Energy storage configuration in transactive distribution systems incorporating integrated network flexibility

The rapid growth of renewable energy sources (RESs) has introduced significant variability and uncertainty into distribution networks, challenging their stable and efficient operation. To address these issues, energy storage systems (ESSs) help mitigate uncertainties from RES generation by enabling local energy exchanges and supporting flexible network operations, including adaptive routing and energy balancing. This study aims to develop a comprehensive optimization framework for transactive-driven ESS configurations in distribution networks with flexible interconnections, integrating both planning and operational considerations to enhance the flexibility, efficiency, and local consumption of distributed energy resources (DERs). A local energy sharing mechanism is proposed, including an innovative wheeling charge calculation model designed for flexible distribution networks with soft open points (SOPs). Then a robust transactive operation optimization model is proposed to handle the uncertainty of DERs' outputs and load demands, considering network operation flexibility as a consequence of SOPs' power adjustments and topology configuration of traditional on-off switches. The ESS configuration problem is formulated as a two-stage optimization, with the first stage determining the optimal storage deployment and the second stage incorporating the robust operational model, solved efficiently via a Column and Constraint Generation (C&CG) algorithm. The proposed models are validated in a modified 33-bus and 118-bus test systems. Results demonstrate that integrating SOPs with network reconfiguration provides flexible routing options for local energy sharing, enhancing local consumptions of DERs; moreover, the proposed ESS configuration optimizes supply-demand balance to improve system efficiency and reduce main grid reliance. It is also observed that ESS configuration is influenced by the local energy-sharing scheme and network flexibility, particularly in terms of SOPs' location and capacity.