Identification of interharmonics using disperse energy distribution algorithm for flicker troubleshooting

It is well known that interharmonics close to the fundamental or harmonics may cause significant flicker. Although International Electrotechnical Commission (IEC) standard is adopted for interharmonic measurement, the interharmonic frequencies may not be obtained accurately under this framework. Based on the frequency resolution at 5 Hz recommended by IEC, this study develops a dispersed energy distribution (DED) algorithm to measure those interharmonics that may cause flicker due to a low frequency fluctuation phenomenon. The relation between the frequency and dispersed leakage from discrete Fourier transform is induced, and the mathematical model is thus established to find the interharmonic frequency. However, the dispersed energy can be collected to retrieve its original amplitude. The performance results based on the periodically varying load verify that the proposed scheme can achieve reliable, rapid and accurate outcome.