Distributed Optimal Frequency Control Considering a Nonlinear Network-Preserving Model
This paper addresses the distributed optimal frequency control of power systems considering a network-preserving model with nonlinear power flows and excitation voltage dynamics. Salient features of the proposed distributed control strategy are fourfold, first, nonlinearity is considered to cope with large disturbances, second, only a part of generators are controllable, third, no load measurement is required, fourth, communication connectivity is required only for the controllable generators. To this end, benefiting from the concept of "virtual load demand," we first design the distributed controller for the controllable generators by leveraging the primal-dual decomposition technique. We then propose a method to estimate the virtual load demand of each controllable generator based on local frequencies. We derive incremental passivity conditions for the uncontrollable generators. Finally, we prove that the closed-loop system is asymptotically stable and its equilibrium attains the optimal solution to the associated economic dispatch problem. Simulations, including small and large-disturbance scenarios, are carried on the New England system, demonstrating the effectiveness of our design.
© 2018 IEEE. Manuscript received September 7, 2017; revised February 13, 2018 and June 15, 2018; accepted July 28, 2018. Date of publication August 1, 2018; date of current version December 19, 2018. This work was supported in part by the National Natural Science Foundation of China under Grants 51677100, U1766206, and 51621065, in part by the U.S. National Science Foundation through Awards EPCN 1619352, CCF 1637598, CNS 1545096, in part by ARPA-E Award DE-AR0000699, and in part by the Skoltech through Collaboration Agreement 1075-MRA. Paper no. TPWRS-01380-2017.