Study On Risk Assessment Of Power Transmission Channel In Forest Regions Based On Spatial-Temporal Features Of Forest Fires

This thesis is supported by Major and Basic Project of State Grid Foresight Science and Technology “Research on transmission line early warning technology based on refined meteorological information(SG20141187)”.Transmission lines are exposed to meteorological environment,it is easy to be affected by the adverse weather and extreme climate,which leads to the interruption of power transmission and influences the safe operation of power grid.Liangshan which located in the southwest of Sichuan,has a high annual temperature,distinguishing climate of wet and aridity,and xerothermic wind disaster frequently occurs in spring,these all make it become a prone-fire area.At the same time,about 70% of the transmission lines pass through the forest regions,the geographical and meteorological environment of transmission channels are complex,so the forest fire occurrence frequency is relatively high,which has brought tremendous impact on the safe operation of the transmission line.In order to study the problem of risk assessment of power transmission channels in forest region under the forest fire conditions,this thesis makes a comprehensive research,the main contents are as follows:a)For the forest fire weather rating assessment problem,using statistical analysis method to analyze the temporal and spatial distribution of forest fire in Liangshan.Through analyzing the influence of temperature,precipitation,humidity,wind speed and other meteorological factors on the forest fire,the main meteorological factors of forest fire danger rating assessment in Liangshan is determined,and meteorological data of the research areas are collected and analyzed according to the chronological orders.The forest fire rating assessment model under the temporal and spatial distribution of forest fire is built based on the quantitative evaluation of these indexes.b)For the problem of the trip probability assessment of the power transmission channels in forest regions,according to the forest fire danger rating evaluation results,forest fire occurrence probability is determined under the forest fire weather ratings,combined with the air gap breakdown probability model under fire conditions,the transmission line fault probability is deduced based on the conditional probability formula,consequently,the trip probability assessment model of transmission line under the temporal and spatial characteristics of forest fires is proposed.Taking the study objective as an example,the test results indicate that the proposed model is valid.c)Aiming at the risk evaluation of load point under forest fire conditions,firstly,through calculating the reliability index of the load point,it can be found that the LOLP and EDNS indexes are relatively high under the forest fire conditions.So,the overload protection of transmission lines which are in operation is checked under the overload current due to power flow transferring after one transmission line tripped out by forest fires.Furthermore,the maximum allowable temperature of conductor are checked when transmission line carrying the emergency overload current,and time of temperature rise to the maximum allowable temperature is calculated,which can provide a decision guide for the operation and maintenance of transmission line.Finally,the corresponding measures of risk reduction are proposed according to the evaluation results.