The Co-phase traction power supply system (CTPSS) is a promising solution in smart electrified railways to improve regeneration braking energy (RBE) utilization and mitigate voltage unbalance (VU). It works by coordinating power flow distribution (PFD) among the energy storage (ES), power flow controller (PFC) and transformer. However, the conventional dispatch may result in increasing extra operation costs and accelerating ES aging. Therefore, a dynamic VU regulation strategy is proposed to plan the VU compensation schedule (VU-CS), which can satisfy the probabilistic limitations of standards. Consequently, a VU dependence model is developed to transform the VU-CS into PFD constraint. Meanwhile, an ES degradation model is introduced to quantify the system operation cost within different scenarios. Taking the PFD as a VU regulation constraint, an economic dispatch scheme of CTPSS is established to obtain a minimum operation cost and maximum RBE utilization. Finally, case study tests verify the efficiency of the proposed approach.The results show that scheme can improve ES cycle life and decrease cost under the probabilistic limitations of VU.