Laplace Transform to Assess Harmonic Distortions at Resonance

A high-harmonic distortion is a well-known negative influence on a grid, mostly caused by a non-linear loads operation. And although this phenomenon is widely-studied, the practical approaches for its quantitative assessment differ. Previously, the authors proposed a Laplace-transform-based approach to calculate a current level of a cumulative effect of all high-harmonics (also known as Total Harmonic Distortion (THD)) on power quality in the grid. The conducted experiments showed that the developed method allows for a more precise THD assessment than the standardized ones based on the Fourier transform. However, additional experiments resulted in a conclusion that this method may provide significantly higher accuracy than the traditional Fourier-transform-based method for THD assessment at series electrical resonance. This paper provides additional theoretical analysis and case studies on a model of a single substation with a capacitor bank to verify the previously developed method and to compare its results with the Fourier-transform-based method.