Identification of the Transient Faults Occurring on the Extra High Voltage Transmission Lines Based on Correlation Analysis and Its Improved Algorithm

A new scheme used in adaptive single-pole auto-reclosure is proposed. It can distinguish a permanent fault from a transient one occurring on the EHV transmission lines. A detailed analysis is made of the characteristics of the electric system after the extinction of the fault arc. A correlation algorithm and its improved modes of Ⅰ and Ⅱ are presented to analyze the permanent fault and the instant one. When the effect of actual line parameter, operation and fault conditions are changing, three modes of correlation algorithm used in the different critenons are compared. An optimum algorithm is obtained and it is proved by EMTP simulation that it is feasible and can be realized by digital relay in real-time applications.