Grid inadequacy assessment for high power injection diversity. Part I: Framework and metrics

Abstract

The integration of more intermittent generation, energy storage, and dynamic loads on top of a competitive market environment requires future grids to handle increasing diversity of power injection states. Grid planners need new tools and metrics that can assess the vulnerability of grids in this future. To this end, we propose a new grid inadequacy assessment framework and a set of metrics that expose a grid’s inherent inability to accommodate high power injection diversity without intervention. We define the metrics based on a previously unexplored characterization of grid inadequacy, that is, we use the size of the power flow infeasible set relative to the size of the power injection set as indicator of inherent grid inadequacy. We circumvent the difficulty of characterizing the high-dimensional sets involved using three approaches: one scenario-based approach and two novel approaches that project the sets in lower dimensions. Illustrative examples show how the metrics can reveal useful insights about existing grid bottlenecks resulting from diverse operating states that may otherwise go unnoticed. As with other metrics, the proposed metrics are only valid relative to the assumptions used and cannot capture all intricacies of assessing grid inadequacy. Nevertheless, the metrics provide a new way of quantifying grid inadequacy that is potentially useful in future research and practice. Part II of the paper studies the application of the metrics in identifying and assessing grid expansion options that are less inherently inadequate than others.