计及铁磁材料饱和特性的地网接地阻抗的计算  

Calculation of Grounding Impedance of Large Substation Considering the Steel Permeability Saturation Characteristics

作　　者：鲁志伟[1] 常树生[1] 谭春力[1] 

机构地区：[1]东北电力大学电气工程学院,吉林132012

出　　处：《高电压技术》2009年第2期290-293,共4页High Voltage Engineering

摘　　要：为了解决因钢材磁导率的非线性使得接地网接地阻抗的计算较为困难的问题,基于矩量法和场路结合的思想,提出了一种计及钢材磁导率饱和特性的接地网接地阻抗计算方法。该方法考虑了接地导体的电阻、自感和导体间的互感,在自感的计算中考虑到钢材磁导率的非线性特性,并分析了大型钢材地网工频接地阻抗。计算结果表明,大型钢材地网工频接地阻抗随经地网入地故障电流的增大而减小。采用几A至几十A测量电流测量得到的地网接地阻抗明显高于较大故障电流下的接地阻抗。Copper is used as grounding material in developed countries, but steel is used as grounding material in China. The permeability and resistivity of steel are higher than those of copper. It is a problem for steel grounding grid to have great potential difference within a grounding grid if the grounding grid is very large. Consequently, based on method of moment and field-circuit coupling theory, a numerical calculation method of substation grounding grids considering the steel permeability saturation characteristic is presented. The self-inductance and resistance of conductors as well as mutual inductance between conductors are taken into account. The nonlinear characteristic of steel permeability saturation is also considered in the calculation of self-inductance. The fault current flows alone the conductors and drains to the ground at the same time. Therefore, the longitudinal current near the feeding current point is high and magnetic intensity inside conductors is high. The permeability is relative low due to high saturation permeability characteristics of steel. The different grounding conductors have different permeability under the short circuit current from several kA to tens of kA. The impedance of a large substation grounding grid is analyzed by the proposed method. The results show that the grounding impedance is reduced as the short circuit current raises. Thus, the measured grounding impedance with measurement current from several amperes to tens of amperes is higher than grounding impedance with great fault current.

关 键 词：变电站 接地网 钢材 接地阻抗 磁导率 饱和特性 

分 类 号：TM862[电气工程—高电压与绝缘技术]