Interharmonics Modelling Using DFT and Grouping Methods

In recent years, a number of power harmonics/interharmonics have been produced due to the increasing use of power electronic systems and time-variant non-linear loads in industry. This phenomenon causes a worse power line pollution in power system. However, it is still a big challenge for DFT to analyze or measure interharmonics. Therefore, this paper unveils the dilemma for using DFT tool in modelling Interharmonics. Some critical cases study with implementation results are introduced and discussed for details.

I. Introduction

The interharmonics can not only create many problems like traditional harmonics but also produce some additional problems. Some cases are disclosed as light and CRT flicker, subsynchronous oscillations, thermal effects, erroneous firing of thyristor apparatus, saturation of current transformer, high frequency overload of passive parallel filter, the loss of useful life of induction motors, voltage fluctuations telecommunication interference, low frequency oscillation of mechanical systeminterference of control and protection signals, acoustic disturbance, and malfunctioning of remote control system, etc. The situation may be worsen as working at low amplitude [1]–[12].