Ultra high-voltage alternating current transmission line protection method based on all-component differential coefficient matrix

Abstract

The invention discloses an ultra high-voltage alternating current transmission line protection method based on an all-component differential coefficient matrix, comprising the following steps that the fundamental frequency electric amount on both ends of an ultra high-voltage alternating current transmission line is measured; the positive, negative and zero sequence current amount on the other end is calculated from that on one end of the line with a long line equation; the fundamental frequency current amount on the other end is calculated through a symmetrical component method; and then a differential coefficient matrix is calculated. A fault type is judged according to the values of all elements of the differential coefficient matrix, and a fault phase is enabled to be correctly tripped. The method is applicable to protecting the whole fault process of the ultra high-voltage alternating current transmission line; and particularly when the ultra high-voltage alternating current transmission line has a single-phase high-resistance grounding short-circuit fault, the method can accurately identify and correctly trip the fault phase, and circuit breakers on both ends of other two normal phase lines are reliable without working.

Description

technical field [0001] The invention relates to a method for protecting an UHV AC transmission line, in particular to a method for protecting an UHV AC transmission line based on a full component differential coefficient matrix. Background technique [0002] At present, China has built the world's first officially grid-connected Jindongnan-Nanyang-Jingmen 1000kV UHV AC transmission line. According to the State Grid Corporation's "Unified Strong Smart Grid Research Report", China will build 39,000 kilometers of UHV AC transmission lines by 2015, and 47,000 kilometers of UHV AC transmission lines by 2020. The backbone grid structure, the national grid pattern of coordinated development of power grids at all levels. The UHV AC transmission network can greatly increase the power transmission capacity, alleviate China's tight transportation situation, help reduce transmission loss, save transmission costs, save energy and reduce emissions, thereby promoting the development of gr...

AI Technical Summary

Problems solved by technology

[0005] However, due to the influence of the load current, in the case of a high-resistance grounding short-circuit fault, whether it is the traditional current differential protection that directly uses the magnitude of the vector sum of the currents at both ends as the operating value, or various special protections based on the Beryllon model The new principle of current differential protection of high-voltage AC transmission lines cannot correctly trip the faulty phase, but trips the three phases by the action of zero-sequence current differential protection

Since the impact of non-full-phase operation on system stability is far less than that of three-phase tripping, the action strategy of tripping three phases by zero-sequence current differential protection will strengthen the impact of faults on grid stability

Images