水平型直流接地极温升试验与仿真  

Test and Simulation for Horizontal Ground Electrode's Temperature Rise

作　　者：杜华珠[1] 文习山[1] 王羽[1] 安韵竹[1] 邢鹏翔[1] 郑泞康[1] 

机构地区：[1]武汉大学电气工程学院,武汉430072

出　　处：《高电压技术》2013年第5期1184-1190,共7页High Voltage Engineering

基　　金：国家重点基础研究发展计划(973计划)(2009CB724500)~~

摘　　要：直流系统在单极运行时,接地极的散流电流会使附近土壤温度升高,同时极址土壤各参数也会随温度发生改变。为研究土壤参数变化情况下的接地极温度场,在考虑接地极自阻的情况下对接地极电流场进行计算,并将电流场计算结果作为温度场的计算条件采用有限元法计算土壤暂态温度场,构成电流场与温度场耦合仿真模型。采用该模型求解直流接地极的暂态温升过程,并采用水平型直流接地极温升试验数据对算法进行验证。试验选取直径30mm、长9m的圆钢作为接地极,加载74h的直流电流,采用霍尔电流传感器和光纤光栅感温光缆对接地极的电流与温度进行采集与记录。试验发现接地极电流注入处的温度曲线表现为尾部上扬,表明土壤电阻率随温度升高而增大,且电阻率的升高也导致了温升更快。根据这一情况,对土壤电阻率与温度的关系进行了拟合,并给出拟合公式。对比实测数据,模型在考虑土壤电阻率随温度变化的情况下,计算结果较为准确。In an HVDC system under monopole operation mode,disperse current from DC grounding electrode will increase the temperature of nearby soil,which eventually leads to the changes in parameters of the soil.Thus,we established a current-temperature-field-coupled calculation model of DC grounding electrode to investigate the temperature field around the electrode in parameter-varying soil.In the model,the temperature field was calculated by the finite element method based on results of current field calculation,which were obtained by calculation after taking ground electrode’s self-resistance into consideration.The transient temperature rise process of DC ground electrode was calculated by the coupled model,and was verified by tests on horizontal grounding electrodes.A 9 m-long round steel with its cross diameter of 30 mm was used as the grounding electrode in the tests.The ground electrode was loaded with DC current for 74 hours continuously;meanwhile,its current divergence and temperature were measured and accorded by hall current sensors and fiber grating sensors,respectively.A special phenomenon occurred in the tests was that the temperature curve at the injecting point tended to be upturn,meaning that soil resistivity increased with temperature,and this increase was accelerated by temperature rise.Hence,soil resistivity varying with temperature was fitted,and the fitted equation was given.Compared with measured data,the results of coupling calculation model were basically accurate since variation of soil resistivity with temperature was taken into account.

关 键 词：水平接地极 温升 电流场 温度场 土壤电阻率 散流电流 

分 类 号：TM862[电气工程—高电压与绝缘技术]