A study on the dual-layer energy storage configuration in photovoltaic distribution networks considering voltage-loss synergy optimisation

To address the challenges of voltage deviation and increased network losses arising from the high integration of photovoltaic (PV) systems in distribution networks, this paper proposes a bi-level optimisation model for configuring distributed energy storage systems (ESS) tailored to high-penetration PV distribution networks. In the proposed model, the upper-level operational layer minimises voltage deviation and network losses to improve voltage quality and reduce power losses, while the lower-level planning layer optimises overall system cost, focusing on the capacity configuration of lithium-based ESS. The bi-level optimisation problem is solved using the Particle Swarm Optimisation (PSO) algorithm to determine the optimal ESS capacity. Case studies on a modified 33-bus distribution system demonstrate that the proposed model effectively reduces voltage deviation by up to 48.1% and network losses by up to 35.1%, while significantly enhancing economic efficiency through coordinated optimisation of operation and planning. This study offers a practical solution for energy storage planning in distribution networks with high PV penetration, balancing technical performance and economic viability.