Nonlinear Control of a Two-Stage 1-MWh Grid-Connected Battery Energy Storage System by Exact Linearization via State Feedback.

This paper presents modeling and nonlinear control of a two-stage 1-MWh battery energy storage system (BESS) connected to a distribution grid. The BESS is based on a cascaded H-bridge (CHB) multilevel converter offering the distribution of the batteries among multiple submodules which provides safer operation and more flexibility in the voltage design of the batteries. The main function of the BESS is to exchange active and reactive power by controlling the current of the CHB using voltage oriented control strategy. Moreover, this paper proposes a nonlinear state feedback exact linearization controller to control the bidirectional buck–boost converter in each submodule to charge/discharge the batteries and stabilize the dc-link capacitor voltage throughout the operation of the BESS. The proposed controller performance is compared with the conventional PI controller and validated through simulation results. [ABSTRACT FROM AUTHOR]