An Approach for Power Quantification Based on Stockwell Transform and CPC Power Theory

This article presents a power calculation method for non-sinusoidal signals with non-stationary characteristics based on currents’ physical components (CPC) power theory and the discrete Stockwell transform (DST). The DST independently localizes the real and imaginary components of the spectrum at any given time interval, being suitable for analyzing non-stationary waveforms. The proposed method allows for an instantaneous tracking of the power components defined in CPC power theory based on a time–frequency analysis provided by the DST. Thus, the proposed method is able to identify alterations in the harmonic content, and consequently track variations on the powers, in all time instants. The proposed method is validated using non-stationary signals, including a scenario with frequency deviation, presenting rather promising results when compared to the Fourier-based approach. Additionally, the proposed method is also assessed in noisy environments by inserting an additive Gaussian noise, based on real oscillographic records, presenting a good performance, which attests its suitability for power quality (PQ) analysis and power calculation.