Study on the Nonlinearity of Power System Oscillation Trajectory

When a large interconnected power system is disturbed by large or small disturbance, its electro-mechanical oscillations become one of the most important factors affecting the system stability. This paper studies the characteristics of electro-mechanical oscillation trajectories with respect to initial conditions decided by disturbances. Influences of the nonlinearity of power system on both the shape and the period of its oscillation trajectories are discussed. Through simulations, the difference of dynamic responses in a real nonlinear system and its linearized system are comprehensively illustrated and compared. This paper´s observations help to understand the mechanism and characteristics of power system electro-mechanical oscillations and offer a valuable case for various analytical methods based on system trajectory identification or on linearization of the nonlinear power dynamic system.