Power quality and cost analysis of industrial electrical distribution systems with adjustable speed drives

In recent years, the use of adjustable speed drives (ASDs) in industrial plants has been steadily increasing. Unlike constant speed drives, ASDs provide precise control of speed corresponding to the varying load requirements. This process improves both energy efficiency and the power factor. The repetitive switching nature of power electronic devices in ASDs, however, introduces distortion to line currents. The impact of this current distortion on the power quality depends on the type of controllers used in these drives. Most of the older existing industrial plants utilize traditional motor drive systems. The process of replacing these constant speed drives with ASDs involves careful consideration of energy savings, power quality and overall cost of conversion.; In this thesis, the electrical distribution system of a typical existing industrial plant will be analyzed. The conversion process of replacing constant speed drives with ASDs is performed. Actual measurements of the power quality parameters of the industrial plant are made and compared with the simulation results. A cost analysis for the conversion from traditional drive to ASDs for this typical industrial plant is presented. Recommended criteria for the conversion process are suggested.