Analysis of single pole auto reclosure in extra high voltage systems

The successful single pole auto reclosure (SPAR) operation in the EHV system increases system stability, improves system reliability, reduces reclosing overvoltages and torsional impacts on generator shafts. The success rate of a SPAR operation is dependent on the time required to extinguish the secondary arc and to rebuild the dielectric strength of the de-ionized arc path. The extinction time of the secondary arc depends on the magnitude of the secondary arc current and the recovery voltage. Without a compensation scheme, a SPAR operation will be unsuccessful in a long EHV transmission line. Based on a three phase reduced system model, the performance of the main parameters of SPAR operations, the secondary arc current and the recovery voltage were analyzed. Detailed sensitivity analysis of SPAR operation in a long single circuit 500 kV transmission line was investigated for different line transposition scheme, line length, prefault line load and fault location using EMTDC software. A review of SPAR compensation methods is also included. Obtained results indicate a strong correlations between conductor configuration, line transposition schemes, line length, prefault line loading, fault location and compensation scheme, and the secondary arc current and the recovery voltage of SPAR operations.