Distributed Optimal Frequency Control Considering a Nonlinear Network-Preserving Model

This paper addresses the distributed optimal fre-quency control of power systems considering a network-preserving model with nonlinear power flows and excitationvoltage dynamics. Salient features of the proposed distributedcontrol strategy are fourfold: i) nonlinearity is considered tocope with large disturbances; ii) only a part of generatorsare controllable; iii) no load measurement is required; iv)communication connectivity is required only for the controllablegenerators. To this end, benefiting from the concept of ’virtualload demand’, we first design the distributed controller for thecontrollable generators by leveraging the primal-dual decom-position technique. We then propose a method to estimate thevirtual load demand of each controllable generator based on localfrequencies. We derive incremental passivity conditions for theuncontrollable generators. Finally, we prove that the closed-loopsystem is asymptotically stable and its equilibrium attains theoptimal solution to the associated economic dispatch problem.Simulations, including small and large-disturbance scenarios,are carried on the New England system, demonstrating theeffectiveness of our design.