Adaptive harmonic estimation technique for reduction the blocking time of transformer for differential protection

摘要

This paper presents a new adaptive methodology for 2nd harmonic estimation of transformer differential protection in order to reduce the blocking time of transformer in inrush condition. The proposed algorithm provides a useful tool for signal estimation in non-sinusoidal power system such as faulty conditions or switching time. This method employs a variable window length algorithm for signal estimation, which is extended through time passing, and uses only post-fault data for signal estimation. Also, conventional Discrete Fourier Transform (DFT) was compared to this method. Moreover, the simulated results presented clearly, the proposed algorithm can accurately estimates the 2nd harmonic in less time than conventional methods like conventional DFT.