Method for pilot protection of circuit based on current capacity and voltage capacity at two ends

Abstract

The invention relates to a method for pilot protection of a circuit based on the current capacity and the voltage capacity at two ends, which comprises the following steps that: 1) two ends of the circuit are provided with same relay protection devices, and each relay protection device measures the current capacity and the voltage capacity of the end and acquires the current capacity and the voltage capacity of the opposite end through a communication channel; 2) each relay protection device performs calculation according to the current capacities and the voltage capacities of the two ends at the same time, the branch impedance of each phase and / or the inter-phase branch impedance are calculated for an alternating current circuit, and the branch resistance is calculated for a direct current circuit; and 3) for the alternating current circuit, a +R axis region is set on an impedance plane as an action region, and the branch impedance falls into the region and is judged as an internal circuit fault, and for the direct current circuit, a fixed resistance value can be set, the branch impedance is smaller than the fixed resistance value and is judged as the internal circuit fault.

Description

Technical field: [0001] The invention relates to the field of relay protection, and more particularly to a line longitudinal protection method based on the current and voltage at both ends of the line. Background technique: [0002] Distance protection and longitudinal current differential protection are the two main types of line protection. Distance protection only reflects the electrical quantity at one end of the line, and it is impossible to quickly distinguish the faults between the end of the line and the opposite bus (or the beginning of the adjacent line). Methods such as shortening the protection range and increasing the action time must be adopted to ensure selectivity; distance protection is affected by the system The impact of oscillation requires the configuration of an oscillation blocking element and an open element that fails again during the oscillation, which increases the complexity of the protection; the distance protection is also affected by the transition ...

AI Technical Summary

Problems solved by technology

However, with the increase of line voltage level, the increase of transmission distance and transmission capacity, factors such as load current, distributed capacitance, transition resistance, current transformer saturation and other factors hinder the further improvement of sensitivity and reliability of longitudinal current differential protection. improve

Images