JPS_V3_N2_RP5 Detection Of Voltage Sag Using Hilbert-Haung Transform Sri Swathi Ch. M. Sai Veerraju Journal on Power Systems Engineering 2322–0376 3 2 28 33 Empirical Mode Decomposition, Intrinsic Mode Functions, Hilbert Transform, Voltage Sag Causes In this paper a method is proposed to detect voltage sag based on Empirical Mode Decomposition (EMD) with Hilbert Transform (called Hilbert-Huang Transform).The main characteristic feature of EMD is that it decomposes a nonstationary signal into mono component and symmetric signals called Intrinsic Mode Functions (IMFs). Further, the Hilbert transform is applied to each IMF to extract the features. The magnitude plot of the Hilbert Transform of one of the IMF correctly detects the event. Three voltage sag causes are taken in this paper (i) fault induced voltage sag, (ii) starting of induction motor and (iii) three phase transformer energization. Simulation/matlab results show the effectiveness of this method. May - July 2015 Copyright © 2015 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=3483