Research On The Control Mechanism Of Charging Congestion And Grid Connection Of Electric Vehicles In Urban Area

Electric vehicles(EVs)can effectively reduce the greenhouse gas emission of transport sector.With the introduction of "carbon peak,carbon neutrality" national longterm climate development strategy,the number of EVs increase continually with a high growing rate in the future.Considering the regularity of EV traveling pattern,as well as the limited charging facility number within a certain region,how to coordinate the limited EV charging resources and reduce the power system impact that imposed by large-scale grid-connected EVs,is becoming a key technical issue that needs to be addressed in the development of EV industry under carbon neutrality background.By selecting charging station and parking lot as the typical application scenario of fast and slow charging technology respectively,the charging congestion and grid-connection control of EVs in the urban area is investigated in this paper to alleviate the charging congestion phenomenon,as well as improve the charging satisfaction and grid reserve support ability of EVs.Firstly,based on the cloud scheduling system model,the information interaction and data feedback mechanism among scheduling system,EV owner and the operator is respectively designed under fast and slow charging scenarios.On this basis,the basic concepts that related to the Lyapunov optimization theory and EV clustering technology are elaborated and derived in detail,as the necessary theoretical basis for the subsequent modelling process of following sections.After that,the charging control strategy of EVs in the charging station is investigated.In order to achieve the dynamic characterisation of EV’s electricity demand in the charging process,a time-slice queue modelling scheme of EV charging process is proposed.On this basis,a stability evaluation mechanism of time-slice queue in charging stations is established based on the Lyapunov function.And a user’s dissatisfaction evaluation mechanism is constructed by taking the traveling time increment that related to the occurance of EV guidance into account.With the consideration of EV guidance feasibility between different charging stations,an EV guidance model is formulated based on the "drift plus penalty " modeling idea of Lyapunov optimization theory.To cope with directly solving infeasible problem of propoed EV guidance model,a transformation strategy is suggested based on the conception of guidance decision matrix,and the characterisation analysis proposed solving strategy is carried out by means of theoretical derivation.Simulation results show that the proposed model can trace the electricity demand fluctuation of EVs dynamically.So as to relief EV charging congestion and improve EV’s charging satisfaction by modifying the EV charging access plans.Finally,the research of EV charging management under slow charging scenario is carried out.With the consideration of EV guidance feasibility between different parking lots,the EV accessing guidance model is constructed to alleviate the charging congestion.On this basis,the reserve declaration boundaries of EV individual and parking lot operator are determined in sequence based on the conception of electricity fluctuation feasible region.Considering the asynchronous problem of EV appointment interval and reserve market time scale,a time-scale correction mechanism is suggested to guarantee the validity of parking lot reserve declaration result,and the day-ahead optimal scheduling model of parking lots is constructed accordingly.Simulation results show that the proposed charging management model can fully evacuate the EV accessing and reserve declaration potential of parking lots,and achieve the goal of parking lot’s economic benefits improvement ultimately.