Detection of a power quality problem of flicker using Hilbert-Huang transform and short term severity calculation

Short term flicker severity (Pst) is an important measure of a power quality problem of flicker and it is defined in the power quality standards of IEC. Calculation of Pst is an accurate way of monitoring the flicker severity. In this work, a novel flickermeter is proposed to estimate the flicker value and Pst. In the proposed method, an algorithm based on Hilbert-Huang Transform (HHT) is applied to obtain the flicker severity. In this method, voltage signal is decomposed into Emprical Mode Decomposition (EMD) and Intrinsic Mode Function (IMF) components. These components are used in the calculation of the frequency and amplitude of voltage flicker. Flicker value Pst, which is a nonlinear function of this amplitude and frequency is calculated by using statistical methods. The results obtained from digital realization of the IEC flickermeter are compared with the results obtained from propose method of HHT. The comparison shows that the proposed method is very successful in estimating voltage flicker and in calculating Pst. It was observed and experimentally verified that the HHT method which can detect the variations in the envelope of the sinusoidal waveform is an efficient way of detecting flicker and calculating Pst.