SU519813A1 - Quadrangle resistance relays - Google Patents

Description

one

The proposed device is related to the field of relay protection and automation of power systems, in particular to the measuring bodies of relay protection based on a comparison of the phase of two or more electrical quantities.

There are known resistance relays with a quadrilateral actuation characteristic comprising nied-successively connected unit for forming compared values, a filter unit, a unit for generating mismatched signals of instantaneous values, a unit for measuring the duration of the mismatch signals and an output unit.

The disadvantage of such a solution is the need for a non-local nusy device that reacts to a current or a negative-sequence voltage and provides zero initial conditions on the selective amplifiers. In this case, there are difficulties associated with improper operation of the starting organ in the event of complex damages in the power system (for example, when a single-phase short-circuit transitions to a phase-to-phase one, asymmetry results in premature launch of the selective amplifiers).

The purpose of the invention is to simplify a scheme that eliminates zero initial conditions on frequency filters.

This is achieved by connecting to the measuring unit the duration of the mismatch of the compared values, set to the setpoint

T

block measuring duration

set to tii -, which is used for the connection

filters in the event of a short circuit.

FIG. 1 shows a block diagram of a resistance relay device; in fig. 2 - electrical circuit switching resonant filter;

in fig. 3 - response characteristics of the resistance relay.

In the block diagram of the relay, the designations are:

and, I are, respectively, the voltage applied to the relay body and the current of the protected circuit; 1 - unit of formation of values

E, I ,, L / + /, j,

25E, K ,, Lf - {- Kj,

required to obtain a given relay characteristic; 2 - a block of filters that ensure the correct operation of the relay of transient processes; 3 is a block for generating instant-value mismatch signal values EI . . A4, 4 - the unit for measuring the duration of the signals is not connected, giving a response signal if the duration of the malfunction doesn’t rot; 5 - output relay

resistance; 6 is a block for measuring the duration of a mismatch signal, giving a trigger signal if the duration of a mismatch T

nn exceeds-; 7-amplifier; 8 - device switching filters.

The combination of blocks 1-5 forms the main relay of resistance with a quadrangular characteristic (Fig. 3, characteristic 9).

The scooper of blocks 1, 2, 3, 6, 7, 8 forms a starting resistance relay, fulfilled according to the same principle, which, thanks to the setting of block 6, measuring pulse duration proportional to the duration of the mismatch or coincidence of the compared values, less than T neck, has the characteristic limited

circular arcs (characteristics 10, And in Fig. 3). At the same time, due to the smaller setpoint in duration, the starting relay operates faster than the main resistance relay.

In the load mode, in the event that the resistance at the terminals of the relay is outside the response characteristic of the start-up resistance relay, unit 8 is in an unresponsive state and the resonant filters (Fig. 2) are turned off from the signal generation path. In this case, the signal from amplifier 7, in addition to acting on block 8, blocks block 4 of measuring the duration of the main resistance relay, prohibiting its operation if the starting resistance relay does not work.

The absence of filters in combination with a small set-up but the duration of block 6 ensures the quick response of the starting resistive relay. At the same time, the block setting 6 is small in terms of the measurement duration, when there are harmonic components in the current and voltage accompanying the transition process, the possibility of a non-selective operation of the relay and expansion of the range of action. However, a false operation of the entire device does not occur here, because in case of a short circuit outside the zone of action, accompanied by an intense transient, until unit triggered impedance relays, unit 4 is blocked and the next, when the triggered relay starts to act non-selectively, unit 8 connects

filters, whereby filtered values are supplied to block 3 containing moral information about the resistance at the input of the relay.

During a short circuit in the zone of the relay, the response time of the relay is much shorter than in the absence of blocks 6, 7, 8 due to the fact that no voltage was applied to the resonant filters prior to the short circuit and they do not store the energy before the emergency (zero initial conditions) ). The efficiency of the introduction of blocks 6, 7, 8 is the greater, the more significantly the load mode point ZH is removed from the short circuit point ZK, since this increases the difference between the values applied to the filters before the short circuit and after its occurrence, which increases the deceleration of the relay in the absence of zero initial conditions. Under heavy loads, when the ZH point approaches the response characteristic of the main relay, it can enter the trigger relay trigger zone and the filters will be connected to the circuit until a short circuit occurs. However, even in this case, which is practically not enough for high-speed resistance relays of the first stages of distance protection, which have small settings, where the invention is proposed to apply, a large deceleration B does not operate, since the values of the .ZH and ZK points are close and, therefore, close pre-emergency and external failure voltages at the filter outputs.

Claims (1)

Invention Formula A quadrangular tripping impedance relay comprising successively connected comparative value generating unit, filter unit, instantaneous value mismatch signaling unit, mismatch signal length measuring unit and output unit, characterized in that, for the purpose of simplification, the output signal unit of instantaneous mismatch The quantities included an additional block for measuring the duration of the mismatch signals with a lower setpoint, connected to the filter block through Consistently connected amplifier and switching unit, with the second output of the amplifier connected to the input of the said block measuring the duration of the mismatch signals. (Duf. 2