Control, interaction mitigation and location for FACTS devices

This dissertation focuses on the investigation and mitigation of the potential dynamic control interactions among multiple UPFC controllers installed in power systems and the optimal location of UPFC for system stability improvement.; Two different interaction phenomena are highlighted by their distinctive frequency characteristics: low frequency modal interaction and high frequency interaction. Due to the difference between the interaction phenomena, two approaches are proposed respectively to eliminate these adverse interactions. By introducing a series of additional global control signals, low frequency modal interactions can be effectively alleviated to improve system dynamic stability performance. Also, a nonlinear hybrid fuzzy logic PI controller is developed in this dissertation, which is shown to be effective in mitigating the high frequency interactions.; It is indicated that the effectiveness of the FACTS device control in improving the stability mainly depends on the location of devices in the network. This dissertation develops a placement sensitivity index, which is derived from the controllability and observability factors of the system to evaluate the interaction phenomena severity.; In addition, this dissertation presents the schematic and basic controls of a reconfigurable FACTS system that can be used to realize the major voltage-sourced-converter FACTS topologies. Furthermore, performance indices are developed for different FACTS devices with Energy Storage System (ESS) and dynamic responses of different FACTS combinations are presented to support the validity of the developed indices and increased controller flexibility introduced by integrating the ESS.