JP2010035364A - Uninterrupted power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an uninterrupted power supply system capable of safely switching systems even if there exists a voltage difference between the systems to be switched. <P>SOLUTION: There are provided one set of unit uninterrupted power supply systems comprising uninterrupted power supply units 11, 12, and 13, and a branching board 41 comprising a system switching means 51 for switching two power supply systems, with at least one being the output of the unit uninterrupted power supply systems, for power supply to a load. The system switching means 51 comprises two mechanical switches 51g and 51h provided between the power supply systems and a common output end, and current adjusting means 51a and 51b connected in series to each of the two mechanical switches 51g and 51h. The current adjusting means 51a and 51b are so controlled for switching that a cross flow between two power supply systems is within a predetermined value when the two power supply systems are switched in no interruption manner. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an uninterruptible power supply system, and more particularly to an uninterruptible power supply system having a branch board having a two-system changeover switch.

  In many cases, the load of a normal uninterruptible power supply system is, for example, a computer that does not allow an instantaneous power failure. Here, the uninterruptible power supply system is a system having at least one uninterruptible power supply, and when operating the load, when the uninterruptible power supply fails or when it is necessary to maintain the uninterruptible power supply Therefore, it is necessary to switch the system between the uninterruptible power supply and the commercial power supply or switch the system between the uninterruptible power supply without interruption.

  When the above system switching is performed, different systems are connected. Therefore, a cross current is generated when the voltage or phase between the two systems does not match at the system switching point. When this cross current is large, the system changeover switch may fail, or the uninterruptible device may stop due to an overcurrent failure.

As a measure to suppress such a cross current, control is performed so that the output voltage and frequency of the two uninterruptible power supply units that perform system switching match the bypass power source, and at the same time, the output of the uninterruptible power supply system that performs system switching is serially Proposals have been made to insert a reactor to suppress cross current (for example, see Patent Document 1).
JP 2007-215344 A (page 4-6, FIG. 1)

  The technique disclosed in Patent Document 1 is effective when the output switching board for performing system switching is arranged in the vicinity of the uninterruptible power supply, but the system switching is performed far away from the uninterruptible power supply. When using a switchboard, the voltage difference due to the wiring cable is generated between the two system inputs in the switchboard due to the wiring length between the uninterruptible power supply and the switchboard. There is a risk of cross current flow.

  The present invention has been made to solve the above-described problems, and provides an uninterruptible power supply system that can safely perform system switching even if there is a voltage difference between the systems that perform system switching. The purpose is to provide.

  In order to achieve the above object, an uninterruptible power supply system of the present invention includes a set of unit uninterruptible power supply systems having at least one uninterruptible power supply, and at least one power supply system of the unit uninterruptible power supply system. In an uninterruptible power supply system including a switching board provided with a system switching unit that switches between two power systems that are outputs and supplies power to a load, the system switching unit includes a common output terminal and each of the power systems Two mechanical switches provided in between, and current adjusting means connected in series to each of the two mechanical switches. When the two power systems are switched without interruption, The current adjusting means is controlled and switched so that the cross current flowing between the power supply systems is within a predetermined value.

  ADVANTAGE OF THE INVENTION According to this invention, even if there is a voltage difference between the systems which perform system switching, the uninterruptible power supply system which can perform system switching safely 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 system configuration diagram of an uninterruptible power supply system according to Embodiment 1 of the present invention.

  In FIG. 1, uninterruptible power supplies 11, 12, and 13 constitute a set of unit uninterruptible power systems. The unit uninterruptible power supply system refers to an uninterruptible power supply system in which, for example, three units of the uninterruptible power supply units 11, 12, and 13 are operated in parallel redundant operation in a steady state. The outputs of the uninterruptible power supply units 11, 12 and 13 are fed to output boards 21 and 22, and the outputs of the output boards 21 and 22 are supplied to output branch boards 31 and 32, respectively, which branch the output of the uninterruptible power supply system. Has been. The outputs of the output branch boards 31 and 32 are branched and supplied to the branch boards 41 and 42 via wiring cables.

  System changeover switches 51 and 52 are provided in the branch boards 41 and 42, respectively. The system selector switches 51 and 52 are supplied with the output system of the output branch board 31 and the output system of the output branch board 32. Then, any one of these output systems is selected and output to supply power to the load. A circuit configuration diagram showing the internal configuration of the system selector switch 51 is shown in FIG. Since the internal configuration of the system changeover switch 52 is basically the same as that of the system changeover switch 51, the description thereof is omitted.

  In FIG. 2, the output system of the output branch board 31 is output to a load via a series circuit of a variable impedance element 51c in the current regulator 51a and a mechanical switch 51g. The output system of the output branch board 33 is output to the load via the variable impedance element 51d in the current regulator 51b and the mechanical switch 51h. Normally, either one of the mechanical switches 51g and 51h is selected and turned on.

  The variable impedance elements 51c and 51d are controlled by control units 51e and 51f provided in the current regulators 51a and 51b, respectively, and the impedances can be changed. The variable impedance elements 51c and 51d can be realized, for example, by using a power transistor in the active region. The control units 51e and 51f are supplied with current detection signals from the current detector 51i that detects the current of the output system of the output branch board 31 and the current detector 51j that detects the current of the output system of the output branch board 32. It is done. In addition, the control units 51e and 51f detect voltage of a voltage detector 51k that detects a voltage of the output system of the output branch board 31 and a voltage detector 51l that detects a voltage of the output system of the output branch board 32 as necessary. A signal is given. In FIG. 2, the control unit 51e is supplied with a voltage detection signal from the voltage detector 51k and the control unit 51f is supplied with a voltage detection signal from the voltage detector 51l. It is good also as a structure which gives both voltage detection signals to both control parts. Moreover, the current detection signal of the current detector 51m that detects the output load current is supplied to the control units 51e and 51f as necessary. For example, the voltage difference between the two power supply systems can be obtained by the voltage detection signal, and the impedance value of the variable impedance element can be obtained. Further, the reliability of current detection can be improved by detecting the load current.

  Next, the operation of FIG. 1 will be described. Now, after the uninterruptible power supplies 11, 12, and 13 perform parallel operation with the output panels 21 and 22 to make a collective power supply, the main branch is branched with the output branch boards 31 and 32, and the branch boards 41 and 42 are supplied with power. Think about the state. At this time, only one of these two power supply system inputs (for example, the mechanical switches 51g and 52g on the output branch board 31 side) is input to the system selector switches 51 and 52 of the branch boards 41 and 42, and each feeder is supplied to each feeder. The power supply is receiving power.

  In the above state, consider switching the power supply system of the branch board 41 from the output branch board 31 side to the output branch board 32 side.

  First, the mechanical switch 51h is turned on to operate the above two power supply systems in parallel. At this time, if the impedance of the variable impedance 51c is set to a predetermined fixed value and the variable impedance 51d is set to the maximum value, the current flowing from the output branch board 31 side, that is, the detected current of the current detector 51i is output from the output branch board 32. Larger than the current flowing from the side, that is, the detection current of the current detector 51l.

  Next, the impedance of the variable impedance 51d is adjusted to decrease. Then, the currents supplied from the above two power supply systems are balanced, and the mechanical switch 51g is opened when the cross current becomes less than the allowable value.

  As described above, if the variable impedance 51d is controlled to an appropriate value and the above two power supply systems are switched, it is possible to perform system switching without interruption while suppressing excessive cross current flow. It becomes. If the cross current does not fall below the allowable value even if the variable impedance 51d is minimized, the variable impedance 51c may be increased.

  In the above description, the above two power systems are outputs of different output branch boards when the uninterruptible power supply units in the unit uninterruptible power supply system are operated in parallel. It may be the output of a spare uninterruptible power supply in the system, or one of them may be a commercial power system. Further, it is obvious that the configuration can be switched to the output system of the second unit uninterruptible power supply system.

  FIG. 3 is a circuit configuration diagram of a system changeover switch used in the uninterruptible power supply system according to Embodiment 2 of the present invention.

  In the second embodiment, the same components as those in the circuit configuration diagram of the system changeover switch used in the uninterruptible power supply system according to the first embodiment of the present invention shown in FIG. The second embodiment is different from the first embodiment in that a short-circuit switch 51n is provided in parallel with the variable impedance element 51c and a short-circuit switch 51o is provided in parallel with the variable impedance element 51d in the system changeover switches 51A and 51b. It is.

  If the short-circuit switches 51n and 51o are turned on during normal operation, the normal energization loss of the impedance elements 51c and 51d can be made substantially zero. When power supply switching between the two power systems is performed, the short-circuit switches 51n and 51o are opened before the mechanical switch 51g or 51h is turned on, and the cross current is suppressed according to the method described in the first embodiment while the power system is switched. The power supply switching is performed, and when this is completed, the short-circuit switches 51n and 51o may be turned on again.

  FIG. 4 is a circuit configuration diagram of a system changeover switch used in the uninterruptible power supply system according to Embodiment 3 of the present invention.

  The same parts as those in the circuit configuration diagram of the system changeover switch used in the uninterruptible power supply system according to the first embodiment of the present invention shown in FIG. The third embodiment is different from the first embodiment in that a single double-throw mechanical switch 51p is used instead of the two mechanical switches 51g and 51h.

  It is clear that the system changeover switch 51B using one double-throw mechanical switch as in this embodiment has the same function as the system changeover switch 51 of the first embodiment using two mechanical switches. .

  FIG. 5 is a circuit configuration diagram of a current regulator used in the uninterruptible power supply system according to Embodiment 5 of the present invention.

  In the current regulator 51q of the fourth embodiment, a semiconductor switching element 51r is used instead of the variable impedance elements 51c and 51d of the first embodiment.

  If the semiconductor switching element 51r is a thyristor element, the control unit 51s controls the energization current of the semiconductor switching element 51r by phase control of the thyristor element. When the semiconductor switching element 51r is a self-extinguishing element, the control unit 51s may perform, for example, PWM control to control the energization current of the semiconductor switching element 51r.

  It is obvious that Example 5 can be used in combination with Example 2 or Example 3 already described.

  FIG. 6 is a circuit configuration diagram of a current regulator used in the uninterruptible power supply system according to Embodiment 5 of the present invention.

  In the current regulator 51t of the fifth embodiment, a series inverter 51u is used instead of the variable impedance elements 51c and 51d of the first embodiment.

  The series inverter 51u is an inverter in which the output of the three phases is separated for each phase, and the control unit 51y controls so that the output is synchronized with the power feeding system. Here, the series inverter means an inverter inserted in series in the system. In FIG. 6, illustration of the DC power supply unit of the series inverter 51 u is omitted, but power may be supplied by combining a transformer and a converter from the power supply system. Thus, if the series inverter which generates a voltage synchronized with the power feeding system is used as the current regulator, the sensitivity of control is improved.

  It is obvious that the fifth embodiment can also be used in combination with the second or third embodiment already described.

  FIG. 7 is a circuit configuration diagram of a system changeover switch used in the uninterruptible power supply system according to Embodiment 6 of the present invention.

  In the sixth embodiment, the same parts as those in the circuit configuration diagram of the system changeover switch used in the uninterruptible power supply system according to the first embodiment of the present invention shown in FIG. The difference between the second embodiment and the first embodiment is that the current selector 51t using the series inverter 51u described in the fifth embodiment is used in the system changeover switch 51C instead of the current regulator 51a. 51b is omitted.

  As in the first embodiment, the control unit 51v of the current regulator 51t includes a current detector 51i that detects the current of the output system of the output branch board 31 and a current detection that detects the current of the output system of the output branch board 32. A current detection signal is supplied from the device 51j. Further, if necessary, the voltage detector 51k for detecting the voltage of the output system of the output branch board 31 and the voltage detection signal of the voltage detector 51l for detecting the voltage of the output system of the output branch board 32, and further the output load current A current detection signal of the current detector 51m to be detected is given.

  Consider that the power supply system of the branch board 41 is switched from the output branch board 31 side to the output branch board 32 side under the same preconditions as described in the first embodiment.

  First, in order to turn on the mechanical switch 51h, the output voltage of the series inverter 51u is matched with the detection voltage and phase of the voltage detector 51l. Then, the mechanical switch 51h is turned on, and the output voltage of the series inverter 51u is adjusted according to the detection current of the current detector 51i and the detection current of the current detector 51j. When the cross current becomes less than the allowable value, the mechanical switch 51g is opened.

  When switching back, the output voltage of the series inverter 51u is matched with the detection voltage and phase of the voltage detector 51l. Then, the mechanical switch 51g is turned on, and the output voltage of the series inverter 51u is adjusted according to the detection current of the current detector 51i and the detection current of the current detector 51j. When the cross current becomes less than the allowable value, the mechanical switch 51h is opened.

  As described above, if the output voltage of the series inverter 51u is controlled to an appropriate value and the two power supply systems are switched, the system can be switched without interruption without suppressing excessive cross current flow. It becomes possible. As described above, the current regulator is provided in any one of the two power supply systems so that the cross current suppression system can be switched because the series inverter 51u generates a boost side voltage and a step down side voltage with respect to the rated voltage. Because it is possible.

  It is obvious that Example 6 can be used in combination with Example 2 or Example 3 already described.

The system block diagram of the uninterruptible power supply system which concerns on Example 1 of this invention. The circuit block diagram of the system | strain changeover switch used for the uninterruptible power supply system which concerns on Example 1 of this invention. The circuit block diagram of the system | strain switch used for the uninterruptible power supply system which concerns on Example 2 of this invention. The circuit block diagram of the system | strain selector switch used for the uninterruptible power supply system which concerns on Example 3 of this invention. The circuit block diagram of the current regulator used for the uninterruptible power supply system which concerns on Example 4 of this invention. The circuit block diagram of the current regulator used for the uninterruptible power supply system which concerns on Example 5 of this invention. The circuit block diagram of the system | strain switch used for the uninterruptible power supply system which concerns on Example 6 of this invention.

Explanation of symbols

11, 12, 13 Uninterruptible power supply 21, 22 Output board 31, 32 Output branch board 41, 42 Branch board 51, 51A, 51B, 51C, 52 System selector switch 51a, 51b, 51q, 51t Current regulator 51c, 51d Variable impedance elements 51e, 51f, 51s, 51v Control units 51g, 51h, 52g Mechanical switches 51i, 51j, 51m Current detector 51k, 51l Voltage detector 51n Short-circuit switch 51p Double-throw mechanical switch 51r Semiconductor switching element 51u Series inverter

Claims (10)

A set of unit uninterruptible power supply systems having at least one uninterruptible power supply;
In an uninterruptible power supply system comprising at least one power supply system and a switchboard having a system switching means for switching between two power supply systems that are outputs of the unit uninterruptible power supply system and supplying power to a load,
The system switching means includes two mechanical switches provided between the respective power supply systems and a common output terminal, and current adjusting means connected in series to each of the two mechanical switches. Have
An uninterruptible power supply system characterized in that when the two power supply systems are switched without interruption, the current adjusting means is controlled and switched so that the cross current flowing between the power supply systems is within a predetermined value. .   The uninterruptible power supply system according to claim 1, wherein a variable impedance element is used as the current adjusting means.   2. The uninterruptible power supply system according to claim 1, wherein a semiconductor switching element is used as the current adjustment means, and current adjustment is performed by switching control thereof. A set of unit uninterruptible power supply systems having at least one uninterruptible power supply;
In an uninterruptible power supply system comprising at least one power supply system and a switchboard having a system switching means for switching between two power supply systems that are outputs of the unit uninterruptible power supply system and supplying power to a load,
The system switching means includes two mechanical switches provided between the respective power supply systems and a common output terminal, and a current adjustment connected in series to either one of the two mechanical switches. Having means,
An uninterruptible power supply system characterized in that when the two power supply systems are switched without interruption, the current adjusting means is controlled and switched so that the cross current flowing between the power supply systems is within a predetermined value. .   The uninterruptible power supply system according to claim 1 or 4, wherein the current adjusting means is a series inverter and performs current adjustment by controlling an output voltage thereof.   6. The short-circuit switch is provided in parallel with the current adjusting means, and the short-circuit switch is turned on at a normal time when switching between the two power supply systems is not performed. Uninterruptible power supply system described in.   The uninterruptible power supply system according to any one of claims 1 to 6, wherein a single double-throw mechanical switch is provided instead of the two mechanical switches.   The unit uninterruptible power supply system has a plurality of uninterruptible power supply units, and the other power supply system of the two power supply systems is also an output of the unit uninterruptible power supply system. The uninterruptible power supply system according to any one of claims 7.   The uninterruptible power supply system according to any one of claims 1 to 7, wherein the other power supply system of the two power supply systems is a commercial power supply.   The second set of unit uninterruptible power supply systems is further provided, and the other power supply system of the two power supply systems is an output of the second set of unit uninterruptible power supply systems. Item 8. The uninterruptible power supply system according to any one of Item 7.

Images