Microgrid Operation with 100% Renewables

A. Mehrizi-Sani
Washington State University, Washington, United States

Keywords: power system, microgrid, inverter, renewables

The power system is slowly moving toward domination by renewable energy resources. This scenario is even more likely in microgrid systems, both in civilian (e.g., hospitals) and military (e.g., remote camps) applications where PV generation coupled with batteries is the most readily available and sustainable mode of generation. Renewable energy resources are typically interfaced to the grid via power electronic inverters. Domination of the power grid inverters represents a significant departure from the conventional power system. For example, (i) frequency is not a measure of generation-load balance, (ii) no inertia exists to act as a stabilizing (or destabilizing) force, (iii) harmonics can be abundant, (iv) synchronous generator-derived stability concepts are not necessarily applicable, and (v) protection requires a complete revisit. The characteristics of power electronics, e.g., their lack of mechanical inertia and their inherent limitations, both help and deteriorate the stability and operation of the power system. Therefore, while such systems do not necessarily face the same challenges as a conventional power system, it does need to address its own unique challenges. We showcase our results in operation of such a system and how it can overcome disturbances and power quality issues to provide a stable power delivery system.