Energy-Based Cooperative Distributed MPC for Frequency Control in Microgrids

This letter develops an energy based cooperative distributed model predictive control (DMPC) scheme for frequency (or voltage) stabilization in microgrids. Firstly, we present a novel integral supply constraint based on Bregman energy functions that ensures equilibrium-independent asymptotic stability of nonlinear microgrid models. Secondly, we design DMPC controllers with integral supply constraints that cooperate towards achieving global microgrid stability via supply sharing. We compare the developed cooperative DMPC scheme with a non-cooperative DMPC scheme that uses passivity-type of constraints and becomes infeasible during a load change scenario. Compared with distributed averaging proportional integral controllers, the developed cooperative DMPC scheme yields shorter settling times (4s versus 18s) and much smaller overshoots. The developed energy based cooperative DMPC scheme results in supply sharing and cooperation among the different generators to achieve frequency stabilization, which is a very desirable property for emerging smart grids with distributed operation.