A multiphase power flow model for μgrid analysis

This paper presents a new advanced model of an electric power system with distributed energy sources forming a microgrid (μgrid). The μgrid is a radial or networked low voltage distribution system with distributed sources. Each source is interfaced to the system via converters. The DC bus of the converter may have energy storage capability via large capacitors or batteries. The μgrid load consists of both single and three phase loads resulting in unbalanced operating conditions. The μgrid circuits may be three-wire, four-wire or five-wire. The grounding of the system may be single point or multipoint. The analysis of this system requires a new approach. This paper presents a new method for modeling and analysis of this system. The approach consists of two steps: (a) modeling each component of the system via a set of quadratic equations no matter how complex the nonlinearities of the model are and (b) a Newton´s method for the solution of the overall network equations. The method is extremely efficient and robust. The proposed method can accommodate various control modes of micro-sources. Examples of these controls are given in the paper.