A new optimization-based algorithm for the estimation of harmonics under power system frequency deviations

In electrical power industry, harmonics are produced by a great number of power electronic devices. Besides, the system frequency of a power line can deviate in the cases of fluctuating and periodically varying loads and transients. This frequency deviation introduces undesirable frequency components in the spectrum. Correct measurement of harmonics under such system frequency deviations has great importance for the protection of power electronics devices. For this goal, this study proposes a new optimization-based algorithm for the estimation of harmonics in these circumstances. In the first phase of the algorithm, the deviated system frequency is estimated. In the second phase, the harmonic components are estimated and fine-tuned correspondingly. Case studies show that the proposed method is robust and precisely estimates deviations in the system's fundamental frequency and measure the amplitudes of harmonic components very accurately. The method requires just a stoppage criterion.