修正的谐波分析法可提高介损在线测量准确度

Modified Harmonics Analysis Approach for Increasing Precision in On-Line Measuring tanδ

谐波分析法在线测量介损时易因频率波动产生泄漏误差 ,为此在非同步采样下推导出介损测量的完整时域表达式 ,提出先估算频率偏差再用它来修正原谐波分析法的改进方法。MATLAB 6 5对原谐波分析法和修正谐波分析法求介损因数的仿真结果表明 ,非同步采样下修正法的准确度显著提高 ,自适应调整采样频率时两周后介损测量最大绝对误差就已≯ 7 5× 10 -3 % ,完全满足介损测量高准确度要求。

When applying harmonics analysis approach to measure tanδ on-line, the measurement accuracy will be influenced by leakage error, because of the fluctuation of the system frequency. Then the veracious expressions of tan δ in time-domain are derived strictly under the condition of asynchronous sampling. The improved method modified by the excursion of frequency on the expressions simulation through MATLAB 6.5 verifies that the modified approach has higher accuracy than the original one, when the adaptive sampling technique is applied, the maximal absolute error doesn't exceed 7.5 10-3% already after two periods, so the modified approach satisfies on-line monitoring of dielectric loss.