Modeling and simulation of overvoltage surges in low voltage systems

Power system disturbances have been present since the inception of the electric utility industry. However, yesterdaypsilas loads are more forgiving of disturbances than todaypsilas modern equipment. The proliferation of sensitive electronic equipments such as PCs, variable speed drives and industrial programmable controllers has made us more aware of power system disturbances, which went unnoticed in the past. In the normal operation of power systems, unavoidable disturbances may happen due to sag, swell, noise, and overvoltage surges. Overvoltage surges, however, are damaging in nature and result in more frustrations and even fire in rare cases. This research aims to investigate overvoltage surges due to possible causes such as lightning and switching operations in a low voltage system. Then it compares simulated overvoltage surges with the design goals of the Information Technology Industry Council (ITI) power acceptability curve. Finally a study was undertaken to see how surge arresters could be used to protect a given system against unacceptable overvoltage levels.