Analysis of power system harmonics using PSNR metric

Abstract

In recent times there has been a wide interest in micro grids. One area of concern in micro grids is the generation of harmonics by active devices such as converters and FACTS devices used for reactive power compensation. The currently available literature focuses on the number of operations and fundamental cycles for estimating harmonics. This usually results in a trade-off between accuracy of estimation and the choice of digital filter parameters. In this work a novel orthogonal frequency division multiplexing (OFDM) principle modified as per the power system scenario has been proposed. Odd harmonics up to 31st order are measured by demodulation as if the power signal is OFDM modulated. All these harmonics are measured using only one cycle of voltage signal. Instantaneous detection of harmonics is made possible using the Discrete Wavelet Transform (DWT) instead of the fast Fourier transforms used in conventional OFDM. DWT is also used for noise elimination before the harmonics are analyzed and the performance of proposed method is analyzed using PSNR under different noise conditions.