Modelling variable frequency drives as part of complex load for grid unbalanced mode computation

Abstract

Variable frequency drives are widely used in industrial enterprises and are therefore an influential part of electric load. The aim of this study was to define a relation between voltage unbalance and variable frequency drive power. The mathematical models of drives with a cycloconverter and the frequency converter with a DC link (independent current and voltage inverter) were elaborated. Mathematical models enable computations of unbalanced modes of power grid with response to electric load impact. This solution increases computation accuracy.