An Accurate Offline Phasor Estimation for Fault Location in Series-Compensated Lines

In series-compensated transmission lines, current and voltage signals measured by the line protection system include considerable subsynchronous frequency components (SSFCs), which are not sufficiently damped within a typical fault clearing time of the line protection system. This does not allow accurate phasor estimation and, therefore, phasor-based fault location. This paper presents an accurate algorithm which effectively filters out unwanted frequency components and noise to perform accurate phasor estimation for fault location in series-compensated transmission lines. Phasor estimation of a theoretical signal is first evaluated by using the proposed method, direct Prony analysis, and four-cycle discrete Fourier transform algorithm. Then, various fault locations of a 500-kV series-compensated transmission line simulated in PSCAD/EMTDC are used to comprehensively evaluate the performance of the proposed technique. It is shown that the proposed method can effectively attenuate SSFCs and other unwanted frequency components in current and voltage signals, allowing accurate phasor estimation to be obtained.