A Multi-Stage Expansion Planning Method for Rural Distribution Networks with Flexible Interconnection

With the increasing penetration of distributed generations and continuous growth of loads, traditional rural distribution networks face severe challenges in both hosting capacity and reliability. Addressing these issues requires planning approaches that strike a balance between economic efficiency in infrastructure development and resilience in operation. Considering the dynamic growth of distributed generations and rural loads over the planning horizon, this paper presents a multi-stage expansion planning approach that coordinates flexible interconnection devices (FIDs) with substation and line construction to improve both economic performance and system reliability. The proposed method account for the time-varying growth of DGs and loads, as well as the declining investment cost of power electronic devices across multiple planning stages. The model holistically considers both economic efficiency and operational reliability, formulating the problem as a mixed-integer second-order cone programming (MISOCP) model to ensure computational efficiency. Case studies conducted on a practical 138-node rural distribution network in Guangxi, China, demonstrate the effectiveness of the proposed method. Compared to traditional single-stage or single-resource planning strategies, results indicate that the proposed multi-stage coordinated strategy achieves a significant reduction in total annualized cost while simultaneously enhancing system reliability, effectively mitigating voltage violations, and achieving a 100% PV accommodation rate without curtailment. This work provides a practical and adaptive planning framework for rural distribution networks, offering valuable insights for achieving cost-effective and resilient network development under rural energy transition.