A numerical method to evaluate bifurcation aspects around generator stability limit

In this paper, a numerical method to evaluate the stability and the orbit radius of limit cycles in a power system is proposed. The method can be a useful tool to estimate the available transmission capacity in a multi-machine power system since it tells us the global stability region around a critical operating point in the case that an unstable limit cycle exists. The effectiveness of the method is demonstrated by comparing the results from the proposed method with those from the software package AUTO applied to the detailed differential equations of a single machine infinite bus system. It has been also applied to the analysis of limit cycles in a longitudinally interconnected power system. As a result, a sustained power oscillation due to a stable limit cycle is evaluated.