Research On The Layout Planning Of Urban Public Charging Piles And Charging Stations

Electric vehicles(EVs),which are clean,environmentally friendly,low-carbon,and efficient,attract more and more attention under the background of increasingly serious environmental pollution and energy crisis.Coupled with the dual role of policy guidance and market demand,the EV industry has shown vigorous vitality in development.Therefore,it is urgently required to carry out scientific and reasonable layout planning for charging facilities.Firstly,the basic knowledge for the layout planning of charging facilities is introduced in this paper.Secondly,the planning ideas and processes are presented.Then,based on the charging demand prediction,the researches on the quantity planning of public charging piles and locating and sizing of charging stations are conducted respectively for a city,and the corresponding planning optimization models and methods are proposed.Based on the available basic data,a practical method is designed to predict the charging demand of EVs.Firstly,according to three types of data about vehicle sales,vehicle ownership and the number of vehicles per capita,the number of EVs is predicted through trend analysis and curve fitting calculation respectively,with the trend of fitting curves being controlled by the target index of future years,and the prediction results are verified by each other.Then,the number of different EVs on different charging facilities,as well as the charging energy demand and charging frequency,are determined,based on the data such as the average daily mileage and the average daily charging times.Finally,the space-time distribution of charging demand is predicted for public fast-charging stations.For the spatial distribution,based on the parking space number of parking lots from the "Controlling Detailed Planning" and the traffic flow at road intersections,the charging demand is allocated to each parking lot and intersection according to the proportion of the corresponding parking space number and traffic flow.For the time distribution,based on the operating rules of EVs,the time period for a day is reasonably divided and the corresponding amout of demand is estimated.For public charging piles,based on charging demand and user experience,a planning optimization model and a heuristic solution method for the quantity planning are proposed.Firstly,an optimization model is established with the objective to minimize the number of public piles,and the constraints of the corresponding number of piles to meet the charging demand,user psychology and economic rationality.Secondly,from the perspective of satisfying economic rationality and charging demand,the maximum allowable economic number of piles and the minimum allowable feasible number of piles are determined separately through the cost-benefit balance and the maximizing equipment utilization.Then,according to the user’s acceptance of the different remaining states of charge of EVs in each functional area,the corresponding charging demand probability and its weight are obtained,so as to determine the reasonable pile-to-vehicle ratios and the minimum allowed user experience number of piles.Finally,based on the obtained economic,feasible and user experience number of piles and the ratio of fast-slow piles,the planned numbers of fast and slow public charging piles are found through enumeration or a simple comparison method of related maximum and minimum values.For public fast-charging stations,based on the dynamic reduction of candidate site redundancy,the optimization models and the corresponding heuristic methods are proposed for the locating and sizing.Firstly,from the perspective of whole society,a planning optimization model is presented to minimize the total cost of grids,charging facility operators and users,which includes the main model of different candidate planning schemes and the sub-model of the number of charging piles for a single candidate planning scheme.Then,taking parking lots as candidate sites,the heuristic method of dynamic reduction of candidate site redundancy and the pile number enumeration method are proposed to solve the optimization model,involving the "weight distance" and "charging nearby" charging based demand allocation,the MV line investment and charging demand based coordination optimization factor of power grids and charging stations for site selection,the site redundancy reduction based scheme generation,the optimal number of charging piles from the enumeration method,and the site redundancy reduction based method solving processes for disorderly and orderly charging.Combined with the comparative analysis of the influence of M/G/s and M/M/s queuing models on the planning optimization schemes for charging stations,a reasonable choice is made between these two controversial queuing models for the charging station planning,and the M/M/s/K/∞ queuing model with capacity limits is finally recommended in this paper.The basic data for the proposed method is easy to obtain,and the heuristic solution method is inclined to an analytic method,which is relatively intuitive,concise and stable.The examples show the practicality and effectiveness of the proposed models and methods.Among them,the sensitivity analysis of relevant influencing factors is carried out for the planning of public fast charging stations,involving the different queuing models,different planning methods,orderly and disorderly charging strategies,different types of medium voltage lines,different spatial distribution of charging demand and changes in charging demand.