植被火条件下考虑导线不均匀温升的弧垂计算

Sag Calculation Considering Conductor s Nonuniform Temperature Rise under Vegetation Fire Condition

架空输电线路下方植被发生火灾时,火焰高温导致导线弧垂增加,进而导致线路的跳闸风险升高。因山火条件下导线受热不均,需要考虑山火条件下导线不均匀温升对弧垂的影响。本文研究搭建了植被燃烧温度测量平台,得到云南松燃烧火焰在不同高度处的温度。以200 m导线档距为例,提出考虑导线不均匀温升的弧垂计算方法,采用多物理场仿真分析了不同火焰位置、火焰桥接情况、导线受火焰影响长度对导线最大弧垂的影响。结果表明:考虑导线不均匀温升条件所得弧垂长度比现有分段式计算结果更为准确,火焰连续区桥接时比烟雾区桥接时的弧垂增加25.12%;导线受火焰覆盖长度对弧垂影响最大,全档距受影响时弧垂可达14.2 m。研究结果可为构建山火条件下的间隙击穿电压预测模型提供参考。

When a vegetation fire occurs under a overhead transmission line,the high temperature will increase the sag of the conductor,which leads to an increase in the trip risk of the line.It is necessary to consider the influence of nonuniform temperature rise of conductor on sag under the condition of vegetation fire.A test platform of vegetation combustion temperature characteristics was built to obtain the vertical flame temperature field distribution of Pinus yunnanensis.Taking 200 m span as an example,a calculate method of sag of conductor under nonuniform temperature rise was proposed.The influence of different flame positions,flame bridging conditions,and flame length on the maximum sag was analyzed by multi-physical field simulation.The simulation results show that considering the nonuniform conductor temperature rise,the sag length obtained is more accurate than the existing piecewise calculation results.The sag in the flame continuous zone increased by 25.12%compared with that in the smoke zone.The flame covering length of conductor has the most significant influence on the sag,and the sag can reach 14.2 m when the total span is affected.The results can provide a reference for accurately constructing the gap breakdown voltage prediction model under wildfire conditions.