JP2008099469A - Control method of uninterruptible power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method suitable for an uninterruptible power system where a plurality of uninterrupted power supply units are connected to one power supply busbar selected between two sets of power supply busbars, and power is supplied to a load unit of the selected power supply busbar. <P>SOLUTION: The system is provided with switches 16a and 16b for switching a voltage correction circuit 16 of UPS 10, linked with the respective states of circuit breakers in a first switch board 60 and a second witch board 70; a multiplier 16c for performing multiplication operations between the output values selected by the switches 16a and 16b; a cross-current suppression circuit 16d, having the same structure and functions as those of a conventional voltage correcting circuit 15 and an adder 16e for adding the output values of the multiplier 16c and the cross-current suppression circuit 16d and outputting the addition operation value to a control circuit 14 of UPS 10, as shown in Figure 3, as the voltage correction value. Thus, parallel operations for UPS 10 and up to UPS 20 can be performed; and while the voltage drop down to the selected power supply busbar is corrected, the terminal voltage in the power supply busbar in a power supplying state can be maintained at a desired value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control method for an uninterruptible power supply system in which a plurality of uninterruptible power supply devices are connected to one power supply bus selected from two sets of power supply buses and power is supplied to a load device of the selected power supply bus. About.

  FIG. 2 is a circuit configuration diagram of an uninterruptible power supply system including two uninterruptible power supply apparatuses (hereinafter abbreviated as UPS) as this type of uninterruptible power supply system.

  In FIG. 2, the circuit breaker 61 of the first switching board 60 and the circuit breaker 71 of the second switching board 70 are closed, and the circuit breaker 62 and the second switching board 70 of the first switching board 60 are closed. Since the circuit 72 is open, AC power is supplied from the UPS 10 and UPS 20 operating in parallel to the A system load device 100 via the A system power supply bus board 80, and the first switching board 60 The circuit breaker 62 and the circuit breaker 72 of the second switching board 70 are closed, and the circuit breaker 61 of the first switching board 60 and the circuit breaker 71 of the second switching board 70 are opened. AC power is supplied from the UPS 10 and UPS 20 operating in parallel to the B system load device 200 via the B system power supply bus board 90.

  FIG. 3 is a circuit configuration diagram of the UPS 10 of the UPS 10 and UPS 20 having the same configuration that perform the above-described power feeding operation, and is used to supply AC power from an input commercial power source to the subsequent stage while converting the AC power to DC power. A converter circuit 11; a storage battery 12 that supplies DC power to a subsequent stage when the commercial power source or the like is in a power failure; an inverter circuit 13 that converts any of the DC power into AC power having a desired frequency and voltage; and a converter circuit 11 and the inverter circuit 13 to a desired operation state, and a voltage correction circuit 15 or a voltage correction circuit 16 to be described later for suppressing a cross current flowing when the UPS 10 operates in parallel with the UPS 20. It is configured.

FIG. 4 is a circuit configuration diagram of the voltage correction circuit 15 in the UPS 10 as a conventional example of the present invention. The voltage correction circuit 15 is configured to share the current commanded to the UPS 10 and the current detector 63 or current of the first switching board 60. A subtraction calculator 15a for obtaining a cross current which is a difference from the output current of the UPS 10 obtained from the detector 64; and a reactive power calculator 15b formed using a known technique for calculating the reactive power component of the cross current; The cross current is suppressed by correcting the output voltage value of the UPS 10 via the control circuit 14 shown in FIG. 3 with the voltage correction value based on the reactive power component output from the reactive power calculator 15b. I am doing so.
JP 2004-23922 A

  In the uninterruptible power supply system shown in FIG. 2, for example, when the A system load device 100 is a regular load device and the B system load device 200 is a reserve load device, the A system power supply bus board 80 and the A system load device 100 are It is installed on the same floor, and the B-system power supply bus board 90 and the B-system load equipment 200 are installed on a different floor from the A-system power supply board 80 and the A-system load equipment 100 for the convenience of maintenance. There may be.

  In the case of the device arrangement as described above, the wiring impedance from the UPS 10 to the A system power supply bus board 80 and the wiring impedance from the UPS 20 to the A system power supply bus board 80 are different due to the installation location of the UPS 10 and the UPS 20. Similarly, the wiring impedance from the UPS 10 to the B-system feeding bus board 90 and the wiring impedance from the UPS 20 to the B-system feeding bus board 90 may be different. In such a case, in the voltage correction circuit 15 shown in FIG. 4 on the assumption that the respective wiring impedances are substantially equal, the terminal voltage at the A-system power supply bus board 80 or the B-system power supply bus board 90 in the power supply state is desired. There was a problem that the value of could not be maintained.

  In addition, when the wiring impedance varies depending on the power supply state as described above, there is a problem that the voltage correction circuit having the circuit configuration described in Patent Document 1 cannot be used.

  The objective of this invention is providing the control method of the uninterruptible power supply system which eliminates the said problem.

The first aspect of the invention is an uninterruptible power supply system in which a plurality of uninterruptible power supply devices are connected to one power supply bus selected from two sets of power supply buses and power is supplied to a load device of the selected power supply bus. In
Each of the uninterruptible power supply devices uses a control method for an uninterruptible power supply system, which is operated in parallel while correcting a voltage drop from the power supply device to the selected power supply bus.

According to a second aspect of the present invention, in the control method for the uninterruptible power supply system according to the first aspect of the present invention,
The voltage drop is derived based on each current flowing through the power supply bus connected from the uninterruptible power supply.

  According to this invention, the terminal voltage at the power supply bus in the power supply state is obtained by operating the uninterruptible power supply in parallel while correcting the voltage drop from each of the uninterruptible power supply to the selected power supply bus. Can be set to a desired value.

  FIG. 1 is a detailed circuit configuration diagram of the voltage correction circuit 16 shown in FIG. 3 as an embodiment of the present invention. The voltage correction circuit 16 includes a first switching board 60 and a second switching board 70 shown in FIG. The switches 16a and 16b that perform switching operations linked to the states of the circuit breakers in FIG. 1, the multiplier 16c that performs multiplication operations between the output values selected by the switches 16a and 16b, and the above-described diagram. 4 is added to the cross current suppression circuit 16d having the same configuration and function as the voltage correction circuit 15 shown in FIG. 4 and the output values of the multiplier 16c and the cross current suppression circuit 16d. The adder 16e is output to the control circuit 14 of the UPS 10 shown.

  The operation of the voltage correction circuit 16 having the circuit configuration shown in FIG. 1 will be described below with reference to the circuit configuration diagram shown in FIG.

  For example, the circuit breaker 61 of the first switching board 60 and the circuit breaker 71 of the second switching board 70 are closed, and the circuit breaker 62 of the first switching board 60 and the circuit breaker 72 of the second switching board 70 Is open, desired AC power is supplied from the UPS 10 and UPS 20 to the A-system load device 100 via the A-system power supply bus board 80. At this time, the switch 16a is connected to the A-system bus current, that is, The detection value of the current detector 63 of the switching board 60 is selected, and the switch 16b selects the A system correction gain, that is, the wiring impedance equivalent value from the UPS 10 to the A system power supply bus board 80, whereby the output value of the multiplier 16c is The value corresponds to the voltage drop from the UPS 10 to the A-system power supply bus board 80.

  At this time, the cross current suppressing circuit 16d is derived from the detected value of the current detector 63 of the first switching board 60, the detected value of the current detector 73 of the second switching board 70, and the rated output capacities of the UPS 10 and UPS 20, respectively. The voltage correction value for suppressing the cross current is derived based on the reactive power component of the cross current that is the difference between the shared current of the UPS 10 and the detection current of the current detector 63 selected by the switch 16a.

  Therefore, the output voltage value of the UPS 10 is corrected via the control circuit 14 shown in FIG. 3 with the addition operation value of the output values of the multiplier 16c and the cross current suppression circuit 16d by the adder 16e as a new voltage correction value. Thus, the UPS 10 can suppress the cross current flowing between the UPS 10 and the UPS 20 while correcting the voltage drop from the UPS 10 to the power supply bus of the A-system power supply bus board 80.

  Similarly, the UPS 20 at this time corrects the voltage drop from the UPS 20 to the power supply bus of the A-system power supply bus board 80, and performs the operation of suppressing the cross current flowing between the UPS 10 and the UPS 20 to thereby perform the UPS 10 and the UPS 20. Therefore, the terminal voltage at the power supply bus of the A-system power supply bus board 80 in the parallel power supply state can also be maintained at a desired value.

Configuration diagram of a voltage correction circuit showing an embodiment of the present invention Circuit diagram of uninterruptible power supply system Partial detailed circuit configuration diagram of FIG. Configuration diagram of a voltage correction circuit showing a conventional example

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,20 ... Uninterruptible power supply, 11 ... Converter circuit, 12 ... Storage battery, 13 ... Inverter circuit, 14 ... Control circuit, 15, 16 ... Voltage correction circuit, 60 ... First switchboard, 61, 62 ... Circuit breaker , 63, 64 ... current detector, 70 ... second switching board, 71, 72 ... circuit breaker, 73, 74 ... current detector, 80 ... A system power supply bus board, 90 ... B system power supply bus board, 100 ... A system load equipment, 200 ... B system load equipment.

Claims (2)

In the uninterruptible power supply system that connects a plurality of uninterruptible power supply devices to one power supply bus selected from two sets of power supply buses and supplies power to the load device of the selected power supply bus.
Each of the uninterruptible power supply devices is operated in parallel while correcting a voltage drop from the power supply device to the selected power supply bus. In the control method of the uninterruptible power supply system according to claim 1,
A control method for an uninterruptible power supply system, wherein the voltage drop is derived based on each of the currents flowing through the power supply buses connected from the uninterruptible power supply.

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