Least Square Method For Impedance Based Fault Location In Ungrounded Networks

Ungrounded and high resistance grounded lines are utilized in distribution networks, and in special transmission networks. The fault current of a line to ground fault is not high enough to activate protective equipment, hence, the power delivery is not interrupted. Pre-fault and fault currents are available after fault occurs. Thus, used for compensation of prefault signals, then filtered using a low pass filter. This allows the introduction of a robust and accurate algorithm for locating single line to ground faults in such ungrounded networks. The algorithm uses symmetrical components extracted from filtered and compensated signals on both ends of a line for an initial estimate of fault location. The fine tuned location is determined by solving nonlinear least square problem that imposes equality constraints related to physical attributes of the fault. The details of the algorithm are already published. In this paper we provide an in depth overview of the algorithm and some numerical results.