新疆哈密特高压直流送端电网地表电位与直流电流分布研究

Research on Ground Potential and DC Current Distribution of Xinjiang Hami UHVDC Sending-End Grid

特高压直流输电系统单极-大地回路运行方式下,直流电流通过接地的中性点流入变压器,会使交流电网遭受直流偏磁影响.论文针对直流接地极周围的地表电位分布展开研究,采用镜像法与行波法,建立水平3层和水平4层土壤结构模型,分别计算不同土壤模型下的地表电位和直流偏磁电流分布.在MATLAB中构建新疆哈密特高压直流送端电网仿真模型,讨论不同土壤分层模型对直流偏磁电流分布的影响.结果表明水平2层分层模型与水平3层模型下地表电位分布存在较大差值,水平3层模型与水平4层模型下地表电位分布曲线几乎重合;采用3层模型计算出的直流电流更接近实测值,能够满足工程计算要求.

Under the single-pole-earth loop operation mode of the UHVDC transmission system,the DC current flows into the transformer through the grounded neutral point,which will cause the AC power grid to suffer from DC bias magnetism.The thesis studies the surface potential distribution around the DC grounding electrode,using mirror image method and traveling wave method to establish horizontal three-story and four-story soil structure models,and calculates the surface potential and DC bias current distribution under different soil models.Power grid in Hami area of Xinjiang is constructed in MATLAB,and the influence of different soil layer models on the distribution of DC bias current is discussed.The results show that there is a large difference in the surface potential distribution between the horizontal two-layer model and the horizontal three-layer model.The surface potential distribution curves under the horizontal three-layer model and the horizontal four-layer model almost coincide;the DC current calculated by the three-layer model is closer to the measured value and can meet the engineering calculation requirements.