Testing the Performance of Grid-Forming Resources: Test Methods and Performance Metrics for Evaluating the Voltage Source Behavior of Grid-Forming Resources presents test methods and performance metrics to rigorously quantify the system-strength benefits of grid-forming (GFM) resources.

As power system operators around the world integrate steadily higher levels of wind, solar, and batteries, GFM technology is recognized as a key enabler of reliable high-renewable grids. Proactive deployment of GFM resources can mitigate reliability challenges that could otherwise require significant transmission infrastructure investment to solve.

The value of proactive deployment of GFM resources is especially true for the hundreds of gigawatts of battery storage capacity in interconnection queues, because the GFM capability can be enabled relatively easily and inexpensively through software changes. A common refrain from large power system operators is, what is GFM control and how can we specify its requirements? This report is an effort to answer that question.

This report provides guidance for evaluating the extent of voltage source–like behavior exhibited by these resources during a short time frame, as the voltage source behavior forms one of the core performance metrics for GFM resources. The report includes test methods that are well accepted by industry as well as new methods that are still evolving and not yet widely used. And it provides example specifications and performance metrics for test methods that can be tailored to the characteristics of the system where a GFM resource is going to be installed.