Decentralized nonlinear excitation control based on wide-area measurements

Recent technological advances in the area of wide-area measurement systems (WAMS) has enabled the use of centre of inertia (COI) signals to improve the transient stability of large power systems. However there is an unavoidable delay involved before COI signals are received at generators. Conventional excitation control of generators is brought forward again to enhance power system stability with the help from WAMS. Based on Lyapunov theory and backstepping concept, a simple nonlinear excitation control is designed for decentralized generators modeled in COI reference coordinate frame. Performance of the proposed excitation control is evaluated for a range of operating conditions using 16-machine, 68-bus power system example. Simulation results shows that decentralized nonlinear excitation control is effective to damp power system oscillations, and the smoothness feature of COI signals guarantees a good performance of excitation control in time delay situations.