JPS5947918A - Protecting relaying device - 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 ground fault line selection type protective relay device equipped with a short circuit priority circuit.

In the ground fault line selection protection method for resistance grounding systems,
In the event of a 2fN ground fault, an undervoltage relay will give priority to a short circuit.
Generally, the ground fault line selection method is locked.

However, in the event of a different-point, different-phase ground fault that straddles the line, the voltage between the lines will drop so much that the undervoltage relay will become inoperable, and there is a possibility that the ground fault line selection method will malfunction.

The present invention was made to solve the above-mentioned problems, and by adding an element to detect a two-wire ground fault from the vector relationship of three-phase voltages in addition to the undervoltage relay, It is an object of the present invention to provide a protective relay device that reliably performs short-circuit priority operation even in the event of a two-wire ground fault in a resistance grounding system.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, in which 1 is the R phase, S
2 is a determination element that determines whether or not the phase line voltage VR8 is smaller than a constant (setting value) K1; 2 is a determination element that determines whether the phase voltage Vx of the R phase is υ larger than the constant; 3 The phase voltage v8 of the S phase is a constant K.

Judgment element 4 determines whether the phase voltage VT of the T phase is larger than the specified phase (-90°) -j9
At 0° path, voltage VTε is obtained. 5 is the voltage VT
90° constant phase (90') phase shift and voltage V? It is a phase shift -j90° circuit that obtains 'k. 6 is a phase comparison circuit that determines whether the phase difference between voltage Vri and voltage Vx is within a set value ±θ; 7 is voltage vTa; 19 o'
8 is an AND circuit that takes the logical product of the outputs of both determination elements 2.3, and 9 is an AND circuit of this AND circuit 8. An AND circuit 1o takes the logical product of the output and the outputs of the internal phase comparison circuits 6 and 7, and 1o is an OR circuit that takes the logical sum of the output of the AND circuit 9 and the output of the determination element 1.

Reference numeral 11 denotes an output signal R of the Re phase two-wire ground fault detection circuit A1, which has a Q configuration of the determination elements 1 to 3, phase shift circuits 4 and 5, phase comparison circuits 6 and 7, AND circuits 8 and 9, and OR circuit 10.
e, the output signal ST of the ST phase two-wire ground fault detection circuit A2 having a similar configuration, and the output signal T of the TR phase two-wire ground fault detection circuit A3.
12 is a ground fault line selection element that takes the differential current voltage 0 and zero-phase voltage Vo k input; 13 has the output of this ground fault line selection element 12 as an input terminal; This is an inhibit circuit that receives the output at each inhibit terminal, and its output becomes the operating output of the ground fault line selection method.

Next, the operation will be described. For example, in the case of an R8 phase two-wire ground fault, the vector relationships among the voltages Vn, Va, and VT of each phase are as shown in Fig. 2 (a) j (b),
The healthy phase voltage VT and the ground fault phase voltages Vx and Va have a certain phase relationship. This phase relationship is v! ε−
j? The phase difference between 0° and the voltage vR is not more than ±θ, and the phase difference between the voltage j90′ Vll and the voltage Va is not more than ±θ.

This line, the determination by the phase comparison circuits 6 and 7 (Fig. 3),
p is detected by the operation of the AND circuit 9. In this case, determination elements 2 and 3 (DVR>, 1, Vs>
The determination result of Kg is added as an AND condition.

When the conditions of the AND circuit 9 are satisfied in this way, the output thereof is applied as an inhibit signal to the inhibit circuit 13 through the OR circuits 10 and 11, and the ground fault line selection method is locked. As a result, Vxs
(K) Even if no determination is made, that is, if the undervoltage relay is inoperable, the short-circuit priority operation is reliably performed.

Note that although the above explanation is for the case of RB phase 2a ground fault,
The same operation occurs when there is a two-wire ground fault in the ST phase and TR phase. That is, the phase voltage of the two wires involved k vs # Vll
If the phase voltage of the remaining p lines is vs, then the line voltage of the two involved lines is less than the set value. and t and c are 7m
When it is detected that the phase difference between 4'9o° and V· is less than ±θ, it is determined that there is a two-wire ground fault.

As described above, according to the present invention, in addition to the undervoltage relay,
By adding an element to detect a two-wire ground fault from the vector relationship of three-phase voltages, short-circuit priority operation is reliably performed even in the case of a two-wire ground fault, even in a resistive grounding system, improving operational reliability. is significantly improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the protective relay device according to the present invention, and FIG. 2 (alp rb+) and FIG. 3 are voltage vector diagrams for explaining the operation. Judgment element, 4 and 5... phase shift circuit, 6 and 7... phase comparison circuit, 8 and 9... AND circuit,
10 and 11... OR circuit, 12... Ground fault line selection element, 13... Inhibit circuit, A1-REI phase 2
Line ground fault detection circuit, A2...BT phase 2-wire ground fault detection circuit,
As...TR phase 2-wire ground fault detection circuit.

Claims (1)

[Claims] (1) In a protective relay device with a ground fault line selection method equipped with a short-circuit priority circuit, the phase voltage of the two wires involved! 1=v
s p vx, and the phase voltage of the remaining wires is -6V, the line voltage of the two involved wires is less than the set value, or the phase difference between V3", -j"' and 71 is ±θ
A protective joint characterized in that when the following and the phase difference between v3εj90' and V is detected to be less than ±θ, a two-wire ground fault is determined and a ground fault line selection method is locked. Electrical equipment.