Power sharing in actuated DC grids in mesh topology

Abstract

Abstract This paper deals with the problem of power sharing in DC micro-grids in mesh topology with multiple active buses. We formally analyze the feedback loop composed by the micro-grid as a multi-agents process, the DC generation units as actuators, the distributed arbitrary loads as disturbances, and a linear consensus based control strategy, in order to characterize its performance in terms of secondary level control objectives as power sharing and mean voltage regulation. Based on existing consensus control strategies, the novelty of this approach relays on the possibility of comparing the performance of different controllers through numeric indicators. Furthermore, the chosen control strategy is not necessarily derived as the Laplacian matrix of an undirected graph. In this way, the proposed strategy can be tuned to achieve optimal behavior in terms of convergence speed, disturbances rejection, or communication links requirements. Furthermore, by doing this we are able to prove that the traditional droop control strategy does not necessarily achieve the desired objectives in mesh topology. Therefore, we focus on the consensus dynamics of the closed loop system, deriving simple test to conclude on its behavior, and to propose a Linear Matrix Inequality (LMI) based procedure to verify the region of voltage deviations at which the control objective can be achieved. Finally, the results of the paper are illustrated through a simulation example.