In this paper, a discrete wavelet transform (DWT) based approach is proposed for power system frequency estimation. Unlike the existing frequency estimators mainly used for power system monitoring and control, the proposed approach is developed for fundamental frequency estimation in the field of energy metering of nonlinear loads. The characteristics of a nonlinear load is that the power signal is heavily distorted, composed of harmonics, inter-harmonics and corrupted by noise. The main idea is to predetermine a series of frequency points, and the mean value of two frequency points nearest to the power system frequency is accepted as the approximate solution. Firstly the input signal is modulated with a series of modulating signals, whose frequencies are those frequency points. Then the modulated signals are decomposed into individual frequency bands using DWT, and differences between the maximum and minimum wavelet coefficients in the lowest frequency band are calculated. Similarities among power system frequency and those frequency points are judged by the differences. Simulation results have proven high immunity to noise, harmonic and inter-harmonic interferences. The proposed method is applicable for real-time power system frequency estimation for electric energy measurement of nonlinear loads.

JO - Metrology and Measurement Systems L1 - http://www.journals.pan.pl/Content/89916/PDF/Journal10178-VolumeXIX+Issue2_11paper.pdf L2 - http://www.journals.pan.pl/Content/89916 IS - No 2 EP - 320 KW - frequency estimation KW - power systems KW - wavelet transforms ER - A1 - Zhang Peng A1 - Li, Hong-Bin PB - Polish Academy of Sciences Committee on Metrology and Scientific Instrumentation JF - Metrology and Measurement Systems SP - 307 T1 - Power System Frequency Estimation Algorithm for Electric Energy Metering of Nonlinear Loads UR - http://www.journals.pan.pl/dlibra/docmetadata?id=89916 DOI - 10.2478/v10178-012-0026-7