An Adaptive Half-Wavelength Line Differential Protection Method Based on Time Difference Method

Abstract

The invention relates to an adaptive half-wavelength line differential protection method based on the time difference method; due to the long electrical distance of the half-wavelength power transmission, there is an obvious time difference in the action time of the protection starting elements on both sides of the line after a fault occurs, according to the principle of wave propagation , the location of the fault point can be estimated by the action time difference of the protective starting elements on both sides. According to the long-line equation, the voltage and current at the protection installations on both sides of the line can be compensated to the fault point, and the current value at the fault point can be obtained, and then the differential current can be calculated. Due to the different sensitivities of the differential protection criteria when faults occur at different points of the line, the braking coefficient and threshold value of the differential protection are adaptively changed according to the location of the fault point to ensure that the differential protection has sensitivity to the entire line.

Description

Technical field: [0001] The invention relates to the field of relay protection, in particular to an adaptive half-wavelength line differential protection method based on the time difference method. Background technique: [0002] Half Wavelength AC Transmission (HWACT) refers to the ultra-long-distance three-phase AC transmission whose electrical distance is close to a power frequency half-wave, that is, 3000 kilometers (50 cycles) or 2600 kilometers (60 cycles). Compared with medium-length (hundreds of kilometers) AC transmission, this ultra-long-distance AC transmission has some completely different characteristics and significant advantages, such as no need to install reactive power compensation equipment; no need to set up intermediate switching stations; overvoltage level Not high; excellent economy, etc. In order to realize the engineering application of half-wave power transmission, it is necessary to conduct further research on the relay protection technology of the ...

AI Technical Summary

Problems solved by technology

[0003] Current differential protection is widely used as the main protection of medium-length AC transmission lines, but the voltage difference along the half-wavelength transmission line cannot be ignored, and the traditional capacitive current compensation method is no longer applicable. To solve this problem, the present invention proposes a An adaptive half-wavelength line differential protection method based on time difference method

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