Integrated Protection Method for Phase-to-Phase Short Circuit and Single-Phase Grounding in Small Current Grounding Power System

Abstract

The invention discloses a comprehensive protection method for phase-to-phase short-circuit and single-phase grounding of a small-current grounding power system. First, the protection device collects three-phase current and zero-sequence voltage, and calculates the mutation amount of each phase current and zero-sequence voltage in real time; and then Detect whether the sudden change of phase current exceeds the limit. If the sudden change of phase current exceeds the fixed value, it will be judged as a phase-to-phase short circuit fault and enter the stage current protection program; otherwise, detect whether the sudden change of zero sequence voltage exceeds the limit. If the sudden change of zero sequence voltage If the amount exceeds the fixed value, it will be judged as a single-phase grounding fault and enter the single-phase grounding line selection program; the invention has two functions of phase-to-phase short-circuit protection and small-current grounding line selection, and can quickly and reliably detect the phase-to-phase short-circuit fault. It acts on tripping, and can accurately select the line and send an alarm signal when single-phase grounding occurs in the small current grounding system; A comprehensive protection device is enough, and there is no need to install a small current grounding line selection device separately, which effectively simplifies the protection configuration.

Description

technical field [0001] The invention belongs to the field of electric power systems, relates to the field of relay protection of electric power systems, and in particular relates to a comprehensive protection method for interphase short circuit and single-phase grounding of a small current grounding power system. Background technique [0002] In the medium and low voltage distribution network, each outgoing line is usually equipped with a staged current protection device. When a phase-to-phase short-circuit fault occurs, an obvious short-circuit current will flow through the protection installation. The device judges the size of the measured current and the set value Determine whether the fault is in the zone or outside the zone, and quickly remove the fault in the zone. [0003] In order to improve the reliability of power system operation, my country's medium and low voltage distribution network usually adopts a small current grounding operation mode. When a single-phase ...

AI Technical Summary

Problems solved by technology

However, each substation must be equipped with a separate line selection device, which not only increases the construction cost, but also makes the operation and maintenance more complicated

Images