Study On The Transmission Line On-line Inspection And Monitoring Technologies Using OPGW-based Communication System

With the transmission line accidents have been increasing in recent years, thetraditional inspection methods were unable to meet the safety and security demands ofpower system gradually. Whether manual inspection or helicopter inspection, thetransmission line inspection work cannot avoid being excessive or omitting and beinginfluenced deeply by the weather. Transmission line condition monitoring system could nottake the place of manual inspection since its low utilization rates and economic benefits.This thesis put forward a kind of on-line inspection system to replace manual inspectionand improve the maintenance efficiency.The thesis firstly proposed the on-line transmission line inspection system functionrequirements and basic structure according to the requirements of power system on thetransmission line manual inspection， subsequently described the design scheme ofterminal tower systems, communication networks and backend host of the on-lineinspection system.Secondly the basic program for the constitute of fiber-optic communication channelbased on Optical Fiber Composite Overhead Ground Wire (OPGW) optical-electricityseparation interface technology is proposed in order to meet the functional requirements ofon-line inspection system for communication network, focusing on using the OPGWoptical-electricity separation interface technology to compose the fiber-opticcommunication network and the advantages of Ethernet Passive Optical Network (EPON)technology. Due to the diversity of EPON networking, the thesis compared several kinds ofcomposite networking such as "single fiber","multiple fiber","Optical Line Terminal (OLT)hierarchical networking" and “networking equipped with optical amplifiers”, and made anevaluation of the networking above from the aspects of basic EPON networking principles,the optical power attenuation, the coverage, the optical power distribution, the number ofaccess points and protection scheme, proposing their scope of use respectively. Also theprotection scheme of the communication network was designed to enhance the reliability ofcommunication channel of on-line inspection system.At the end of the thesis, the PSCAD/EMTDC modeling of transmission line with accurate simulation of grounding modes was established, with which the case of groundfault at the tower was analyzed, discovering the distribution characteristics of OPGWground short-circuit current. According to the analysis above, the fault location algorithmwas proposed which was based on OPGW current amplitude distribution characteristics.