剩余电流的分形盒维数抗噪性研究

Research on the Anti-Noise of the Fractal Box Dimension of Residual Current

在分析传统小波阈值降噪法的基础上,提出一种优化的小波阈值降噪法,利用该方法对剩余电流信号降噪后,再叠加不同强度的噪声分析其盒维数的抗噪性,优化的小波阈值降噪法和传统软、硬阈值降噪法相比具有明显的优越性。剩余电流检测是剩余电流保护技术的关键环节,为了反映出复杂环境下剩余电流的特性,对剩余电流分形盒维数的抗噪性进行研究。通过加入噪声模拟原始信号,应用所述优化阈值降噪法对剩余电流仿真信号降噪处理,然后加入白噪声,根据信噪比的变化,研究其盒维数的变化。结果表明,剩余电流信号的盒维数在信噪比较小时与噪声强度呈线性关系,在信噪比较大时其盒维数基本不受噪声影响,剩余电流的分形盒维数具有一定的抗噪性。

Based on the analysis of traditional wavelet threshold de-noising method,an optimized wavelet thresh-old de-noising method is proposed.After the residual current signal is de noised by this method,the noise of different intensity is added to analyze the anti noise performance of box dimension.Compared with the traditional soft and hard threshold de-noising method,the optimized wavelet threshold de-noising method has obvious advantages.Residual current detection is the key link of residual current protection technology.In order to reflect the characteristics of residual current in complex environment,the anti noise property of fractal box dimension of residual current is studied.By adding noise to simulate the original signal,the residual current simulation signal is denoised by using the optimized threshold denoising method described,and then white noise is added to study the change of box dimension according to the change of signal-to-noise ratio.The results show that the box dimension of the residual current signal has a linear relationship with the noise intensity when the signal-to-noise ratio is small,but it is not affected by the noise when the signal-to-noise ratio is large,and the fractal box dimension of the residual current signal has a certain anti noise property.