基波频率修正方法在测量介质损耗中的应用

Application of Fundamental Frequency Correction Method in Measuring Dielectric Loss

分析了电网的系统频率波动对监测变压器套管tanδ的影响,提出一种基于基波频率修正原理的介质损耗因数测量方法。该方法将电压、电流信号在时域内过滤其直流分量,修正所测电信号的基波频率,对原信号采用样条插值法进行插值计算,并进行整周期反复采样,截取整周期样本长度进行快速傅里叶计算,得到基波电压和基波电流的相位夹角,求出其余角的正切值即为介质损耗因数。仿真试验及现场应用的结果表明:采用该方法可实现对变压器套管介质损耗的准确测量。

The effect of grid system frequency fluctuations on the monitoring transformer bushing was analyzed,and a method of measuring the dielectric dissipation factor based on the fundamental frequency correction was proposed. The DC components of the voltage and current signals were filtered in time domain through this method,and the fundamental frequency of measured electric signals was corrected.Then the origin signals were calculated with spline interpolation and sampled repeatedly in a whole period. The phase angle between fundamental voltage and current was obtained by fast Fourier calculation for the samples in the whole period,and the tangent value of the coangle was obtained,which is the dielectric dissipation factor. This method can accurately measure the dielectric dissipation factor of transformer bushing according to the results of simulation and practical application.