JP4527064B2 - Uninterruptible power supply system - Google Patents

Description

  The present invention relates to an uninterruptible power supply system, and more particularly to an uninterruptible power supply system configured to operate a plurality of uninterruptible power supply apparatuses in parallel.

  An uninterruptible power supply in a conventional uninterruptible power supply system uses two power sources, an AC input power source and a commercial power source, as inputs. Usually, an uninterruptible power supply receives AC input power as an input, converts AC to DC via a converter, and supplies the storage battery and power to the inverter. The inverter supplies power to the load via the inverter-side switch and the load switch.

  When the AC input power fails, the converter stops (gate block), and an inverter that receives DC power from the storage battery supplies power to the load via the inverter-side switch and the load switch. In this way, power supply to the load can be continued.

  When the inverter is inspected or inspected, or when the inverter is stopped due to some reason, the inverter side switch is opened, and the load switch is switched to the backup commercial power source side to perform the backup operation.

  If the commercial power supply fails during the backup operation, power cannot be supplied to the load. There is a parallel redundant system as a system configuration in which this backup operation is not performed as much as possible. In this parallel redundant system, N uninterruptible power supply units are operated in parallel to supply power to the load, and the capacity of each uninterruptible device is the same even if one of the N uninterruptible devices is out of order (N-1). Select a capacity that can supply power to the load on the stand.

  By adopting such a parallel redundant system, even if one uninterruptible power supply stops during normal operation, operation can be continued by simply disconnecting the inverter-side switch of the uninterruptible power supply that has stopped. Therefore, a highly reliable uninterruptible power supply system can be realized.

Even in the above-described parallel redundant system, for example, if one of the N uninterruptible power supply units is maintained and another one of the uninterruptible power supply units stops during operation, Open the power device inverter side switch and switch the load switch to the commercial power source side to perform backup operation. In this backup operation state, when the load is excessive and the overcurrent continues, a proposal has been made to continue operation by switching to a separately provided bypass circuit for maintenance (see, for example, Patent Document 1).
Japanese Patent Laying-Open No. 2004-56918 (page 3-4, FIG. 1)

  According to the technique disclosed in Patent Document 1, the operating rate of the uninterruptible power supply system is improved. However, a backup operation using a commercial power source or a backup operation using a maintenance bypass circuit is a last resort. This is because the system is completely stopped when a power failure occurs during the backup operation. Therefore, for example, if a state where parallel redundancy is lost during maintenance inspection of one inverter can be automatically detected, the inverter can be quickly returned to parallel operation to maintain operation as a parallel redundancy system. The rate can be further improved.

  The present invention has been made in view of the above, and an object thereof is to provide an uninterruptible power supply system capable of improving the operating rate by automatically detecting a state in which parallel redundancy is lost and issuing an alarm. To do.

In order to achieve the above object, an uninterruptible power supply system according to a first aspect of the present invention includes a converter for converting alternating current supplied from an alternating current power source into direct current, and a direct current output of the converter or a storage battery provided outside. An inverter that converts the direct current from the converter into an alternating current and supplies the same to a common load; a switching means that selectively switches power supply to the load to either the inverter side or the bypass commercial power supply side; and It comprises a plurality of uninterruptible power supply units provided on the output side and comprising current detection means for detecting the current flowing into the load, and each uninterruptible power supply unit obtains the load capacity from the output of the current detection means. Load capacity detection means to detect, the current number N of uninterruptible power supply units detected based on the operation signal of each uninterruptible power supply unit, and a preset uninterruptible power supply system And a available capacity calculating means for calculating the allowable load for parallel redundancy is established as a whole system by calculating from the number of the available capacity calculating means, the uninterruptible power system number and the number of operating N Means for calculating the larger maximum number Nmax, and when the operating number N and the maximum number Nmax are equal, the allowable load capacity is the rated capacity of the uninterruptible power supply,
When the operating number N is different from the maximum number Nmax, the allowable load capacity is set to a value obtained by multiplying the rated capacity of the uninterruptible power supply by (N-1) / N, and detected by the load capacity detecting means. An alarm signal is generated when the load capacity exceeds the allowable load.

The uninterruptible power supply system according to the second aspect of the present invention is a converter that converts alternating current supplied from an alternating current power source into direct current, and direct current output from the converter or a direct current from a storage battery provided outside is converted into alternating current. A plurality of uninterruptible power supply units comprising an inverter for conversion and supplying to a common load, and a current detection means provided on the output side of the inverter for detecting current flowing into the load, and power supply to the load Common switching means for selectively switching between the inverter side and the bypass commercial power supply side, and each uninterruptible power supply unit detects a load capacity from the output of the current detection means. The detection means, the current number N of uninterruptible power supply units detected based on the operation signal of each uninterruptible power supply unit, and the preset number of uninterruptible power supply systems And a available capacity calculating means for calculating the allowable load for parallel redundancy is established as a whole system by calculating the available capacity calculating means, among the uninterruptible power system number the number of operating N, Means for calculating the larger maximum number Nmax, and when the operating number N and the maximum number Nmax are equal, the allowable load capacity is the rated capacity of the uninterruptible power supply, and the operating number N and the maximum number Nmax Are different from each other, the allowable load capacity is set to a value obtained by multiplying the rated capacity of the uninterruptible power supply by (N-1) / N, and the load capacity detected by the load capacity detecting means is equal to the allowable load. It is characterized in that an alarm signal is issued when exceeding.

  ADVANTAGE OF THE INVENTION According to this invention, the uninterruptible power supply system which can improve an operation rate by automatically detecting the state where parallel redundancy is lost and issuing a warning can be provided.

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

  Hereinafter, an uninterruptible power supply system according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a circuit configuration diagram of an uninterruptible power supply system according to Embodiment 1 of the present invention.

  The uninterruptible power supply devices 1a and 1b are supplied with commercial AC power from an AC input power source 2 provided in common. AC is also supplied from a common commercial power source 3.

  The alternating current supplied from the alternating current input power source 2 to the uninterruptible power supply devices 1a and 1b is converted into direct current by the converters 4a and 4b in the uninterruptible power supply devices 1a and 1b, respectively. Storage batteries 5a and 5b provided outside uninterruptible power supply devices 1a and 1b are connected to DC output portions of converters 4a and 4b, respectively. The DC outputs of converters 4a and 4b are input to inverters 6a and 6b, respectively. The inverters 6 a and 6 b supply alternating current to the common load 9 via the switching switches 7 a and 7 b and the load switches 8 a and 8 b in the load switching device 8, respectively. Here, normally, the storage batteries 5a and 5b are configured to be charged from the converters 4a and 4b or other charging circuits, respectively. However, when the AC input power supply 2 is interrupted, this DC output is supplied to the inverters 6a and 6b, respectively. Power to

  AC power supplied from the commercial power supply 3 to the uninterruptible power supply devices 1a and 1b is switched over via the semiconductor switches 10a and 10b and bypass switches 11a and 11b provided in parallel to the semiconductor switches 10a and 10b, respectively. Power is supplied to the output sides of 7a and 7b. Therefore, the switching switch 7a, the semiconductor switch 10a, and the bypass switch 11a in the uninterruptible power supply 1a are provided with a switching circuit that switches whether power is supplied from the inverter 6a to the load 9 or from the commercial power supply 3 to the load 9. Forming. The same applies to the uninterruptible power supply 1b. The semiconductor switches 10a and 10b are provided to overlap the commercial power supply and the inverter power supply for a short time when switching.

  The normal single uninterruptible power supply system is configured to automatically switch to the bypass power supply system from the commercial power supply 3 when the inverter 6a or 6b is stopped due to failure or when it is stopped for maintenance. .

  However, in the present invention, since a parallel redundant system in which the inverter 6a and the inverter 6b are always operated in parallel is considered, even if any one of the inverters is disconnected, the bypass power feeding system from the commercial power source 3 is switched. It has no configuration.

  The main circuit configuration of the present invention has been described above. Below, the control part which becomes the point of this invention is demonstrated. In the following description, the uninterruptible power supply devices 1a and 1b have the same control part, so only the uninterruptible power supply device 1a will be described, and the description of the uninterruptible power supply device 1b will be omitted.

The input current of the load switch 8a is detected by the current detector 21a. This instantaneous current detection value is input to a maximum load detection circuit 22a which is load capacity detection means . For example, the maximum load detection circuit 22a constantly monitors a load current that continues for a predetermined value for a first predetermined time, converts the maximum value of the load current within a second predetermined time into a load capacity, and outputs a comparison. One input of the device 23a. Alternatively, the effective current at the third predetermined time is obtained by calculation and converted to the load capacity. By including a time element in this way, it is possible to reduce the influence of transient phenomena and noise.

  The other input of the comparator 23a is supplied with the output of an allowable load calculation circuit 24a described later in detail. The allowable load calculation circuit 24a is provided with an operation signal from the operation control circuit 25a that manages the operation control of the uninterruptible power supply 1a and an operation signal from another uninterruptible power supply 1b that constitutes a parallel redundant system. The comparator 23a outputs an alarm signal when the load capacity as the output of the maximum load detection circuit 22a is larger than the allowable load as the output of the allowable load calculation circuit 24a.

  In the above description of the first embodiment, for the sake of simplicity, the number of uninterruptible power supply units constituting the parallel redundant system is two, but this may be expanded to N (N is an integer of 3 or more).

  FIG. 2 is an internal configuration diagram of the allowable load calculation circuit 24 of the present invention.

  The operation signals of all the uninterruptible power supply units constituting the parallel redundant system are given to the uninterruptible power supply unit operation number detection circuit 31, and the current uninterruptible power supply unit operation number (N) is obtained here. The number of operating units (N) and the number of uninterruptible power supply system systems set in advance by the uninterruptible power supply system number setting unit 32 are compared by the maximum value detection circuit 33, and the larger value is the maximum value (Nmax). As one input of the determination circuit 34. The other input of the determination circuit 34 is given the number of operating units (N) which is the output of the uninterruptible power supply operating unit number detecting circuit 31, and determines the maximum value (Nmax) and the number of operating units (N).

When the determination circuit 34 determines that the number of operating units (N) and the maximum value (Nmax) are equal,
The determination circuit 34 selects the switch 36 on the setting circuit 35a side. When the determination circuit 34 determines that the number of operating units (N) is not equal to the maximum value (Nmax), the determination circuit 34 selects the switch 36 on the setting circuit 35b side. The output of the switch 36 becomes an input of the allowable load adjustment circuit 37, and the allowable load adjustment circuit 37 outputs an allowable load (kVA) in which a parallel redundant system is established according to the number of operating uninterruptible power supply systems. To do.

  In the above, the setting circuit 35a is selected when the number of operating units (N) is equal to the maximum value (Nmax), and thus the parallel redundant system is basically functioning. Accordingly, the setting circuit 35a outputs the rated capacity of the uninterruptible power supply. At this time, the allowable load adjustment circuit 37 may output, for example, 90% of the rated capacity in consideration of a margin for the uneven load sharing in the parallel redundant system.

  In the above, the setting circuit 35b is selected when the number of operating units (N) is smaller than the maximum value (Nmax). At this time, it is necessary to set the setting circuit 35b so that the load 9 can be continuously operated even if one of the N vehicles stops. Accordingly, the setting circuit 35b takes a value obtained by multiplying the rated capacity of the uninterruptible power supply by (N-1) / N. At this time, the setting of the allowable load adjustment circuit 37 may be performed in the same way as when the number of operating units (N) and the maximum value (Nmax) are equal.

For example, consider a case where a parallel redundant system is configured using four 500 kVA uninterruptible power supply units for a load of 1500 kVA. At this time, if all four are in operation,
Since N = Nmax = 4 in the above, the output of the allowable load calculation circuit 24 is the rated capacity of 500 kVA. When three of the four units are operated in parallel, the output of the allowable load calculation circuit 24 is 500 kVA × (3-1) / 3 = 333 kVA. Similarly, when two of the four units are operated in parallel, the output of the allowable load calculation circuit 24 is 500 kVA × (2-1) / 2 = 250 kVA.

  As described above, according to the present invention, it is possible to automatically detect a state in which parallel redundancy is lost, and an alarm can be output at this time. For example, when the load factor of the load 9 increases during maintenance inspection of one uninterruptible power supply and this alarm is output, the maintenance is immediately stopped and the uninterruptible power supply is inserted into the system. Thus, parallel redundancy can be recovered. In addition, when the load factor is low, when the load increases in a state where, for example, one of the uninterruptible power supply systems that intentionally configure parallel redundancy for energy saving is in parallel operation, and the alarm signal is output, The uninterruptible power supply can be automatically inserted by using this alarm signal as a trigger. In addition, when operating at a load factor exceeding the rated load, it is possible to switch to the bypass power supply side and prevent the risk of equipment damage due to insufficient load capacity on the bypass power supply side with an alarm signal in advance. Become.

  In the first embodiment, all the uninterruptible power supply devices have the same internal configuration, which is suitable for standardization. As the current detectors 21a and 21b, those conventionally used for control and the like can be used, and it is not necessary to newly provide them.

  In addition, according to the present invention, when the number of systems is initially reduced and an uninterruptible power supply is added as the load capacity increases to form a parallel redundant system, this is much easier than before. Can be performed. In this case, it is possible to function as a parallel redundant system without changing the setting of the uninterruptible power supply system number setting unit 32.

  FIG. 3 is a circuit configuration diagram of the uninterruptible power supply system according to the second embodiment of the present invention.

  About each part of this Example 2, the same part as each part of the circuit block diagram of the uninterruptible power supply system which concerns on Example 1 of FIG. 1 is shown with the same code | symbol, and the description is abbreviate | omitted. The difference between the second embodiment and the first embodiment is that the switching switches 7a and 7b, the semiconductor switches 10a and 11a, and the bypass switches 11a and 11b, which are constituent elements of the uninterruptible power supply 1a and 1b, are replaced by the whole. A common bypass switching device 12 is provided, and the switching switch 7, the semiconductor switch 10, and the bypass switch 11 in the bypass switching device 12 collectively supply power from the uninterruptible power supply device to the bypass power supply from the commercial power supply 3. It is the point which comprised so that it might switch to.

  According to the above system configuration, the output of the load switching device 8 is connected to the load 9 via the switching switch 7. Therefore, when the parallel redundancy of the parallel redundant system composed of the uninterruptible power supply devices 1a and 1b is lost, and when a trouble that prevents continuous power supply to the uninterruptible power supply side occurs, the semiconductor switch 10 and the bypass The switching switch 11 is used to switch to bypass power feeding from the commercial power source 3 at once.

  In this way, even in the uninterruptible power supply system configured so that the switching function to bypass power supply is not provided to each uninterruptible power supply, the state in which the parallel redundancy is lost is automatically set as in the case of the first embodiment. It is possible to improve the operation rate of the uninterruptible power supply system.

  In the second embodiment, as in the first embodiment, the uninterruptible power supply can be standardized. Further, if the installation capacity on the bypass power supply side is taken into consideration in advance, it is easy to cope with expansion.

The circuit block diagram of the uninterruptible power supply system which concerns on Example 1 of this invention. The internal block diagram of the allowable load calculation circuit of this invention. The circuit block diagram of the uninterruptible power supply system which concerns on Example 2 of this invention.

Explanation of symbols

1a, 1b Uninterruptible power supply 2 AC input power supply 3 Commercial power supply 4a, 4b Converter 5a, 5b Storage battery 6a, 6b Inverter 7, 7a, 7b Switching switch 8 Load switchgear 8a, 8b Load switch 9 Load 10, 10a, 10b Semiconductor switch 11, 11a, 11b Bypass switch 12 Bypass switching device

21a, 21b Current detector 22a, 22b Maximum load detector 23a, 23b Comparator 24, 24a, 24b Allowable load calculator 25a, 25b Operation control circuit

31 Uninterruptible power supply operation number detection circuit 32 Uninterruptible power supply system number setting device 33 Maximum value detection circuit 34 Determination circuit 35a, 35b Setting circuit 36 Switch 37 Allowable load adjustment circuit

Claims (5)

A converter that converts alternating current supplied from an alternating current power source into direct current;
An inverter that converts the direct current output of the converter or direct current from an external storage battery into alternating current and supplies it to a common load;
Switching means for selectively switching power supply to the load to either the inverter side or the commercial power supply side for bypass;
It is provided on the output side of the switching means, and is composed of a plurality of uninterruptible power supply units comprising current detection means for detecting current flowing into the load,
Each uninterruptible power supply is
Load capacity detection means for detecting a load capacity from the output of the current detection means;
Parallel redundancy is established as a whole system by calculation from the current number N of uninterruptible power supply units detected based on the operation signal of each uninterruptible power supply unit and a preset number of uninterruptible power supply systems An allowable load capacity calculating means for calculating the allowable load of
The allowable load capacity calculating means includes:
A means for calculating the larger maximum number Nmax of the number of uninterruptible power supply systems and the number N of operating units;
When the operating number N and the maximum number Nmax are equal, the allowable load capacity is the rated capacity of the uninterruptible power supply,
When the operating number N is different from the maximum number Nmax, the allowable load capacity is set to a value obtained by multiplying the rated capacity of the uninterruptible power supply by (N-1) / N,
An uninterruptible power supply system characterized in that an alarm signal is issued when the load capacity detected by the load capacity detection means exceeds the allowable load. A converter that converts alternating current supplied from an alternating current power source into direct current;
An inverter that converts the direct current output of the converter or direct current from an external storage battery into alternating current and supplies it to a common load;
A plurality of uninterruptible power supply units provided on the output side of the inverter and comprising current detection means for detecting a current flowing into the load;
A common switching means for selectively switching power supply to the load to either the inverter side or the bypass commercial power source side;
Each uninterruptible power supply is
Load capacity detection means for detecting a load capacity from the output of the current detection means;
Parallel redundancy is established as a whole system by calculation from the current number N of uninterruptible power supply units detected based on the operation signal of each uninterruptible power supply unit and a preset number of uninterruptible power supply systems An allowable load capacity calculating means for calculating the allowable load of
The allowable load capacity calculating means includes:
A means for calculating the larger maximum number Nmax of the number of uninterruptible power supply systems and the number N of operating units;
When the operating number N and the maximum number Nmax are equal, the allowable load capacity is the rated capacity of the uninterruptible power supply,
When the operating number N and the maximum number Nmax are different, the allowable load capacity is set to a value obtained by multiplying the rated capacity of the uninterruptible power supply by (N-1) / N,
An uninterruptible power supply system characterized in that an alarm signal is issued when the load capacity detected by the load capacity detection means exceeds the allowable load. The uninterruptible power supply system according to claim 1 or 2, wherein the rated capacity of the uninterruptible power supply is multiplied by a predetermined reduction rate. The load capacity detecting means constantly monitors a load current that continues for a predetermined value or more within a first predetermined time, and detects the maximum value of the load current within a second predetermined time by converting it into a load capacity. The uninterruptible power supply system according to claim 1 or 2, wherein The uninterruptible power supply system according to claim 1 or 2, wherein when the alarm signal is issued, the standby uninterruptible power supply unit is automatically inserted and operated.

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