A Multi-stage Expansion Planning Method for Distribution Networks Based on Explicit Reliability Index

Modern distribution networks are often constructed in grid and operated in a radial manner to improve the transfer capacity under fault conditions. The traditional distribution network planning method generally adopts the two-stage iterative calculation method of planning design and reliability evaluation, which can only obtain an extensive planning scheme; the resulting planning scheme is either over invested or unable to meet specific reliability requirements. Therefore, a multi-stage distribution network expansion planning method considering reliability constraints is proposed. The reliability index calculation process is analyzed and embedded into the planning model, which can accurately consider the fault isolation, load transfer and recovery strategies. Based on the linearized power flow, the planning model is a typical mixed integer linear optimization problem, which can be effectively solved. The performance of the proposed method is verified in the Portugal 54-node system. The simulation result proves the effectiveness and flexibility of this method.