STOCHASTIC APPROACH TO SMALL DISTURBANCE STABILITY IN POWER-SYSTEMS

This paper examines the almost-sure asymptotic stability of coupled synchronous machines encountered in electrical power systems, under the effect of fluctuations in the interconnection system due to varying network conditions. A linearized multimachine model is assumed with one of the machines having negligible damping weakly coupled to the other machines with positive damping. Furthermore, the fluctuations are assumed to contain both harmonically varying and stochastically varying components. For small intensity excitations, the physical processes are approximated by a diffusive Markov process defined by a set of Ito equations. Results pertaining to the almost-sure asymptotic stability are derived using the maximal Lyapunov exponent obtained for the Ito equations. Assumptions made for the modeling and analysis are consistent with possible operating conditions in an electrical power system.