线性插值方法在PT励磁特性曲线求取中的应用

为求取较为精确PT励磁特性曲线,引入了线性插值方法.首先对测量的伏安特性数据的线性区数据进行线性插值,线性区数据和整体数据增多,相应地增加了线性区数据的权重;然后对于PT励磁特性曲线模型,在深度饱和区之前对PT励磁特性曲线取7次多项式,在深度饱和区采用线性模型;最后,综合运用上述插值后数据、最小二乘法对PT励磁特性曲线模型进行拟合.线性插值的方法一方面解决了线性区数据样本点不足的问题;另一方面计算实例表明线性插值方法提高了励磁特性曲线在线性区和深度饱和区之前的饱和区的拟合精度,同时对于深度饱和区采用线性模型的方法,使得深度饱和区拟合精度没有降低.这样从整体上提高了PT励磁特性曲线模型的拟合精度.

A Getting Excitation Characteristic Curves of PTs With Linear Interpolation Method

For the sake of getting more precise curves,the paper introduces the linear interpolation method and section excitation characteristic curves.First,the paper makes interpolation to the linear part of measured voltage-current characteristic data,the weight of linear data is increased with more linear data.Second to the excitation characteristic curves of PTs,the paper adopts the 7 order polynomial function before the part of saturation depth and uses linear model at the part of saturation depth;Last,the paper fits the excitation characteristic with the aforesaid and the least square method.On one hand,the paper solves the problem of lacking data.On the other hand,the calculation sample shows that the fitting accuracy has been greatly improved before the part of saturation depth.At the same time,the fitting accuracy is not reduced at the part of saturation depth with linear model.Above all,the total fitting accuracy is improved.