Research On Distributed Consistency Optimal Charging Control For Electric Vehicles

This paper investigates the participation of plug-in electric vehicles in power distribution network dispatching as a flexible load,the power allocation of charging stations,and the control of modular charging systems,respectively.The details of the study are as follows.Firstly,a distributed consistent optimal charging scheme for electric vehicles considering the power distribution network load is proposed for the problem of safety operation threat caused by large-scale plug-in electric vehicles connected to the power distribution network.The scheme adopts a two layers optimization structure,in which the upper layer establishes an objective function with the goal of reducing the fluctuation of the power distribution network load and satisfying the power demand of charging stations,and uses a particle swarm optimization algorithm to solve the power allocated to charging stations by the grid at each time.The lower layer establishes the objective function with the objectives of maximizing the overall user benefit and reducing the charging current fluctuation in the case of oversupply of charging station power.Further,a distributed charging protocol based on dynamic average consistency is proposed to solve for the optimal charging power of each electric vehicle in the framework of a multi-agent system.The protocol is fully distributed through mutual coordination among the intelligences to complete the power distribution,which can realize plug-and-play of electric vehicles with good robustness and scalability.The scheme can meet the overall user demand while ensuring the safe operation of the power distribution network.Simulations verify the feasibility of the scheme.Secondly,the dynamic average consistent distributed charging protocol is targeted at the problems of slow convergence and high communication resource loss in solving the optimal charging problem of electric vehicles,a distributed fixed-time charging strategy based on event-triggered charging is proposed in the framework of multi-agent system.The distributed consistency protocol is designed according to the fixed-time convergence theory,and the convergence time of the system depends only on the parameters of the consistency protocol.To reduce the communication resource loss of the system,an event-triggered mechanism is designed,where an agent interacts with its neighboring agent with information only when the triggering condition is reached.A rigorous proof of the convergence of the system to the optimal solution in a fixed time and the absence of Zeno behavior is given.Simulations verify the effectiveness of the designed strategy.Finally,an adaptive predetermined performance controller is proposed for a modular charging system for electric vehicles to solve the problem of sudden changes in output voltage caused by load variations.A time-varying barrier Lyapunov function is introduced and combined with the backstepping method to design the controller to ensure that the output voltage of the system can be limited to a predetermined range.Further,a finite-time load estimator is proposed to estimate the load variation in real time considering the variation of the system load when the electric vehicle is accessed and left,and the estimated value is fed back to the controller to enhance the robustness of the system.A rigorous proof of the bounded output voltage and stability of the system is given.Simulations verify the effectiveness of the designed controller.