Development of a programmable load

Abstract

The Voltage Dip Test Facility at the University of the Witwatersrand utilises a resistive load during testing of variable speed drives. This method produces valuable results regarding the performance of drives under dip conditions. It has been shown that load type does influence the performance of drives and this variation cannot be tested under current conditions as only linear loading is attainable with resistive loads. This thesis proposes a programmable load based on the concept of field-oriented control of an induction motor. The concepts involved with field-oriented control are discussed and shown to be suitable for this application. An implementation strategy utilising custom-designed software and an off-the-shelf VSD is developed and executed. The performance of the programmable load is analysed under both steady-state and dynamic conditions.