特高压直流输电线路与接地极对地电场观测的干扰

Interference on Geoelectric Field Observation from UHVDC Power Lines and Its Ground Electrode

随着特高压直流输电工程的建设,直流输电线路对地电场观测的干扰越显突出。为此,根据地电场观测仪器的工作原理,分析了直流输电线路干扰地电场观测的原因,认为线路合成场和接地极入地电流使大地土壤电位分布发生了变化,从而影响了埋设在土壤中的地电场观测仪器电极间的电场。采用Deutseh假设法,研究了合成场和入地离子流在土壤中的电位分布,发现入地离子流会对地电场观测产生干扰。提出了研究入地电流对地电场观测干扰的复杂土壤模型,并推导了该模型下点电流源在土壤中的Green函数表达式,计算了入地电流对地电场观测的干扰水平。结果表明,直流输电线路入地电流为地电场观测干扰的决定性影响因子;若取0.5mV/km为电场强度干扰限值,则正常运行时的干扰范围可达30km以上。

The interference on geoelectric field observation （GFO） from UHVDC power lines becomes increasingly prominent with the growth of UHVDC transmission projects. Thus, we analyzed the interference by the mechanism of GFO equipment, and found that the potential distribution between the electrodes in soil of GFO equipment was changed by the ground current from ground electrode and the synthesis electric field of power lines. Using the assumption method proposed by Deutseh, we researched the potential distribution in soil regarding to the synthesis electric field and ground ion flows and found that the ion flow in the earth affected GFO. Consequently, we proposed a complex soil model to study the interference on GFO from ground current, derived Green＇s function of the model, and calculated the interference. The results show that the ground current from grounding electrodes of power lines is the decisive impact factor of interference. Typically, if the allowable interference value is 0.5 mV/km, the effective distance of interference from an operating power line could be above 30 km.