“…Therefore, these signals can be expressed through Fourier series representations as where the terms are constant complex quantities, are slowly varying Fourier series coefficients of the perturbation process with their maximum frequency content considered to be half of the reference frequency , and H represents the number of harmonics considered in the analysis. Here a column vector that contains Fourier coefficients of a variable is defined as the SV of that variable [27, 28]. For example, the SV of is defined as where T denotes the transpose operator.…”