Rms and Power Measurements: A Wavelet Packet Transform Approach

This study provides the theoretical basis for the use of wavelet packet transform (WPT) approach for root mean square (rms) and power/energy measurements. The proposed approach can simultaneously measure the distribution of the rms and power with respect to individual frequency bands directly from the wavelet transform coefficients (WTCs) associated with concurrent voltage current pair. Their dependent quantities such as power factor and total harmonic band distortion can be calculated as well. Uniform frequency bands are yielded from the WPT decomposition process of power system waveforms and can be used for identifi cation of harmonic components. The frequency bands also retain both the time and frequency relationship of the original waveforms, which is one of the major benefits provided by this approach. The approach is evaluated by its application to both analytical and actual power system waveforms.