HARMONICS ANALYSIS AND VISUALIZATION OF AN INTERRUPTED ELECTRICAL SIGNAL

Abstract

In recent times there has been a wide interest in micro-grids. One area of concern in microgrids is the generation of harmonics by active devices such as converters and FACTS devices used for reactive power compensation. Accurate detection of harmonics is essential for their elimination. 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. Harmonics up to 31st are measured by demodulation as if the power signal is OFDM modulated. All these harmonics are measured using only one cycle of voltage signal and the number of operations required for the for the measurement are less with the existing demodulated methods. This method is compared with existing methods and the results justify its application. 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 used for noise elimination before the harmonics are analysed.