| In recent years,with the shortage of traditional energy resources and the deterioration of environmental pollution,the development of electric vehicles and the technology of wind power and photovoltaic has been vigorously promoted.However,the randomness of large-scale electric vehicles' charging behaviors and the fluctuation of output of renewable energy will bring great challenges to the operation and control of power system.Considering that the electric vehicle has the characteristics of source,load and fast response to the electricity grid,the vehicle-to-grid technology can be used to solve the problem of source-load coordinated dispatching of micro-grid.As one of the participants in the electricity market,the most important issue is how to use the economic leverage of charging and discharging tariffs to motivate electric vehicle users to participate in the dispatching.Therefore,aiming to the problems of large imbalance of power in the supply and demand and the low utilization rate of renewable energy of micro-grid,this paper takes the interaction between electric vehicles and power system as the research object and has conducted in-depth research on the strategy of dynamic charging and discharging price of electric vehicles considering the demand side response of users.The specific research contents are as follows:Peak-valley periods division based on the method of fuzzy clustering.The scientific and rational division of peak-valley periods is the basis for the implementation of peak-valley electricity price.In order to give full play to the role of the price mechanism,the peak-valley periods should be re-divided.Firstly,the fuzzy membership function method is used to extract and calculate the peak and valley membership index of each time period on the load curve.Based on this,the fuzzy clustering algorithm is proposed to correct and divide the peak-valley time periods again.Then,in order to verify the rationality and feasibility of the results,the method of calculating the load change rate is put forward.Finally,we take a regional micro-grid as an example and the peak-valley periods division scheme of the micro-grid is obtained.The strategy formulation of the dynamic time-of-use price for electric vehicle charging taking user satisfaction into account.Under the guidance of peak-valley electricity price,electric vehicle users will tend to charge when the demand is low,which leads to another peak of power system.In this background,we research the travelpatterns of types of electric vehicle users to establish the grid connection scenes and predict the controllable capacity of electric vehicles of the next day.The charging preferences of 3 different types of users are studied and a comprehensive satisfaction degree model is established to obtain different users' charging strategies.Furthermore,a pricing strategy based on dispatching requirements of micro-grid is proposed.The simulation shows that the charging price can fully guide users to arrange the charging plan reasonably and realize the optimal control of the charging load of the electric vehicles.The strategy research on the discharging price considering the risk preference of electric vehicle users.Since the charging load of electric vehicles cannot fully realize the balance of supply and demand of the micro-grid,this paper discusses the users' behaviors when electric vehicles feed electricity back to the power system.Considering the psychological and profit risks,we adopt conditional value at risk as the risk metric of electric vehicle users when participating in the transaction and found the optimal reserve energy and automatic response decision model thus to formulate the incentive discharging price for electric vehicles according to the operation demands of the supply and demand side combined with the demand side response theory.The results show that the discharging price will effectively stimulate users to participate in the transaction of electricity market and bring benefits to both parties. |
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