采用向量匹配法的油纸绝缘系统扩展Debye模型参数识别

Parameter Identification Based on Vector Fitting Method for Extended Debye Model of Oil-paper Insulation System

为了从时域数据中获取更丰富的表征油纸绝缘系统绝缘状态的信息,提出了一种获取油纸绝缘系统扩展Debye模型参数的方法。首先通过快速Fourier变换(FFT)获得极化去极化电流(PDC)实验的去极化电流频谱,然后使用向量匹配法(VFM)和时域非线性拟合算法(FNA),确定其频谱的极点和留数分布,最后根据极点和留数计算得到各支路参数。针对实验室不同老化程度和不同温度下的油纸绝缘模型,开展了验证性的PDC和频谱(FDS)实验,利用PDC实验数据求取了相应的扩展Debye模型,据此获得了介损(tanδ)随频率的变化曲线,并与FDS所得结果进行了比较。结果表明,PDC所得结果与FDS曲线在低频段一致,验证了所提方法的正确性。进而提出在对油纸绝缘设备绝缘状况进行测试时,采用FDS做高频测试,而采用PDC代替FDS做低频测试,从而减少测试时间,即将PDC与FDS这2种方法相结合,可以提高现场油纸绝缘设备的检测效率。

In order to obtain more specific information of insulation states of oil-paper insulation system from time-domain data, we proposed a novel method for parameter identification of extended Debye model for oil-paper insu- lation system. In the method, the depolarization current spectrum of polarization and depolarization current （PDC） in experiments was obtained by the fast Fourier transform （FFT）. Then combining the vector fitting method （VFM） and non- linear fitting algorithm （FNA）, we derived the distribution of the poles and residues of the obtained spectrum, and calculated the branch parameters of extended Debye models. The PDC and frequency domain spectrum （FDS） measure- ments were performed on some oil-impregnated pressboard samples, which were in various aging states and under different temperatures. The corresponding extended Debye models to the samples were obtained from the PDC measure- ment, based on which curves of tang varying with frequency were figured out and then compared with those from FDS measurements. The tang obtained from PDC agrees well with that from FDS under low frequencies, which verifies the proposed method. With further analysis, it is suggested that, for oil-paper insulation system, FDS measurement should be conducted in high frequency range but replaced by PDC measurement in low frequency range, for saving time, i.e. the combination of FDS and PDC methods could help to improve the efficiency of measurement of on-site oil-paper equipment.