Controller design and stability analysis of grid connected DC microgrid

DC microgrids are desired to provide the electricity for the remote areas which are far from the main grid. The microgrid gets popularity because DC power sources such as photovoltaics (PVs), battery banks, and fuel cells can be interconnected without AC/DC converters. The stochastic nature of PV power and variation in the demand are responsible for voltage fluctuations in the DC microgrids. The voltage stability is a most important issue in the case of DC microgrids. The challenging thing is to maintain the microgrid voltage up to a reference value for the variable load. This paper focuses on designing a controller to obtain the voltage stability of the microgrid. Two controllers [PI and fuzzy logic PI (FL-PI)] are designed for the voltage stability analysis of the DC microgrid. Real-time simulation results show that upon appropriate choice of controller parameters, the DC microgrid voltage can be kept constant regardless of the wide range of voltage variations of the source and the load. The simulation results show the comparison of two controllers. The FL-PI controller shows much better performance than the conventional PI controller for the DC grid voltage control. With the inclusion of the proposed controllers, controlled voltage will be obtained, whatever may be the load and its variation.