Flexibility studies in system planning at ERCOT

System flexibility, or the ability of a power system to respond to variability and uncertainty in demand and supply, is an important factor that helps determine whether a power system can accommodate large amounts of variable generation such as wind and solar. As such, flexibility is becoming a key area of system assessment in ERCOT, which has seen dramatic growth in wind generation in recent years and expects to see continued wind growth along with solar growth in the near future. In this paper, a methodology for studying system flexibility in a planning context is presented, including some challenges in realistically modeling the system to ensure the accuracy of these studies. The results of flexibility studies that were performed using EPRI's InFLEXion tool are also shown. Finally, the next steps in improving flexibility studies and incorporating them into ERCOT's system planning process are described.