三相配电变压器行波传变特征分析

利用配电变压器传变故障初始行波波头,可以解决配电线路行波故障测距中线路末端信号不易获取的问题.在已经证明配电变压器能有效传变行波信号的基础上,本文对三相配电变压器的行波传变特征进行了研究.以目前通用的配电变压器为例,分析了各种类型故障初始行波传变到配电变压器低压侧的信号特征及规律,研究发现,尽管中性点非有效接地系统单相接地故障后线路稳态线电压保持不变,但其故障暂态过程仍产生电压行波线模分量,并且它们可以有效传变到配电变压器低压侧.在此基础上,提出只利用变压器低压侧的两个线电压信号就可以有效获取各种类型故障初始行波信号,为利用三相配电变压器获取故障初始行波信号的现场实现提供了理论依据.现场试验证明了所述方法的正确性.

Analysis of Travelling waves Transform Characteristics of Three- Phase Distribution Transformers

Using distribution transformers to catch travelling waves can solve the problem of how to catch travelling waves generated by fault on feeders' terminal.Based on the result that transformer can transform travelling waves effectively,this paper researches the transform characteristic of travelling waves in three-phase distribution transformers.Taking the popular three-phase distribution transformers as example,the characteristics and the rules of travelling wave signals catched in the transformers' low-voltage side under different type of faults are analyzed.The results show that although the line-to-line voltage of stable state after single-phase earth fault in the neutral non-effective grounding system keeps invariable,transient process of the fault produce aerial mode component of traveling waves,and it can be transformed effectively to the transformers' low-voltage side.On this base,the idea that travelling waves generated by different type of faults can be catched effectively with only two line-to-line-voltage signals in the transformers' low-voltage side is proposed,which provide the reality basis for the three-phase distribution transformers used as measurement transformers of travelling waves.Experimental test verify the feasibility and correctness of the proposed method.