单相单柱旁轭变压器直流偏磁运行性能测试与分析

Test and Analysis on Operating Performance of Transformer With Single-Phase Three-Limb Core Under DC Bias

分析了直流输电系统双极不平衡运行时地中直流电流对交流变压器励磁特性的影响。在三沪二回直流输电系统大功率调试期间,测试了受端直流接地极附近具有单相单柱旁轭铁心结构的交流变压器的运行性能。在双极平衡运行及不平衡运行的条件下,测量了变压器有载运行时的振动、噪声、油温、油色谱等参数,分析了变压器振动、噪声与双极运行不平衡度、主变的视在功率、油温等参数的相关性,以及直流偏磁对单相单柱旁轭的变压器运行性能的影响。测试结果表明,在双极不平衡运行期间,接地极附近交流站内变压器出现了不同程度的偏磁现象,但油温及油色谱等参数未出现异常,可以承受由此带来的偏磁影响。

The impact of DC current in the earth on excitation characteristic of AC transformer under bi-polar asymmetric operation of HVDC power transmission system is analyzed.During the high-power commissioning of two circuit HVDC transmission system from the Three Gorges to Shanghai,the operating performance of single-phase AC transformer with three-limb core located near DC grounding pole at receiving end is measured and tested,and the relationship of vibration and noise of the transformer with such parameters as unbalance degree of bi-polar operation,apparent power of main transformer and oil temperature as well as the influence of DC-bias on operating performance of single-phase AC transformer with three-limb core are analyzed.Measurement and test results show that during bi-polar asymmetric operation of HVDC power transmission system the DC-bias phenomena to different extent appear in transformers inside the AC substation near the grounding pole,however the oil temperature and oil chromatograph are in normal condition,thus such a DC-bias phenomena are sustainable.