利用S变换时频等值线图与幅值包络向量实现电压凹陷的分类

提出了一种基于S变换的电压凹陷分类方法.该方法基于各种电压凹陷在三相幅值凹凸性、凹陷持续阶段特定谐波成分以及幅值突变次数等方面的不同特征,通过应用具有良好时频分析能力的S变换提取这些特征,并采用修正一阶中心矩、时频等值线图、相位变化曲线等环节实现对电压凹陷的分类.分类过程简明,可对故障、故障自清除、感应电动机起动以及变压器励磁等多种原因引起的电压凹陷进行正确分类.仿真验证了该方法的有效性.

Classification of Voltage Dips Using Time-Frequency Contour and Amplitude Envelope Vectors by S-Transform

This paper proposed a novel classification method for voltage dips (sags) based on S-transform (ST). Different voltage dips have distinct characteristics of three-phase magnitude, harmonics and phase angle shift. And S-transform is an excellent time-frequency representation and very suitable for feature extraction of power quality disturbances like voltage dips. Using time-frequency contour and amplitude envelope vectors of the module matrix from S-transform, these distinct characteristics of voltage dips are extracted. Corrected first central moments are introduced to quantify the three-phase magnitude, time-frequency contours are applied to present the harmonics and phase angle curves are used to reflect the phase angle shifts. Simulation results show that the proposed method can classify voltage dips caused by short circuit faults, motor induction, transformer energizing and faults self-extinguishing concisely and correctly, so it is a practical approach for voltage dips classification.