Risk And Safety Assessment Of Distribution Network With Distributed Generation And Electric Vehicle

With the access of distributed generation(DG)and electric vehicle(EV),the traditional single power radial distribution network becomes new distribution system full of power source and load.It can improve the power supply reliability and the power quality of distribution network and reduce the network loss to a certain extent,thereby bringing greater operational benefits and economic benefits.However,due to the uncertainty of DG and EV,it may cause voltage fluctuation and power flow change of power grid,node voltage out-of-limit,line overload and even loss of load,and then increase the vulnerability of the distribution system.The study of the risk and safety assessment of distribution network with DG and EV begins at home and abroad in order to ensure the safety and stability of power system.In view of this,this paper mainly contains two parts:the risk assessment of distribution network and the security evaluation of distribution network,the main work of this paper is as follows:This paper studies the characteristics of the distributed generation output and the charging randomness of DG and EV,establishes the probability model of wind power generation,photovoltaic power generation and electric vehicle charging,calculates and analyzes the dynamic probabilistic power flow of distribution network with DG and EV,finally proposes operational risk assessment method based on the node voltage risk indicator and the branch power flow out-of-limit.Taking IEEE 33 node distribution system as an example,this paper evaluates the system risk of distribution network with DG and EV at every moment in one day and does statistical analysis.It is proven that the proposed risk indicator can reflect the risk degree of the distribution system accurately.Based on the risk assessment theory and "N-1" safety criteria,it uses load point loss risk indicator and line overload risk indicator and comprehensive risk indicator to evaluate the risk degree of system and finds the vulnerable nodes and lines through statistical analysis for the fault and power supply recovery of distribution system with DG.Based on the heuristic algorithm,it proposes the fault recovery strategy of a combination of priority line transfer and distributed generation islanding,discusses the location of DG from the view of reducing the risk of system load point loss at the maximum degree.Taking IEEE 33 node distribution system for example,it is proven that the assessment indicator can reflect the risk degree of distribution network with DG and the fault recovery and DG location strategy can effectively reduce the system risk and provides reference for distribution network planning and risk prevention.This paper proposes a comprehensive assessment method of distribution network safety based on triangular fuzzy-analysis hierarchy process(TF-AHP),which evaluates the safety of distribution network from distribution network,scheduling and secondary system,electric primary equipment,safety power supply and emergency management,establishes safety comprehensive assessment indicator system and assessment model algorithm,develops distribution network safety analysis and decision support platform which can evaluate the current state of distribution network accurately and quickly.Taking the distribution network of one city as an example,this method can identify the vulnerable links and put forward preventive measures.