Stochastic models for study of electromechanical transient process in power systems

A simplified stochastic model considering stochastic excitation was developed for the study of the electromechanical transient process in power systems. First,stochastic models considering stochastic excitation were built for electromechanical transient processes in the one-machine infinite bus( OMIB) system and the two-machine power system. Then,based on the EEAC theory,the stochastic models considering stochastic excitation for the multi-machine power system were deduced. The results show that under approximate conditions,the stochastic model of the multi-machine power system can be simplified as the model of the OMIB system,and the model parameters may be constant or time-varying according to different assumptions. The stochastic excitation may be considered the superposition of stochastic excitations that have different frequencies. Finally,simulations were performed. The simulation results show that,when affected by the stochastic excitation,the rotor angle curve exhibited regular oscillations with frequencies that were almost the same.