Protection Scheme for Loop-Based Microgrids

This paper presents a protection scheme for loop-based microgrids, which is divided into four levels, including load-way, loop-way, feeder, and microgrid. The scheme applies a dual protection strategy at the load-way level and a single protection strategy at the other three levels, which are designed to handle various types of faults in grid-connected and island modes of microgrids. The microgrid primary and back-up protections are taken into consideration at each level for grid-connected and island modes. The plug and play characteristics, time constraints of low voltage ride through, and unbalanced faults are considered for distributed generations. This paper demonstrates that the microgrid reliability is improved by coordinating the logics in the four proposed protection levels. The Illinois Tech microgrid is used as a design testbed to verify the effectiveness of the proposed protection scheme.