使用快速加窗离散希尔伯特变换和插值算法的时域无功测量方法(英文)

Time Domain Reactive Power Measurement Employing Fast Windowed Discrete Hilbert Transform and Interpolation Algorithm

根据时域积分的无功测量原理,对一种基于加窗离散希尔伯特变换(windowed discrete Hilbert transform,WDHT)和矩形自卷积窗(rectangular self-convolution window,RSCW)滤波的无功测量方法进行分析,找出非同步采样条件下该方法的误差产生的根本原因,将快速加窗离散希尔伯特变换和插值算法应用于原方法的改进中,有效地提高了测量的速度和精度。理论推导证明,使用改进方法,只需将瞬时无功序列与矩形自卷积窗先做乘积再求和即可实现瞬时无功序列的滤波,其实现过程简单、计算量小。仿真中,在不考虑信号含噪的情况下分别使用2、3、4阶矩形自卷积窗,改进方法的精度相对于原方法分别提高约1、3、5个数量级。当信号含噪时,改进方法的精度整体上仍优于原方法。改进方法已成功应用于一款多功能电表的软件设计中。实验表明,使用2阶矩形自卷积窗时,改进方法的测量精度比原方法高出约1个数量级,其测量时间减少约51%。

According to the theory of measuring reactive power with the time-domain integral method, this paper analyzed a measuring approach based on windowed discrete Hilbert transform （WDHT） and rectangular self-convolution window （RSCW） filtering, and figured out its source of errors under asynchronous sampling. Fast WDHT and interpolation algorithm were utilized, and the measuring speed and accuracy were effectively improved. Theoretical derivation demonstrates that when using the improved method, the filtering process can be achieved by first multiplying the instantaneous reactive power sequence with RSCW and then calculating the sum of them. The realization procedures are very simple＂ with small calculation. In the simulation process, without noise in signals, the measuring precision of the improved method is about 1, 3, and 5 orders of magnitude higher than that of the previous one, when 2, 3 and 4-order RSCW are used respectively. And when white noise exists in signals, the measuring precision of the improved method is still higher. The improved method has been successfully applied to the software design of a multifunctional electrical meter. In the experiment with 2-order RSCW, the measuring precision of the improved method is approximately promoted by 1 order of magnitude, and the measuring time is reduced by 51% compared with the previous method.