A Novel Hierarchical Section Protection Based on the Solid State Transformer for the Future Renewable Electric Energy Delivery and Management (FREEDM) System

The effectiveness of a protection scheme in any power grid is essential to the reliability of the supply. One of the main goals of the FREEDM systems is to increase supply reliability to end users. However, traditional protection methods, including over current, sequential components, and wide differential area protection, are not suitable for this system for several reasons that will be explained in the paper. A new protection strategy is presented in this paper. This protection scheme takes advantage not only of the system configuration but mostly of the solid state transformer capability and design to minimize any circuit and communication that are needed for a successful protection strategy. A real time digital simulator (RTDS) is used to model a sample FREEDM system in order to verify the proposed protection scheme. Hardware-in-the-loop (HIL) testing was performed to verify the proposed protection scheme.