Protection and Fault Locating Method of Series Compensated Lines by Wavelet Based Energy Traveling Wave

Series capacitors (SCs) in transmission lines increase the complexity of transmission line protection. In this paper, a wavelet based energy traveling wave protection and fault locating method for series compensated transmission lines is proposed. The method requires GPS synchronized measurements at both ends of the line. The paper first presents the propagation properties of transient currents with different frequency, and then a proper frequency band condition is generated to minimize the transient attenuation. The method uses energy traveling wave in certain frequency band extracted by wavelet transform, and the wavefront time difference of two measurement units at each end of transmission line is introduced for the purpose of executing tripping logic and computing fault location. Numerical simulations verify that the method provides a robust protection criterion and an accurate fault locating method, independently of type, fault impedances and locations along the line. The algorithm also works for different SCs locations, and it is not influenced by MOV/air gap operation.