Research On Modeling And Control Strategy Of Charging Station With Hybrid Power Supply

The ongoing research in the field of electric vehicles(EVs)and the growing global awareness for a pollution free environment,will lead to an increase in the number of EVs in the near future.However,the proliferation of these EVs will add stress to the already overloaded grid and create new challenges for the distribution network.To address these issues,it's time to develop charging station infrastructure coupled with smart charging strategies,thus reducing the stress imposed on the grid.Based on above viewpoints,the structure of charging station system has been analyzed and improved.Then the control strategies of hybrid power supply and the electric vehicle charging points have been researched in detail and depth in this thesis.The specific research contents are as follows:1.The framework of charging station system has been improved and a hybrid power supply system has been designed.The photovoltaic power generation system in hybrid power supply system can mitigate the stress on grid and reduce the consumption of traditional energy sources.Then,based on the load characteristics of Electric Vehicles,the modeling of the charging station system has been completed and the circuit models for each component in hybrid system have been analyzed.Finally,the power flow and power supply modes of hybrid system are illustrated in detail.2.The control strategies of the hybrid power supply system(HPSS)have been designed to solve the power fluctuation problem and realize the power sharing of whole system.An AC-DC integrate controller has been designed in HPSS that contains a two-layer control.The first layer control is responsible for maintaining the dc bus voltage and current.The power allocation is addressed in the second control layer and a power scheme algorithm(PSA)is carried out to maximize the system efficiency and address power fluctuation problems.3.The control strategy of hybrid system has been further improved to reduce the stress on grid while it is in the situation of overloaded.The charging algorithm and control strategy of the electric vehicle charging points have been analyzed in detail and a smart charging algorithm has been designed.The designed control strategy is a self-regulated process of EVs,and the whole fluctuating power is assumed by the charging EVs proportionally based on SOC during the adjustment process.Thus,the output power of AC system in hybrid power supply system will not be affected,which can alleviate the stress on overloaded grid.Finally,main concluding remarks are summarized and presented at the end of this thesis as well as some interesting problems which deserve further study.