Study On Operation State Evaluation Method Of Overhead Transmission Line

Overhead transmission line is an important part of the power system,is the power transmission path and is the bridge connecting power supply and demand sides.The transmission line operating condition affects the reliability and security of the power system operation directly.Evaluating and analyzing the state of transmission line can provide the information basis for the state overhaul and guide equipment state overhaul scientifically.It has important significance for eliminating hidden faults,predicting fault development trend,reducing the system failure probability and improving the operation reliability of the whole system.This paper deeply analyzes the causes of transmission line fault,such as bird damage,lightning stroke,wind drift,icing,pollution flashover,external damage and so on,which laid a foundation for selecting evaluation index scientifically.This paper researches the overhead transmission line unit and transmission line overall state evaluation method.Based on the above analysis,line maintenance strategy,state information required to collect in line inspection work,classification of line patrol cycle and principle of making patrol cycle are given.This paper focuses on the transmission line state evaluation method.Principle of the establishment of transmission line state evaluation index system is given and state evaluation index system is established.In this method,the important part of transmission line is regarded as the primary evaluation indicators,parameters of each part closely related to fault line is regarded as the secondary indicators and the range of the evaluation index value is determined according to the operation experience.The related theory of extenics is studied.According to the theory,classical domain and joint domain of transmission line state evaluation and the matter-element model to be evaluated of two transmission lines are constructed.Using nine scale analytic hierarchy process(AHP)method to calculate weights of five primary indicators and secondary indicators belonging to them and to check consistency.Through the total level sorting,the final weight is obtained.Based on the related theory of extenics,the matter-element correlation function matrix is obtained by calculation.Combined with weight coefficient of each index andcalculation result of correlation function values,calculating evaluated objects associated degree levels on each grade,finally determining the grade of transmission line,and the evaluation results are analyzed.