Robust Dynamic Co-Planning of Distribution Feeders and Virtual Distribution Feeders Considering Emergency Rating and Battery Degradation

Rapid load growth and increasing operational uncertainty pose significant challenges to conventional distribution network planning. To address these challenges, this paper proposes a robust dynamic co-planning framework for distribution feeders and virtual distribution feeders (VDFs). Firstly, a dynamic co-planning model is developed to jointly optimize feeder reinforcement and battery energy storage system (BESS)-based non-wire alternatives over a multi-year horizon. Then, a robustness index (RI) is proposed to quantitatively evaluate the robustness of planning solutions under operational uncertainties without relying on assumed probability distributions. Four objectives are optimized simultaneously: (1) net present value cost (NPV), (2) cumulative overload quantity (COQ), (3) incremental capacity idle rate (ICIR), and (4) robustness index (RI). In addition, feeder emergency rating and battery degradation are incorporated to capture feeder-side thermal flexibility and storage aging characteristics in the planning process. Finally, the proposed method is tested on a modified IEEE 33-bus system. The results show that the proposed framework achieves a superior trade-off between cost, utilization, and robustness than conventional approaches, while reducing unnecessary BESS deployment and improving the physical consistency of the planning results.