Optimizing energy storage capacity for enhanced resilience: The case of offshore wind farms

This paper investigates the influence of different configurations of the offshore wind farms (OWF) network on the optimal capacities of battery energy storage systems (BESS) in the face of high-impact low-probability (HILP) events that cause short- to medium-term outages. Large-scale OWFs have garnered increasing attention from investors due to their smaller land footprint and higher energy production potential. However, the external environment, the internal installation, and the long distance from the onshore facilities pose significant challenges to the operations of the OWFs and the stability of the energy supply. These factors render systems highly susceptible to HILP contingencies, while timely post-disaster management, such as addressing subsea transmission cable failures, is challenging. Although BESS has long been considered a viable strategy to improve the resilience of the system, the decision-making process to determine the optimal BESS capacity is underexplored. This is more pronounced when considering the diverse OWF topologies that can significantly impact energy supply efficiency and, consequently, impact the stable operation of BESS. This study employs a methodology based on sequential “planning + operational” modeling approach that integrates Agglomerative Hierarchical Clustering (AHC), an optimal OWF network configuration algorithm, a stochastic system failure scenario generation approach, and an optimal BESS capacity model. Comprehensive profiles of optimal BESS capacity are derived corresponding to different clustering levels. Applying the proposed model to three different OWF cases derived the optimal BESS capacity, balancing resilience enhancement and economic considerations. In the context of the modeling settings in this study, this optimal capacity is approximately 16% of the daily electricity generation at full capacity, excluding the capacity factor. Optimal BESS capacity not only standardizes and facilitates the design process of more resilient OWFs to short- and medium-term system failures, but also provides policymakers with a basis to consider and implement strategies to coordinate the use of OWF energy and other available power generation technologies in the market. This study bridges the research gap between OWF topology studies and discussions on system resilience while shedding light on the relationship between optimal BESS capacities and the ideal number of clusters.