Fault Analysis and Protection of low-voltage DC Microgrid Equipped by Renewable Energy Resources

This chapter consists of two sections, 'Modelling of DC Microgrids' and 'Protection of DC Microgrids. In the first section, the new developments in DC Microgrids are discussed, then, the Modelling of renewable energy resources based DC Microgrid using characteristics and mathematics equations of each component are presented and then they are simulated by MATLAB. Afterward, the fault analysis and fault current behavior of the studied DC Microgrid are investigated. In the second section, a method of protecting the DC Microgrid and locating the fault in different parts of the system are proposed. The proposed method protects DC Microgrid using localized protection devices. And, the effectiveness of the proposed protection method is validated in a DC Microgrid with ring configuration. GENERAL INTRODUCTION This chapter is summarized as follows: in the first section, the new developments on DC Microgrids are discussed and future trends of DC Microgrids in power grid, aircraft and vehicles are introduced. Then, a DC Microgrid including Photovoltaic (PV), Wind Turbine (WT), battery, DC motor, and power electronic converters is simulated in MATLAB for fault studies. In addition, the behavior of these components during fault is investigated by mathematical and simulation analysis. The protection challenges and constraints are also discussed in this section. In the second section, the new protection methods for DC Microgrids are presented and compared, then, a protection method based on the characteristics of the DC Microgrids and DC current nature is proposed. The protection method uses communication links and localized protection devices to locate and detect fault. In addition, this method uses the equation of current and voltage variation to find the location of fault. Finally, the proposed protection method isolates the faulty zone and insures the normal operation of other zones. The presented method uses the characteristics of current to detect the location of faults in the DC Microgrid. As a final point, the results of the proposed methods are shown, and the effectiveness of these methods is demonstrated by simulation in MATLAB environment.