Analysis of traveling wave front and its application in fault location

The operating environment of the high voltage dc (HVDC) transmission lines is more complex than that of the ac lines, thus the dc transmission lines have higher probability of faults. Fast and accurate fault location can ensure the safe operation of the dc power grid, which has great social and economic benefits. However, single-ended traveling wave fault location method has the problem of inaccurate discrimination and calibration of the reflected wave as well as wave velocity uncertainty, and the fault analysis method is subject to line model. In this paper, the expression of the fault traveling wave front in time domain is deduced based on the frequency-dependent characteristic of the dc transmission lines and the propagation function approximation. The obtained expression is related to the fault distance. Then a basic fitting function (BFF) of the same form as the traveling wave front expression is selected to fit the actual measured traveling wave front. When a fault occurs, solving the equations of the obtained fitting parameters and the fault distance can locate the fault. The simulation results show that the proposed fault location method can fast and correctly locate the fault in the dc transmission lines, with the attribute of anti-fault-impedance.