Towards the construction of a class of grid operational flexibility metrics

The increased net load uncertainty and variability due to higher levels of renewable energy resource integration into grids require the clear understanding and quantification of grid operational flexibility (GOF) and associated impacts. However, there is no widely-accepted methodology to assess flexibility, guide policy formulation and quantify the value of operational flexibility. Recent efforts towards improved flexibility assessment have focused on feasible net load ramps, operational margins and robustness bounds. In this paper, we propose an approach to GOF assessment focused on the economic impacts related to net load variability/uncertainty accommodation. We illustrate the application of the proposed approach through representative study cases on a modified version of the IEEE Reliability Test System operated under a multi-settlement system. Our results indicate that the market outcomes provide a concrete basis for GOF assessment in general, and in particular, the impacts due to ramping limitations provide insights into a grid's ability to accommodate net load variability/uncertainty.