基于场路直接耦合模型的交流电网直流偏磁电流分布研究  

Study of DC-bias Current Distribution in AC Power System Based on Direct Field-circuit Coupled Model

作　　者：阮江军[1] 徐闻婕 丁志锋 吴泳聪 孙翔[3] 邹国平[3] 

机构地区：[1]武汉大学电气工程学院,武汉430072 [2]国网江苏省电力公司经济技术研究院,南京210008 [3]国网浙江省电力公司电力科学研究院,杭州310014

出　　处：《高电压技术》2017年第4期1333-1340,共8页High Voltage Engineering

摘　　要：直流输电系统单极大地方式运行会导致交流系统部分变压器处于直流偏磁状态。基于场路直接耦合方法,建立了±800 k V溪浙和±800 k V灵绍特高压输电工程的直流偏磁计算模型,确定了建模范围和地网参数,并对土壤模型进行了修正,将直流偏磁电流计算值与现场测试结果进行了对比,测试站点的总的相对平均误差≤5%,验证了计算模型的准确性。进一步计算分析了单极大地运行方式下,直流接地极周围110 k V及以上电压等级变电站中变压器的直流偏磁电流分布规律,结果表明:站点的直流电流随着站点与直流接地极之间距离的增加而减小;多台变压器并列运行时,流过每台变压器的直流电流将大幅度下降;首末站点间跨度增大时,流经两站点的电流将增大。研究可为大型交流电网直流电流分布计算和直流偏磁治理提供参考。DC transmission system in monopole-grounded return operation mode may lead to DC magnetic bias of some transformers in AC power system. Based on the direct field-circuit coupled method, the DC magnetic bias calculation models of ±800 kV Xi-Zhe and ±800 kV Ling-Shao UHV transmission project were built. The modeling range and the ground grid parameters were determined, while the soil model was modified as well. The calculated values of DC biasing current were compared with the test results and the total relative average error of each testing station was no more than 5%, verifying the accuracy of the calculation model. The DC biasing current distribution regularities of the substations above 110 kV around the grounding electrode was calculated and analyzed further. The results indicate that the DC current of the substation decreases as the distance between the substation and the grounding electrode increases. When transformers are in parallel operation, the DC current of each transformer decreases greatly. The DC current flowing through the starting and terminal substations will increase with their distance. This research can provide reference to the calculation of DC current distribution in large AC grid and the management of DC magnetic bias.

关 键 词：直流偏磁 变压器 场路耦合模型 高压直流输电 接地极 交流电网 电流分布 

分 类 号：TM721.1[电气工程—电力系统及自动化]