Research On Optimal Operation Strategy Of Electric Bus Charging And Swapping Station

Electric bus has the advantages of energy conservation and environmental protection,so it is an important trend of green development of public transport in the future.Charging and swapping stations are the main energy supply places for electric buses.If large-scale batteries are charged disorderly in the station,the safe operation of power grid will be affected.At the same time,the development of electrified urban rail transit and distributed generation technology also brings new challenges to the operation of power grid.Under this background,considering the flexibility of charging and swapping rule and the schedulability of batteries charge and discharge,this paper carries out the research on the optimal operation of electric bus charging and swapping station(EBCSS)located in conventional area and public transportation hub in the urban respectively.The main research contents are as follows:(1)The charging and swapping rule modle of EBCSS is established.Firstly,the operation mode of EBCSS is analyzed,and considering the flexibility of batteries replacement after single operation of electric buses,establishes the swapping rule model.Then,the buses swapping demand model and batteries charging demand model are established based on the swapping rule.Finally,The matching model for the buses swapping demand and batteries charging demand is established considering the separation between buses and batteries under the electric buses swapping mode.The model set up three indexes which contains charging scheduling margin,charging economy,and battery equilibrium,and proposes the matching strategy based on entropy weight method.(2)For EBCSS located in the conventional area,a two-stage charging optimization strategy is proposed.According to the coexistence of operational regularity and uncertainty of electric buses,the strategy includes two stages: day-ahead charging optimization and real-time rolling correction based on the centralized control structure of EBCSS.Firstly,based on the charging and swapping rule model,considering the operation constraints of EBCSS and electric buses,this paper proposes the day-ahead charging optimization strategy aiming at minimizing the charge cost and charge load fluctuation.And a joint optimization method based on binary particle swarm optimization and GUROBI solver is proposed to get the best charging and swapping rule and charging scheme.Then,real-time rolling correction charging strategy corrects the deviation between the actual and day-ahead operation rollingly based on the dayahead optimal scheme,and proposes an abnormal state processing strategy.Finally,in order to verify the effectiveness of the method in this paper,the comparative simulation analysis is carried out between the method in this paper and different operating strategies.(3)EBCSS located in urban traffic hub is taken as the research object.Photovoltaic and DC traction power supply system of urban rail transit are connectd to the EBCSS to constitute microgrid system of urban public transportation hub,and the energy collaborative optimization strategy for microgrid system is proposed.Firstly,the mathematical model of each unit in microgrid is established,including the power boundary model of EBCSS and the regenerative braking energy utilization modle of urban rail transit.Then,based on the hierarchical control structure,the system side proposes an energy collaborative optimization strategy for microgrid system based on adjustable robust optimization method to consider the operation uncertainty of each unit.And the EBCSS side follows the operation instructions issued by the system side,and establishes an optimal power distribution model for EBCSS with the objective of minimizing the state transition times of total batteries charge and discharge.Finally,the effectiveness of the proposed optimization object and method is verified by simulation analysis.