JPH079562Y2 - Abnormal unit determination circuit for uninterruptible power supply - Google Patents

Description

[Detailed description of the device] A. Industrial field of application The present invention relates to an abnormal unit discriminating circuit of an uninterruptible power supply unit that detects a failure unit of a plurality of CVCF (constant voltage constant frequency) units operating in parallel. is there.

B. Outline of the Invention The present invention is an uninterruptible power supply system in which three or more CVCF units are operated in parallel. By using a discriminator circuit configuration in which the abnormal state is a non-operating state (or operating state), a stop command is issued only to the abnormal unit so that the operation of the sound unit can be continued.

C. Conventional technology To operate multiple CVCF units in parallel, output voltage,
The frequencies must match. If a failure occurs in one unit during parallel operation, a cross current will flow between the abnormal unit and the sound unit. In that case, since the DC voltage rises in the unit into which the cross current has flowed, the DC overvoltage is detected and the parallel release is performed as a protective operation. There are the following two cases as abnormal modes.

(I) Abnormal unit voltage drop or phase delay.

(II) Abnormal unit voltage rise or phase lead.

In the case of (I), current flows from the sound unit to the abnormal unit, and the abnormal unit stops due to DC overvoltage.
In the case of item (II), current flows from the abnormal unit to the sound unit, and the sound unit stops due to DC overvoltage.

D. Problems to be solved by the device When an abnormality is determined by detecting the DC overvoltage in this way, (I
If the operation of the abnormal unit is continued and the sound unit is stopped as described in I), a situation will occur.

E. Means for Solving the Problems The present invention relates to an uninterruptible power supply system in which three or more CVCF units are operated in parallel, and all other units are operated when the DC overvoltage relay of the unit is operating (or not operating). It is characterized in that the circuit configuration is such that the abnormality determination condition is that the DC overvoltage relay of (3) is in a non-operating (or operating) state.

F. Action For example, when the DC voltage of one unit exceeds the set value, the DC voltage of another unit does not both exceed the set value, or when the DC voltage of one unit does not reach the set value, another When both the DC voltage of the unit exceeds the set value, it is determined that a unit is abnormal.

At other times, one unit is determined to be normal and its operation continues.

G. Embodiment FIG. 1 and FIG. 2 show an embodiment of the present invention.
This is the case of operating CVCF units in parallel. The units A, B, and C have the same configuration, and AC (alternating current) input is rectified by the forward conversion unit (rectification circuit) 1, smoothed by the capacitor 2 and used as the input of the inverter (inverse conversion unit) 3. The output (AC output) is combined with the output of another unit through the thyristor switch 4.

The forward conversion unit 1, that is, the voltage across the capacitor 2 (DC voltage) and the output (set value) of the setter 5 are added to the operational amplifier 6 and compared, and the comparison result indicates the operation or non-operation of the DC overvoltage relay. I'm trying to control.

Then, in order to determine the abnormality of the No. 1 unit A, as shown in FIG. 2, the output of the operational amplifiers (comparators) 6A to 6C of the units A to C (the detection voltage is an overvoltage and the logic level is set). "H") is used. That is, the output of the comparator 6A is connected to the NOT circuit 11A and the NAND circuit (NAND).
The inputs of the circuit 12A and the outputs of the comparators 6B and 6C of the other units B and C are input to the AND circuit 13A, and are also input to the NOT circuits 14A and 15A, respectively, and the outputs of the NOT circuits 14A and 15A. Is input to the AND circuit 16A. The output of the NOT circuit 11A is used as the input of the NAND circuit 17A together with the output of the AND circuit 13A, and the output of the AND circuit 16 is used as the input of the NAND circuit 12A. In this circuit configuration, the outputs of the NAND circuits 12A and 17A are "0", which is abnormal.

This is when the DC overvoltage relays of units B and C operate and the DC overvoltage relay of unit A does not operate, and when the DC overvoltage relays of units B and C do not operate and the DC overvoltage relay of unit A operates. The unit A is determined to be "abnormal".

The mode of the above-mentioned unit A abnormality determination is as follows.

As is clear from this table, when the DC overvoltage relay of the unit is operating (or not operating), all other units are inactive (or operating) (situation I,
III) is the condition for abnormality determination, only the abnormal unit is subject to the stop measures, and the operation of the sound unit is continued.

H. Device drop As described above, according to the present invention, in a system in which three or more CVCF units are operated in parallel, the DC voltage of each unit is detected and compared with the set value, and the DC overvoltage relay is used as a result. When controlling, the circuit configuration is such that when the DC overvoltage relay of the relevant unit is operating (or not operating), it is determined that all the DC overvoltage relays of other units are inactive (or operating). It becomes possible to stop the operation of the other healthy units and continue the operation of the other healthy units, which is effective when the operational reliability is remarkably improved.

[Brief description of drawings]

FIG. 1 shows an embodiment of an abnormal unit discriminating circuit of an uninterruptible power supply according to the present invention. FIG. 1 is a configuration explanatory view of a CVCF parallel operation system, and FIG. 2 is a block diagram of the abnormal unit discriminating circuit. . 1 ... Forward converter, 2 ... Capacitor, 3 ... Inverter, 4 ...
Thyristor switch, 5 ... Setting section, 6 ... Comparator,
7A, 14A, 15A ... Negation circuit, 12A, 17A ... Nand circuit, 13A, 16A
… And circuit.

Claims (1)

[Scope of utility model registration request] 1. In an uninterruptible power supply system in which three or more CVCF units are operated in parallel, when the DC overvoltage relays of the unit are operating (or not operating), the DC overvoltage relays of all other units are not operating (or An abnormality unit determination circuit for an uninterruptible power supply, which has a circuit configuration in which an operation determination state is an abnormality determination condition.