交直流混联系统对变压器保护性能的影响及解决措施  

The Adverse Impacts on Transformer Protection Performance by Hybrid AC-DC Transmission Grid System and Counter-measures

作　　者：索南加乐[1] 张健康[1,2] 张军民[1] 粟小华[2] 孙成[1] 杜斌[1] 

机构地区：[1]西安交通大学电气工程学院,陕西省西安市710049 [2]西北电力调度通信中心,陕西省西安市710048

出　　处：《电力系统自动化》2010年第3期101-106,共6页Automation of Electric Power Systems

摘　　要：在交直流混联系统中,直流偏磁和换相失败都会对变压器差动保护产生不利影响。以西北电网交直流混联系统为分析对象,分别研究了变压器差动保护在这2种情况下的运行性能。仿真数据表明:直流偏磁严重的变压器发生区内弱故障时,差动电流中的2次谐波将会引起变压器差动保护拒动;直流系统换相失败时,交流系统电流可以看成一个谐波源,此时发生内部故障时,变压器差动保护也会由于差动电流中2次谐波的存在而使保护拒动。为了解决这些问题,文中采用了基于故障分量综合阻抗的保护方案。理论分析和仿真验证都表明新方案在变压器直流偏磁或换相失败时仍然具有很高的灵敏度和可靠性。In a hybrid AC-DC transmission grid, DC bias and commutation failure have adverse effects on the behavior of transformer differential protection. With the model of an actual hybrid AC DC transmission grid in northwest of China, the performance of differential protection under these two situations are discussed. Simulation results show that the second order harmonic produced by DC bias may cause miss-operation of differential protection in the event of minor internal faults. The results also reveal that under the circumstances of commutation failure, where the current of the AC system can be seen as a harmonic source, the differential protection may refuse operation when internal faults happen because of the high second order harmonic. The protection scheme based on fault component integrated impedance is used to solve these problems. Theoretical analysis and simulation results show that the scheme is with high sensitivity and reliability even when minor internal faults happen under the situation of DC bias or commutation failure.

关 键 词：直流偏磁 换相失败 交直流混联系统 2次谐波 故障分量综合阻抗 

分 类 号：TM772[电气工程—电力系统及自动化]