Hedging against asset-heavy network expansion delays through rapid deployments of FACTS and BESS

Transmission expansion delays represents a critical barrier to the timely and cost-effective development of modern power systems, particularly for integrating renewable energy. Although network congestions arising from postponed major infrastructure projects (e.g., new transmission lines) can severely impact system efficiency, these effects can be mitigated through the rapid deployment of flexible technologies such as FACTS devices and Battery Energy Storage Systems (BESS). In this paper, we propose a two-stage stochastic optimization framework that complements first-stage, asset-intensive network expansion decisions with second-stage, scenario-dependent investments in flexible transmission assets, including FACTS and BESS. The formulation explicitly captures the probabilistic nature of project delays, accounting for zonal variations in the likelihood of such delays and their implications for system planning. Through a set of case studies, we demonstrate that the strategic use of FACTS and BESS can serve as an effective hedge against the adverse impacts of transmission expansion delays.