A multistage expansion planning method for distribution networks incorporating an adaptive short-term correction mechanism

Multistage expansion planning for distribution networks (DMEP) must jointly address uncertainty and reliability, while coordinating the scheduling, siting, and scaling of diverse distributed energy resources (DER). To overcome the limitations of traditional long-term planning in adapting to dynamic operational demands, this paper proposes a bilevel planning model incorporating an adaptive short-term correction mechanism. In the upper level, probability distributions of source–load growth rates are modeled to determine long-term expansion schemes for substations, feeders, and distributed generations. In the lower level, a short-term correction mechanism is introduced to address source–load fluctuations and support flexible DER operation, enabling stage-by-stage rolling deployment of energy storage (ES). Distinct from fixed phase boundaries, an adaptive phase partitioning strategy is developed to dynamically identify the optimal expansion timing, avoiding premature investment and excessive operational burdens. Furthermore, reliability constraints are incorporated into DMEP, with ES siting optimized through key node assessment and network expansion designed using a graph-theoretic approach, enhancing both nodal supply security and regional power balance. Case studies demonstrate that the proposed method effectively addresses source–load uncertainties and operational risks of vulnerable nodes and branches, reducing the total planning cost by 7.64 %. Validation on a 54-node system further confirms its scalability and practical value.