一种改进不完全S变换的电压暂降检测方法

Detection of voltage sag by a modified incomplete S-transform

为实现对电压暂降的准确快速检测,提出了一种改进不完全S变换(MIST)的电压暂降检测方法。该方法对从电网中采集到的电压信号进行快速傅里叶变换,获得信号的主要频率点;对各主频点进行改进的S变换,获得信号主频特征分量;利用这些特征分量信息实现对电压暂降扰动特征量的检测。首先描述了改进不完全S变换的原理及其参数选择的原则,然后详细叙述了电压暂降特征量的提取方法,最后对实际信号进行了仿真。仿真结果表明,该方法可有效地提取电压暂降的幅值、持续时间、相位跳变等特征信息,并且准确率高,运算量小,同时具有一定的抗干扰能力。

In order to realize the detection of voltage sag fast and accurately, a novel method for detecting voltage sag by a modified incomplete S-transform is proposed. The main idea of the method is as follows： first of all, the fast Fourier transform of the voltage signal sampled from the power network is made to obtain the main frequency points of the signal. And then, the modified S-transform of each frequency point is performed to attain the components of main frequency characteristic quantities. Finally, an implementation of the detection of the characteristic quantities of voltage sag is carried out by the components. The principles of the proposed modified incomplete S-transform and the choice of the parameters are described, and then the extraction method of the features of voltage sag is stated in detail, and finally the practical signals are simulated. The obtained results show that the characteristic quantities such as the amplitude, duration and a sudden change of the phase of voltage sag can be extracted by the proposed method, and that it is characterized by high precision, less computation and good anti-interference performance.