Research On Charging Strategy Of Electric Private Vehicle Considering Travel Uncertainty

Electric vehicles(EVs)gradually repelacing fuel vehicles as the major transportation for people because of the advantages of low carbon energy,environmental protection and so on.Due to the trip characteristics and uncertainty charging behaviors of the owners,large-scale disordered charging will cause the randomly increased fluctuation of residential load and add the expected overload running time of distribution transformer.What's worse,it will lead three-phase load unbalance and other issues.According to the these above all,by formulating a charging guidance strategy for electric vehicles connected to the distribution system and guiding them charging orderly,the dynamic probability fluctuation degree of the residential area,the voltage quality,the expected overload running time of the distribution transformer,and the three-phase of the distribution system can be effectively improved as well as reducing the charging cost of EV owners,and exciting the enthusiasm of the vehicle owners' responce to the charging strategy.The paper mainly includes the following contents:1)A dynamic probabilistic model for residential area load under charging uncertainty of electric vehicles is established.Firstly,according to the electric vehicles statistical distribution data of the travel characteristics,different charging scenario models are constructed by using Latin hypercube sampling technology.Secondly,the price elasticity coefficient is introduced to quantitatively describe the response probability of electric vehicle to time-sharing tariff,and the charging load model of electric vehicle is established,which mainly includes charging scheme and dynamic probability model of charging load considering uncertainty of time-sharing tariff response.Thirdly,based on the previous works,the dynamic probability distribution of the total load power in residential quarters at each period is obtained by semi-invariant method and Gram-Charlier infinite series to establish the load dynamic probability model for residential area.2)A time-sharing pricing guidance strategy for charging electric vehicles in residential areas based on uncertainty measure is proposed.Firstly,the dynamic probability fluctuation of load in residential area is measured by the introducing information entropy and probability of exceeding limit in physics.On the premise of the expected overload time of transformers in residential areas don't exceed the allowable value,the pricing strategy model is put forward to maximize the expected revenue of electric vehicle agents.Secondly,bilayer particle swarm optimization algorithm is used to optimize the pricing strategy.Time-sharing price constraints are used at the bottom of the algorithm,and top-level system constraints are dealt with the top of the algorithm.Finally,a residential area is taken as an example for simulation study.The results show that the proposed pricing strategy not only guarantees the agent's income,reduces the risk of transformer overload operation in residential districts at different periods effectively,but also decreases the uncertainty of total load fluctuation in residential districts3)The charging strategy of electric vehicle considering unbalanced three-phase load is established.Firstly,this paper analyzes the travel characteristics of electric vehicles and studies the influence of the randomness of electric vehicle charging on the three-phase load imbalance of power distribution system.Secondly,this paper considers the system constraints and plans the electric vehicle charging scheme with the minimum three-phase load imbalance of the power distribution system as the goal.Thirdly,the double-level optimization algorithm is used to optimize the charging strategy.The bottom layer solves the charging scheme to improve the imbalanced three-phase load of the electric vehicle,and the top layer obtains the voltage deviation constraint of the distribution system by power flow calculation.Finally,an improved distribution system topology is applied to simulate the charging strategy,which verifies the effectiveness and practicability of the charging strategy to improve the unbalanced three-phase load of distribution system.