The Method Of Resilience Evaluation And Improvement For Distribution Network Under Earthquake Disasters

In recent years,increasingly frequent extreme disasters have brought many challenges to grid security.As an important power supply link,the distribution network is directly connected with users,the blackout of which has brought immeasurable losses on people’s daily life and economic activities.Improving the resilience of the power grid especially the distribution network under extreme disasters,is a guarantee to effectively improve the quality of power supply and the user’s satisfaction,and minimize the economic losses caused by disasters.In terms of assessment and improvement of the resilience of distribution networks,the main work of this thesis is as follows.The resilience evaluation metrics of distribution network are constructed from preand post-disaster perspectives.Firstly,the influencing factors of resilience of distribution network are analyzed.Then,to assess networks strength and resilience resource allocation,the resilience metrics are proposed according to grid robustness,emergency power supporting ability,and failure repair capability from the pre-disaster perspective.At the same time,in order to evaluate the capability of distribution network to restore power supply for the power loss load and maintain the stable operation of important loads,two metrics of load recovery rate and emergency power maintenance rate are presented from the post-disaster perspective.The analytic hierarchy process,entropy method and grey relational analysis are used to construct the resilience assessment model of pre-disaster distribution network.The importance of each assessment metric to the resilience is compared,so as to obtain its weight.It provides theoretical guidance for the network strengthening and resilience resource allocation.Meanwhile,the particle swarm optimization is used to solve the optimal allocation scheme of pre-disaster resilience resources and the optimal recovery scheme of post-disaster distribution network,which accelerates the resilience recovery process of distribution network.The method of improving the resilience of distribution network considering earthquake disaster is studied.Firstly,analyze the types of earthquake disasters and the attenuation laws of ground motion parameters.Secondly,the relationship between the ground motion parameters and the tower loss probability is established,and the tower loss probability under different conditions is calculated,thus constructing the line loss analysis model.Then,the methods of resilience improvement are analyzed from four aspects: network strength,resilience resource allocation,line repair strategy and power supply path of emergency resources.Finally,the proposed model and method are verified by examples,which prove their rationality and effectiveness.Constructing resilience metrics from pre-disaster and post-disaster perspectives,not only can assess the capability of resisting extreme disasters and rapid recovery of distribution network,but also provide the theoretical support for the development of resilience improvement schemes.The proposed metrics and methods lay a foundation for further research on the resilience of distribution network under earthquake disasters.