Nonlinear Harmonic Electric Energy Metering System Based on the Wavelet Transform

Background: To solve the problem of accurate measurement of nonlinear harmonic electric energy, a method for improving harmonic electric energy measurement based on the discrete wavelet packet decomposition and reconstruction algorithm was proposed. Objectives: A reactive energy measurement method combined with Hilbert transformation was designed, and the frequency characteristics of wavelet function were discussed. An excessively high sampling rate could reduce the accuracy of harmonic power measurement. By setting the discrete wavelet packet transformation decomposition, the stepping of the wavelet form resulting from the excessively large wavelet packet decomposition scale was eliminated using the moncoband reconstruction algorithm. Methods: Experimental results showed that the detection error obtained by numerical simulation using the wavelet transform algorithm was close to the standard instrument, with the maximum reference error of 0.013%-0.030%. Results and Conclusion: The feasibility and measurement accuracy of the nonlinear harmonic electric energy metering system were verified, providing an effective method for accurately detecting the harmonic, interharmonic, and time-varying harmonic components of the electric power system.