JP2006271074A - Uninterruptible power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a common reserved uninterruptible power supply system, capable of extending blackout backup time, if blackout occurs in a commercial power supply during normal operation. <P>SOLUTION: This power supply system is composed of: a forward converter for converting AC of the commercial power supply into DC; a reverse converter which converts a DC output of the electronic power rectifier to AC again; an energy-storing part for supplying the DC power to the reverse converter during blackout of the commercial power supply; a plurality of working UPS1A, 1B, having a bypass switching circuit for continuing load feed by the commercial power supply or another power supply; one reserved UPS1C formed out of the same structure as the working UPS and having a first switching device for continuing the load feed, when one of the working UPSs is stopped, because of failure or inspection; and a second switching device, which can feed the output of a reserved UPS1C to the input of the plurality of working UPS1A, 1B, if a blackout occurs in the commercial power supply. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an uninterruptible power supply system, and in particular, as a backup power supply in the event of a power failure, a plurality of regular uninterruptible power supply devices that constantly supply power to a load, and a backup non-use configured as a backup of these regular uninterruptible power supply devices The present invention relates to a common standby uninterruptible power supply system composed of a blackout power supply.

  Conventionally, an uninterruptible power supply (hereinafter simply referred to as UPS) has been used as a power source for an important load such as a computer that does not allow an instantaneous power outage. Further, during normal operation and inspection for 365 days, When continuous power supply by UPS is required, in order to supply power to the load from multiple UPSs that always supply power to the load, and even when a failure occurs in the normal UPS or when inspection is performed A so-called common backup uninterruptible power supply system including a configured backup UPS is used as a highly reliable system.

  In a common standby uninterruptible power supply system, a single standby UPS is generally configured for a plurality of UPSs.

  Ordinary UPS receives AC from commercial power supply, converts to DC with forward converter through AC input circuit breaker, and then converts back to AC again with reverse converter, and stable with AC output circuit breaker. The AC output is supplied to the load. The forward converter stores DC energy in a storage battery, which is an energy storage unit, via a DC input circuit breaker.

  When a power failure occurs in the commercial power supply, the AC output is continuously supplied to the load by supplying the DC energy of the storage battery to the inverter. In addition, in the event that a failure occurs in the forward converter or the reverse converter, in order to continuously supply an AC output to the load, the commercial power supply or another bypass input power supply is connected via a bypass circuit breaker. A bypass circuit that supplies power to the load is provided, and an uninterruptible switching circuit composed of a thyristor and a contactor switches the input to the load without instantaneous interruption.

  Also, the maintenance bypass circuit for maintenance and inspection is branched from the primary side of the bypass circuit breaker of the bypass circuit so that maintenance and inspection of the internal circuit of the regular UPS can be performed while continuing to supply power to the load. A route for supplying power to the load through the circuit breaker is provided. During maintenance inspection by the maintenance bypass circuit, the maintenance bypass circuit breaker is turned on and the AC output circuit breaker is turned off.

  In a single uninterruptible power supply system composed of one common UPS, the bypass input power supply is a commercial power supply in the same manner as the normal AC input.

  The common standby uninterruptible power supply system is a system configured to supply AC power to the load without interruption for 24 hours, 365 days including normal operation, failure, and inspection. In the event of a failure or inspection of a plurality of normal UPSs, a standby UPS that supplies power to a load via a standby power supply switchboard is used instead of the normal UPS.

In the configuration as described above, it is an important issue to operate the system efficiently. For example, when the service UPS fails, the system is temporarily switched to the commercial bypass side, and the backup UPS is started and then switched to the backup UPS side. Proposals have been made to reduce standby no-load power loss of standby UPS by switching operation (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-87998 (page 2-4, FIG. 1)

  The method disclosed in Patent Document 1 is made by paying attention to reducing the loss during standby operation of the standby UPS. However, when the commercial power supply fails, the energy of the storage battery for the standby UPS is effectively used. Increasing system availability is also a major issue.

  Generally, the capacity of the backup UPS is set to the capacity of one normal UPS, because the probability that a plurality of normal UPSs fail at the same time is extremely small. Moreover, the capacity of the storage battery of the energy storage unit attached to each UPS is determined by the power outage compensation time requested by the plant. In general, the storage battery for each regular UPS and the storage battery for the backup UPS are all configured with the same capacity. The This is because when one of the normal UPSs fails or stops during inspection, the load is supplied from the backup UPS to the load, so the storage battery capacity of the energy storage unit of the standby UPS must be the same as that of the normal UPS. Because there is.

  However, during normal operation, a plurality of normal UPSs operate without any abnormality and load power is supplied. Therefore, when the commercial power supply fails in such normal operation state, the energy storage unit of the standby UPS In many cases, the storage battery is not used effectively.

  This is an example of a common standby uninterruptible power supply system in which the capacity of two normal UPSs and spare UPSs is 100 kVA, and the load capacity is 100 kVA for the first normal UPS and 80 kVA for the second normal UPS. This will be explained using numerical values.

  It is assumed that each UPS storage battery of this common backup uninterruptible power supply system is configured by selecting a capacity on the condition of a power failure compensation time of 10 minutes at 100 kVA. Consider a case where a power failure occurs in an AC input from a commercial power source in a normal operation state.

  At this time, each of the two regular UPSs is operated by the DC power of the storage battery, which is the energy storage unit for the UPS, and continues to supply the load.

  10 minutes later, when the storage battery voltage of the first UPS falls below the lower limit of the DC voltage range of the UPS and the failure stops, it switches to the bypass circuit of the backup UPS power supply, and the power from the storage battery of the backup UPS from this bypass circuit Is continuously supplied to the load.

  Since the load of the second UPS is 80%, the storage battery voltage is less than the lower limit of the DC voltage range of the UPS in the same manner as the first UPS in (10 + α) minutes. The normal UPS is also out of order and switched to the bypass circuit supplied by the power supply of the spare UPS 1. The above (10 + α) portion is 12.5 minutes when the simple calculation is performed under the condition that the load factor of the storage battery × the operation continuation time is constant.

  However, as described above, since the backup UPS is configured with 100 kVA having the capacity of one normal UPS, if the second UPS is switched to power supply to the backup UPS due to a failure stop, the load of the backup UPS The capacity becomes 180 kVA (100 kVA + 80 kVA), and the capacity is exceeded, so that the backup UPS also stops and the load power supply is cut off.

  As described above, the backup UPS is also selected under the same storage battery capacity selection conditions as the two regular UPSs. In this example, this is a power failure compensation time of 10 minutes at 100 kVA.

  However, in this example, the backup UPS storage battery is switched from the first UPS to the power supply from the backup UPS (10 minutes after a power failure), and then the second UPS to the standby UPS. (After 12.5 minutes after a power failure) As a result, only 2 and a half minutes can be used until the capacity of the spare UPS becomes over, thus reducing the overall power failure backup time.

  That is, in the configuration of the conventional common backup uninterruptible power supply system disclosed in Patent Document 1, the storage battery of the backup UPS does not use the storage battery capacity effectively when a power failure occurs in the commercial power supply during normal operation. There was a problem.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a common standby uninterruptible power supply system capable of extending a power failure backup time when a power failure occurs in a commercial power supply during normal operation. It is said.

  In order to achieve the above object, a common standby uninterruptible power supply system according to the present invention includes a forward converter that converts alternating current of a commercial power source into direct current, and a direct current output of the forward converter is again converted into alternating current to load. A plurality of inverters including a reverse converter for supplying power, an energy storage unit for supplying DC power to the reverse converter during a power failure of the commercial power supply, and a bypass switching circuit for continuing load power supply by the commercial power supply or another power supply A normal UPS and a first switching means for continuing load power supply when one of the normal UPSs is stopped due to a failure or inspection, and one unit having the same configuration as the normal UPS. It is characterized by comprising a backup UPS and a second switching means capable of supplying the output of the backup UPS to the inputs of the plurality of service UPSs when the commercial power supply fails.

  According to the present invention, when a power failure occurs in the commercial power supply in a normal operation state where all of the normal UPS and the standby UPS are operating smoothly, the backup UPS storage battery is effectively used. A common backup UPS system capable of extending the time can be provided.

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

  Hereinafter, a common backup uninterruptible power supply system according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a block configuration diagram of a common standby uninterruptible power supply system according to Embodiment 1 of the present invention.

  The commercial UPSs 1A and 1B receive AC inputs (commercial side) 3A and 3B from the commercial power sources 2A and 2B, respectively, and are converted to DC by the forward converters 5A and 5B via the AC input circuit breakers 4A and 4B, respectively. Further, the inverters 6A and 6B reversely convert back to alternating current, and the instantaneously uninterruptible switching circuits 9A and 9B, and further through the AC output breakers 10A and 10B in the output panels 21A and 21B, the stable AC output 15A, 15B is supplied to the loads 16A and 16B, respectively. Further, the forward converters 5A and 5B store DC energy in the storage batteries 12A and 12B which are energy storage units via the DC input circuit breakers 11A and 11B, respectively.

  When a power failure occurs in the commercial power supply 2A, the AC output 15A is continuously supplied to the load 16A by supplying the DC energy of the storage battery 12A to the inverter 6A. Similarly, when a power failure occurs in the commercial power supply 2B, the operation by the storage battery 12B is performed. Also, in the event that a failure occurs in the forward converters 5A, 5B or the reverse converters 6A, 6B, the alternating current 22A, 22B is continuously supplied to the loads 16A, 16B in the same manner as described above. Bypass circuits 8A and 8B for supplying bypass AC inputs 25A and 25B different from inputs 2A and 2B via bypass circuit breakers 7A1 and 7B1, respectively, are provided, and uninterruptible switching circuits 9A and 9B each composed of a thyristor and a contactor are provided. It is configured to switch without interruption. The bypass AC inputs 25A and 25B are supplied from the spare UPS 1C as will be described later. However, in order to secure a bypass power source even during maintenance and inspection of the spare UPS 1C, the bypass AC inputs 25A and 25B are supplied from commercial power sources 17A and 17B different from the power source of the spare UPS 1C. The AC input can be fed through the bypass input circuit breakers 7A2 and 7B2.

  The standby UPS 1C has the same internal circuit configuration as the regular UPS 1A. The AC input (commercial side) 3C is input from the commercial power source 2C, and is converted into DC by the forward converter 5C via the AC input circuit breaker 4C. Further, the inverter 6C reversely converts it back to alternating current, and supplies the alternating current output 15C to the standby power switch 19 via the uninterruptible switching circuit 9C. In preparation for a power failure of the commercial power supply 2C, the storage battery 12C is connected to the DC part of the backup UPS 1C via the DC input circuit breaker 11C, as in the case of the normal UPS 1A. Further, in order to continuously supply the AC output 15C even if a failure occurs in the forward converter 5C or the reverse converter 6C, an AC input 18C from an AC power source 17C different from the AC input 2C is used. A bypass circuit 8C that is supplied via the bypass circuit breaker 7C is provided, and is configured to be switched without instantaneous interruption by an uninterruptible switching circuit 9C composed of a thyristor and a contactor.

  The AC output 15C is input to the standby power supply branch board 19, and the standby power supply branch board 19 is configured to selectively switch the AC output 15C as follows.

  One of them is a system for supplying the bypass AC inputs 25A and 25B described above to the bypass circuits 8A and 8B via the bypass circuit breakers 7A1 and 7B1, and this is used when the normal UPS 1A or 1B fails.

The second system is a system that supplies power to the load via maintenance bypass circuit breakers 20A and 20B provided in the output panels 21A and 21B via the maintenance bypass circuits 13A and 13B, respectively.
This system is provided so that the maintenance and inspection of the internal circuits of the service UPSs 1A and 1B can be performed while supplying power to the loads 6A and 6B. At the time of maintenance inspection by the maintenance bypass circuits 13A and 13B, the maintenance bypass circuit breakers 20A and 20B are turned on and the AC output circuit breakers 10A and 10B are turned off.

  In the last system, the AC output 15C of the backup UPS 1C is used as the AC input (backup UPS side) 23A and 23B at the time of a power failure when the AC power supply is interrupted, and the UPS 1A and 1B are used through the bypass input circuit breakers (spare UPS side) 24A and 24B. As described later, when a power failure occurs in the commercial power source during normal operation, the power backup time is extended by effectively using the capacity of the storage battery 12C for the backup UPS 1C.

  Next, the operation of the uninterruptible power supply system according to Embodiment 1 of the present invention will be described with reference to FIGS.

  FIG. 2 shows a power supply operation of the service UPS 1A when the commercial power supply 2A is normal. As shown in the figure, the AC input 3A of the commercial power source 2A is supplied to the forward converter 5A via the input circuit breaker 4A, and the DC power obtained by the forward converter 5A is converted back to AC by the inverse converter 6A. Power is supplied to the load, and the storage battery 12A is charged via the DC circuit breaker 11A.

  FIG. 3 shows the power supply operation of the service UPS 1A when the commercial power source 2A (and 2B, 2C) is out of power. When the AC inputs (commercial side) 3A, 3B, and 3C are blacked out, the service UPS 1A automatically switches to DC operation using the DC power of the storage battery 12A as a power source and continues load feeding without instantaneous interruption.

  At the same time, the AC input circuit breaker (commercial side) 4A is turned OFF, the bypass input circuit breaker (spare UPS side) 24A is turned ON, and the AC input (spare UPS side) 23A from the output power of the backup UPS 1C is input.

  When the bypass input circuit breaker (spare UPS side) 24A is turned on in this way, the output power from the backup UPS 1C is limited to the output of the forward converter 5A of the normal UPS 1A so that the capacity of the backup UPS 1C does not exceed the capacity. To control.

  At this time, the output limit value of the forward converter 5A of the regular UPS 1A is a value obtained by dividing the capacity of the spare UPS 1C by the number of regular UPSs.

  For example, in the system configuration example shown in FIG. 1, assuming that the capacities of the common UPS 1A and 1B and the spare UPS are all 100 kVA, the output limit value of the forward converters 5A and 5B per unit of the common UPS 1A and 1B is 100 kVA / 2 = 50 kVA. Become.

  As a result, when a power failure occurs in the AC inputs (commercial side) 3A, 3B, the service UPSs 1A, 1B receive a maximum of 50 kVA from the output power of the backup UPS 1C, and the remaining batteries 12A, 12B are configured by the service UPSs 1A, 1B, respectively. Supplied from DC power.

  As a result, the DC power of the storage battery 12C for the backup UPS 1C is also effectively used as the AC power supply for the normal UPS 1A and 1B simultaneously with the power failure of the AC input (commercial side) 3A, 3B and 3C, and the normal UPS 1A and 1B are used as the backup UPS 1C. AC input (spare UPS side) 23A, 23B and DC power of its own storage batteries 12A, 12B can be used together, so that the discharge current of the storage batteries 12A, 12B is also reduced, and the power failure backup time can be extended. it can.

  FIG. 4 summarizes the operation at the time of the power failure described above in a flowchart.

  When the AC input (commercial side) 3A fails (ST1), the full load is transiently supplied with the DC power of the storage battery 12A (ST2), the AC input circuit breaker 4A is turned off (ST3), and the bypass input circuit breaker (standby) (UPS side) 24A is turned on (ST4). Then, the AC input (spare UPS side) 23A recovers and the forward converter 5A is operated (ST5), and the output of the forward converter 5A is operated so as to become a predetermined output limit value (ST6). ), The storage battery 12A supplies the remaining power required by the load (ST7), and the power failure backup time is extended by continuing this combined operation (ST8).

  If the first embodiment described above is applied to the case where the loads of the normal UPS 1A and 1B are 100 kVA and 80 kVA, the UPS 1A can be operated for about 5 minutes after the standby UPS 1C is operated for 10 minutes unless the loss of the normal UPS 1A and 1B is considered. It turns out that it becomes.

  A common standby uninterruptible power supply system according to Embodiment 2 of the present invention will be described below with reference to FIGS. FIG. 5 is a block diagram of a common standby uninterruptible power supply system according to Embodiment 2 of the present invention.

  About each part of this Example 2, the same part as each part of the common backup 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 second embodiment is different from the first embodiment in that DC current detectors 26A and 26B for detecting the load factors of the service UPSs 1A and 1B are provided at the input portions of the inverse converters 6A and 6B, respectively. The current limit adjustment circuits 27A and 27B adjust the output limit values of the forward converters 5A and 5B according to the detection signals, respectively.

  That is, in the second embodiment, the normal UPSs 1A and 1B include the AC inputs (commercial side) 3A and 3B, and the AC inputs (spare UPS side) 23A and 23B and the normal UPSs 1A and 1B by the output power of the backup UPS 1C when the power failure occurs. The share of the DC power supply of the storage batteries 12A, 12B constituting the limit value is determined according to the load factor of each of the normal UPSs 1A, 1B, and the AC input (spare UPS side) 23A, 23B of the backup UPS 1C is a forward converter The capacities input to 5A and 5B are respectively controlled so as to reach this limit value, and the remaining shortage capacity is supplied from the DC power of the storage batteries 12A and 12B for the regular UPS 1A and 1B, respectively.

  Hereinafter, the control operation will be described with reference to FIGS.

  FIG. 6 shows the power supply operation of the UPS 1A when the commercial power source 2A is normal. In this case, as in the case of the first embodiment, the AC input 3A of the commercial power source 2A is supplied to the forward converter 5A via the input circuit breaker 4A, and the DC power obtained by the forward converter 5A is inversely converted. The battery 6A is again converted to alternating current and supplied to the load, and the storage battery 12A is charged via the direct current circuit breaker 11A.

  FIG. 7 shows the power supply operation of the UPS 1A when the commercial power source 2A (and 2B, 2C) fails. When the AC inputs (commercial side) 3A, 3B, and 3C are blacked out, the service UPS 1A automatically switches to DC operation using the DC power of the storage battery 12A as a power source and continues load feeding without instantaneous interruption.

  At the same time, the AC input circuit breakers 4A and 4B are turned off, the bypass input circuit breaker (spare UPS side) 24A is turned on, and the AC input (spare UPS side) 23A by the output power of the spare UPS 1C is input.

  As in the case of the first embodiment, when the bypass input circuit breaker (spare UPS side) 24A is turned ON, the output power from the backup UPS 1C is the forward converter 5A of the normal UPS 1A so that the capacity of the backup UPS 1C does not exceed the capacity. A limit value is set to the output of the control.

  The output limit value of the forward converter 5A of the regular UPS 1A at this time is a value obtained by multiplying the capacity of the spare UPS 1C by the number of the regular UPSs and the load factor of the regular UPS 1A. This load factor is obtained by calculating the ratio between the current detected by the current detector 26A and the full load current.

  In the case of the first embodiment, for example, when the capacity of the service UPS 1A, 1B and the backup UPS 1C is 100 kVA, and the load capacity of the load 16A connected to the service UPS 1A is extremely small, for example, 50 kVA, it is attached to the service UPS 1A. The power outage backup time ends before the capacity of the storage battery 12A to be used effectively.

  For this reason, this point was further improved in Example 2, where the actual load capacities of the common UPS 1A and 1B are detected by the DC current detectors 26A and 26B, and the current value is converted into a load factor. A value obtained by multiplying the load factor by 1 / the number of common UPSs of the spare UPS capacity is used as the AC input from each of the spare UPS 1C, and the remaining capacity is supplied from the DC power of the storage batteries 12A and 12B for the regular UPS 1A and 1B. It is what I did.

  For example, in the configuration example of FIG. 5, the capacity of the normal UPS 1A, 1B and the backup UPS 1C is 100 kVA, respectively, and the load capacity of the normal UPS is No. 1 UPS 1A is 60 kVA, no. Consider an example in which 2 common UPS 1B is 40 kVA.

  When a power failure occurs in the AC input (commercial side) 3A, 3B, in this Example 2, No. The 1-use UPS 1A inputs (100/2 = 50) kVA × 0.6 = 30 kVA from the output power of the backup UPS 1C, and the remaining 30 kVA for No. 1 is input. The battery is supplied from the storage battery 12A for the single use UPS 1A. No. Similarly, since the two common UPSs 1B share (100/2 = 50) kVA × 0.4 = 20 kVA, the power supplied from the spare UPS 1C is 50 kVA in total.

  As can be seen from the above, when the service UPSs 1A and 1B are configured in two units, the sharing ratio between the service UPSs 1A and 1B and the backup UPS 1C is halved.

  For example, in the case of a system having three regular UPSs, the load capacity is set to No. 1 regular UPS is 60 kVA, no. 2 Common UPS is 50 kVA, No. 3 If the regular UPS is 40 kVA, the output capacity supplied from the backup UPS is No. (100/3 = 33.3) kVA × 0.6 = 20 kVA, no. 23.3 kVA × 0.5 = 16.7 kVA, no. For 3 regular UPS, 33.3 kVA × 0.4 = 13.3 kVA.

  As can be seen from the above, in the case where three regular UPSs are configured, the sharing ratio between the regular UPS and the spare UPS is 2/3 and 1/3, respectively.

  In the second embodiment, the output capacity supplied from the backup UPS 1C is determined by the load factor (actual load capacity) of each of the regular UPSs and the number of the regular UPSs. Therefore, compared to the first embodiment, the storage battery 12A for the regular UPS 1A and 1B. , 12B and the AC input by the output power supply 15C from the backup UPS 1C become more efficient, so that the load power supply time (power failure backup time) at the time of power failure can be further extended.

  FIG. 8 summarizes the above-described operation during a power failure in a flowchart.

  When the AC input (commercial side) 3A fails (ST1), the full load is transiently supplied with the DC power of the storage battery 12A (ST2), the AC input circuit breaker 4A is turned off (ST3), and the bypass input circuit breaker (standby) The UPS 24A is turned on (ST4). Then, the AC input is restored and the forward converter 5A is operated (ST5), and the output of the forward converter 5A is obtained by multiplying the value obtained by dividing the spare UPS capacity by the number of units by the load factor detected by the current detector. The battery is operated to reach the limit value (ST6A), the remaining power required by the load is supplied by the storage battery 12A (ST7A), and the power failure backup time is extended by continuing this combined operation (ST8).

  If Example 2 described above is applied to the case where the loads of the normal UPSs 1A and 1B are 100 kVA and 80 kVA, the UPS 1A further operates after about 11 minutes of operation with the standby UPS 1C at 90 KVA output unless the loss of the normal UPS 1A and 1B is considered. It turns out that it becomes possible to drive less than 5 minutes.

  The second embodiment can also be applied when the load factor of each regular UPS changes during a power outage backup operation.

  FIG. 9 is a block diagram of a common standby uninterruptible power supply system according to Embodiment 3 of the present invention.

  About each part of this Example 3, the same part as each part of the common backup uninterruptible power supply system which concerns on Example 2 of FIG. 5 is shown with the same code | symbol, and the description is abbreviate | omitted. The third embodiment is different from the second embodiment in that the detection signals of the DC current detectors 26A and 26B are supplied to an optimum limit calculator 28 provided in common as a system. The current limit adjustment circuits 27A and 27B adjust the output limit values of the forward converters 5A and 5B according to the calculated limit values.

  Here, the optimum limit calculator 28 calculates the limit value of the forward converters 5A and 5B that gives the longest power failure backup time as a whole system from the load rates of the normal UPSs 1A and 1B, and becomes this limit value. Thus, the forward converters 5A and 5B are controlled.

  As described above, an example of calculating the optimum limit value of the optimum limit calculator 28 when the backup UPS 100 kVA, the load factor 100% of the regular UPS 1A, and the load factor 80% of the regular UPS 1B is shown below.

  As a way of calculation, it is assumed that the storage battery 12A and the storage battery 12B are simultaneously used with the specified voltage or less, and for the sake of simplicity, the storage battery 12C is also set to the specified voltage or less at the same time.

  If the limit values expressed by the ratio of the regular UPSs 1A and B to the rated output under the above conditions are LA and LB, the following equations are established.

First, the power outage backup operation time of the backup UPS is
10 (minutes) x 1 / (LA + LB) (1)
Next, the power outage backup operation time of the regular UPS1A is
10 (minutes) x 1 / (1-LA) (2)
Finally, the power failure backup operation time of the regular UPS1B is
10 (min) x 1 / (0.8-LB) (3)
From the condition that all of the above are equal, that is, all the storage batteries are used up simultaneously,
LA = 0.4, LB = 0.2 (4)
The power failure backup time at this time is 16.7 minutes.

  As described above, if the optimum limit value is calculated under the condition that the energy of all the storage batteries is used up at the same time and the forward converter is controlled to that value, the longest power failure backup time can be obtained.

  FIG. 10 summarizes the operation at the time of the power failure described above in a flowchart.

  When the AC input (commercial side) 3A fails (ST1), the full load is transiently supplied with the DC power of the storage battery 12A (ST2), the AC input circuit breaker 4A is turned off (ST3), and the bypass input circuit breaker (standby) (UPS side) 24A is turned on (ST4). Then, the AC input is restored and the forward converter 5A is operated (ST5), and the optimum limit calculator detects the input currents of the reverse converters of all the normal UPSs, and all the normal UPSs are obtained from the load factors obtained. The optimum limit value is calculated (ST9). Next, the output of the forward converter 5A is operated so as to be the output limit value given from the above-mentioned optimum limit calculator (ST6B), and the storage battery 12A supplies the remaining power required by the load (ST7B). The power failure backup time is extended by continuing the combined operation (ST8).

  In the above calculation example, the reserve UPS storage battery 12C is also used as a condition of using up energy at the same time, but it is not always necessary to do so. In addition, when there is a regular UPS with a very small load factor, the calculation result may be negative. If the normal UPS with a negative calculation result has a forward converter that can be regenerated, the normal UPS may be regenerated. Otherwise, the normal UPS of the normal UPS with a negative calculation result may be used. The limit value may be set to 0, and the other limit UPS may be calculated again under the condition that the energy of the storage battery is used up at the same time to obtain the optimum limit value of the other limit UPS.

  The third embodiment is particularly effective when there is no change in the load factor of each regular UPS during a power outage backup operation.

The block block diagram of the common backup uninterruptible power supply system which concerns on Example 1 of this invention. FIG. 6 is a diagram illustrating a power supply operation of the normal UPS when the commercial input is normal in the first embodiment. FIG. 3 is a power supply operation explanatory diagram of a service UPS at the time of a commercial input power failure in the first embodiment. The operation | movement flowchart of service UPS at the time of the commercial input power failure in Example 1. FIG. The block block diagram of the common backup uninterruptible power supply system which concerns on Example 2 of this invention. FIG. 10 is a diagram for explaining a power supply operation of a service UPS when the commercial input is normal in the second embodiment. FIG. 10 is a power supply operation explanatory diagram of a service UPS at the time of a commercial input power failure in the second embodiment. The operation | movement flowchart of service UPS at the time of the commercial input power failure in Example 2. FIG. The block block diagram of the common backup uninterruptible power supply system which concerns on Example 3 of this invention. 9 is an operation flowchart of a service UPS at the time of a commercial input power failure in the third embodiment.

Explanation of symbols

1A, 1B UPS for regular use
1C spare UPS
2A, 2B, 2C Commercial power supply 3A, 3B, 3C AC input (commercial side)
4A, 4B, 4C AC input circuit breakers 5A, 5B, 5C Forward converters 6A, 6B, 6C Reverse converters 7A1, 7B1, 7C Bypass circuit breakers 7A2, 7B2 Bypass input circuit breakers 8A, 8B, 8C Bypass circuits 9A, 9B , 9C Uninterruptible switching circuit 10A, 10B, 10C AC output circuit breaker 11A, 11B, 11C DC input circuit breaker 12A, 12B, 12C Storage battery 13A, 13B Maintenance bypass circuit (14 missing number)
15A, 15B, 15C AC output 16A, 16B Load 17A, 17B, 17C Commercial power supply 18A, 18B, 18C Bypass input 19 Spare power supply switchboard 20A, 20B Maintenance bypass circuit breaker 21A, 21B Output panel 22A, 22B AC output 23A, 23B AC input (spare UPS side)
24A, 24B Bypass input circuit breaker (spare UPS side)
25A, 25B Bypass AC input 26A, 26B DC current detector 27A, 27B Current limit adjustment circuit 28 Optimal current limit calculator

Claims (7)

A forward converter for converting AC of commercial power to DC,
An inverse converter that converts the DC output of the forward converter into AC again and supplies power to the load;
An energy storage unit for supplying DC power to the inverter at the time of a power failure of the commercial power supply;
A plurality of regular UPSs equipped with a bypass switching circuit for continuing load feeding by the commercial power source or another power source;
One standby UPS having a first switching means for continuing load power supply when one of the regular UPSs is stopped due to failure or inspection; and having the same configuration as the regular UPS;
A common backup uninterruptible power supply system comprising: a second switching unit capable of supplying the output of the backup UPS to the inputs of the plurality of service UPSs when the commercial power supply fails. 2. The common bypass switch according to claim 1, further comprising a maintenance bypass switching means for continuing load power feeding by the commercial power source or another power source in order to maintain and inspect the regular UPS or the spare UPS. Standby uninterruptible power system. When the commercial power supply fails
The plurality of service UPSs are operated by using both the DC power of the energy storage unit connected to each service UPS and the AC power of the backup UPS. Item 3. The common backup uninterruptible power supply system according to item 1 or item 2. The backup UPS supplies power capacity obtained by dividing the power that can be supplied by the backup UPS by the number of service UPSs to each service UPS.
4. The common standby uninterruptible power supply system according to claim 3, wherein each of the service UPSs supplies the remaining necessary power capacity from the energy storage unit of the service UPS. The backup UPS supplies the capacity obtained by dividing the power capacity that can be supplied by the backup UPS by the number of service UPSs and the load factor of each service UPS to each service UPS.
4. The common standby uninterruptible power supply system according to claim 3, wherein each of the service UPSs supplies the remaining necessary power capacity from the energy storage unit of the service UPS. The standby UPS obtains by calculation the power capacity to be supplied to each of the regular UPSs so that the operation durations of the energy storage units of the plurality of regular UPSs are equal.
According to the result of this calculation, the backup UPS supplies power to each service UPS,
4. The common standby uninterruptible power supply system according to claim 3, wherein each of the service UPSs supplies the remaining necessary capacity from an energy storage unit of the service UPS.   As a result of the calculation, the service UPS having a negative solution corrects the solution to 0, calculates again for the service UPS other than the service UPS, and supplies the backup UPS to each service UPS. The common standby uninterruptible power supply system according to claim 6, wherein a power capacity to be calculated is obtained.

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