Online EMD with Fourier Transform for active shunt filter operation under non sinusoidal supply conditions

Abstract

The aim of this paper is to compute reference current for the operation of shunt active filter under non-sinusoidal supply condition using local Empirical Mode Decomposition (EMD) and Fourier Transform. The online application of local EMD on distorted voltage waveforms extracts the fundamental oscillating mode which serves two purposes -one in determining the sinusoidal unit template in phase with fundamental component of supply voltage and two in estimating the fundamental frequency of the system using Hilbert Transform. The fundamental frequency information is utilized by the Fourier Transform to extract the magnitude of fundamental and harmonic components present in load current. The fundamental load current magnitude together with unit voltage templates gives an estimate of the reference current. The case study is done under distorted voltage with unknown system frequency in MATLAB/ SIMULINK platform.