New delay-dependent steady state stability analysis for WAMS assisted power system

Wide Area Measurement System (WAMS) provides new control approaches to maintain power system security, but it inevitably brings time delay which may be the one of unstable reasons in power system. Conventional steady state stability analysis, based on linear control theory and Eigenvalue calculation method, is not fit for WAMS assisted power system because of neglected influence of time delay. By introducing time delay features of exciter and power system stabilizer, a new steady state stability model with time-varying delay is first proposed for WAMS assisted power system. By using Lyapunov-Krasovskii functional, a new delay-dependent steady state stability criterion for power system is derived, which overcomes the disadvantages of Eigenvalue calculation method of power system steady state stability. The proposed model and criterion are tested on the synchronous-machine infinite-bus power system and test results verify the correctness of the proposed model and its criterion, and the effectiveness of steady state analysis method in the environment of WAMS.