A Framework to Enhance Grid Resilience for Long-Term Planning of Transmission Systems

Along with the retirement and phase-out of more dispatchable conventional generators, these factors are leading to tighter operating reserve margins and greater weather dependency of the power system. Additionally, transmission systems are increasingly exposed to more intense and frequent extreme weather events due to climate change. Consequently, ensuring power system resilience is becoming a critical priority for power system operators and planners. In this context, policymakers are asking transmission system operators (TSOs) to enhance resilience against extreme events, while simultaneously pursuing power system decarbonization.

Traditionally, resilience investment planning has been incremental and highly targeted. Based on historical operational information, TSOs identify specific components within their system that are vulnerable to specific extreme weather conditions. Investment planning to upgrade these specific components focuses on analyzing the tradeoff between the investment cost of the upgrade and the economic outcome of its improved performance under those specific weather conditions. This piecemeal approach does not integrate effectively with conventional capacity expansion planning, since potential synergies between investment decisions to address multiple types of extreme weather events are not adequately captured. As a result, component-level resiliency planning leads to sub-optimal investment decisions for the system in the long term.

Therefore, TSOs need a more holistic and integrated planning approach that combines the investment decisions necessary for resource adequacy with those required for system resilience.

Such an approach should enable the determination of the best portfolio mix of generation and transmission solutions for ensuring adequacy and flexibility, while also providing recommendations on the effective management of economic decisions and risks inherent to the energy transition under an increasingly uncertain climate outlook.

This article proposes a comprehensive framework for integrated resilience investment planning.

It assesses the resilience of power system against extreme weather-based risks and provides investment decision support that improves its ability to reliably provide continuity of service.

It combines various computational and numerical techniques to examine a variety of system operational scenarios due to different types of high-impact low-probability (HILP) events. The resulting outputs include recommendations for generation and transmission network expansion for reliable and resilient system performance at the lowest possible cost. Conceptually, the framework leverages numerous scenarios, each representing a different realization of an event’s impact on the power system’s generation and transmission components. The scenarios serve to assess various options under different circumstances. By capturing the variability from the large number of generated scenarios, the output investment recommendations reflect the tradeoffs between investment costs and acceptable levels of decision-makers’ risk. The framework is tested and validated for some benchmark test grids, and some example results are presented.