The load oscillation energy and its effect on low-frequency oscillation in power system

Low frequency oscillation is a potentially dangerous phenomenon in power systems involving exchange of power among generators and loads in different areas. The study of the low frequency oscillation mainly concentrated on the analysis and control of generator in the past. As important parts of power sys tem, loads have a significant effect on the low frequency oscillation of the interconnected power system. In this paper, we study the effect of load to the low frequency oscillation by analyzing the characteristic and distribution of the load oscillation energy. Firstly, the equations of the load oscillation energy are introduced, which derived from the linearization of system dynamic equations. Then, based on the load oscillation energy, the distribution of the oscillation energy in a variety of static loads and internal induction motors is analyzed in a single-machine infinite-bus sys tem. Different kinds of load have different effects on low frequency oscillation. Moreover, in the interconnected 4-generator 2-area system with weakly damped free oscillation, the oscillation energy distributions of the different kinds of load at different locations, as well as different induction motor load capacity ratio are analyzed. Finally, the effect of load characteristics on the low frequency oscillation is summarized from the perspective of oscillation energy.