结合频率信息的相关函数法用于介质损耗的测量

Application of correlation function method integrated with frequency information to measurement of dielectric loss

当电力系统频率波动时用相关函数法计算介质损耗(介损)存在误差,为了提高精确度提出了结合频率信息的改进相关函数法。改进算法使用加汉宁(Hanning)窗插值算法获得电力系统频率,然后根据频率和抛物插值公式获取整周期的采样序列,对所得整周期的采样序列采用基于辛卜生公式的改进相关函数法计算介损。原算法与改进算法的仿真结果表明改进算法精确度远高于原算法,信号频率为49～51Hz范围内它使介损最大误差从10-2减少到了10-4,针对实测信号改进算法的精确度也远高于原算法,表明改进算法能有效减轻频率波动给介损测量带来的误差。

Dielectric loss calculated by correlation function method has large error when signal frequency is different from power frequency. For improving the accuracy, modified correlation function method integrated with frequency information is presented. Harming windowing interpolation algorithm is used to acquire signal frequency, integral period signal is gotten based on the signal frequency and the parabolic interpolation formulas. The modified correlation function method based on Simpson formulas is used to calculated dielectric loss. Dielectric loss of simulation signal is calculated by the original algorithm and the improved algorithm, the result indicates that the accuracy of the improved algorithm is much higher than that of the original one, the maximal error decrease from 102 to 10-4 after using of the proposed algorithm when the signal frequency is in the range of 49 to 51Hz, so the algorithm can alleviate error caused by frequency fluctuation effectively.