An improved robust stability criteria for power system with time-varying delays

This paper addresses the robust stability problem for power system with time-varying delays. By constructing a novel Lyapunov function and introducing some free-weighting matrices, an improved robust stability criterion is developed, where the restrictions on the derivative of time-varying delay are removed so as to reduce its conservatism. The obtained results formulated in the form of linear matrix inequalities (LMI) can be effectively solved by the LMI toolbox. Finally, a single machine system is employed to calculate the delay margin and to validate the effectiveness and practicality of the proposed method.