Visualizing power quantities under non-sinusoidal and time-varying conditions

Traditional analysis of waveform distortion assumes balanced and steady-state conditions. However, due to the widespread use of power electronics, non-linear loads and a multiplicity of harmonic-producing loads, power signals are becoming increasingly distorted and time varying. This complex scenario demands appropriate analysis. This paper illustrates the visualization of power quantities under time-varying conditions based on the defitions of IEEE Standard 1459. The Sliding Window Recursive Fourier Transform is used to decompose real signals in time-varying harmonics and subsequently it calculates the main parameters as function of time. These include symmetrical components, total harmonic distortions and apparent power. This visulization can lead to a better understanding of the nature of power signals under time-varying conditions.