Research On Reliability Of Overhead Distribution Network Under Typhoons

Being one of the major natural hazards in the coastal areas,typhoons cause a lot of economic losses and casualties each year.Among them,their impact to the power system is the most extensive,which will directly affect the industrial production,transportation and communication systems,hospitals and other lifeline functions.Therefore,it is necessary to investigate the reliability of the power system under the influence of typhoons.Because the high voltage transmission systems are usually designed against a long return period of wind speed,their failure reliability is relatively low,comparing with that of the medium-and low-voltage distribution lines,of which collapse of poles and break of lines commonly occur.Therefore,this paper focuses on the reliability of the distribution network under typhoons.Since poles and wires are the most common failure members in typhoons,failure of poles and wires is considered in this reserch.Based on the researches in domestic and overseas in this field,the reliability of overhead distribution network under the influence of typhoons is studied from the perspective of component reliability analysis.The functional reliability analysis method for the overhead distribution network is propsed,and corresponding analysis models are built.The method for analyzing the internal forces of the pole and wire are obtained by reference to the recommended method in the design codes for transmission lines,and the mechanical derivation.By adopting the available probabilistic resistance models for pole and wire,the models for single pole and wire reliability analysis under typhoons are obtained based on the basic principle of reliability theory.To correct the errors induced by using a detached pole and wire model,and to take into accout the different configurations of poles and lines,and the fluctuation winds,finite element analysis of pole-wire system considering their coupling using ANSYS software is conducted.The results are compared with thouse of the pole and line detached models under mean wind speed.The results of the easy pole and line detached model are modified by those of the pole-line coupling model.A unified geographic coordinate system is established for connecting the components of the distribution network,and the distribution network with the typhoon wind filed.A new data structure is established for the storage and calculation of the position information of the poles and lines.A pole-line topology analysis model based on adjacency matrix and ArcGIS platform is proposed.Combined with the CE wind field simulation,the vulnerability model of the distribution network is established.Based on the ArcGIS platform,the direction network connectivity analysis is carried out,and the power supply reliability of the distribution network is obtained.The effectiveness of the method is demonstrated by an example.Results of this paper will provide a tool for scenario analysis of distribution networks before typhoon comes,loss estimation by typhoons,disaster preparedness and emergency responses to typhoons.It also builds the basis for the policy design and risk con trol for insurance and reinsurance companies against typhoons.