JPS58137923A - Control system for breaker - 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 relates to a method for eliminating the phenomenon of no current zero.

In the conventional innovation system, a resistor was installed in a star-shaped connection on the neutral point side of the generator, and when an accident was detected, it was connected in series to the roaring phase.

This nine-way resistor was required for three phases and was expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for quickly eliminating the no-current phenomenon in order to prevent damage to the circuit breaker and maintain stability.

Zero current occurs when the transient DC component of the current exceeds the AC current, and the attenuation of the transient @ current component is determined by the actance and resistance up to the fault point. The accident that is a problem with this no special photo is a short circuit of 21 or 3 wires, so we install resistance or capacitance for only 2 phases, and when the accident is detected,
The idea is to insert a resistor or capacitance in series in the circuit of the relevant phase to hasten the attenuation of the @ current component and to solve the problem of zero current.

In the power transmission system shown in FIG. 1, a generator Gri, a step-up transformer T0, a power transmission @1. Line 8 via transformer T11
is supplying electricity to. In the same figure, point F″″C″
In the event of a C accident, the electric 151Ef component CT1 and CT,
, the current passing through the circuit breaker CB and CB is transmitted to each other by the transmission line C0, and if it is determined that there is an accident in the internal direction, that is, between CBI and CB, protection is provided. Relay devices BY and RY, circuit breakers CB and CB.

Issue a cutoff command to eliminate the accident. However, if an accident occurs while generator G is in advanced phase operation, the alternating current component will fall below the transient direct current component, no zero point will occur in the current, and the breaker will open, but will not be able to shut off. There is a risk of destruction. Since a two-wire short circuit is the most severe in terms of zero zero, a two-wire short circuit will be explained below. In order to prevent the breakage of the circuit breaker described above, an example will be described in which the switch 8 is opened and the resistor Rt is inserted by the operation of the safety relay device RY.

Figure 2 shows this part in detail. That is, the protection relay BY is the current transformer CT.

Judging by the output of ~CT, , if an accident or no zero is detected, a command to open the circuit breaker S, ~S, is issued as necessary, and a resistor R1- is inserted in one line in the circuit. . In other words, in case of %lb2M short circuit, switch 8. and S@
When open, C12 wire is shorted, the switch is s, *.

On the other hand, if the resistance of the circuit is r and the inductance tL,
As is already known, the decay time constant T1 of the transient DC component when an AC voltage is applied is r...
...It is expressed as (1). On the other hand, the time constant r or r when the above resistor R or 28 resistors are inserted.

% ``l >''@> τ, and by inserting a resistor, the problem of non-zero can be quickly resolved.

Here, faults may be detected by conventionally used current detection or undervoltage detection, or by methods such as zero-zero detection, measuring the period of current, or the like.

Figure 3 shows an example of installation on the generator side.
In this case as well, similar effects can be obtained.

Next, the reason why a two-wire short circuit is the most severe regarding zero zero will be explained.

Accidents involving ground faults are affected by the large zero-sequence impedance of the resistor.

Therefore, the DC component attenuates quickly, and the zero-zero time tends to be shorter than in a 21m short circuit.

The reason why 2-wire short circuits are more severe in short-circuit accidents is that in 2W4 short circuits, compared to 3I [short circuits], the DC component determined by the prefault tide current and the DC component peak determined by the fault occurrence angle occur at the same accident occurrence angle. By showing a trend that results in a value.

The above explanation is based on an example in which a resistor is inserted, but even with a method in which a capacitance is inserted, an increase in the alternating current component can be expected, and the problem of no zero can be solved.

According to the present invention, it is only necessary to install the inserting resistor or medium resistance for two phases, and it is necessary to install the inserting resistor or medium resistance for only two phases.
Just insert them in one row in the circuit. Therefore, compared to the conventional method, it is possible to reduce the cost, shorten the time for the zero-zero phenomenon to occur, and simultaneously achieve both the prevention of breaker damage and the maintenance of stability due to the speeding up of the breaker time. is extremely large.

[Brief explanation of drawings]

@ Figure 1 shows an embodiment of the present application, Figure 2 shows details of the embodiment, and Figure 3 shows another embodiment. G... Generator % Ttl @ Tt l... Transformer, S... Grid, t... Transmission line, CB1. CB,
...breaker, CT. CT,...Current transformer, R, Y, RY,...
・Protective relay, R...resistance, S...switch, co-
...Transmission line, F early 3 countries CB / (1

Claims (1)

[Claims] 1. In a method of controlling circuit breakers installed in the power system, a resistor or capacitance is installed on the two phases on the neutral point side of the generator F'i transformer, which is connected in a star pattern, to prevent accidents. 1. A control method for a circuit breaker, characterized in that when a detection relay and a current zero detection device operate together, they are connected in series to the above resistance or capacitance t-wrinkle phase circuit.