The Extent and Limitations of Correlating Measured Interharmonics and Measured Voltage Fluctuations

Abstract

Amplitude modulation is a well-known cause of voltage fluctuations resulting in luminous lamp flicker. Amplitude modulation can be more generally quantified in terms of interharmonics. The theoretical correlation between interharmonics and lamp flicker has been firmly established analytically. Many have also demonstrated a correlation between measured interharmonics and measured lamp flicker. The feasibility of the attempts to generally correlate the measured values have been explored in this work. This is accomplished by calculating normalized correlation coefficients for measured interharmonics and measured short-term flicker severity for several industrial loads, each for multiple hours. Measurements are made consistent with the International Electrotechnical Commission's standards. It is concluded that measured lamp flicker and measured interharmonics are strongly correlated in general provided particular measured interharmonic phasor pairs are properly combined, weighted and grouped.