Detection and Location of Fault in Microgrid using Discrete Wavelet Transform based Technique

In this paper a new wavelet transform based method for detection and identification of fault location has been proposed in microgrid with Distributed Generation (DG). Fault detection is challenging for this DG system due to the bi-directional power flow and the issue of fault current which consists of source current and DG current both during fault. The wavelet transform analysis determines the content of frequency with time simultaneously of nonstationary transient signal. The proposed method evaluates the approximate and detail wavelet coefficients at different level of frequency band by Discrete Wavelet Transform (DWT) for detection of the fault reliably. This process starts with tracking the signal of phase voltages at terminal of DG, Point of Common Coupling (PCC) and utility side and by DWT decomposition each signal will be processed. The energy of detail DWT coefficients of each faulty signal considering both the symmetrical and unsymmetrical fault have also been computed. This energy content has been analyzed further to identify the location of the fault. This unique and simple technique has been verified successfully using an existing microgrid network in West Bengal, India for unbalanced and balanced fault detection and location of fault.