Energy loss minimising function of variable speed drive filters

With their many benefits, Variable Speed Drives (VSDs) have grown rapidly in their usage in recent years. However, a unfortunate side effect of their usage is the introduction of harmonic distortion in the power system and reduction of true power factor (TPF). Low true power factor means poor electrical efficiency. The lower the true power factor, the higher the apparent power drawn from the distribution network.<br>A filter connected at the input side of a VSD converter reduces energy losses in the power supply system by reducing harmonics and improving the true power factor. In this thesis, a typical three-phase rectifier is used as an example to present a methodology of designing such filters in technical and economic terms. The relationship between the cost of input filters and the energy cost reduction they provide on the power supply side of VSDs is discussed. By extending the same method to different loads, filters are designed and power savings are calculated. The pricing of relevant harmonic filters is also discussed.<br><br>The basics of harmonics and the power factor are presented in the introduction. The summary of the results and suggestions for further research are contained in the last sections of the thesis.