The parallel mobile charging service for free-floating shared electric vehicle clusters

Abstract

Due to the simple rental procedures and unrestricted parking spots, free-floating shared electric vehicles (SEVs) are widely selected by travelers. A large number of SEVs gather together and even form SEV clusters at popular destinations. In most studies, the low-charge SEVs are usually relocated to charging stations to recharge their batteries. This paper proposes the parallel mobile charging service to route mobile charging vehicles (MCVs) to charge SEVs at their parking spots. The MCV routes are optimized through a mixed integer nonlinear optimization model where MCVs with limited battery capacity could recharge their batteries at available charging stations and sequentially or simultaneously charge the filtered SEVs at the same SEV cluster node. The parallel mobile charging service proposed without relocating SEVs fully takes advantage of SEV clusters (i.e., cluster-based overlapping idle time windows and small inter-vehicle distance) and MCVs (i.e., charging multiple SEVs simultaneously). An adaptive large neighborhood search algorithm is developed to solve large-scale instances where a generalized cost function is constructed to balance the effects of battery capacity violations and time window violations on solutions. Comparing with the optimization solver CPLEX, the adaptive large neighborhood search algorithm developed demonstrates high performance. In addition, the cluster-based parallel acceleration time ratio is introduced to demonstrate the advantages of parallel services in utilizing the cluster-based overlapping time windows.