Use of FACTS Devices for Power Flow Control and Damping of Oscillations in Power Systems

Due to the deregulation of the electrical market, difficulty in acquiring rights-of-way to build new transmission lines, and steady increase in power demand, maintaining power system stability becomes a difficult and very challenging problem. In large, interconnected power systems, power system damping is often reduced, leading to lightly damped electromechanical modes of oscillations. Implementation of new equipment consisting high power electronics based technologies such as Flexible Alternating Current Transmission Systems (FACTS) and proper controller design become essential for improvement of operation and control of power systems. The aim of this dissertation is to examine the ability of FACTS devices, such as Thyristor Controlled Series Capacitor (TCSC), Unified Power Flow Controller (UPFC) and Static VAr Compensator (SVC) for power flow control and damping of electromechanical oscillations in a power system. A power flow control strategy is based on linearization of active and reactive power flows around an operating point. A control strategy for damping of oscillations, including several FACTS devices and PSSs, is based on different approaches, both off-line and on-line, e.g. residue based method, pole shifting method and genetic algorithms. The robustness of each approach is discussed. One part of this dissertation deals with location of FACTS devices considering multiple tasks, power flow control and damping of oscillations. The results of the case studies demonstrate advantages and disadvantages of the considered control approaches.