Hybrid Fault Location Method for Two Terminal Mixed Lines using One Ended Measurements

There has been a huge growth in the number of mixed lines mainly due to increased renewable integration to the grid. Mixed lines consist of overhead line (OHL) is connected to underground cable (UGC). This paper presents fault location method for mixed lines by combining power frequency (impedance) and traveling wave approaches. Four fault locations are determined based on first two traveling wave reflection times measured at one end of the mixed line and propagation velocities of the mixed line. Correct fault location is selected between the four using faulted sub-section information. Faulted sub-section is identified using the impedance-based method. Traveling waves are extracted from current measurement recorded in disturbance recorder (DR) using notch (Butterworth band pass) filter without using any special sensors. PSCAD/EMTDC simulation studies shows that proposed method is found to be very accurate. This method is unaffected by fault inception angles, arc resistances, fault locations, measurement noises and fault types.