The power quality impact of adjustable speed drives in industrial distribution system

Abstract

Applications of adjustable speed drives (ASDs) have benefited many industrial facilities. The primary function function of any speed drive is to control the speed of a motor. This control technique can significantly impprove the motor system efficiency and reduced system losses. ASD connected in power system generate harmonics and it is also sensitive to voltage sag produced by short circuit faults in line transmission or distribution. In the recent year the both of harmonic and sag have become power quality problems faced by many industrial customers and utility. This paper presents harmonic simulation results and sag magnitude occurred in power system taken from IEEE Test Industrial System by using ETAP program package. For the purpose of simulation, ASD modeled as six and twelve pulse types are to be harmonic sourcesFrom the simulation results show that a six pulse ASD type gives harmonic distortion higher than a twelve pulse ASD into the system. The sag magnitude was determined based on the different fault location. The most severe voltage sags that occur are the faults close the supply to the feeders.