A Three-Layer Stochastic Energy Management Approach for Electric Bus Transit Centers With PV and Energy Storage Systems

Abstract

Along with the increasing electric bus (EB) penetration, the impact of the extensive charging load on the distribution system has been aggravating. To mitigate such impact, energy storage systems (ESSs) and photovoltaic (PV) are usually installed in the EB transit centers (EBTCs). In this article, a three-layer stochastic energy management approach is proposed for EBTCs to reduce the operation cost while maintaining local voltage quality. In the first layer, a modified robust optimization over time (ROOT) approach is developed to obtain the charging/discharging margin with minimum EBTC operation cost. In the second layer, the voltage regulation impact on the local voltage quality is estimated through power flow analysis considering voltage fluctuation and line loss minimization. In the third layer, the charging/discharging strategy is optimized with dynamic programming based on a modified greedy algorithm. The performance of the proposed approach is evaluated in a case study based on the IEEE 123-bus test feeder and the real operation data obtained from St. Albert Transit in Alberta, Canada. The results indicate that the proposed approach can not only minimize the EBTC operation cost but also well maintain the local voltage quality, in comparison with existing energy management approaches.