Accurate Modeling of DC Microgrid for Fault and Protection Studies

DC Microgrid is a new power system scheme consist of Distributed Energy Resources (DER), storage and DC loads. The fault and protection analysis for this DC Microgrids is a challenging study, due to the high rise time and. Therefore, proposing an accurate DC Microgrid model is an essential part of accurate fault analyzes. Based on the dynamic model of all components, an accurate and dynamic model of DC Microgrid is proposed in this paper. The proposed method divided into five parts: DER including of Wind Turbine (WT) and Photovoltaic (PV) energy resources, transmission line, power electronic converter, battery energy storage and DC loads. Moreover, based on the characteristics of the loads and converters, the behavior of this part is similar to a Constant Power Load (CPL), and it influences the dynamic of the DC Microgrid. In addition, to calculate short circuit current of CPLs, a new time-based formula is presented. This paper investigates the detailed behavior of CPL fault current on DC microgrid operation. The sensitivities of the fault current on CPL are analyzed. Simulation is implemented in a case study to evaluate the effectiveness of the proposed model of DC Microgrid.