System Frequency Response and Low Voltage Power Factor Correction - A Case Study

Summary form only given. In order to reduce losses, control voltage, and reduce power factor penalties, industrial customers often apply power factor correction at the low voltage level (e.g. 480 volts). This power factor correction may or may not be tuned to avoid creating harmonic resonance problems. However, even tuned capacitor banks can result in harmonic resonance problems when combined with the frequency response characteristics of the distribution system. This paper describes a particular problem involving distribution system resonance conditions that magnify overall harmonic distortion levels on the distribution system and also interact with the customer power factor correction systems to create problems with tuned capacitor banks. Various solutions to the problem are evaluated and an optimum solution involving filtering on the primary distribution system is described. This is an important problem involving interaction between customer systems and the supply systems that has not been adequately characterized previously in the literature