Research into the loss of synchronism in power systems due to disturbances based on an analysis of electromechanical waves

  • Nikolai N. Lizalek Novosibirsk State Technical University, Novosibirsk, Russia
  • Vladimir V. Vasiliev Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: Power systems, electromechanical waves, oscillatory structures, oscillators of the system, possible and actual trajectories of motion, energy-time diagrams, unstable pair


In this paper, we suggest studying the stability of power systems under disturbances by analyzing the processes of synchronism loss, given electromechanical waves in power system that form an oscillatory structure of motion. In contrast to the classical formulation of the stability problem, an indispensable part of the study on the loss of synchronism is the location of an out-of-step cutset in the system (the spatial structure of instability).  The problem of synchronism loss analysis has two statements:  the prediction of possible instability structures and the determination of the instability structures in specific emergencies. The prediction of instability structures is made based on the equal areas method applied to the motion of excited oscillators in the system. In this case, possible instability structures are selected by comparing the energy and time characteristics of the unstable motion. The analysis of the processes of synchronism loss in power systems for a given emergency involves the calculation of the kinetic energy of mutual oscillations of an unstable pair of an oscillatory structure. The identification of the unstable pair of subsystems enables the out-of-step cutset to be located. The excess kinetic energy of the mutual motion of the unstable pair subsystems becomes an energy characteristic of the loss of synchronism.