JPS59188333A - Distance 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 relates to a distance relay for power system protection.

A conventional distance relay of this type is shown in FIG. In the figure, 1 is an input quadrant, 2 is a gear-enclosed quadrant, 3 is a differential arithmetic unit, 4 is a phase discriminator, and 5 is a pulse extension circuit.

In addition, a 1 and a 2 are grid voltage input terminals, bl,
b2 is a current input terminal, and C is an output terminal of the distance relay.

Next, the operation will be explained. In order to find the line impedance up to the failure point using the voltage E and current of the system, it operates as follows.

The current generator generates a voltage v2 whose phase is advanced by 90° by the gapped transformer 2, and calculates the vector difference V with the system voltage E, that is, Vl, by the differential calculator 3. Figure 2 shows
FIG. 2 is a vector diagram showing a vector relationship between these voltages and currents.

At this time, if the phase difference between the voltages V2 and V is 90° or less, the impedance up to the failure point is smaller than the set impedance 2 and falls within the operating range, as shown by the shaded area P□ in FIG.

The phase discriminator 4 detects the phase difference between the voltages v2 and V in this way, and its output signal is a pulse output for each half wave, so it is converted into a continuous signal by the pulse extension circuit 5.
An output signal serving as a command is output from an output terminal C, except for a breaker (not shown).

However, due to an increase in the short-circuit capacity of the system, if a fault current that exceeds the circuit breaker's fault current occurs, the fault cannot be removed even if the breaker is tripped. In some cases, a current limiting device (hereinafter abbreviated as CLD) is installed on the side.

FIG. 3 is a circuit configuration diagram of this CLD, and as shown in the figure, the CLD consists of a capacitor 6, a reactor 7, a nonlinear element 8
When the passing current to the line is small, the capacitance value C of the capacitor 6 and the inductance L of the reactor 1 resonate in series, and the impedance is almost zero, but the passing current is When the voltage across the capacitor 60 increases, the current is bypassed by the nonlinear element 8 and the impedance L of the reactor I is inserted, which makes it possible to limit the current.

Conventional distance relays protect the failure point below a certain impedance and instantly issue a command to trip the breaker. Distance relay 10 installed at electric station A in Fig. 4
The protection range is just before the B electric station, and the line impedance 2 between them is set in advance.

However, when the fault current exceeds a certain level, the CLD operates,
The impedance portion of the reactance 7 will be inserted into the line. In the case of a near-end failure at electric station B, the total impedance up to the failure point is (L + Z), which is outside the protection range of the distance relay 10, and the original protective operation cannot be performed.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and has a CLD simulating circuit inside.
It is an object of the present invention to provide a distance relay whose set impedance is increased in response to an increase in CLD glue actance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A distance relay according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 5 shows a circuit diagram of the distance relay of this embodiment. Note that the same reference numerals in FIG. 5 as in FIG. 1 indicate the same or corresponding parts, and therefore the explanation will be omitted. In Fig. 5, 11 is the original set impedance 2, and 12
is a CLD simulating circuit, which has a circuit similar in configuration to the CLD circuit 9 shown in FIG. 3 on the secondary side of the input transformer 2.

Next, the operation of the distance relay having such a configuration will be explained with reference to FIG. 6.

A fault occurs in the power transmission alignment, and at the same time as the CLD circuit 9 operates, the CLD simulation circuit 12 also operates, the reference vector v2' changes from ZI to ((Z+L) I), and the fault point is determined to be within the protection zone. can do.

FIG. 6 is a vector diagram showing the relationship among input voltage V□, input current I, and reference vector v2'.

As is clear from FIG. 6, the protective operating range is expanded compared to the conventional operating range P method, and it is now possible to make judgments even in the operating range P2.

As described above, according to the distance relay of the present invention, since the set impedance 2 of the distance relay is configured to be similar to that of the CLD, the protection range of the power transmission line can be kept constant regardless of the operation of the CLD, and reliable protection can be achieved. Relay operation becomes possible.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional distance relay, Figure 2 is a vector diagram showing the relationship between current and voltage vectors of a conventional distance relay, Figure 3 is a circuit diagram of a CLD, and Figure 4 is a diagram of a distance relay in a power system. FIG. 5 is a circuit configuration diagram of a distance relay according to an embodiment of the present invention, and FIG. 6 is a vector diagram showing the relationship between current and voltage vectors of the distance relay according to the same embodiment. . DESCRIPTION OF SYMBOLS 1...Input Quadrance, 2...Gear Tube Enclosed Quadrance, 3...Differential Arithmetic Unit, 4...Phase Discriminator, 5...
・Pulse extension circuit, 6.-capacitor, 7.-reactor, 8.-nonlinear element, 9..CLD, 10.--
Distance relay, 11... Setting impedance, 12...
・CLD simulation circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent Masuohisa Oiwa l Figure 2 Figure 3 Figure Q Figure 6 Figure 175

Claims (1)

[Claims] In a distance relay for a power system in which a current limiting device is installed on a power transmission line, a simulated circuit similar to the current limiting device is installed on the secondary side of the input current detecting current of the power system, and the actance of the current limiting device is A distance relay characterized in that the set impedance is increased in accordance with the increase in the current limiter, so that constant detection can be performed regardless of the operation of the current limiting device that is a direct impedance to a failure point of the power transmission line.