A distributed control scheme for voltage regulation in DC distribution systems

In this paper, a distributed control scheme is proposed to mitigate the challenges of voltage regulation in DC distribution systems and facilitate high penetration of distributed and renewable energy resources. The proposed control scheme consists of two main stages. In the first stage, a distributed state estimation algorithm is implemented to estimate the voltage profile in a DC distribution system and enhance the AC/DC converter operation in order to keep the system voltage within its specified limits. Further, in case of occurrence of voltage violation that cannot be handled by the AC/DC interfacing converter a reconsideration of power management would take place. Thus, in the second stage, a distributed power management optimization problem is formulated to maximize the total DGs' revenue; while keeping the voltages of all system buses within limits. The formulated problem is classified as a convex optimization problem under global constraints. A distributed Lagrangian Primal-Dual Subgradient (DLPDS) algorithm that is superior in solving such optimization problems is proposed in this work.