass voltage of the uninterruptible power supply 21 or the uninterruptible power supply 22, the overlap type switching device from the uninterruptible power supplies 11 and 12 through the switch 71b of the output branch circuit 71 The voltage applied to 82 matches the voltage applied from the uninterruptible power supply devices 21 and 22 to the overlap type switching device 82 via the switch 72b of the output branch circuit 72. Under this condition, the overlap type switching device 82 supplies power to the load facility 92 from bypass power supply from the switch 72b of the output branch circuit 72, and from the sound uninterruptible power supply devices 11 and 12 to the switch of the output branch circuit 71. When switching to power supply via 71b, no cross current flows between the uninterruptible power supply units 11 and 12 and the uninterruptible power supply units 21 and 22. Accordingly, it is possible to easily switch without changing the power supply state from the sound uninterruptible power supply devices 11 and 12.

  Hereinafter, an uninterruptible power supply system according to Embodiment 4 of the present invention will be described with reference to FIGS. 5 and 6.

  FIG. 5 is a circuit configuration diagram of an uninterruptible power supply system according to Embodiment 4 of the present invention. In the fourth embodiment, the same parts as those in the circuit configuration diagram of the uninterruptible power supply system according to the third embodiment of the present invention shown in FIG. The fourth embodiment is different from the third embodiment in that the bypass input commercial power supply 5 for the uninterruptible power supply devices 11 and 12 and the bypass input commercial power supply 6 for the uninterruptible power supply devices 21 and 22 are combined. The point which became the structure which became another power supply, the point which added the voltage of commercial power supply 5 for bypass inputs as a signal given to voltage / frequency command circuit 101C, and the output for inverters 11b and 12b as the output signal of voltage / frequency command circuit 101C This is the addition of a frequency command.

  The internal configuration of the voltage / frequency command circuit 101C is shown in FIG. As shown in FIG. 6, failure signals of the uninterruptible power supply 21 and the uninterruptible power supply 22 are given to the OR circuit 109, and the output of the OR circuit 109 is used as one input of the AND circuit 102. Other circuits are basically the same as the voltage / frequency command circuit 101A of the second embodiment. In FIG. 6, the output voltage command and the output frequency command, which are the outputs of the voltage / frequency command circuit 101B, are given in parallel to the inverter 11b and the inverter 12b, but the voltage / frequency command circuit is used for the uninterruptible power supply 11. The uninterruptible power supply 12 may be provided separately.

  Since the switching operation by the overlap type switching device of the present embodiment is basically the same as that of the third embodiment, and the control effect is basically the same as that of the second embodiment, description thereof will be omitted. .

  FIG. 7 is a circuit configuration diagram of an uninterruptible power supply system according to Embodiment 5 of the present invention. In the fifth embodiment, the same parts as those in the circuit configuration diagram of the uninterruptible power supply system according to the third embodiment of the present invention shown in FIG. The fifth embodiment is different from the third embodiment in that it is provided on the output side of the parallel connection circuit 51 in place of the individual uninterruptible switching circuits 11c and 12c provided in the uninterruptible power supply devices 11 and 12, respectively. A configuration in which the uninterruptible switching circuit 61 is provided collectively, and a parallel connection circuit instead of the individual uninterruptible switching circuits 21c and 22c provided in the uninterruptible power supply devices 21 and 22 in the same manner. This is a configuration in which an uninterruptible switching circuit 62 is collectively provided on the output side of 52.

  As described above, the uninterruptible power supply units 11 and 12 and the uninterruptible power supply units 21 and 22 are normally operated in parallel by the parallel connection circuits 51 and 52, respectively. For example, when any uninterruptible power supply device fails during parallel operation, the sound uninterruptible power supply device that has been operating in parallel with the same set is also stopped and switched to bypass power feeding. This is because it is not necessary to provide the uninterruptible switching circuit 6 for the uninterruptible power supply individually, and only one unit is required for each set.

  The uninterruptible power supply system of FIG. 7 is a system based on the above concept, and its operation is basically the same as that of the uninterruptible power supply system according to Example 3 of FIG. Therefore, the voltage / frequency command circuit 101B is the same as that of the third embodiment shown in FIG.

  FIG. 8 is a circuit configuration diagram of an uninterruptible power supply system according to Embodiment 6 of the present invention. About each part of this Example 6, the same part as each part of the circuit block diagram of the uninterruptible power supply system which concerns on Example 5 of this invention of FIG. 7 is shown with the same code | symbol, and the description is abbreviate | omitted. The difference between the sixth embodiment and the fifth embodiment is that the bypass input commercial power supply 5 for the uninterruptible power supply devices 21 and 22 and the bypass input commercial power supply 6 for the uninterruptible power supply devices 11 and 12 that form a set are different. The point which became the structure which became another power supply, the point which added the voltage of commercial power supply 5 for bypass inputs as a signal given to voltage / frequency command circuit 101C, and the output for inverters 11b and 12b as the output signal of voltage / frequency command circuit 101C This is the addition of a frequency command.

  As described in the fifth embodiment, the uninterruptible power supply system of FIG. 8 operates basically the same as the uninterruptible power supply system according to the fourth embodiment shown in FIG. Therefore, the voltage / frequency command circuit 101C is the same as that of the fourth embodiment shown in FIG.

1, 2, 3, 4 Commercial power supply 5, 6 Bypass input commercial power supply 11, 12, 21, 22 Uninterruptible power supply 11a, 12a, 21a, 22a Converter 11b, 12b, 21b, 22b Inverter 11c, 12c, 21c, 22c, 61, 62 Uninterruptible switching circuit 31, 32, 41, 42 Storage battery 51, 52 Parallel connection circuit 51a, 51b, 52a, 52b Switch 71, 72 Output branch circuit 71a, 71b, 72a, 72b Switch 81, 82 Overlap type switching device 91, 92 Load facility 101 101A, 101B, 101C Voltage / frequency command circuit 102 AND circuit 103, 106 Switch 104 Voltage setter 105 Voltage detector 107, 108 Frequency detector 109 OR circuit

Claims (5)

A first power source is configured to convert AC of a commercial power source into DC by a converter, convert the DC to AC again by an inverter, and switch the output to bypass power feeding from a commercial power source for bypass input by an uninterruptible switching circuit. And a second uninterruptible power supply,
A first and a second output branch circuit for branching the respective outputs of the first and second uninterruptible power supply devices into two systems via respective switches;
First overlap switching for switching the power supply to the first load facility without instantaneous interruption using one branch output of the first output branch circuit and one branch output of the second output branch circuit as inputs. Equipment,
Second overlap switching for switching the power supply to the second load equipment without interruption without using the other branch output of the first output branch circuit and the other branch output of the second output branch circuit as inputs. Equipment,
Voltage / frequency command means for providing at least one of an output voltage command and an output frequency command for each of the inverters;
The voltage / frequency command means includes:
When a switching preparation command is given from the overlap switching device, and any of the uninterruptible power supply devices fails,
The output voltage command to be given to the sound uninterruptible power supply is switched from a predetermined constant voltage to the voltage of the commercial power supply for bypass input of the uninterruptible power supply that has failed ,
The voltage of the commercial power supply for bypass input of the failed uninterruptible power supply,
The overlap switching device is switched from bypass power supply to sound uninterruptible power supply power supply by obtaining the output branch circuit from the output side of the switch supplying power to the load equipment. An uninterruptible power supply system characterized by preventing a cross current between the first and second uninterruptible power supply units . The bypass input commercial power sources of the first and second uninterruptible power supply devices are each composed of separate systems,
The voltage / frequency command means includes:
When a switching preparation command is given from the overlap switching device, and any of the uninterruptible power supply devices fails,
The output frequency command given to the healthy uninterruptible power supply is switched from the frequency of the commercial power supply for bypass input to the frequency of the commercial power supply for bypass input of the failed uninterruptible power supply. The uninterruptible power supply system according to claim 1. Multiple units configured to convert AC of commercial power to DC by a converter, convert this DC to AC again by an inverter, and switch the output to bypass power supply from a commercial power supply for bypass input by an uninterruptible switching circuit First and second sets of uninterruptible power supply equipment, comprising: an uninterruptible power supply apparatus of the first and second parallel connection means capable of connecting outputs of the plurality of uninterruptible power supply apparatuses in parallel;
A first and a second output branch circuit for branching the respective outputs of the parallel connection means into two systems, each via a switch;
A first overlap for switching the power supply to the first load facility without interruption, with one branch output of the first output branch circuit and one branch output of the second output branch circuit as inputs. A switching device;
Second overlap switching for switching the power supply to the second load equipment without interruption without using the other branch output of the first output branch circuit and the other branch output of the second output branch circuit as inputs. Equipment,
Voltage / frequency command means for providing at least one of an output voltage command and an output frequency command for each of the inverters;
The voltage / frequency command means includes:
When a switching preparation command is given from the overlap switching device, and any of the uninterruptible power supply units fails,
The output voltage command given to the uninterruptible power supply in a healthy set is switched from a predetermined constant voltage to the voltage of the commercial power supply for bypass input of the failed uninterruptible power supply.
As well as
The voltage of the commercial power supply for bypass input of the failed uninterruptible power supply,
The overlap switching device is switched from bypass power supply to sound uninterruptible power supply power supply by obtaining the output branch circuit from the output side of the switch supplying power to the load equipment. An uninterruptible power supply system characterized by preventing a cross current between the first and second uninterruptible power supply units . A plurality of uninterruptible power supply units that convert commercial power AC into direct current with a converter and convert this direct current back into alternating current with an inverter, and parallel capable of connecting the outputs of the plurality of uninterruptible power supply units in parallel First and second sets of uninterruptible power supply equipment comprising: connection means; and an uninterruptible switching circuit capable of switching the output of the parallel connection means to bypass power supply from a commercial power supply for bypass input;
A first and a second output branch circuit for branching the respective outputs of the uninterruptible switching circuit into two systems through respective switches;
A first overlap for switching the power supply to the first load facility without interruption, with one branch output of the first output branch circuit and one branch output of the second output branch circuit as inputs. A switching device;
Second overlap switching for switching the power supply to the second load equipment without interruption without using the other branch output of the first output branch circuit and the other branch output of the second output branch circuit as inputs. Equipment,
Voltage / frequency command means for providing at least one of an output voltage command and an output frequency command for each of the inverters;
The voltage / frequency command means includes:
When a switching preparation command is given from the overlap switching device, and any of the uninterruptible power supply units fails,
The output voltage command to be given to the uninterruptible power supply of a healthy set is switched from a predetermined constant voltage to the voltage of the commercial power supply for bypass input of the failed uninterruptible power supply ,
The voltage of the commercial power supply for bypass input of the failed uninterruptible power supply,
The overlap switching device is switched from bypass power supply to sound uninterruptible power supply power supply by obtaining the output branch circuit from the output side of the switch supplying power to the load equipment. An uninterruptible power supply system characterized by preventing a cross current between the first and second uninterruptible power supply units . The bypass input commercial power supplies of the first and second sets of uninterruptible power supply facilities are each composed of separate systems,
The voltage / frequency command means includes:
When a switching preparation command is given from the overlap switching device, and any of the uninterruptible power supply units fails,
The output frequency command given to the uninterruptible power supply in a healthy set is switched from the frequency of the commercial power supply for bypass input to the frequency of the commercial power supply for bypass input of the failed uninterruptible power supply. The uninterruptible power supply system according to claim 3 or 4.

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