直流输电大地电流对交流系统影响的网络分析算法

直流输电系统单极大地回路运行方式导致电网部分变压器振动加剧，噪声增大，影响了设备安全。为此，以直流接地极与交流接地极存在一定强度耦合的观点分析了电网变压器直流偏磁事例，在此基础上提出变压器中性点直流分量的网络算法。算法应用黑箱理论，将复杂的大地电流场计算变换为电路计算，将电场-电路交替问题演化成纯电路问题，使分析简化。同时，提出了交流接地极源极与受极的概念，有助于从理论及工程应用层面分析直流大地电流对交流电网的影响。

Network algorithm to analyze effects of DC transmission ground current on AC system

The monopolar ground circuit operation mode of DC transmission system gives rise to excessive vibration and noise of some transformers in the power grid,which impacts the safety of equipment.Holding that there exists to a certain extent coupling between DC and AC earth electrodes,the authors analyze the transformer DC magnetic biasing in the grid,and present the network algorithm for the DC component of transformer neutral point.Using black-box theory,the algorithm converts complicated earth current field computation into circuit computation,changing the field-circuit alternation problem into pure circuit matter,thus greatly simplifying the analysis.Meanwhile,the concepts of source and receiving AC earth electrodes are presented,which facilitates the analysis of the effects of DC ground current on AC power grid from the perspectives of theory and engineering application.