Power system oscillations, especially electromechanical oscillations, have been a major concern in power system planning and operation. Given the characteristics and nature of these oscillations, these problems can be studied well using Hopf bifurcation theory, which describes the onset of an oscillatory problem in nonlinear systems.; This thesis presents two indices to predict and detect oscillatory problem in power systems using Hopf bifurcations; one of them is preferred as an on-line operational tool due to its higher computational speed. Application of these indices on several test power systems, including the IEEE 50-machines test system and two nonlinear systems, is also included in this thesis to demonstrate the usefulness of the indices. Simulation results indicate that the indices are smooth and fairly linear with respect to the loading factor of the system.; The thesis also clearly demonstrates the direct association between electromechanical oscillations and Hopf bifurcations in power systems. The mitigation of the oscillation problem or Hopf bifurcation from the generator side using PSS controllers, and from the transmission side using FACTS controllers is studied in detail. A new placement technique for a shunt-FACTS controller for the purpose of oscillation damping is also proposed.; The increasing trend in the number of FACTS controllers used in power systems could lead to some undesirable interactions between FACTS and power system controllers or among FACTS controllers. The importance of and tools needed to study this problem are demonstrated in a test system through the analysis of a negative interaction leading to an oscillatory unstable condition.
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