基于CDEGS和ANSYS的直流接地极仿真计算研究

Simulation Study of the DC Grounding Electrode Based on CDEGS and ANSYS

UHVDC工程建设之前,相关设计单位运用CDEGS进行了大地电位升的模拟仿真计算,工程投运后,接地极入地电流对极址附近变电站变压器的影响很大,其原因与极址大地电阻率模型建立不准确和地表电位分布计算不够精确有关。分析了直流输电接地极对周围地表电位造成的影响,并对直流输电接地极电流场的计算方法进行了推导。参考陕北换流站接地极工程中陕北接地极大地电磁测深(MT)法实测大地分层电阻率数据,建立的6层大地土壤模型,应用CDEGS软件和ANSYS软件,分别计算了接地极方圆0~100 km范围内大地电位升分布,重点对2种方案计算结果中0~50 km范围的大地电位分布结果进行了比对,计算结果表明,ANSYS计算结果数值上均略小于CDEGS计算结果,相差约0.6 V。2种方案计算结果均可对现场单极运行调试提供参考。

Before the construction of the UHVDC project,the relevant design units use the CDEGS to simulate the ground potential rise.After the project is put into operation,the grounding current of the grounding electrode has a great influence on the transformer near the electrode site and the reason for it is related to the inaccurate modeling of the grounding resistivity of the electrode and imprecise calculation of the surface potential distribution.In this paper,the influence of the DC ground electrode on the surrounding earth surface potential is analyzed and the calculation method of the current field of the DC transmission grounding electrode is derived.Based on the measured data of the layered earth resistivity by Magnetotelluric sounding（MT）method and the 6-layer soil model of the electrode grounding work of North Shaanxi Converter Station,using CDEGS software and ANSYS software,we calculated the ground potential distribution within a radius of 0~100 km from the electrode respectively,with focus on comparison of the results of the ground potential distribution within a radius of 0-50 km.The calculation results show that the numerical results of the ANSYS method are slightly smaller than the CDEGS calculation results with a difference of about 0.6 V.The calculation results of the two schemes can provide reference for the commissioning of the single pole operation on the job-site.