Optimal Co-Planning of Multi-Port Soft Open Points and Energy Storage Systems for Improving Hosting Capacity and Operation Efficiency in Distribution Networks

Soft open points (SOPs) and energy storage systems (ESSs) are seen as promising options to improve hosting capacity (HC) for renewable energy sources and the operation efficiency of distribution networks. However, there is a need for proper co-planning of multi-port SOPs (MSOPs) and ESSs to better exploit their spatial and temporal flexibility. Thus, this paper proposes a co-planning method to determine the locations, capacities, and integration forms of MSOPs and ESSs that can achieve optimal cooperative benefits in terms of HC and operation efficiency while guaranteeing cost-effective investments. A two-layer stochastic programming model is formulated with a cooperative benefits metric combining the degree of branch current's temporal even distribution and network loss sensitivity. To regulate the cost-effectiveness level, the profit constraint that accounts for stochastic electricity prices is developed in the two-layer model. Moreover, a convex MSOP-ES model, based on Kirchhoff's law and current polynomials, is embedded in the two-layer model, enabling multiple integration of MSOPs and ESSs. Then, a customized decomposition algorithm and a sequential strategy of siting and sizing solve this two-layer programming problem. Case studies on the IEEE 33-bus distribution network and a real distribution network are executed to validate the effectiveness of the proposed method.