JP2017050933A - Uninterruptible power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an uninterruptible power supply system capable of performing highly efficient power supply while keeping power supply reliability.SOLUTION: Three uninterruptible power supply devices including power supply side breakers connected in parallel to inverters 7a to 7c to switch bypass power supplies without interruption and non-interruption changers composed of a power supply side contactor and a semiconductor switch perform parallel redundant operation to supply power to a load 11. One of the uninterruptible power supply devices is taken as a specific device 1c; the remaining devices are taken as non-specific devices 1a, 1b. The non-specific devices comprise a load sharing controller for controlling output current so that uniform sharing with respect to the load is established at the time of normal operation. The specific device comprises a load sharing controller and a standby current controller that, in order to become in a state in which a load can be supplied with power immediately, controls output current of a corresponding inverter; and is capable of being switched to any of the controllers, where switching to the standby current controller is performed when the non-specific devices are in normal operation and switching to the load sharing controller is performed when a non-specific device is in a failure state or stop state.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention relate to an uninterruptible power supply system that includes a plurality of uninterruptible power supply devices and is capable of parallel redundant operation.

  In a conventional redundant redundant uninterruptible power supply system aiming at high reliability, the current control circuits of the inverters that supply AC power to the loads included in each uninterruptible power supply connected in parallel are the same. Only the shared current control circuit can be operated.

JP 2011-188706 A

  In the above-mentioned conventional parallel redundant uninterruptible power supply system, even though the load is light and the uninterruptible power supply can be stopped, redundancy can be maintained, but the uninterruptible power supply connected in parallel has continued to operate. The system efficiency as an uninterruptible power supply system was decreasing. Also, if the uninterruptible power supply is operated in the inverter stopped state if it is connected in parallel to improve efficiency, parallel redundancy will be lost until the inverter is recovered from the inverter stopped state, and load power supply reliability may be reduced. It is done.

  The present embodiment has been made to eliminate the above-described drawbacks, and an object thereof is to obtain an uninterruptible power supply system capable of highly efficient power supply while maintaining power supply reliability.

  According to a representative example of the embodiment, at least three uninterruptible power supply units each including an inverter that outputs AC power are provided, and each uninterruptible power supply unit supplies power to a load by parallel redundant operation. The uninterruptible power supply system includes a load sharing control device that controls an output current of a corresponding inverter so that the load sharing is equal to the load during operation. At least one of the power interruption power supply devices is switchable with respect to the load sharing control device, and a standby current control device that controls the output current of the corresponding inverter so that power can be immediately supplied to the load. Except when the uninterruptible power supply unit in operation is in a failure state or a stopped state, the remaining uninterruptible power supply unit capable of normal operation and the standby current control unit Wherein a UPS system to allow feeding continuously to the load by the uninterruptible power supply provided with the standby current controller operable by switching to a load sharing control device.

  According to the embodiment described above, it is possible to provide an uninterruptible power supply system capable of highly efficient power supply while maintaining power supply reliability.

FIG. 3 is a diagram for explaining a schematic configuration of the first embodiment. The figure for demonstrating the inverter driving | running determination circuit of FIG. The figure for demonstrating the inverter control apparatus of FIG. The figure for demonstrating the operation | movement of FIG. FIG. 5 is a diagram for explaining a schematic configuration of a second embodiment. FIG. 5 is a diagram for explaining a schematic configuration of a third embodiment. FIG. 6 is a diagram for explaining a schematic configuration of a fourth embodiment.

  Hereinafter, although embodiment is described, the outline composition is the conventional uninterruptible power supply system. At least one of the uninterruptible power supply units can be switched to the load sharing control device, Equipped with a standby current control device that controls the output current of the corresponding inverter so that power can be supplied immediately, and when the uninterruptible power supply in operation is faulty or stopped, the remaining normal operation is possible An uninterruptible power supply system that enables continuous power supply to the load with an uninterruptible power supply and an uninterruptible power supply with a standby current controller that can be operated by switching from a standby current controller to a load sharing controller. is there.

  A conventional uninterruptible power supply system includes at least three uninterruptible power supply devices including inverters that output AC power to each, and each uninterruptible power supply device supplies power to a load by parallel redundant operation. Each uninterruptible power supply is provided with a load sharing control device for controlling the output current of the corresponding inverter so that the load sharing becomes equal to the load during operation.

  Hereinafter, Embodiment 1 of the uninterruptible power supply system will be described with reference to FIG. 1. Here, a plurality of units capable of parallel redundant operation, for example, three uninterruptible power supply devices 1 a, 1 b, and 1 c, and an AC output from these units. Electric power is supplied to the load 11. Here, the uninterruptible power supply devices 1 a and 1 b are referred to as non-specific uninterruptible power supply devices, and the uninterruptible power supply device 1 c is referred to as a specific uninterruptible power supply device.

  First, the uninterruptible power supply 1a will be described. For example, two power sources, ie, an AC input power source 2a constituting the first AC power source and a bypass power source 3a constituting the second AC power source are input. The uninterruptible power supply 1a inputs AC power from the AC input power source 2a to the converter 5a through the AC input circuit breaker 4a to convert it into DC power, and inputs the converted DC power to the inverter 7a to generate AC. The electric power is converted into electric power, and AC power is supplied to the load 11 via the inverter-side contactor 10a, and the DC power converted by the converter 5a is supplied to power storage means, for example, the storage battery 6a to charge the storage battery 6a. When the charging is completed, the discharge power is supplied to the inverter 7a, and the AC power obtained here is supplied to the load 11.

  The inverter 7a outputs a sine wave based on an inverter control command 9a which is an output of the inverter control circuit 8a, and supplies power to the load 11 via the inverter side contactor 10a.

  Further, AC power from the commercial power source 3a is supplied to the load 11 via a bypass circuit 17a described below. The bypass circuit 17a includes a power supply circuit breaker 14a and an uninterruptible switching device including a semiconductor switch 12a connected in parallel with the power supply contactor 13a.

  Further, a sequence control circuit 21a is provided, which outputs a failure detection signal 22a when a failure of the uninterruptible power supply 1a itself is detected, and further detects a stop detection signal 23a when a stop of the uninterruptible power supply 1a itself is detected. Is output.

  The configuration described above is the same for the uninterruptible power supply 1b, and the same portions are denoted by the same reference numerals and the description thereof is omitted.

  Here, the uninterruptible power supply 1c is different from the uninterruptible power supplies 1a and 1b in that the sequence control circuits 21a and 21b and the inverter control circuits 8a and 8b are not provided, and are newly shown in FIG. An inverter operation determination circuit 24 and an inverter control device 30 shown in FIG. 3 are provided.

  As shown in FIG. 2, the inverter operation determination circuit 24 includes logical sum elements 25a, 25b, and 25c. The logical sum element 25a has a failure detection signal 22a and a stop detection signal 23a as outputs from the sequence control circuit 21a. The failure detection signal 22b and the stop detection signal 23b, which are outputs from the sequence control circuit 21b, are input to the input of the logical sum element 25b, and the logical sum elements 25a and 25b are input to the input of the logical sum element 25c. An output is input, and an inverter operation switching command 26, which is an output of the OR element 25c, is input to the inverter control device 30.

  As shown in FIG. 3, the inverter control device 30 includes an inverter control circuit (current command generation circuit) 15 that outputs an inverter current command, a load sharing control device such as a shared current control circuit 16, and a standby current control device such as a standby current control. The inverter current command, which is an output from the circuit 28 and the inverter control circuit 15, can be switched to either the shared current control circuit 16 or the standby current control circuit 28, and the inverter operation switching command from the inverter operation determination circuit 24. 26 is provided with a switching device 27 that can be switched by 26. The switching device 27 comprises an input side switching circuit 27a and an output side switching circuit 27b. The input side switching circuit 27a is provided on the output side of the inverter control circuit 15 and on the input side of the shared current control circuit 16 and the standby current control circuit 28. Thus, the output side switching circuit 27 b is provided on the output side of the shared current control circuit 16 and the standby current control circuit 28.

  When the AC input power source 2a fails, the converter 5a stops (gate block), and the inverter 7a feeds the load 11 via the inverter-side contactor 10a with the DC power from the storage battery 6a as an input. Power supply can be continued.

  Failure detection signals 22a and 22b and stop detection signals 23a and 23b, which are output signals from the sequence control circuits 21a and 21b of the uninterruptible power supply devices 1a and 1b, are sent to the inverter operation determination circuit 24 of the specific uninterruptible power supply device 1a. Entered. The output of the inverter operation determination circuit 24, that is, the inverter operation switching command 26 is input to the inverter control device 30.

  Next, the operation of the first embodiment described above will be described with reference to FIG.

  FIG. 4A shows the operation state set first. That is, no. 1 UPS 1a and No. 1 2 50% load power is supplied to each UPS 1b. 3 UPS 1c is connected to the main circuit, but power supply to the load 11 is not performed (0% load power supply). Specifically, the standby current control circuit 28 is connected. .

  FIG. 4B shows the operating state when an abnormality occurs. That is, from the state of FIG. 1 When a failure occurs in the UPS 1a, a failure detection signal 22a is given from the sequence control circuit 21a to the inverter operation determination circuit 24. As a result, the outputs of both the OR elements 25a and 25c in FIG. An inverter operation switching command 26 is given from the operation determination circuit 24 to the inverter control device 30, and the switching circuits 27a and 27b are simultaneously switched. 3 By switching the inverter control system of the UPS 1c to the normal shared current control circuit 16, switching can be performed immediately (for example, 4 ms or less). Here, 4 ms or less means no instantaneous interruption (within ¼ cycle−0 V).

  FIG. 4C is a time chart showing the state of FIG. 4A and the state of FIG.

  As described above, the specific uninterruptible power supply 1c is provided with the standby current control circuit 28 and the shared current control circuit 16 and can be switched between them. The failure of the nonspecific uninterruptible power supply 1a, 1b When the detection signals 22a and 22b or the stop detection signals 23a and 23b are input, the standby current control circuit 28 is immediately switched to the shared current control circuit 16, so that an efficient uninterruptible operation without impairing power supply reliability. A power system is obtained. In contrast, in the conventional system, since all inverter control circuits have only a shared current control circuit, there is a case where power cannot be supplied immediately by the uninterruptible power supply when an abnormality such as a failure occurs in another unit. .

  Further, in the inverter control device 30 of FIG. 3, since the switching circuits 27a and 27b are provided on the input side and the output side of the sharing current control circuit 16 and the standby current control circuit 28, the sharing current control circuit 16 and the standby current control circuit 30 Even if the current control circuit 28 includes an integral element, it operates reliably.

  Furthermore, when the upper system of the uninterruptible power supply is in a different state, for example, even when one is commercial and the other is a private power generation facility, the two uninterruptible power supplies are always connected to the load 11. By taking the synchronization, it is possible to improve the load power supply reliability by making it possible to supply the uninterruptible power supply that is always synchronized to the load 11.

  Furthermore, a system that is not fed by an inverter has a higher energy density than a lead-acid battery such as a large-capacity storage battery system such as a lithium ion secondary battery (SCiB, etc.). By applying a storage battery system that can do this, the power outage backup operation time can be extended.

  Here, the bypass circuits 17a, 17b, and 17c will be described. For example, in the case of an uninterruptible power supply system of 500 k × (3-1) = 1000 kVA, the uninterruptible power supply devices 1a, 1b, and 1c are configured as 500 kVA, and the three units are configured. When the power supply cannot be continued, the inverter-side contactor 8 is turned off, and the power supply to the load 11 can be continued by disconnecting the other uninterruptible power supply devices 1b and 1c from the load power supply path. . Further, when the other uninterruptible power supply 1b cannot continue to be fed by the inverter 7b due to a failure, and when the amount of power cannot be fed by the sound uninterruptible power supply 1c, the semiconductor switches 12a and 12b , 12c and the commercial power supply side contactors 13a, 13b, 13c are turned on to supply power to the load 11 from the power supply system via the commercial power supply 3 and the commercial circuit breakers 13a, 13b, 13c. Power supply can be continued.

  FIG. 5 is for explaining the second embodiment, in which the uninterruptible power supply devices 1a, 1b and 1c are all configured identically. Specifically, the uninterruptible power supply 1c newly outputs a failure detection new signal 22c of the uninterruptible power supply 1c itself or a stop detection signal of the uninterruptible power supply 1c itself, and a sequence control circuit 21c of FIG. The inverter operation determination circuit 24 included in the uninterruptible power supply 1c is set to 24c, the inverter operation command 26 which is the output is set to 26c, and the inverter control apparatus included in the uninterruptible power supply 1c in FIG. 30 is set to 30c, the inverter control output 9 which is the output is set to 9c, and the uninterruptible power supply devices 1a and 1c are also configured in the same manner, and are as follows.

  That is, the failure detection signals 22a, 22b, and 22c and the stop detection signals 23a, 23b, and 23c from the sequence control circuits 21a, 21b, and 21c other than itself are input to the inverter operation determination circuits 24a, 24b, and 24c, respectively. It is like that. Specifically, the failure detection signals 22b and 22c and the stop detection signals 23b and 23c are input to the inverter operation determination circuit 24a, and similarly, the failure detection signals 22a and 22c and the stop detection signal 23a, 23c is input, and failure detection signals 22a and 22b and stop detection signals 23a and 23b are input to the inverter operation determination circuit 24c.

  Inverter operation switching commands 26a, 26b, and 26c, which are outputs from the inverter operation determination circuits 24a, 24b, and 24c, are input to the inverter control devices 30a, 30b, and 30c, respectively. Inverter control outputs 9a, 9b, 9c, which are the outputs of the inverter control devices 30a, 30b, 30c, are input to the inverters 7a, 7b, 7c, respectively. The rest of the configuration is the same as in FIG.

  Therefore, as in the embodiment of FIG. 1, when the uninterruptible power supply 1a, 1b is operating at 50%, or when the uninterruptible power supply 1a becomes faulty, the inverter operation determination circuits 24b, 24c Operation switching commands 26b and 26c are output, and inverters 7b and 7c are operated by inverter control outputs 9b and 9c from inverter control devices 30b and 30c. As a result, uninterruptible power supply devices 1b and 1c become 50%, respectively. The same effect can be obtained.

  FIG. 6 is for explaining the third embodiment. The difference from the embodiment of FIG. 1 is that the bypass circuits 17a, 17b, 17c provided in the uninterruptible power supply devices 1a, 1b, 1c in FIG. All are omitted, and a common bypass circuit 17 including the commercial power supply side circuit breaker 14, the semiconductor switch 12, the commercial power supply side contactor 13, and the inverter side contactor 10 is provided, and this is connected in parallel to each uninterruptible power supply 1a, 1b, 1c. Connected. The rest of the configuration is the same as in FIG. Therefore, the same effect as the embodiment of FIG. 1 can be obtained.

  FIG. 7 is for explaining the fourth embodiment. The uninterruptible power supply devices 1a, 1b and 1c are all configured identically. In FIG. 1, the bypass circuit 17a provided in each uninterruptible power supply device 1a, 1b and 1c. , 17b, 17c are all omitted, and a common bypass circuit 17 including the commercial power supply side circuit breaker 14, the semiconductor switch 12, the commercial power supply side contactor 13, and the inverter side contactor 10 is provided, which is connected to each uninterruptible power supply 1a, 1b and 1c are connected in parallel. The rest of the configuration is the same as in FIG. Therefore, the same effect as the embodiment of FIG. 1 can be obtained.

  In the foregoing embodiment, the inverters 7a, 7b and 7c have inputs to which DC power from power storage means such as the storage batteries 6, 6a, 6b and 6c, or AC power from the AC power supplies 2a, 2b and 2c is supplied as DC power. DC power from converters 5a, 5b, 5c, or power storage means, for example, DC power from storage batteries 6, 6a, 6b, 6c and DC power from the converters 5a, 5b, 5c However, the present invention is not limited to this, and any device may be used as long as AC power can be obtained from the inverters 7a, 7b, and 7c by some means.

  Needless to say, the above description of FIG. 4 includes the following contents. That is, an uninterruptible power supply system that includes at least three uninterruptible power supply devices each including an inverter that outputs alternating current power, and supplies power to a load by parallel redundant operation of the uninterruptible power supply device, When one of the uninterruptible power supply units is a specific uninterruptible power supply unit and the rest is a nonspecific uninterruptible power supply unit, the nonspecific uninterruptible power supply units are connected to the load when each is in normal operation. The output current of the corresponding inverter is controlled so that the load sharing is equalized, and the specific uninterruptible power supply can be switched to either a standby current control method that prevents power supply to the load or the shared current control method. There is a first operation process in which only the non-specific uninterruptible power supply is operating to supply power to the load, and the non-specific uninterruptible that is in an operating state during the first operation process. The shared current control from the standby current control system in which the power supply to the load is blocked by the inverter of the specific uninterruptible power supply except for the uninterruptible uninterruptible power supply when the power supply is in an abnormal state such as failure or stop A second operation process in which power is supplied to the load with this and the remaining non-specified uninterruptible power supply, and the uninterruptible power supply that is in an operation state during the second operation process When it becomes a state, it is an uninterruptible power supply system which passes through the 3rd operation | movement process which supplies electric power to the said load using the bypass system of a bypass alternating current power supply.

  The inverter operation switching commands 26, 26a, 26b, and 26c from the inverter operation determination circuits 24, 24a, 24b, and 24c described in the above-described embodiment are provided separately from the uninterruptible power supply devices 1c, 1a, 1b, and 1c. (Not shown) may be obtained.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Uninterruptible power supply device, 2 ... AC input power supply, 3 ... Commercial power supply, 4 ... AC input circuit breaker, 5 ... Converter, 6 ... Storage battery, 7 ... Inverter, 8 ... Inverter control circuit, 9 ... Inverter control output, 10 Inverter side contactor, 11 ... Load, 12 ... Semiconductor switch, 13 ... Commercial power source side contactor, 14 ... Commercial power source side circuit breaker, 15 ... Inverter control circuit (current command generator), 16 ... Shared current control circuit, DESCRIPTION OF SYMBOLS 17 ... Bypass circuit, 21 ... Sequence control circuit, 22 ... Failure detection signal, 23 ... Stop detection signal, 24 ... Inverter operation determination circuit, 25 ... Logical sum circuit, 26 ... Inverter operation switching command, 27 ... Switching circuit, 28 ... Standby current control circuit, 30... Inverter control device.

Claims (9)

Comprising at least three uninterruptible power supply units each including an inverter that outputs AC power, and supplying each of the uninterruptible power supply units to a load by parallel redundant operation, In the uninterruptible power supply system equipped with a load sharing control device that controls the output current of the corresponding inverter so that the load sharing becomes equal to the load during operation,
At least one of the uninterruptible power supply units is switchable with respect to the load sharing control device, and a standby current that controls the output current of the corresponding inverter so that power can be immediately supplied to the load. When the uninterruptible power supply device in operation is in a failure state or stopped state, the remaining uninterruptible power supply device capable of normal operation and the standby current control device to the load sharing control device are provided. An uninterruptible power supply system characterized in that power can be continuously supplied to the load by an uninterruptible power supply device equipped with the standby current control device operable by switching. An uninterruptible power supply system comprising at least three uninterruptible power supply devices each including an inverter that outputs alternating current power, and supplying each of the uninterruptible power supply devices to a load by parallel redundant operation,
When one of the uninterruptible power supplies is a specific uninterruptible power supply and the rest is a non-specific uninterruptible power supply,
The non-specific uninterruptible power supply device includes a load sharing control device that controls the output current of the corresponding inverter so that the load sharing is equal to the load when each is in normal operation,
The specific uninterruptible power supply corresponds to a standby current control device that controls the output current of the corresponding inverter so that the load can be immediately supplied to the load and the load sharing to be equal to the load A load sharing control device for controlling the output current of the inverter to be switched to any one of them, and when the non-specific uninterruptible power supply device is in normal operation, the standby current control device is switched to the non-specific uninterruptible power supply. When at least one of the devices is in a failure state or in a stopped state, the load sharing control device is switched and operation continues with the specific uninterruptible power supply and the non-specific uninterruptible power supply capable of normal operation. An uninterruptible power supply system. An uninterruptible power supply system comprising at least three uninterruptible power supply devices each including an inverter that outputs alternating current power, and supplying power to the load by parallel redundant operation of the uninterruptible power supply device,
When one of the uninterruptible power supplies is a specific uninterruptible power supply and the rest is a non-specific uninterruptible power supply,
The non-specific uninterruptible power supply is controlled so that the output current of the corresponding inverter is controlled so that the load sharing is equal to the load when each is in normal operation,
The specific uninterruptible power supply can be switched to either a standby current control system that blocks power supply to the load or the shared current control system, and only the non-specific uninterruptible power supply operates to power the load A first operating process of supplying
When the non-specific uninterruptible power supply in the operating state during the first operation process is in an abnormal state such as failure or stop, except for the abnormal uninterruptible power supply, the inverter of the specific uninterruptible power supply is A second operation process of switching from the standby current control method in which power supply to the load is blocked to the shared current control method and supplying power to the load with this and the remaining non-specific uninterruptible power supply device;
When the uninterruptible power supply that is in an operating state during the second operation process enters the abnormal state, a third operation process is performed in which power is supplied to the load by utilizing a bypass system of a bypass AC power supply. And uninterruptible power system. At least three bypass circuits each including an inverter that outputs AC power and having a bypass power source connected in parallel to the inverter and having a non-instantaneous switching device for switching the bypass power source to non-instantaneous interruption An uninterruptible power supply system comprising an uninterruptible power supply, wherein each uninterruptible power supply is configured to supply power to a load by parallel redundant operation,
When one of the uninterruptible power supplies is a specific uninterruptible power supply and the rest is a non-specific uninterruptible power supply,
The non-specific uninterruptible power supply device includes a load sharing control device that controls the output current of the corresponding inverter so that the load sharing is equal to the load when each is in normal operation,
The specific uninterruptible power supply corresponds to a standby current control device that controls the output current of the corresponding inverter so that the load can be immediately supplied to the load and the load sharing to be equal to the load A load sharing control device for controlling the output current of the inverter to be switched, and can be switched to any one of them, and when the non-specific uninterruptible power supply is in normal operation, the standby current control device is switched, and the non-specific uninterruptible power supply An uninterruptible power supply system, wherein when the power supply device is in a failure state or a stopped state, the load sharing control device is switched. At least three bypass circuits each including an inverter that outputs AC power and having a bypass power source connected in parallel to the inverter and having a non-instantaneous switching device for switching the bypass power source to non-instantaneous interruption An uninterruptible power supply system comprising an uninterruptible power supply, wherein each uninterruptible power supply is configured to supply power to a load by parallel redundant operation,
Each uninterruptible power supply corresponds to a load sharing control device that controls the output current of the corresponding inverter so that the load sharing is even with respect to the load, and to be able to supply power immediately to the load And a standby current control device for controlling the output current of the inverter that can be switched to any one of them, and when at least two of the uninterruptible power supply devices are operating normally, each of these is a load sharing control device The remaining uninterruptible uninterruptible power supply becomes a standby current control device, and when one of the operating uninterruptible power supplies is in a failed state or stopped state, the uninterruptible state in that failed state or stopped state An uninterruptible power supply system characterized in that the remaining uninterruptible power supply apparatus in a normal state excluding the power supply apparatus can be switched from a standby current control apparatus to a load sharing control apparatus. Comprising at least three uninterruptible power supply units each including an inverter that outputs AC power, and supplying each of the uninterruptible power supply units to a load by parallel redundant operation; and An uninterruptible power supply system comprising a common bypass circuit connected in common between an output and the load, and having a common bypass circuit having an uninterruptible switching device for switching the bypass power source and the bypass power source uninterruptedly,
When one of the uninterruptible power supplies is a specific uninterruptible power supply and the rest is a non-specific uninterruptible power supply,
The non-specific uninterruptible power supply device includes a load sharing control device that controls the output current of the corresponding inverter so that the load sharing is equal to the load when each is in normal operation,
The specific uninterruptible power supply corresponds to a standby current control device that controls the output current of the corresponding inverter so that the load can be immediately supplied to the load and the load sharing to be equal to the load A load sharing control device for controlling the output current of the inverter to be switched to any one of them, and when the non-specific uninterruptible power supply device is in normal operation, the standby current control device is switched to the non-specific uninterruptible power supply. An uninterruptible power supply system, wherein the load sharing control device is switched when the device is in a failure state or a stopped state. Comprising at least three uninterruptible power supply units each including an inverter that outputs AC power, and supplying each of the uninterruptible power supply units to a load by parallel redundant operation; and An uninterruptible power supply system including a common bypass circuit that is connected in common between an output and the load and has a non-instantaneous switching device for switching the bypass power source and the bypass power source to uninterruptible power,
Each uninterruptible power supply corresponds to a load sharing control device that controls the output current of the corresponding inverter so that the load sharing is even with respect to the load, and to be able to supply power immediately to the load And a standby current control device for controlling the output current of the inverter that can be switched to any one of them, and when at least two of the uninterruptible power supply devices are operating normally, each of these is a load sharing control device The remaining uninterruptible uninterruptible power supply becomes a standby current control device, and when one of the operating uninterruptible power supplies is in a failed state or stopped state, the uninterruptible state in that failed state or stopped state An uninterruptible power supply system characterized in that the remaining uninterruptible power supply apparatus in a normal state excluding the power supply apparatus can be switched from a standby current control apparatus to a load sharing control apparatus.   The load sharing control device and the standby current control device output an operation switching command to their own inverter when at least one of the detection signals of a failure state or a stop state of an uninterruptible power supply device other than itself is input. From an inverter operation determination circuit, an inverter output current command generation circuit, and a switching circuit that switches between a shared current control circuit and a standby current control circuit based on an inverter operation switching command from the inverter operation determination circuit. The uninterruptible power supply system as described in any one of Claims 1-7 comprised.   The input of each inverter includes DC power from power storage means, DC power from a power converter that converts AC power from an AC power source into DC power, or DC power from the power storage means and the power conversion. The uninterruptible power supply system according to any one of claims 1 to 7, wherein any one of the direct-current power from the power supply is supplied.

Images