Smart Charging Of Electric Vehicles And Planning Of Shared Charging Facility

As the two research directions related to electric vehicle infrastructure,the planning of charging facilities and the orderly charging of electric vehicles play an important role in the future development of electric vehicles.Optimizing the charging of electric vehicles can effectively improve the safe and economic operation capability of the distribution system,and is of great significance for its safe operation.By using the radial operating structure of the distribution system and the method of iteratively correcting node voltage,the dimensionality of the optimized variables can be greatly reduced and the calculation speed can be increased.This method has been applied to the three-phase balanced distribution system with a minimum network loss as the objective function,a normal load model as a constant power load,and with no consideration of node voltage and branch power constraints.This dissertation proposes a method to extend it to the general situation,that is,the objective function is the minimum power supply,minimum operating cost or maximum profit of the distribution system,which is no longer limited to the minimum network loss.And the load model is no longer limited to constant power load.Moreover,the three-phase unbalance,node voltage,and branch power constraints of the distribution system are taken into account.The dissertation analyzes the impact of the load model on the optimization results.It is found that when the load model contains only constant power and constant impedance loads,the optimization model is still a linear constrained convex quadratic programming model in each iteration.And when the load model contains constant current load,the optimization model is no longer a linear constrained convex quadratic programming model in each iteration,but it is still a linear constrained convex programming model.Finally,the convergence and calculation speed are verified by simulation.EV sharing as a possible future development direction for electric vehicles in big cities has already started trial operation in some countries.However,there are few studies on the planning of charging facilities in China.Due to the unbalanced distribution of vehicles in the trial operation of foreign shared electric vehicles,the user demand cannot be fully released.Therefore,the charging facilities of shared electric vehicles are planned for this problem in the dissertation.The characteristics of the planned shared electric vehicle charging facility are clarified,and the relocation cost is introduced to ensure the full release of the user's requirements.The total number of charging piles is determined in accordance with the queuing theory and operational profit requirements based on the total charging load of the shared electric vehicles.The number of charging piles in the target area is calculating based on the service area ratio and the direction of the charging traffic flow.At the same time,how much additional charging demand for ordinary electric vehicles that the shared electric vehicle charging station can be released is calculated to solve the problem of low usage of the public charging piles in the city,and to take into account the revenue of the operators,so as to reduce the idle rate of charging piles and alleviate the pressure on the construction of urban charging facilities.The method realizes the real-time balance of the distribution of shared electric vehicles,which greatly releases the user's requirements and ensures the profit of the operators.According to the simulation results,the feasibility of the method is verified,and the reasons for the difficulties in the profitability and development of the demonstration operation are put forward,which provides a choice for the subsequent related planning work.