Evaluation Of Operation State And Diagnosis Of Invisible Fault For Overhead Transmission Lines Based On Bayesian Networks

Overhead transmission lines are the vitals of power system. Its main function is to transmit electricity. Compared to a system, it is a single facility. Its operation state can make the difference between reliable power system and bad system. The operation state of overhead transmission lines are the key to the safety and reliability of the whole power system. Especially to old transmission lines, the frequent evaluations of its operation state can accurately mastery its operation state, eliminate potential faults in time and prolong its lifes in the purpose of increasing capital usage.This thesis puts forward a method for evaluation of operation state for overhead transmission lines based on Bayesian Networks, which in the first place discusses the significance of evaluation of operation state for overhead transmission lines, introduces the current state of Bayesian Networks,evaluation of state and diagnosis of fault at home and abroad. Subsequently, this thesis detailedly introduce the theory of Bayesian Networks, including trait,reasoning,learning and model building of Bayesian Networks, and so on. Afterwards, it brings in the method for evaluation of operation state of 5 import components about the overhead transmission lines, namely, pole,insulator,hardware fitting,wire and ground lines,base and grounding device. The overhead transmission lines will go through the evaluation of operation state based on evaluating outcomes of the five components. With every component given corresponding sub-system, the evaluation of operation state will be carried out through the state analysis of the sub-systems, followed by some introduction of concrete contents and evaluation criteria for each sub-system.Regarding the application of Bayesian Networks, the thesis presents the method of evaluation of operation state about the overhead transmission lines based on Bayesian Networks, establishes the math model of evaluation of operation state about the overhead transmission lines, and gives the basic description of the evaluatioin model of every part of the whole overhead transmission lines. Regarding the bilateral reasoning technique of Bayesian Networks, this thesis presents the math model of diagnosis of invisible fault about the overhead transmissioin lines.According to the math model of the evaluation of operation state about overhead transmission lines, the Visual Bacic.NET language is used to compile evaluation of operation state system software to the overhead transmissioin lines. The system can evaluate operation state of the overhead transmission system with "good", "warning", and "poor" operation state probability, the graph results of lines have better view effect. The system can also analyse the invisible fault through the whole overhead lines for the repair staff to detect problem.The thesis gives evaluation analysis to the actual overhead transmission lines by using evaluation system. With the comparison between the evaluation results against the actual operation state, revealing that the system is effective in evaluating and rating, which proves that the evaluation system used in this thesis is workable.