Linear Optimal Power Flow Model for Modern Distribution Systems: Management of Normally Closed Loop Grids and On-Load Tap Changers

Modern distribution systems face new challenges due to the rise of small‑scale renewable energy resources and the electrification of energy demand. Additionally, the complexity of network management increases with the exchange of flexibility services between distribution and higher voltage levels. The system operator’s role involves optimizing the planning and operation of the distribution network. In current scenarios, this includes managing flexibility resources (such as generators, demand response, and on‑load tap changers) and implementing new operating strategies (such as closed‑loop topologies and dynamic reconfiguration). This paper proposes a reformulation of one of the most used linear approximations of the Optimal Power Flow model for distribution networks. The novelty of this reformulation lies in integrating equations to handle tap‑changing transformers with closed‑loop/meshed network operation, while preserving the original linear formulation and computational tractability.