A fault-location method for VSC-HVDC transmission lines based on natural frequency of current

This paper presents a novel method for locating fault on VSC-HVDC transmission line using one terminal current data. The proposed method is developed based on the natural frequency of distributed parameter line model. In the presence of the large shunt capacitor at both terminals of the VSC-HVDC line, the high frequency traveling wave is approximately totally reflected at the terminals. It is found that the value of natural frequency of VSC-HVDC transmission line is only related to fault distance and wave speed. Using this characteristic, a single-end fault location method is developed. The natural frequency can be obtained by the PRONY algorithm. Compared with traveling wave method, this approach can use any section of the in-fault data to locate fault, without having to capture the instant at which wave-front arrives, which requires higher sampling rate. A short data window is sufficient for extracting natural frequency accurately in practice. The proposed method is verified using the frequency-dependent line model in EMTDC. The simulations have demonstrated validity, rapidity and accuracy of the proposed fault location algorithm.