抑制直流偏磁电阻的全网优化计算

Global Network Optimized Resistance to Restrict Transformers Direct Current Magnetic Bias

摘要: 当高压直流输电系统双极电流不对称或单极大地回路运行时，巨大的接地极电流入地会使接地极附近变电站的变压器产生直流偏磁，对交流系统造成不利影响。中性点串接电阻是抑制直流偏磁的有效方法。本文基于增量网络的灵敏度分析方法，以变压器中性点电流极限值为约束条件，提出了全网优化接地电阻的计算方法。以天广直流输电线路北郊附近的变压器仿真表明，这是一种简单有效的抑制全网变压器直流偏磁电流的方法。全局优化接地电阻的计算方法可以为实际工程提供参考价值。

Abstract: When bipolar current of high voltage direct current transmission system operating asymmetrically or monopolar-ground return operating, huge direct current will pour into the ground through the earthing electrode and thus, transformers nearby will be influenced by direct current magnetic bias and add harm on alternating system. Installing resistance in serial of neutral grounding transformers is an effective method to restrict transformers direct current magnetic bias. The paper presents an optimized configuration method of ground resistance to make all the currents through the transformer neutral point in the grid within its limits on the basis of increment network sensitivity analysis. The proposed method is verified by the data from tian-guang HVDC, and the verification result shows that it is a simple and effective method of restricting all the neutral direct current magnetic bias by optimized resistance. The global network optimized resistance method can provide reference value for practical project.