提升广义S变换在暂态电能质量检测中的应用

Application of Lifting Generalized S-transform in Signal Detection of Transient Power Quality

S变换作为一种信号分析工具,由于其高斯窗口函数形态固定,在实际应用中受到限制。广义S变换采用自适应高斯窗口函数,使其对暂态电能质量扰动信号的检测分析具有了更高的适应性和灵活性。提出了一种利用时频聚集特性准则来选取高斯窗口函数调节参数的广义S变换改进方法,基本思想是通过对高斯窗口函数调节参数的优化选取,使得广义S变换在分析信号过程中的时频聚集特性值达到最大,这样可以使信号在任意一点都具有较高的时频分辨率。通过仿真与实验的对比分析,结果表明该方法在暂态电能质量信号方面具有更高的检测精度以及信号去噪能力。

S-transform as a tool of signal analysis has been limited in practical applications because of the f＇lxed shape of its Gauss window function. Some existing modified S-transform algorithms have better adaptability and flexibility by an additional parameter in the Gauss window function. However, the additional parameter is selected by empirical data in some modification, which have exposed errors brought by human factors. In this paper, a new improvement is achieved by introducing the measurement criteria of time-frequency concentration which can be used to optimize the additional parameter of the Gauss window function. The core of this scheme is to obtain an optimal parameter through maximizing the value of measurement criteria of time-frequency concentration. The algorithm is tested on a set of synthetic signals and a voltage sag disturbance signal. The results show that the proposed method has higher detection accuracy and ability to resist the cross term interferences than other modification.