On the phase sequence characteristics of interharmonics

Summary form only given. Phase sequence is an important attribute of voltages and currents in three phase power systems. This paper investigates the sequence characteristics of interharmonic components. Three common cases involving interharmonics are analyzed. These are variable frequency drives (VFD), motors with fluctuating mechanical loads and general fluctuating impedance loads. The results reveal that interharmonics can have either positive or negative sequence. The general rule is that the sequence of interharmonics is the same as that of the supply system components being modulated. If the modulated frequency is negative, the sequence of the corresponding interharmonic component will change from positive to negative or vice versa. The findings of this paper will help to improve our understandings on the characteristics of interharmonics and can be useful for the development of interharmonic simulation programs