Power system stability in the presence of FACTS elements

Flexible AC Transmission System (FACTS) utilizes high power electronic devices to enhance the control of electric power flow in transmission networks. Fast electronic switching operation in FACTS devices results in system periodic topology varying. This thesis proposes a comprehensive methodology for power system small signal stability analysis. The proposed small signal stability analysis consists of two stages: (a) system analysis to determine the periodic steady state conditions, and (b) system eigenvalue analysis. The frequency domain modeling techniques for FACTS elements and generators are developed for system steady state analysis. Both models are validated by an alternative method. The system equations are solved using Newton's iterative algorithm. The FACTS element topology status is also obtained through the system steady state analysis. This thesis also proposes an effective method for system state space formulation. The system small signal stability analysis is based on eigenvalue analysis on system periodic state transition matrix. The proposed methods are applied on three practical power systems with different types of FACTS elements. The results are presented and discussed.