  Online estimation of electromechanical oscillation parameters provides
essential information to prevent system instability and blackout and helps to
identify event categories and locations. We formulate the problem as a state
space model and employ the extended Kalman filter to estimate oscillation
frequencies and damping factors directly based on data from phasor measurement
units. Due to considerations of communication burdens and privacy concerns, a
fully distributed algorithm is proposed using diffusion extended Kalman filter.
The effectiveness of proposed algorithms is confirmed by both simulated and
real data collected during events in State Grid Jiangsu Electric Power Company.
