Analysis of ERCOT regulation-up and regulation-down operational reserves

The short-term production variability of utility scale renewable generation is compensated for by Operational Reserves. At first sight, it might be expected that the required reserves would increase with the amount of renewable installed power. However, this has not recently been the case in ERCOT, where operational reserves requirements have decreased over time. A closer look reveals that other changes have occurred over time as specified in Nodal Protocol Revision Requests (NPRRs). This paper presents a statistical analysis of the impact of different NPRR changes over ERCOT procured Regulation-Up and Regulation-Down operational reserves. The significance of them was assessed by using the Regression Discontinuity Design method. The results suggest that eventually more renewable generation can be introduced without a significant increasing of operational reserve requirements.