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Hierarchical Scheduling and Utility Disturbance Management

Researchers: Anna Lindholm, Charlotta Johnsson

The research is part of the Process Industry Centre (PIC), and is performed in collaboration with Perstorp AB and researchers from the Department of Mathematics and the Department of Management and Engineering at Linköping University.

The chemical industry has during the past decades become a global marketplace with strong competition between manufacturers, which requires a more agile plant operation to increase flexibility and decrease production costs. Planning, scheduling, and control are some key features that have large economic impact on process industry operations. In this research project, a hierarchical approach to integrate scheduling (on a timescale of days) with production control (on a timescale of hours) is suggested. The approach focuses on sites with several interconnected production areas with continuous production. 

The scheduling level is denoted production scheduling (PS) and the production control level detailed production scheduling (DPS)in agreement with the ISA-95 terminology. The production scheduling takes orders, forecasted orders, and the actual production per day as inputs to make a production schedule for a month ahead divided into daily time periods. The objective of the production scheduling is to make a production schedule that serves as an input to the lower level in the hierarchy, the detailed production scheduling. The production schedule is updated every day in receding horizon. The objective of the detailed production scheduling is to handle daily disturbances at the site in order to minimize the economical influence of these disturbances. Reference values for the sales of products are given by the production schedule, and predicted disturbance trajectories are also given as input for the detailed production scheduling. The detailed production schedule has a timescale of hours and is updated every hour in receding horizon.


The focus for the detailed production scheduling is currently disturbances in the supply of utilities, such as steam and cooling water. Utilities are often shared between the production areas at a site, and management of these disturbances thus becomes an interesting topic when production areas are also connected by the flow of products. A generic method for minimizing the effects of disturbances in utilities has been developed, which requires a model of the site. Different modeling approaches have been suggested and the objective has been to start with simple and quickly obtained models, and step by step move towards more elaborate models. The current model for utilities assumes a linear relation between the supply of a utility to an area and the production in the area. 

The research is conducted in close collaboration with process industrial companies, in particular with Perstorp, that is a world leader within several sectors of the specialty chemicals market.

Publications

 

Anna Lindholm: Hierarchical Scheduling and Utility Disturbance Management in the Process Industry. PhD Thesis ISRN LUTFD2/TFRT--1097--SE, Department of Automatic Control, Lund University, Sweden, October 2013.

Anna Lindholm, Nils-Petter Nytzén: "Hierarchical production scheduling in the process industry". In 18th Nordic Process Control Workshop, Oulu, Finland, August 2013.

Anna Lindholm, Pontus Giselsson, Nils-Hassan Quttineh, Helene Lidestam, Charlotta Johnsson, Krister Forsman: "Production scheduling in the process industry". In 22nd International Conference on Production Research, Foz do Iguaçu, Brazil, July 2013.

Anna Lindholm, Pontus Giselsson: "Minimization of economical losses due to utility disturbances in the process industry". Journal of Process Control, 23:5, pp. 767–777, June 2013.

Anna Lindholm, Charlotta Johnsson, Nils-Hassan Quttineh, Helene Lidestam, Mathias Henningsson, Joakim Wikner, Ou Tang, Nils-Petter Nytzén, Krister Forsman: "Hierarchical scheduling and utility disturbance management in the process industry". In IFAC Conference on Manufacturing Modelling, Management and Control (MIM2013), Saint Petersburg, Russia, June 2013.

Anna Lindholm, Charlotta Johnsson: "Plant-wide utility disturbance management in the process industry". Computers and Chemical Engineering, 49, pp. 146–157, February 2013.

Anna Lindholm, Pontus Giselsson: "Formulating an Optimization Problem for Minimization of Losses due to Utilities". In International Symposium on Advanced Control of Chemical Processes, Singapore, July 2012.

Anna Lindholm, Charlotta Johnsson: "A Tool for Utility Disturbance Management". In 14th IFAC Symposium on Information Control Problems in Manufacturing (INCOM), Bucharest, Romania, May 2012.

Anna Lindholm, Charlotta Johnsson, Tore Hägglund, Hampus Carlsson: "Reducing revenue loss due to disturbances in utilities using buffer tanks - A case study at Perstorp". In Conference on Foundations of Computer-Aided Process Operations (FOCAPO2012), Savannah, Georgia, USA, January 2012.

Anna Lindholm, Charlotta Johnsson, Tore Hägglund, Hampus Carlsson: "Reducing revenue loss due to disturbances in utilities using buffer tanks - A case study at Perstorp". In 17th Nordic Process Control Workshop, Kgs Lyngby, Denmark, January 2012.

Anna Lindholm: "Utility Disturbance Management in the Process Industry". Licentiate Thesis ISRN LUTFD2/TFRT--3253--SE, Department of Automatic Control, Lund University, Sweden, October 2011.

Anna Lindholm, Hampus Carlsson, Charlotta Johnsson: "A General Method for Handling Disturbances on Utilities in the Process Industry". In 18th IFAC World Congress, Milano, Italy, August 2011.

Anna Lindholm, Hampus Carlsson, Charlotta Johnsson: "Estimation of Revenue Loss due to Disturbances on Utilities in the Process Industry". In 22nd Annual Conference of the Production and Operations Management Society , Reno, Nevada, U.S.A., April 2011.

Anna Lindholm: "A method for improving plant availability with respect to utilities using buffer tanks". In 31st IASTED conference on Modelling, Identification and Control (MIC), Innsbruck, Austria, February 2011.

Anna Lindholm, Hampus Carlsson, Charlotta Johnsson: "Availability Estimations for Utilities in the Process Industry". In 16th Nordic Process Control Workshop, Lund, Sweden, August 2010.

 


2017-01-23