摘要
针对电能质量信号去噪问题,提出改进的小波熵自适应阈值去噪法。利用小波变换分解电能质量信号,计算小波分解后信号子带区间的小波熵,将小波熵和自适应阈值相结合确定高频系数阈值门限,采用改进折中指数阈值函数对电能质量信号去噪处理,最后重构降噪后的电能质量信号。通过对四种典型带噪电能质量信号(电压突降信号、暂态振荡信号、电压中断信号、谐波信号)去噪处理,并与无偏风险阈值、极大极小阈值的去噪性能比较,对比可知在输入信噪比为20dB时,对于不同的电能质量信号,改进的小波熵自适应阈值去噪法的输出信噪比是最大的。
An improved denoising method for power quality signal based on wavelet entropy adaptive threshold has been presented in this paper..The power quality signal is decomposed by wavelet transformatioin , so as to calculate the wavelet entropy after the decomposition.The wavelet entropy and adaptive threshold are combined to determine the threshold of high frequency coefficients.An improved trade -off exponent threshold function is adopted to denoise the power quality signal in order to obtain the reconstructed signal .Through denoising four typical power quality signals （voltage sag signal, voltage transient oscillatory signal, voltage interruption signal and harmonic signal ） and compared with the methods of unbiased risk threshold and the max -min threshold method, the simulation results based on the proposed method show that a larger output signal -to -noise ratio will be obtained with the input signal -to -noise ra-tio as 20dB.
出处
《电测与仪表》
北大核心
2014年第15期68-73,共6页
Electrical Measurement & Instrumentation
关键词
电能质量信号
去噪
自适应阈值
小波熵
阈值函数
power quality signal
denoising
adaptive threshold
wavelet entropy
threshold function
