A Hetero-Functional Graph Resilience Analysis of the Future American Electric Power System

Abstract

As climate change takes hold in the $21^{st}$ century, it places an impetus to decarbonize the American Electric Power System with renewable energy resources. There is a broad technical consensus that these renewable energy resources cannot be integrated alone but rather require a host of profound changes in the electric grid’s architecture; including meshed distribution lines, and energy storage solutions. One question that arises is whether these three types of mitigation measures required by decarbonization will also serve as adaptation measures when the climate changes and extreme weather phenomena become more prevalent. Consequently, this paper presents a structural resilience analysis of the American electric power system that incrementally incorporates these architectural changes in the future. Building upon a preliminary study, the analysis draws on an emerging hetero-functional graph theory based upon the inter-connectedness of a system’s capabilities. The hetero-functional graph analysis confirms our formal graph understandings from network science in terms of cumulative degree distributions and traditional attack vulnerability measures. The paper goes on to show that hetero-functional graphs relative to formal graphs more precisely describe the changes in functionality associated with the addition of distributed generation and energy storage as the grid evolves to a decarbonized architecture. Finally, it demonstrates that the addition of all three types of mitigation measures enhance the grid’s structural resilience; even in the presence of disruptive random and targeted attacks. The paper concludes that there is no structural trade-off between grid sustainability and resilience enhancements and that these strategic goals can be pursued simultaneously.