Multi-layer optimization method for siting and sizing of distributed energy storage in distribution networks based on cluster partition

In the context of China's "dual carbon goals" the integration of Distributed Energy Storage (DES) systems into the grid is an effective method to enhance the utilization of clean energy. However, the siting and sizing of these systems remain significant challenges. This paper proposes a multi-layer optimization strategy based on cluster planning for the siting and sizing of DES, aimed at improving both the cleanliness and economic efficiency of distribution networks. Firstly, the distribution network is divided into clusters according to the network structure and node load characteristics. Then, a multi-layer coordinated siting and sizing model for DES is established based on these clusters. In the upper layer, clusters serve as basic units, and the objective is to minimize the net cost by planning the Energy Storage (ES) configuration for each cluster. The middle layer focuses on regulating the voltage state of the clusters, to optimize the voltage levels. This layer makes adjustments to the ES configurations and power distribution between the upper and lower layers accordingly. In the lower layer, nodes within each cluster are considered basic units, and the goal is to minimize network losses by optimizing the placement of ES within the clusters. For this model, the upper and lower layers interact through voltage control constraints in the middle layer, serving as both objective quantities and variables for each other. The solution is obtained through an iterative cycle. Simulations on the IEEE-118 bus system demonstrate that compared to a single-layer model strategy, the ES cost is reduced by 22.88 %, the number of installation nodes is reduced by 3, the total system network loss is reduced by 9.60 %, and the regulation effect on voltage fluctuations is improved by 8.60 %. The application of this method in actual distribution networks has also achieved significant results. This approach effectively enhances economic benefits and facilitates the efficient consumption of new energy sources, promoting the broader application of clean energy and injecting new momentum into the sustainable development of humanity.