基于波形识别的变压器自适应制动比率差动保护原理

THE PRINCIPLE OF SELF-ADAPTIVE RESTRAINT RATIO COEFFICIENT DIFFERENTIAL PROTECTION OF TRANSFORMER BASED ON WAVEFORM IDENTIFICATION

带多段折线或非线性特性的比率差动保护引起了广泛的关注 ,其中三折线比率制动特性的差动保护已在变压器保护中得到了应用 ,但是 ,如何整定各段折线拐点及非线性特性依然是一难题。文中分析了差动不平衡电流、电流互感器 ( TA)饱和、TA传变误差及波形相关系数之间的关系 ,并通过大量的仿真计算 ,得到了 TA传变误差与相关系数的比率关系 ,在此基础上 ,提出了一种根据波形相关系数自动调整制动比率特性的变压器差动保护原理。

The transformer differential protections with the characteristic of multi ratio restraint or non linear restraint have been concerned. In fact, the three ratio restraint has been applied in transformer protection. However, it is difficult to set the inflexions of piecewise line or the characteristics of non linear restraint exactly. In this paper, the relationships are discussed among differential current, CT(current transformer) saturation, CT error and the waveform correlation coefficient. By calculating and analyzing a great deal of simulated data, the ratio relationship between CT error and waveform correlation coefficient is established. Then, a principle of self adaptive restraint ratio coefficient transformer differential protection based on waveform correlation coefficient is presented.