Synchronized Approach Based on Empirical Fourier Decomposition for Accurate Assessment of Harmonics and Specific Supraharmonics

Waveform distortion is one of the most common disturbances in power quality in real power grids. Accurate assessment of the distortion level for voltage and current is a challenge for researchers, as a result of simultaneous occurrence of a large number of time-varying spectral components and the problem of proper synchronization of measurement window. The article presents a new method for assessing low-frequency harmonics (LFH) and high-frequency harmonics (HFH), which are supraharmonics with a frequency that is a multiple of fundamental frequency. The proposed method is based on discrete Fourier transform analysis using a “flat-top” window, where the sliding measurement window is synchronized with the short-term fundamental period by using empirical Fourier decomposition. The presented approach focuses on increasing the accuracy of assessment of LFH and HFH in power grids only by modifying the synchronization of measurement window. The presented approach makes significant modifications to the current IEC standard unnecessary, which in turn allows its faster implementation on a large scale. The proposed approach is also compared with other synchronized methods presented in recent literature and with methods suggested by IEC standards. The presented research results confirm the accuracy of the proposed solution.