A general criterion of interval time-varying delay power system stability based on interval fragment

The time-delay in state variables can impacts the stability of power system. The problem about stability analysis of linear systems with time-varying delays is concerned. A general criterion of the system asymptotic stability is established by segmenting delay intervals. Corollaries under different conditions are given. The three delay intervals with delay information are segmented finitely based on the idea of time-delay segment. And a general Lyapunov functional formula is constructed. The information on the bound of the delay is fully exploited. A general sufficient condition is derived with less conservative for the system asymptotic stability. Different methods are used comprehensive during the calculation process of the functional derivative, such as the piecewise analysis, the convex combination technique and integral inequality. Analyzing WSCC 3-machine 9-bus system indicate that the delay stability margin is less conservative than the results in the other literature and verify the effectiveness of the stability criterion.