Bi-hierarchy capacity programming of co-phase TPSS with PV and HESS for minimum life cycle cost

•A scheduling optimization model for co-phase TPSS with PV and HESS is proposed, which takes the three-phase voltage unbalance as the constraint and short-term operating cost as the objective. It can sufficiently coordinate HESS- PFC and PV to achieve traction load peak-shaving and valley-filling and improve power quality comprehensively.•Considering the interactive influence of PFC reliability and HESS charge/discharge, an integrated lifetime evaluation model of HESS-PFC is established. The PFC reliability assessment and battery degradation process are embedded into the model to evaluate the PFC and battery lifetime for the lower long-term investment cost.•A bi-hierarchy capacity programming strategy is designed to combine long-term investment cost and short-term operating cost for achieving minimize life cycle cost. In the upper layer, the capacity of HESS-PFC as the input of the lower layer is planned. In the lower layer, the optimization scheduling results is fed back to the upper layer. A globally optimal solution is obtained through multiple iterations.