A Traveling Wave Natural Frequency-Based Single-Ended Fault Location Method Adaptive to System Impedance

Under unknown or changed local end impedance of faulty line,a single-ended fault location method using natural frequency of single-ended traveling wave in transmission line is researched.By means of analyzing the influence mechanism of system impedance in existing fault location algorithms based on single-ended natural frequency and assuming that the resistance and inductance of local-end are parameters to be indentified,a nonlinear objective function is constructed by natural frequencies of fault traveling wave, and its local optima is solved by Nelder-Mead search algorithm to achieve the computing impedance that can meet the requirement.Such computing impedance does not represent the value of actual impedance,however correct local reflection angle under corresponding frequency can be attained by this computing impedance and accurate fault location can be finally implemented.The reliability and adaptability of the proposed method are verified by PSCAD/EMTDC-based simulation experiments.A lot of simulation results show that under uncertain system impedance and without adding electrical variables,accurate fault location can be implemented by the proposed algorithm and the fault location result is independent to fault distance,the type of fault and transition resistance, meanwhile,during the computing process the accuracy of fault location can be evaluated.