A study on boundary of small disturbance stability region

Small disturbance stability region (SDSR) is a framework for understanding, evaluating the small disturbance stability of power systems in a more accurate and efficient way. With the definition in parameter space, SDSR can provide global information to engineers such as load margin, control direction and so on. This paper concentrates on demonstrating and analyzing the boundary of SDSR, which consist of local bifurcation points. Via a modified Philips-Heffron model, a thorough study on a simple system is performed to identify the important role of an induction motor (IM) model in SDSR´s boundary constitution. Furthermore, simulation in a 9-bus system with composite load model confirms that IM and static load model has different significant impact on SDSR´s boundary of power systems. Finally, the paper tests the conclusion in a practical bulk power system.