Nonlinear dynamic process monitoring using deep dynamic principal component analysis

Data-driven method has gained its popularity in fault detection. Conventional methods are associated with one-single-layer process monitoring. Information extracted by such a method may not be sufficient to detect some faults for complicated process systems. Inspired by the deep learning conception, a multi-layer fault detection method, namely Deep Principal Component Analysis (DePCA) was proposed previously in the literature. DePCA has the capability to extract deep features for a process resulting in better fault detection performance. However, it assumes that the value of the variable at each moment is unrelated, which is not suitable for complex nonlinear dynamic system. To address the concerns, by adopting dynamic PCA to extract dynamic features, a new deep approach, namely Deep Dynamic Principal Component Analysis (DeDPCA), is proposed. In the new approach, both Dynamic feature and nonlinear feature can be extracted in different layers so that more process faults can be detected. A Tennessee Eastman process case study was then employed for application and validation of the DeDPCA, which indicates the proposed method is suitable for monitoring complex dynamic nonlinear processes.