As power grids add more renewable energy and large-scale battery storage, utilities face a growing challenge: how to stress-test tomorrow's electricity systems before investing billions to build them. Wind, solar and battery-backed grids behave differently from traditional power systems. They are faster, more complex and harder to predict, especially during faults, extreme weather or sudden demand spikes. But using today's simulation tools to test those scenarios can take days, which limits how many "what-if" questions engineers can realistically ask.