Chemical Engineering Program, Texas A&M University at Qatar, Doha P.O. Box 23874, Qatar.
Electrical and Computer Engineering Program, Texas A&M University at Qatar, Doha P.O. Box 23874, Qatar.
Sensors (Basel). 2022 Jul 26;22(15):5564. doi: 10.3390/s22155564.
Multiscale PCA (MSPCA) is a well-established fault-detection and isolation (FDI) technique. It utilizes wavelet analysis and PCA to extract important features from process data. This study demonstrates limitations in the conventional MSPCA fault detection algorithm, thereby proposing an enhanced MSPCA (EMSPCA) FDI algorithm that uses a new wavelet thresholding criterion. As such, it improves the projection of faults in the residual space and the threshold estimation of the fault detection statistic. When tested with a synthetic model, EMSPCA resulted in a 30% improvement in detection rate with equal false alarm rates. The EMSPCA algorithm also relies on the novel application of reconstruction-based fault isolation at multiple scales. The proposed algorithm reduces fault smearing and consequently improves fault isolation performance. The paper will further investigate the use of soft vs. hard wavelet thresholding, decimated vs. undecimated wavelet transforms, the choice of wavelet decomposition depth, and their implications on FDI performance.The FDI performance of the developed EMSPCA method was illustrated for sensor faults. This undertaking considered synthetic data, the simulated data of a continuously stirred reactor (CSTR), and experimental data from a packed-bed pilot plant. The results of these examples show the advantages of EMSPCA over existing techniques.
多尺度主成分分析（MSPCA）是一种成熟的故障检测和隔离（FDI）技术。它利用小波分析和 PCA 从过程数据中提取重要特征。本研究展示了传统 MSPCA 故障检测算法的局限性，从而提出了一种改进的 MSPCA（EMSPCA）FDI 算法，该算法使用了新的小波阈值准则。这样，它改善了残差空间中故障的投影和故障检测统计量的阈值估计。当用合成模型进行测试时，EMSPCA 在相等的误报率下将检测率提高了 30%。EMSPCA 算法还依赖于在多个尺度上基于重构的故障隔离的新应用。所提出的算法减少了故障模糊，并因此提高了故障隔离性能。本文将进一步研究软阈值和硬阈值、抽取和非抽取小波变换、小波分解深度的选择及其对 FDI 性能的影响。开发的 EMSPCA 方法的 FDI 性能通过传感器故障进行了说明。这项工作考虑了合成数据、连续搅拌反应器（CSTR）的模拟数据和填充床中试工厂的实验数据。这些示例的结果表明了 EMSPCA 相对于现有技术的优势。
