Research of Transient Stability Margin Affected by Single-phase Reclosing

The reliability can be enhanced by using single-phase reclosing, but when reclose to permanent faults, it is another surge on system. So there is necessity to study on the influence of reclosing sequence on transient stability margin. In the case that transient and permanent fault is not effectively identified, the influence of sequence and time of single-phase reclosing on transient stability margin in Southern China Power Grid of 2005 year is studied using software FASTEST when single-phase fault is occurred on 500 kV Anshun - Tianshengqiao transmission line in this paper. Simulation results indicate that when the terminal without fault uses non-voltage detecting and recloses first instead of the two terminals use non-voltage detecting in turn, the transient angle, voltage and frequency stability margin can all be enhanced and the working condition of breaker can be improved. A method combined with fault location algorithm to modify the sequence of single-phase reclosing online to enhance transient stability and lower the surge when reclose to permanent fault is proposed.