Study on Fault Location of Distribution Mixed Feeders Based on Double Terminal Method of Traveling Waves

Using transient traveling waves generated by fault to locate single-phase earth fault or short circuit fault in distribution feeders mixed with overhead lines and cables is proposed.Transient characteristics of mode component of original traveling waves generated by fault are analyzed,the results show that transient process of single-phase earth fault in neutral non-effective grounding systems produce aerial mode component of traveling waves,though stable state of line-to-line voltage keeps constant after fault is occurred.Therefore,either single-phase earth fault or short circuit fault can use aerial mode component of traveling waves with steady-parameter as measurement signals.Traveling waves will refract and reflect complexly in distribution mixed feeders when it transmits in distribution feeders,so double terminal method of traveling waves is suitable for the fault location.Aiming at the difference of wave rate in overhead lines and cables,fault point seeking algorithm based on time mid-point is proposed.On the basis of analyzing reflection rules of voltage traveling waves and current ones in the end of the feeders,principle of choosing right traveling waves measurement signals is proposed.Experimental test verify the feasibilities and correctness of the proposed method.