SPLTRAK Abstract Submission
Multiple Inverter Microgrid Experimental Fault Testing
Nicholas S. Gurule, Javier Hernandez-Alvidrez, Matthew J. Reno, Jack Flicker
Sandia National Laboratories, Albuquerque, NM, United States

For the resiliency of both small and large distribution systems, the concept of microgirds is arising more often. The ability for sections of the distribution system to be “self-sufficient” and operate under its own energy generation is a desirable concept. This would allow for only small sections of the system to be without power after being affected by such events as a fault or a natural disaster, and allow for a greater number of consumers to go through their lives as normal. Research is needed to determine how different forms of generation will perform in a microgrid, as well as how to properly protect an islanded system. While synchronous generators are well known and generally accepted amongst utility operators, inverter-based resources (IBRs) are less common. An IBR’s fault characteristic varies between manufacturers and is heavily based on the internal control scheme. Additionally, with the internal protections of these devices to not damage the switching components, IBRs are usually limited to only 1.1-2.5p.u. of the rated current depending on the technology. This results in traditional protection methods such as overcurrent devices being unable to “trip” in a microgrid with high IBR penetration. Moreover, grid-following inverters (commonly used for photovoltaic systems) require a voltage source to synchronize to before operating and do not provide any inertia to a system. The grid-forming counterparts on the other hand can operate as a primary voltage source, and provide an “emulated inertia” to the system. This study will look at a small islanded system with a grid-forming inverter, and a grid-following inverter subjected to a fault.