JPS6285630A - Zero phase monitoring circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Fields of application on construction The present invention relates to a zero-phase monitoring circuit.

B0 Summary of the Invention The present invention provides a zero-phase monitoring circuit in which voltages or currents inputted through one set of transformers are added in a vectorial manner and inputted to a determination section, and the other set of Transformer group voltage or l! The zero-phase circuit can be constantly monitored by providing the summed output of the current and comparing and determining it.

C8 Conventional technology Zero-phase circuits required for protection relays, measurement circuits, etc. are normally
Voltage and current are zero. Therefore, when an actual accident occurs and the zero-sequence voltage or zero-sequence current is detected and the maintenance relay is operated or measured, it is necessary that the sum circuit be in normal condition. However, since the voltage and current of the zero-phase circuit are usually zero, it is difficult to monitor whether the zero-phase circuit is normal or not.

For this reason, conventionally, in order to monitor the zero-phase circuit, a special electrical input is automatically applied to the zero-phase circuit at a certain period, for example, once a day or once a week. They were testing to see if there were any disconnections or defects in the shorting elements.

D0 Problems to be Solved by the Invention As mentioned above, with the conventional zero-phase circuit monitoring means, even if a defect occurs in the zero-phase circuit, it cannot be detected until the next test cycle, making it difficult to detect the defect. Delays are inevitable. Furthermore, the short sight means applies a special electrical input to the zero-phase circuit, and therefore requires a switching circuit that disconnects the normal circuit and applies the electrical input. As described above, conventional devices have disadvantages such as a decrease in reliability due to the large number of additional circuits required for testing and switching circuits.

SUMMARY OF THE INVENTION An object of the present invention is to provide a zero-phase monitoring circuit that does not require the addition of a switching circuit or a special E-sensor, and has improved operational reliability.

Means for Solving the E0 Problem The present invention provides two sets of transformers to which each phase voltage or each phase' current of a three-phase main current is provided separately, and one set of transformers of these transformer groups. an adder that adds the outputs of the transformer group vectorwise; an adder that adds the outputs of the other transformer group in the transformer group; and an adder that adds the outputs of the transformer group vectorwise; The apparatus is provided with a determination section which compares and determines both addition outputs, and outputs a determination of normality or abnormality based on the determination result.

20 Effects With the above configuration, the present invention compares the power outputs of the transformer groups input to the determination section, and when the comparison results are equal, it is determined to be normal, and when they are not equal, it is determined to be abnormal, and the zero-phase circuit is activated. Can be constantly monitored. Therefore, there is no need to provide a switching means or the like in the zero-phase circuit.

G. Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a circuit diagram of a voltage zero-phase circuit as a first embodiment of the present invention. In the figure, from the output of a voltage transformer (transformer FT or instrument transformer PI) (not shown) to terminal 12
, 13, 14, each phase voltage va of the three-phase father flow is applied to
* vl) g V (B is an electronic circuit with the ability to perform auxiliary transformation! 1, 2.3, filter, and amplification +1 7゜8.
The signals are individually applied to the determination unit 11 via the terminals 9 and 9. Note that the output V of the electronic circuits 7 to 9. , is calculated by one by an adder that adds vectorially, although not shown. The formula is as follows.

Vat “Vb*” Va! = Vat On the other hand, each phase voltage va e vl) e ■(! is the auxiliary transformer 4
It is added to the primary winding of ゜5.6. Each of these auxiliary transformers 4.5.6 is connected to the electronic circuit 10 by having its secondary winding connected in a 1σ series and having resistors 12, 13, and 14 connected in parallel to each secondary winding. The output of the accompaniment circuit 10 is added with a voltage Vo expressed by the following equation by an adder (not shown).
w is obtained.

Va + vb + vc = v0'.

Note that the electronic circuit 10 has filter and amplification functions as described above. The output of the electronic circuit 10 is applied to the determination section 11.

The voltages Vat and v0' are compared in the determination section 11.

With the above configuration, in the first embodiment, if the zero-phase circuit is normal in a normal state in which no short-circuit accident occurs in the power system, the voltage is V.

At t=7'o, the slope becomes 0, and two zero-sequence voltages V. t and ■. ′ and match, the monitoring result is determined to be normal.

Here, if the auxiliary transformer 1 is disconnected or short-circuited, or if an element failure occurs in the electronic circuit 7, the result will be vow\0,
VO2\v0', and since the comparison does not match, the monitoring result is determined to be abnormal.

Next, a second embodiment will be described with reference to FIG.

From the output of a current transformer (not shown) to terminals 32, 33, 34
The IC is applied to the determination unit 31 via auxiliary current transformers 21, 22, 23 and electronic circuits 27, 28, 29 having filter and amplification functions. , in the adding section that adds vectorially, from the process a, +! Handwork at = Work 0! It is added as follows.

Also, from the output of a current transformer (not shown) to terminals 35, 36°3
Each phase of the three-phase alternating current added to 7'9 flow 1. More, engineering.

are applied individually to the auxiliary current transformers 24, 25, 26,
Its output ends are connected in parallel and connected to an electronic circuit 31.

The second output of this electronic circuit is a current generator of the following formula. ′, is obtained.

Engineering, 10 to 10 IC = Engineering. '.

Note that the electronic circuit 31 has a filter and sound amplification function as described above. The output of electronic circuit 30 is applied to determination circuit 31 .

The above-mentioned snow drift work q and work *' are compared in the determination section 11.

With the above configuration, the second embodiment can operate normally if the monitoring circuit is normal when no short-circuit accident occurs in the power system.

, = engineering. ′, ζO, and two zero-sequence currents, and
, match, so the monitoring result is determined to be normal.

Here, if an abnormality occurs in the electronic circuit 271, for example, the work will be 0. ＼工0′.

Therefore, the comparison in the determination unit 11 does not result in a match, and therefore, an abnormality in the monitoring circuit is detected.

几As described in the detailed description of the invention, the present invention provides a three-phase alternating current with each phase voltage or each phase voltage υ11. two sets of transformers, each of which is given separately, an adder that vectorially adds each output of one set of transformers of these transformer groups, and another set of transformers of said transformer group. The output of this adder and the output of the adder added vectorially are given, and both addition outputs are compared and judged, and based on the judgment result, a judgment is made as to whether it is normal or abnormal. Since a determination unit that outputs output is provided, it is possible to constantly monitor abnormalities in the zero-phase circuit of a three-phase AC power system, where the amount of electricity is zero under normal conditions, and speed up the detection of abnormalities. Since it is not necessary to switch the zero-phase circuit as in the conventional method, the reliability of the monitoring circuit can be improved.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a first embodiment of the invention, and FIG. 2 is a circuit diagram of a second embodiment of the invention. 1~6...Single phase transformer, 7~10.27~30...
Filter, electronic circuit with amplification function, 11, 31.
...Judgment circuit, 12-14...Resistor, 21-26...
・Single-phase current transformer. NF) Mitsu Gei

Claims (1)

[Claims] two transformer groups to which each phase voltage or each phase current of three-phase alternating current is applied separately; an adder that adds each output of one transformer group of these transformer groups in a vectorial manner; and the transformer. An adder adds the outputs of the other transformer group in the transformer group, and the output of this adder and the vectorially added output of the adder are given, and the outputs of both additions are compared and determined. , and a determination unit that outputs a determination of normality or abnormality from the determination result.