Transformed periodic orbit mechanism of low frequency oscillations in power systems

摘要

Some low frequency oscillations (LFOs) with constant amplitude in power systems cannot be explained by the mechanisms such as negative damping, forced oscillation, autoparametric resonance, and bifurcation. In this paper, the concept of transformed periodic orbits is introduced to describe the earlier unexplained periodic steady-state phenomena in power systems. The algorithm of calculating the transformed periodic orbit is presented based on the trapezoidal integration method. Then, a novel mechanism of LFOs is proposed; that is, a transformed periodic orbit emerges when bifurcations or large disturbances occur in power systems. This kind of LFOs can be eliminated by decreasing the generator output power greatly. Simulations on a single-machine infinite-bus system and the IEEE 9-bus system have demonstrated the rationality of the proposed mechanism. Copyright (C) 2015 John Wiley & Sons, Ltd.