Steady state identification for on-line data reconciliation based on wavelet transform and filtering |
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Affiliation: | 1. Institute Polytechnique de Grenoble Saint Martin d?Hères 38400, France;2. COMSATS Institute of Information Technology, Islamabad 44000, Pakistan;3. King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia;4. Brunel University, Uxbridge, Middlesex UB8 3PH, UK;1. Institute for Advanced Studies in Basic Sciences, P.O. Box 45195-1159, Zanjan, Iran;2. IDAEA-CSIC, Jordi Girona 18-26, Barcelona 08034, Spain;1. LOOP – Process Observation and Optimization Laboratory, Department of Electrical and Computer Engineering, Université Laval, Québec, Québec, Canada;2. LOOP – Process Observation and Optimization Laboratory, Department of Mining, Metallurgical, and Materials Engineering, Université Laval, Québec, Québec, Canada |
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Abstract: | In order to derive higher value operational knowledge from raw process measurements, advanced techniques and methodologies need to be exploited. In this paper a methodology for online steady-state detection in continuous processes is presented. It is based on a wavelet multiscale decomposition of the temporal signal of a measured process variable, which simultaneously allows for two important pre-processing tasks: filtering-out the high frequency noise via soft-thresholding and correcting abnormalities by analyzing the maximums of wavelet transform modulus. Wavelet features involved in the pre-processing task are simultaneously exploited in analyzing a process trend of measured variable. The near steady state starting and ending points are identified by using the first and the second order of wavelet transform. Simultaneously a low filter with a probability density function is employed to approximate the duration of a near stationary condition. The method provides an improvement in the quality of steady-state data sets, which will directly improve the outcomes of data reconciliation and manufacturing costs. A comparison with other steady-state detection methods on an example of case study indicates that the proposed methodology is efficient in detecting steady-state and suitable for online implementation. |
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Keywords: | Signal processing Steady-state detection Wavelet analysis Plant-wide application Data cleansing |
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