Research On Distributed Charging And Discharging Dispatching Strategies For Electric Vechicles Considering Wind Power Accomodation

With the dual background of the shortage of oil resources and environmental pollution,electric vehicles are bound to be widely used as new energy tools.However,when the number of electric vehicles is too large,the uncontrolled charging and discharging will bring the negative effects such as the increase of peak-valley difference,the increase of network loss and the decrease of node voltage.The effective control strategy can be used to guide the charging and discharging of electric vehicles,and cooperate with the power grid dispatching department to achieve the smooth running of system,which will reduce the negative impact on the operation of the power grid.At the same time,the phenomenon of wind curtailment and power limitation is serious as the increase in installed capacity of wind power in china,the electric vehicle load and wind power output can be coordinated dispatching to maximize the consumption of wind power and reduce abandoned wind.This paper studies the charging and discharging scheduling strategy of electric vehicles.Firstly,the impact of uncontrolled charging on the operation of the grid is studied,building the orderly charge mathematical model that minimizing losses,minimizing load variance,maximum load factor,and aiming at valley-filling to guide the electric vehicles for orderly charging.The charging optimization results were analyzed,and comparing the characteristics of different optimization targets,then providing a theoretical basis for practical application.Secondly,the existing orderly charging strategies have the disadvantages of slow optimization and unsuitable solution when the number of electric vehicles increases.In this paper,the distributed wind power in the distribution network is treated as a negative load,and a distributed charging and discharging scheduling model for electric vehicles is established with equivalent load valley-filling which can effectively improve the efficiency of optimization problems.Meanwhile,three-phase load balance,node voltage and transformer capacity constraint are considered,equivalent load valley-filling is realized by the charging and discharging of electric vehicle under the premise of the reliable operation of the distribution network.Finally,a power transmission and distribution bi-layer dispatching strategy that takes into account the charging and discharging of electric vehicles is proposed.The electric vehicle load is regarded as a transferable load in the transmission network layer,which promotes the absorption of large-scale clustered wind power;The distribution network layer utilizes the distributed charging and discharging scheduling strategy of the electric vehicle to lead the user's reasonable charging and discharging,to realize the coordinated dispatch of charging and discharging loads of electric vehicles and cluster wind power.Through the example analysis,the electric vehicle orderly charging strategy has the same effect in the charging profiles of electric vehicles with the target of the minimizing losses,minimizing load variance,maximum load factor and the valley-filling valley.However,when the number of electric vehicles is too large,the optimization calculation time will become too long.The distributed charging and discharging scheduling strategy of electric vehicle established in this paper can effectively reduce the optimization calculation time,the three-phase load balance caused by the charging and discharging of electric vehicles is solved,and the equivalent load valley-filling can be realized.The bi-layer dispatching strategy of transmission and distribution network is proposed in the end taking into account the load of electric vehicles,the coordinated scheduling of electric vehicle load and wind power can effectively improve the utilization rate of large-scale cluster wind power.