JPS5959015A - Ac/dc mixed contact detecting relay - 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 The present invention also relates to an AC/DC cross contact detection relay applied to a parallel system.

Conventionally, in parallel systems in which AC and DC transmission lines run in parallel, a circuit system such as the one shown in Figure 1 is often used as a means of detecting a short circuit between the two transmission lines, that is, a dry circuit. has been done. In this Figure 1, 1 and 2 are AC bus bars, 5, 4, 5.6 are circuit breakers connected to the respective power transmission systems, 7 and 8 are transformers for forward and reverse conversion, and the father @conversion device 9 , 10 are provided with an AC secondary voltage.

Further, 11 and 12 are DC reactors inserted into the DC transmission line, 15 is a first DC current transformer represented by, for example, a Kramer type that is an application of a saturation type DC transformer, and 14 is a DC reactor that allows only the commercial frequency to pass through in its entirety. The first filter 15 is a first level detector for detecting the output signal sound of the filter 14.

Next, when a power cross-contact fault occurs, such as a short circuit between the transformer line of the parallel system and the DC transmission line, an alternating current component current is also applied to the DC transmission line. Therefore, the short circuit current flowing through the DC transmission line is detected by the full DC current transformer 15, and is inputted to the level detector 15 through the filter 14, thereby detecting the occurrence of an accident and causing all necessary protective actions to be performed. I'm doing it like that.

However, in conventional AC/DC cross contact detection relays, the inverter
It is well known that an alternating current flows through the DC line even when the rotational current fails, and with conventional detection circuits, it is possible to completely stop both the AC and DC transmission systems due to the nature of the accident that occurred, such as an AC/DC cross-contact accident. Is it unclear whether 1υi should be stopped or only the DC transmission system should be stopped as if two-phase commutation had failed? There were drawbacks such as I'l.

The present invention has been made to eliminate the above-mentioned conventional drawbacks, and uses two sets of commercial frequency intrusion relays installed on two phases of a DC power transmission system to prevent AC/DC cross-contamination accidents or two-phase commutation failure accidents. Accurate judgment and prompt implementation of system protection measures =
The purpose of the present invention is to provide an AC/DC cross contact detection relay with high performance.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The same parts as in Figure 1 are shown in the second figure with the same reference numbers.
In the figure, 16 is a second DC current transformer that detects the current flowing between the neutral line of the DC transmission system and the ground, 17 is a second filter that allows only commercial frequencies to pass through, and 18 is a second level detector. , 19 and 20 are inverter circuits, 21, 22
, 2.5 is an AND circuit that constitutes a logic circuit together with the respective inverter circuits, 24 is a two-phase commutation failure detection output, 2
5 is a short circuit detection output between the neutral line and the AC line, and 26 is an AC/DC cross contact detection output.

Next, the entire operation of the present invention will be explained using FIG. 3.

First, when a two-phase commutation failure occurs in DC power transmission, alternating current flows only in the DC system, as shown in FIG. 3 (2L). In addition, when a short circuit occurs between the AC line and the neutral line or the return line, the current is commutated to the neutral line and the ground line as shown in Figure 8fbl', but when the DC line positive pole of electric wire,
Alternatively, no alternating current flows to the negative electrode side. Furthermore, at the point where the current line and the DC transmission line meet, alternating current is commutated to all of the neutral wire, ground wire, and DC transmission line, as shown in Figure 3 fcl. Therefore, in order to identify all of these accidents without fail (as shown in Fig. 2), the DC current transformers 16 and 16 detect all alternating fN currents in the positive terminal side of the DC transmission line and the grounding wire of the neutral line, respectively.
When detecting alternating current, only the commercial frequency is passed through filters 14 and 17t, and level detectors 15 and 18vc perform all fault current judgments, and output all logic when it is judged that alternating current exists. 111, inverter circuit 19.20 and AND circuits 21, 22, 2
5- to identify the accident.

The output 24 of the AND circuit 21 is logic 11 when the two-phase rotation fails.
1, the output 25 of the AND circuit 22 becomes "1" when there is a ground fault to the neutral wire, and the output 26 of the AND circuit 26 becomes "111" when there is a ground fault.The conditions for logical operation are shown in Figure 3 (d).
It is shown in l.

Although the above embodiment describes an example of a circuit system in which a current transformer is provided at the grounding wire of the neutral line and the positive terminal of the DC power transmission, the circuit system is not limited to this, and for example, a circuit system as shown in FIG. Even with the configuration of the DC transformers 15 and 16, the same effect as that of the embodiment shown in FIG. 2 can be obtained.

As described above, according to the present invention, two sets of a DC current transformer for current detection, a filter that passes only five AC components, and a level detector for the output signal of the filter are provided at predetermined locations on all DC transmission lines, The output signals of each level detector are led to a logic circuit and combined for automatic judgment, and the results can be used to identify AC/DC cross contact accidents, ground faults between the neutral line and AC line, and 2411 commutation failures. This is extremely effective in quickly clarifying the accident situation of the tar-parallel system and taking accurate protective measures.

[Brief explanation of the drawings] Figure 1 is a circuit configuration diagram showing a conventional contact detection relay system.
Figure 2 is a circuit configuration diagram showing one embodiment of the present invention, Figure 3
al, (bl, (c) is an alternating current or a 2
An explanatory diagram showing the flow of alternating current at the time of a phase commutation failure accident, the same figure (cll is a logical operating condition diagram, and Fig. 4 is a circuit configuration diagram showing another embodiment of the present invention. 1.2...・Countercurrent bus, 5, 4, 5.6... Breaker, 7.8... Conversion transformer, 9.10... Termination converter, 11.12... DC reactor, 15 ...First
DC current transformer, 14... first filter, 15...
First level detector, 16...Second DC current transformer, 1
7... Second filter, 18... Second level detector, 19, 20'... Inverter times F each, 21.2'
2.23...AND circuit, 24...2 fl, 1 commutation failure output, 25...neutral line ground fault output, 26...
・Output of AC/DC contact. The same reference numerals in the figures indicate the same or (f).

Claims (2)

[Claims] (1) Also, a first DC current transformer installed on the ground line side of the DC transmission neutral line in the parallel overhead transmission system, and a second DC current transformer installed on the positive transmission line side of the Iσ current transmission line. , the above-mentioned No. 1. Second
The first one is connected to the DC current transformer of 1. a second filter; and the first filter. The output signal of the second filter is fully binarized and the level is judged. a second level detector; and a second level detector; The first... The output signal of the second level detector and the logic discrimination circuit automatically determine whether there is a cross-contact fault, a ground fault between the neutral wire and the AC circuit, or a two-phase commutation failure. Detection relay. (2) Above 1. The AC/DC cross contact detection relay according to claim 1, wherein the second DC current transformers are provided on both sides of the ground point on the neutral line of the DC transmission line.