The optimal configuration planning of energy hubs in urban integrated energy system using a two-layered optimization method

•A novel expansion planning model for urban integrated energy system is proposed.•The transportation network is incorporated into the model, in which fast and slow charging modes are considered.•A layered-based framework for the optimization model of the urban integrated energy system is proposed.•A two-layer optimization algorithm is designed to solve the proposed model.•Simulation results based on a real case in China indicate the superiority of the proposed approach.