Research On The Evaluation Of Overhead Transmission Line Operation Risk Under The Bad Meteorological Disasters

Overhead transmission line which bears the responsibility of transferring and distributing the electricity is the most numerous and complex part in power system network. It operates in the wilderness over a long period of time where weather condition is complex and the environment is harsh. And it is often out of operation. At the same time, each part of power system is interrelated and inseparable. Once somewhere fails to work, it will lead to a chain reaction which spreads to the entire power system network and causes large area blackout, resulting in huge economic losses and serious social impact. With the global climate becoming increasingly anomalous and natural disasters becoming more multiple, overhead transmission line is facing more and more severe challenges, and the power system network security and stability problems caused by are prominent gradually.Aiming at the serious threat of bad weather disasters bringing to the safe operation of overhead transmission line, this paper carries out the research on the evaluation of overhead transmission line operation risk. The main content of this work shows as follows:Firstly, the harm of lightning, ice and other typical bad meteorological disasters on the line is discussed, and their influence mechanisms are analysed. This paper summarizes the existing risk assessment methods. On this basis, evaluation models of lightning and ice are established, namely, the differentiated and multi-level lightning risk evaluation model of “tower-tower section-line”, and the corrected icing risk evaluation model based on the BP-Markov combination method, which assesse the risk probability and risk status of lightning and ice respectively.Secondly, this paper also takes full account of simultaneity the meteorological disasters erupt along the transmission line corridor, and researches and establishes the evaluation model of overhead transmission line operation risk under the multiple meteorological disasters. The model uses the product of risk probability, risk weight coefficient, risk consequence to describe comprehensive risk value of overhead transmission line. Accordingly, on the base of previous study of risk occurrence probability, the paper combines entropy method with AHP to calculate risk weight coefficient, and then uses least square method to optimize value. Also, the paper adopts the risk of harm extent and the social influence to evaluate and determine the risk consequence comprehensively.Thirdly, this paper also writes MATLAB programs to realize the model and algorithm, and then uses line running case to verify the practicability of the model.The risk evaluation model proposed calculates the comprehensive operation risk value of overhead transmission line under bad meteorological disasters by multi-level, wide angle, multiple combination, layer by layer reasoning calculation method. The result of this paper will provide the reference for the comprehensive and systematic analysis of line. But due to the limitation of the data of the line, the generalizability and reliability of the evaluation model have to be further verified after the line running database improves gradually.