中文摘要：

为提高大型电力变压器内部快速暂态仿真计算的准确性,需要准确描述电力变压器的宽频衰减特性。提出了一种基于实测变压器策动点函数或转移函数确定频变衰减因子的方法。首先通过理论分析,建立频变衰减因子的拟合公式;然后通过实测电力变压器策动点导纳函数,采用矢量匹配的方法,获得实测导纳函数的极点分布;最后利用所获得的极点的虚部和实部的关系,对频变衰减因子拟合公式的系数进行优化选取。通过750 k V和1 000k V两台电力变压器的实例,验证了上述方法的可行性,并获得了这两台变压器的频变衰减因子拟合公式。矢量匹配法可以有效地从实测大型电力变压器端口策动点导纳离散数据中提取极点,拟合得到的曲线与实测曲线比较一致。两台电力变压器衰减因子的频变曲线非常相近,所获得的曲线可以用于大型电力变压器特快速暂态仿真。

英文摘要：

In order to improve the accuracy of internal fast transient simulation in large power transformers, broadband attenuation characteristics of transformers should be precisely described. Thus we presented a method for determining the frequency-dependent attenuation factor of power transformers based on the measured transfer function or driving point function. Firstly, a fitting formula of frequency-dependent attenuation factor is established by theoretical analysis. Se- condly, vector fitting method （VFM） is applied for extracting the poles distribution from the measured driving point admittance function. And finally, the coefficients of the frequency-dependent attenuation fitting formula are optimized and selected by fitting the imaginary part and the real part of the extracted poles. The feasibility and effectiveness of this me- thod are verified by two real large power transformers of 750 kV and 1 000 kV, and the frequency-dependent attenuation factor formulas of these two large power transformers are obtained by this method. Poles can be effectively extracted from the measured driving point admittance function of power transformer and the fitted curves are very close to the measured ones. Frequency-dependent curves of these two large transformers are quite close to each other and the obtained formulas can be applied on the simulation of very fast transient.