Research On Reliability Evaluation Of Distribution Network With Distributed Generations And Electric Vehicles

With energy shortage and environrment pollution becoming more and more obvious,using clean and renewable energy generation in power system,and replacing the traditional fuel vehicles by electric vehicles become the effective measures to solve the crisis of energy and environment,the development of distributed power generation technology and electric vehicles is highly concerned by governments around the world.The reliability evaluation of distribution network is an important part of the power grid planning and construction,so it is very significant to evaluate the reliability of the system.Distributed generators and electric vehicles will change the structure and the operation mode of the traditional distribution system to affect the reliability of the system.Therefore,it is necessary to evaluate the power supply reliability of distribution system including distributed generations and electric vehicles.In this thesis,the distribution network reliability study with DG and EV is studied based on the traditional reliability evaluation of distribution network,and the influence of distributed power and electric cars on the reliability of distribution network is analyzed in detail.Taking wind power and photovoltaic power generation for research objects,the probabilistic models of wind power generation and photovoltaic generation are proposed.A joint probability model based on the Copula theory is established for the power output of wind-PV hybrid generation system,which considers the correlation properties of wind and PV power outputs.A reliability evaluation method for distribution network based on sequential Monte Carlo simulation is presented.The numerical example is given to verify the accuracy of the model and method.Example results show: the access of distributed generators can improve the reliability of distribution network to a certain extent;In addition,the wind-PV hybrid generation system can better improve the reliability of distribution network.In addition,when the DG is connected to different locations of the distribution network,the system reliability is improved differently.Taking private electric vehicle as the research object,based on the residentscommuting patterns,the control strategy and model of charging and discharging time are established.A numerical example is given to verify the accuracy of the model and method.Example results show: a large number of electric vehicles access to the distribution network for charging operation,will have an adverse impact on the reliability of the system,grid connected electric vehicles can reduce this effect by sending back to the grid during peak hours.Compared with the quick charging mode,slow charging mode can reduce the adverse effects caused by electric cars on the reliability of the grid;In addition,through the comparative analysis,the wind-PV hybrid generation system can improve the negative impact of electric vehicle on system reliability.