Stability Analysis and Controller Design of a Wide-Area Time-Delay System Based on the Expectation Model Method

Stochastic time delay is a new challenge for communication networks in wide-area damping control (WADC) systems. Uncertainties introduced by stochastic time delays increase the difficulty of modeling, analyzing the stability, and designing the controller. In this paper, a new approach for stability analysis and controller design through expectation modeling is proposed to solve for the uncertainty in wide-area controlled power systems introduced by the effect of a stochastic time delay. In the proposed method, the expectation model that considers the detailed stochastic time delay distribution is derived to accurately model the effect of a communication network on the wide-area control performance. Through a matrix transformation of the expectation model, the eigenvalue of the WADC system that considers time delay can then be calculated; this eigenvalue can be used for analyzing the system stability. A novel expectation model-based controller design procedure is established, through which traditional methods can be applied in the controller design of a power system with a stochastic time delay. Finally, the effectiveness of the stability analysis and controller design methods are validated through simulations in a power system of four generators and two areas with an HVDC link, and a power system with eight generators and 36 buses.