As part of the Year 9 Annual Review and Site Visit by the National Science Foundation (NSF), students and faculty demonstrated several features of the FREEDM System design. Our high bay lab in the Keystone Science Center on Centennial Campus at NC State is known as the Green Energy Hub (GEH). The GEH was designed with a 12 kilovolt loop feeder rated at 1 Megawatt. It has a 40 kilowatt solar array on the roof, connections to multiple electric vehicle chargers, and an outdoor equipment pad for connection to other devices.

The lab demonstrations included a medium voltage Solid State Transformer (SST), medium voltage operation of the Fault Isolation Device (FID), remote connection to the Hardware in the Loop facility located at Florida State University for demonstration of Volt VAR Control (VVC) algorithms, and several features of the FREEDM system as applied to a home energy management scenario.

More details can be found in the project descriptions but here are a few highlights:

• SST soft switching and efficiency measurement at steady state
• SST short circuit current protection
• FID operation at 3.5 kV and 50 amps
• VVC confirmation through application of FREEDM Distributed Grid Intelligence (DGI)
• Coordination of multiple emulated loads and sources using a Home Energy Management System
• Optimized scheduling considering forecast errors
• Coordination of 3 low voltage SSTs using DGI