Risk Assessment on Factors Leading to Inter-Area Resonance

This paper studies factors which may have a critical effect on the inter-area resonance phenomenon. Inter-area resonance is caused by an interaction between forced oscillation and electromechanical inter-area mode, and under certain circumstances, may lead to instability in a power system. The phenomenon is analyzed under various conditions in a Nordic 57 model which represents a simplified model of the Nordic power system. The studied factors are the location, frequency, power component, and amplitude of the forced oscillation source. The main finding is that while most studied factors affect the phenomenon, not all cause critical effects independently. However, when combined with other unfavorable factors and system operating conditions, these factors may cause severe consequences in a power system. Extensive analysis suggests that a combination of different unfavorable factors may, in fact, lead to broad power outages. Based on the results, this paper offers a risk matrix that can be used to evaluate the combined effects of different factors that may lead to high-risk situations. The risk matrix can be used by transmission system operators when evaluating inter-area resonance risks in their system.