Research and Application of Small Shifts Detection Method Based on MEWMA-PCA

For the detection problem of small shifts in chemical industry,a new multivariate statistical process monitoring method is proposed.The method extends the conventional EWMA(Exponent Weighted Moving Average) to MEWMA(Multivariate EWMA),and combines it with PCA to form a new MEWMA-PCA.Then two statistics(T_MEWMA-PCA² and Q_MEWMA-PCA) and their corresponding statistical limits are built.The statistical performance indices and their influential ingredients are detailedly analyzed.A case study of the Tennessee Eastman(TE) process shows that the proposed method is feasible and efficient,and the process monitoring performance is evidently improved,hence enhancing the reliability and stability of the process.