Research And Implementation Of Evaluation System Of Operation State For Overhead Transmission Lines Based On The Bidirectional Bayesian Network

As the key role of electrical energy and power grid to realize the transmission of electrical, overhead transmission line’s operation capacity concerns whether the operation of the whole electric power system is safe and reliable, high efficiency and economy or not, so the security maintenance and reliability maintenance on line has become necessary. However, mastering the line’s operation state before maintenance is quite important, state evaluation is the key to ensure the long-term stable and normal operation of the line, the efficiency and accuracy of state evaluation greatly influence the follow-up maintenance decision. Therefore, how to use a reasonable and effective method on the state evaluation of overhead transmission lines has very important realistic significance and practical value.This paper analyzes the merits and drawbacks as well as the difficulties and facilities of many existing methods for state evaluation, and comparative analysis of Bayesian Network technology, searching and studying Bayesian network’s development, the basic theory, learning methods and reasoning methods and so on. According to the characteristics of overhead transmission lines in operation, this paper puts forward the state evaluation of overhead transmission line using Bayesian Network technology, establishes the state evaluation model based on Bayesian Network, constructs the directed acyclic graph structure of the state evaluate, and parameters learning of state evaluate, uses the unique bidirectional inference skill of Bayesian network to reason and judge the operation state of line( "normal", "attention", "abnormal", "serious"), or to distinguish the hidden state weak point. In addition, the feedback correction mechanism is set in order to complete the amendment of evaluation results to update the network’s structure and parameters, and ensure the accuracy of calculation and correctness of evaluation results.According to the established the state evaluation model based on Bayesian network, making mathematical model and simulation by MATLAB, the evaluation results is intuitive visible, from which not only the state probability distribution can be directly obtained, but also a very good understanding of the whole operation of the line. In addition, based on the mathematical modeling, design and develop the expert system of operation state evaluation of overhead transmission lines, the whole software development based on the platform of JAVA and MATLAB, which realizes the functions including state evaluation, query and statistical analysis of the defects, intelligent alarm and so on. Combined with the actual situation of line operation, at last, through the experiment on the actual lines gives the results of state evaluation, which show that the expert system can fully integrate the data to make an systematical and comprehensive state assessment, practical and feasible with high accuracy, and can effectively protect operation of the whole transmission line and even the whole power system in a normal and stable state.