Fault Location in Extra Long HVdc Transmission Lines using Continuous Wavelet Transform

In this paper, fault location accuracies in a 2400 km long overhead HVdc line and 300km long underground cable HVdc line using the two-terminal travelling wave method are investigated. The paper proposes to use continuous wavelet transform for detecting the arrival time of travelling waves, and shows that it provides better accuracy when compared with the commonly used discrete wavelet transform based technique. Furthermore, the results show that the continuous wavelet transform based wave front detection can provide adequate accuracy in the fault location in extra long overhead lines and long underground cables. The influence of noise on the fault location accuracy is discussed. The results also show that either dc terminal voltages or the surge capacitor currents can be used in dc line fault location.