Dynamic VAr planning in a large power system using trajectory sensitivities

This paper presents the results of an investigation of a voltage collapse case in a heavily stressed, large power system. The study is focused on examining the impact of a fault at the bulk transmission level in the system during summer peak load conditions. The power system under study has significant amount of air conditioning load. The power system components modeled in detail include both static and dynamic loads at key distribution feeders, over excitation limiters, switchable shunts, STATCOM, and static VAr compensators. The impact of induction motors on voltage stability is studied with the focus on trajectory sensitivity. The concept of trajectory sensitivity index is proposed as a method to identify the location for dynamic VAr support to mitigate the short-term voltage instability problem caused by large disturbances. The comparison of SVCs and STATCOM performance is discussed.