Distributed Automatic Load Frequency Control With Optimality in Power Systems

With the increasing penetration of renewable energy resources, power systems confront new challenges in maintaining power balance and the nominal frequency. This article studies load-side frequency control to handle these challenges. In particular, a fully distributed automatic load control (ALC) algorithm, which only needs local measurement and local communication, is proposed. We prove that the load control algorithm globally converges to an optimal operating point that minimizes the total disutility of users, restores the nominal frequency and the scheduled tie-line power flows, and respects the load capacity limits and the thermal constraints of transmission lines. Furthermore, the global exponential convergence of the reduced ALC algorithm without considering the capacity limits is proved and leveraged to study the dynamical tracking performance and robustness of the algorithm. Finally, the effectiveness, optimality, and robustness of the proposed ALC algorithm are demonstrated via numerical simulations.