Decentralized nonlinear coordinated excitation and steam valve adaptive control for multi-machine power systems

•Lyapunov’s theory is used to design both excitation and steam valve decentralized controllers.•A modified HOSMD is designed to estimate the derivatives of unavailable variables and states.•Both transient stability and voltage regulation performances are considered.•Effectiveness of proposed scheme is validated under various scenarios.

In this paper, a decentralized nonlinear coordinated excitation and steam valve adaptive control combined with a modified high-order sliding mode differentiator is designed for multi-machine power system stability enhancement. The proposed control scheme is based on Lyapunov’s direct method and requires only local information on the physically available measurements of relative angular speed, active electric power and terminal voltage with the assumption that the power angle and mechanical power input are not available for measurement. Each synchronous generator is considered as a classical fifth order model that includes turbine dynamics. The simplicity of the proposed scheme and its robustness with respect to large perturbations, change in operating point and parameter uncertainties constitute the main positive features. Simulation results in the case of the Kundur 4-machines 2-area power system show the effectiveness, robustness and superiority of the proposed scheme over the classical AVR/PSS.