Fault cause identification based on characteristics of transition resistances for transmission lines

Affected by the bad operating conditions, the transmission line faults often occur. Thus timely fault cause identification is needed to make reasonable plan for power restoration so that to reduce the outage time. From the analysis of the fault mechanism, we know the most essential difference between all kinds of faults, is the distinction of transition resistances in the grounding channel. The transition resistances of each fault have two properties: resistance magnitude and volt-ampere characteristics, which can be reflected by the average value and standard deviation of the calculated transition resistance instantaneous value respectively. Therefore, a algorithm by combining the two characteristics of transition resistances for fault cause identification has been proposed in this paper. Use the electrical information during fault period to calculate the transition resistances instantaneous value. In order to obtain a high accuracy, this pa per use Richardson extrapolation to slove the discrete numerical differential problem involved in the calculation. According to the comparison analysis of several typical actual faults, the paper set a criterion to identify the cause of transmission line faults. Eventually, a number of actual sample tests show that the proposed algorithm works well.