基于S变换的电压凹陷分类专家系统

提出了基于时频分析方法S变换的电压凹陷分类专家系统。分析了由故障、故障自清除、变压器激磁和感应电机启动等原因引起的电压凹陷在三相幅值凹凸性、谐波含量、幅值突变次数和相位跳变等方面的不同特征，利用S变换良好的时频分析能力提取并量化这些特征信息，并引入了幅度因子、谐波增量、幅值突变次数和最大相位增量等指标，由此建立专家系统推理算法和判别规则。采用二十进制转换分类方式输出分类结果。给出了对多级电压凹陷进行简单判别的方法。通过仿真和实际算例验证，该专家系统可对所考查的电压凹陷进行准确分类判别。

S-transform-based Expert System for Classification of Voltage Dips

Based on the time-frequency representation, known as S-transform, an expert system for classification of voltage dips (sags) is proposed. Different voltage dips, induced by faults, self-extinguishing faults, transformer energizing and motor induction, are analyzed and distinguished according to their distinct characteristics in three-phase magnitude, harmonics, step changes and phase angle shift. Applying S-transform, these characteristics are extracted and quantified using magnitude factor, increments of harmonics, numbers of step changes, and increments of maximum phase angle shift. Then the illation algorithm and rules of expert system are constructed, and a binary-decimal conversion classification approach is introduced for well and truly outputting the classification results. Moreover, a simple method for analysis of multistage voltage dips is presented. The results of simulation and actual examples show this expert system is effective for classifying voltage dips.