SU505073A1 - Relay protection device for high-voltage network - Google Patents

Description

or from the power line, wind the additional supporting winding and connect it via an adjustable capacitor to the voltage transformer circuit on the phase voltage and a, if, or and respectively.

By bringing the reference current turned to 90 ° in the magnetic circuit of the relay, the total magnetic flux acting on the movable part of the relay depends on the phase angle between the current and the voltage in the element being monitored.

The effect of the reference current on the total magnetic flux of the relay in various modes of line operation is explained by the vector diagram of the magnetic fluxes in FIG. 2

As can be seen from FIG. 2, with the capacitive nature of the current, the vector of total flux coupling is obtained by arithmetic difference of flux vectors of the working and supporting windings of the relay

- op. ).

With the inductive nature of the current (single-phase short circuit of phase L), the total flux coupling vector is obtained by arithmetically adding flux vectors of the working and supporting windings of the relay (fr, 4-ifona).

In the remaining cases (load mode and two-phase short circuit to earth of phases 5 and C), the total flux coupling vector is formed by geometrically combining the flux coupling vectors of the reference and working windings of the relay (

 -fr, + IjJon,)

Thus, with the capacitive nature of the current, the relay has a low sensitivity, which corresponds to the phase angle between the current and the voltage in the line f 90 ° (see Fig. 3).

The gap between the specified angles corresponds to the load currents when the current is directed to the line or to the substation buses.

Summation of working and reference current

it takes place directly on its magnetic core, and there is no need for full compensation, which allows the magnitude of the reference current to be selected according to the condition of ensuring the minimum response current of the relay when offset from the uncompensated component of the capacitive current, as well as from the compensating reference current itself.

Thus, the proposed relay can

perform a number of operations such as: phase-by-line monitoring of the disconnection of a long transmission line at the opposite end; phase control of power discharge of a heavily loaded extended power line; implementation of different sensitivity of the zero sequence current relay depending on the direction of the short circuit current.

When the direction of the short-circuit current from the bus to the line, the sensitivity increases, and the line coarsens from the line to the cables. This expands the scope of application of the relay for automation and relay protection.

Claims (1)

Invention Formula A relay protection device for a high-voltage network containing current and voltage transformers, an electromagnetic relay with a working winding and a capacitor, characterized in that, in order to increase the sensitivity to short-circuit currents to the earth, reduce the sensitivity to the capacitive current of the line and extend the functionality of the device, The device uses a two-winding relay, one of the windings of which (working) is connected to the winding of the current transformer included in one of the phases of the protected network, and the other through condensation The switch is connected to the winding of the transformer of the voltage of the same phase of the protected network, and the capacitor is made adjustable.