Method and device for relay protection of distribution electrical networks from single-phase ground faults

Abstract

The invention relates to the field of energy, specifically to distribution electrical networks operating with an isolated and compensated neutral, and is intended for selective relay protection of connections from single-phase ground faults (SGF) in 6-35 kV electrical networks. The method for relay protection of distribution electrical networks from single-phase ground faults involves the use of a grounding transformer, the power of which is determined by the magnitude of the total capacitive current in the network and the tripping current of the relay protection from single-phase ground faults. When a single-phase ground fault occurs, an RC damper generates an IORC signal for the device control unit, which opens a current regulator, passing current from the grounding transformer into the electrical network and regulating the current. The current regulator is opened by the IORC signal from the RC damper immediately upon the occurrence of a single-phase ground fault.In a power grid with a long-term single-phase ground fault, the inductive current from the grounding transformer is regulated by the device's control unit to the required current values ​​via a current regulator with a delay of at least 0.1 seconds from the moment the single-phase ground fault occurs. A relay protection device for distribution power grids against single-phase ground faults comprises a grounding transformer with a device control unit connected between the power grid and the ground, as well as a relay protection unit for single-phase ground fault connections, a current regulator with a control unit, an RC damper, and a triac current regulator. The advantages of the proposed invention include reliable and safe operation of power grids with high power supply efficiency and the potential for expanding the scope of application to 6-35 kV power grids.

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