EMTR‐based fault location for DC line in VSC‐MTDC system using high‐frequency currents

Abstract

An improved electromagnetic time-reversal (EMTR)-based method is proposed for fault-location of voltage-source converter multi-terminal high-voltage direct current systems (VSC-MTDC) transmission lines in this study. After a brief description of the EMTR, its application to lossless transmission line is mathematically demonstrated. Assuming that the DC faults are isolated by AC breakers, a window of adequate transients is used. If the protection has identified the faulted line correctly, only the recorded measurements at both ends of the faulted line should be time-reversed and further calculated. To eliminate the influence from AC side, the 0/1-mode observed currents and high-pass elliptic filter are adopted. After the processed signals are set as current sources, the current effective value at each pre-set fault position is calculated, with the peak value at the real fault-location. The simulation test cases are based on a five-terminal VSCHVDC modified from the China Nanau demonstration project. The results show that the improved method has good performance to deal DC line faults with high resistance and different types. Besides,, the results are not affected by measurement errors. Compared with the travelling wave-based method, the proposed method does not need to employ high sampling rates and precise fault-occurred time; meanwhile, it can achieve more precise results.