Frequency Response in the Western Interconnection with Significantly High Shares of Inverter-Based Resources: 100% Renewable Case

The investment in solar and wind power plants continues to accelerate given the economical and policy incentives provided. This paper studies the integration of these resources and displacement of synchronous generators in the Western Interconnection. It specifically assesses the potential impacts that significant shares of inverter-based resources (IBR) could have on the frequency response of this system operating with high percentages of renewable energy. To this end, it replaces the extant synchronous generators with IBRs in four phases, and closely emphasizes whether the underfrequency load shedding (UFLS) plan is instigated. The results suggest that operation under high shares of IBR could activate the UFLS plan. They also show that IBR power plants with headroom reserve could enhance frequency even under very low inertia conditions because of their ability to respond quickly.