Controller Design of DC Microgrids with Multiple Sources and Constant Power Loads

This paper addresses the modeling and controller design of large scale dc microgrids with nonlinear loads. First, the dynamic models of the sources and loads are discussed in detail, placing particular emphasis on generators with passive rectification and Constant Power Loads (CPLs) with input filters. These models will be defined as source and load nodes which along with internal nodes, will be integrated to the rest of the network through a graph theoretic approach. The proposed modeling method is general and can be applied to arbitrary networks with resistive lines. Controller design is then proposed based on dynamic consensus techniques and the gains are optimized using Linear Matrix Inequalities (LMI). This technique guarantees the stability and robustness of the system in the presence of CPLs or current source loads. A case study for a four generator system with multiple loads is presented and compared with detailed simulations.