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针对噪声成分严重影响电能质量扰动信号分析的问题,引入基于时—频分割的图像平滑改进全局阈值的方法开展电能质量信号降噪。通过时—频分割,降低对信号整体采用统一阈值降噪导致的高频域微弱扰动成分损失缺陷。首先,通过S变换对电能质量信号进行时—频分析,根据不同扰动信号扰动成分时—频域分布特点,开展时—频分割;然后,利用图像平滑改进全局阈值降噪方法针对不同时—频区域计算最优阈值,开展去噪处理;最后,采用S变换逆变换对降噪后的信号进行波形还原。仿真试验表明,该方法有效降低了噪声干扰,且改善了采用单一阈值降噪导致的波形失真问题。
Aiming at the problem that the noise component seriously affects the signal analysis of power quality disturbances, the method of smoothing the global threshold based on the time-frequency segmentation is introduced to reduce the noise of power quality signal. Through the time-frequency segmentation, reduce the signal of the overall use of uniform threshold noise reduction caused by high-frequency weak disturbance component loss defects. Firstly, the time-frequency analysis of power quality signals is carried out by S transform, and the time-frequency segmentation is carried out according to the time-frequency distribution characteristics of disturbing components of different disturbance signals. Then, by using image smoothing to improve the global threshold denoising method, Area to calculate the optimal threshold, to carry out denoising; Finally, the use of S transform inverse transform the noise reduction signal waveform reduction. Simulation results show that this method can effectively reduce the noise interference and improve the waveform distortion caused by the single threshold noise reduction.