Adaptive single pole auto‐reclosing using discrete wavelet transform

This paper proposes a new algorithm for adaptive single pole auto-reclosing (SPAR) using discrete wavelet transform (DWT). The faulted phase voltage signal is captured at a sampling rate of 2.5 kHz. The sym8 wavelet function is used to decompose the signal into level 1 and to define an index function (INDF), which is obtained from the sum of absolute values of detail coefficients of the captured signal at the level 1 resolution. Finally, a decision function (DEF) is defined by computing the second derivative of the INDF. By evaluating the sign of the DEF, transient (arcing) faults are distinguished from permanent faults and also the secondary arc extinction instant can be identified. The significant advantage of the proposed algorithm is that it does not require any threshold level and therefore its performance is independent of fault location, line parameters and operating conditions. Furthermore, it can be used in transmission lines with reactor compensation. The proposed method has been successfully tested under a variety of fault location and load angle on a 400 kV overhead line, with and without reactor compensation, using the Electro-Magnetic Transient Program. The test results validate the algorithm ability in distinguishing between arcing and permanent faults and determining the instant of secondary arc extinction. Copyright © 2010 John Wiley & Sons, Ltd.