Economic Dispatch for DC Microgrids: An Optimal Power Sharing Approach with Batteries

In this paper, we propose a hierarchical control structure comprising three layers which is able to (i) achieve economic dispatch for islanded DC microgrids, (ii) compensate load and generation disturbances with batteries performing power sharing and (iii) stabilize non-passive constant power loads. The batteries are charged economically optimally by the third layer controller such the state of charges (SOCs) remain constant. The proportional power sharing of the batteries is achieved by employing a novel control law which solves the linearized steady-state power flow equations in real time. The microgrid is stabilized by using voltage controllers for batteries and active damping elements. A numeric method to verify closed-loop asymptotic stability is derived. The power sharing of the batteries and stability achieved with the proposed control is demonstrated in a simulation.