A study of load and line characteristics on power system damping performance

Loads supplied by controlled power electronic converters are increasingly emerging into power systems. Generally, it is assumed that these loads are having constant power load characteristics. However, modeling of an EV charging load having power electronic grid interface and a voltage controlled dc link, has identified a load characteristic which combines constant power and negative exponential load behaviour. In this paper, a study of load characteristics including electric vehicle charging has been carried out. Further, impact of feeder resistance on power system damping is evaluated on a single machine infinite bus system, for a range of static load characteristics. Despite the belief that line resistance add damping to the power system, we have identified that this fact depends on the voltage dependent characteristics of the loads.