SU836714A1 - Device for interlocking relay protection system at voltage transformer failures - Google Patents

Description

I

The invention relates to the relay protection of power lines and can be used to prevent incorrect actions of protection in the event of faults in voltage transformers.

A device is known for preventing the false triggering of protections in the event of a breakdown of voltage circuits D1 containing three intermediate voltage suppressors. In addition, each STP has two primary windings, one of which is connected to the phase voltage from the star, and the other - to the same voltage from the open triangle. The voltage of the secondary windings of the PTN is rectified and the OR circuit is applied to the reagent element.

Disadvantages of the device: failure of the complexity and failure when the voltage disappears from the primary side of the voltage transformer.

Closest to the proposed device is a device for blocking relay protection in the event of breaks in the secondary circuits of a voltage transformer 2. The device contains a four-winding intermediate transformer, two primary and one compensation windings, connected to the voltage circuit through additional resistors. A polarized relay is connected to the secondary winding of the transformer via a rectifier.

A disadvantage of the known device is immunity to a voltage that is completely lost on the primary side of the voltage transformer.

The purpose of the invention is the expansion of the functional capabilities of the device.

Claims (2)

This is achieved by the fact that the device for blocking the relay protection in case of malfunctions of a voltage transformer, contains more than a multi-winding transformer with two primary ones. 3 compensation and secondary windings, the first output of one primary winding of which is connected to zero, and the second through resistors to the phases of a voltage transformer connected to a star, and the compensation winding is connected to the terminals of an open triangle of additional voltage transformer windings, and A polarized relay is connected to the secondary winding via a rectifier. It is additionally equipped with a capacitive power take-off unit from the phase of the transmission line and a capacitor connected in parallel with the resistor, connecting B nnomu with multiple winding transformer primary winding and the transformer phase voltages, phase homonymous otbora- capacitive power, and other / the primary winding of the transformer is connected to said power take-off unit. FIG. a scheme of a multiwinding transformer with output elements is presented; in fig. 2 is a diagram of a voltage transformer and a power boring unit; in fig. 3 is a vector diagram of the device operation. The blocking device contains a multi-winding transformer 1 (Fig. L) with four windings, one of which, winding 2, is connected to the star's neutral wire formed by the phase voltages of the main winding of transformer voltage 3 through resistors 4, 5, 6 of the same size. In one of the phases corresponding to the phase in which power is taken from the power line, capacitor 7 is connected parallel to the resistor. Thus, a current flows in winding 2 through winding 2 caused by the inequality of the total resistance of the star's rays (Fig. 3). This current has a capacitive character in relation to the phase of the voltage applied to the star's beam with a parallel active resistor D and capacitor 7. The second winding 8 is connected to the transformer 9 of the power take-off unit from the power line through the adjustable resistor 10 control synchronism, and in the absence of the latter - a resistor equivalent to it. The current flowing through the p® winding 8. also has a capacitive nature with respect to the phase of the voltage from which the selection is made. The polarity of the windings 2 and 8 is chosen so that the magnetic fluxes from the star currents and the selection transformer are in antiphase, and the values of the capacitor 7 and resistor 10 ensure that the ampere-turns in the windings 2 and 8 are equal. The winding 12 is turned on through the resistors 13 and 14 zero sequence of the additional winding of the voltage transformer 15. A polarized relay 18 is connected to the winding 16 via a rectifier 17. A toggle switch 19 is installed in the capacitor 7 circuit, disconnecting the capacitor in case of repair of the power take-off unit. The device works as follows. In the normal mode, the magnetic fluxes in the core of the blocking transformer against currents in winding 2 and about current 8 compensate each other. There is no current in winding 12, since there is no zero sequence voltage in the normal mode. The polarized relay is in an inoperative position allowing the protection action. In the event of a break of one, two, three phases or the neutral wire of the main winding circuits of a voltage transformer 3, the complete removal of the voltage from its primary side, simultaneous disconnection of circuit breakers in the main and additional voltage windings of the transformer, as well as in case of a transformer malfunction 9 the power take-off the magnetic flux balance in the core of the blocking transformer is disturbed, which leads to the appearance of an EMF on the winding 16, and the relay 18 operates, preventing the protection from malfunctioning or giving a fault signal awns. I When voltage symmetry breaks in a high-voltage network that are not related to the occurrence of a voltage sequence, the nature of voltage changes both in the main winding of the voltage transformer and in the power take-off transformer is the same; therefore, the balance of magnetic fluxes is preserved The lock is not activated. When a zero-sequence voltage appears on the higher voltage side, the magnetic flux balance is maintained due to the appearance of current in the compensation winding 12 from the open triangle voltage. In the case of repair of the power take-off unit of the toggle switch 19, the capacitor 7 is disconnected, while the magnetic flux balance is maintained, since the resistors 4, 5, 6 form a symmetrical star, and there is no current from the repaired selection transformer in the winding 8. At the same time, for the time of repair, the interlock only works if one or two phases of the main winding of the voltage transformer are cut off. The invention The device for blocking relay protection in case of malfunction of a voltage transformer, containing a multiwinding transformer with two primary, compensation and secondary windings, the first output of one primary winding of which is connected to zero, and the second through resistors to the phases of the voltage transformer, Connect 4 star to star, the compensated winding is connected to the openings of the open triangle of the additional windings of the voltage transformer, and to the secondary winding via a rectifier connected — a polarized relay — distinguished by the fact that, in order to expand the functionality, the device is additionally equipped with a capacitive power take-off unit from the phase of the transmission line and a capacitor connected in parallel with a resistor connected to the primary winding of the multiple-winding transformer and the voltage transformer of the same name phase capacitive power take-off, and the other primary winding is connected to the transformer of the said power take-off unit. Sources of information taken into account in the examination 1. Fedoseev A. M. Relein protection of electrical systems. M, Energy, 1976, 2. USSR author's certificate number 440737, cl. H 02 H 1/04, 1974. To Siggle Protection LICHYG, G & ff, ff // OmS.H OmS.K AS C t 15 and b с о н к Phage. 2