Modeling and simulation of flicker due to interharmonics

Interharmonics are spectra components whose frequencies are not integral number of the supply fundamental frequency. When a voltage waveform contains interharmonics, the root mean square (rms) and peak magnitude of the waveform will fluctuate. This is because the periods of the interharmonic components are not synchronous with the fundamental frequency cycle. This fluctuating magnitude is essentially is a form of flicker. If the magnitude is sufficiently large and the fluctuation frequency is in a large perceptible by human eyes, a light flicker will occur. As a result, devices that produce interhamonics have been considered as a major source of light flicker. Variable frequency drives (VFDs) are widely used in various industry applications due to their efficiency and energy cost savings aspect. In spite of advanced technology and improved reliability of modern VFDs, they considered not only as harmonic sources but also interharmonic sources. The interharmonic-flicker curve based on rms and peak magnitude fluctuations and on the IEC flickermeter is presented.