| Transmission line is an important part of power system, therefore, the safe operation of power system cannot do without reliable transmission network. However, due to the influence of lightning strike, cutting off high voltage equipment, secondary arc current, over voltage and so on, power frequency freewheeling arc comes into being, which causes great damages to the power equipments. This paper, referring to previous studies, focuses on the extinguishing characteristics of power frequency freewheeling arc under strong airflow. Moreover, a new lightning protection gap, which can quickly extinguish freewheeling arc, is developed based on the "dredging" theory.This paper, started from "black box" models of arc, discusses general characteristics of arc based on MATLAB platform; Coupling model, between strong airflow model and arc model, is built by using finite element software AUTODYN. Airflow velocity, pressure and arc deformation are analyzed, which helps to enrich and perfect theory of gas blast arc-quenching, at Gauss points in space; Under the guidance of theoretical conclusion, three trials are done, namely:time test of lightning triggering, gas blast arc-quenching test of power frequency freewheeling current, gas blast arc-quenching test of large short circuit current. Relevant tests prove that the new lightning protection gap can feasibly and reliably extinguish power frequency freewheeling arc, at the same time, the combination of theory and practice greatly improves the correctness of trail results; Actual operation charts of the new lightning protection gap are showed, and evaluation and analysis of operation effect are made finally. |
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