{"title":"Mathematical modeling and system analysis for preventing unsteady bulging in continuous slab casting machines","authors":"J. Landauer , L. Marko , A. Kugi , A. Steinboeck","doi":"10.1016/j.jprocont.2024.103232","DOIUrl":null,"url":null,"abstract":"<div><p>In the continuous casting of steel slabs, the ferrostatic pressure in the liquid core of the strand leads to bending, i.e., bulging, of the strand shell between the guiding rolls. Unsteady bulging means that this bending process is time-varying. During the continuous casting process, the emergence of unsteady bulging can be observed, leading to unwanted mold level fluctuations and lowering the quality of the cast strand. This work presents a detailed nonlinear beam model, an approximated nonlinear beam model, and a control-oriented linear model to gain new insights into the mechanism of unsteady bulging. Simulation results show that the linear model allows real-time computation, making it feasible to design advanced model-based control and state estimation strategies. The developed models are validated using measurements from the literature and an industrial continuous casting plant. More specifically, these models permit, for the first time, a detailed stability analysis of the overall mold level control loop, which gives a system-theoretic explanation for the root cause of unsteady bulging and why it is tied to particular frequencies of mold level fluctuations. This analysis shows that the emergence of unsteady bulging is related to an unstable closed-loop system and opens up different strategies to eliminate the observed instability.</p></div>","PeriodicalId":50079,"journal":{"name":"Journal of Process Control","volume":null,"pages":null},"PeriodicalIF":3.3000,"publicationDate":"2024-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0959152424000726/pdfft?md5=45f455a3a6bb2015c35dc203f8cc750a&pid=1-s2.0-S0959152424000726-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Process Control","FirstCategoryId":"94","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0959152424000726","RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"AUTOMATION & CONTROL SYSTEMS","Score":null,"Total":0}
引用次数: 0
Abstract
In the continuous casting of steel slabs, the ferrostatic pressure in the liquid core of the strand leads to bending, i.e., bulging, of the strand shell between the guiding rolls. Unsteady bulging means that this bending process is time-varying. During the continuous casting process, the emergence of unsteady bulging can be observed, leading to unwanted mold level fluctuations and lowering the quality of the cast strand. This work presents a detailed nonlinear beam model, an approximated nonlinear beam model, and a control-oriented linear model to gain new insights into the mechanism of unsteady bulging. Simulation results show that the linear model allows real-time computation, making it feasible to design advanced model-based control and state estimation strategies. The developed models are validated using measurements from the literature and an industrial continuous casting plant. More specifically, these models permit, for the first time, a detailed stability analysis of the overall mold level control loop, which gives a system-theoretic explanation for the root cause of unsteady bulging and why it is tied to particular frequencies of mold level fluctuations. This analysis shows that the emergence of unsteady bulging is related to an unstable closed-loop system and opens up different strategies to eliminate the observed instability.
期刊介绍:
This international journal covers the application of control theory, operations research, computer science and engineering principles to the solution of process control problems. In addition to the traditional chemical processing and manufacturing applications, the scope of process control problems involves a wide range of applications that includes energy processes, nano-technology, systems biology, bio-medical engineering, pharmaceutical processing technology, energy storage and conversion, smart grid, and data analytics among others.
Papers on the theory in these areas will also be accepted provided the theoretical contribution is aimed at the application and the development of process control techniques.
Topics covered include:
• Control applications• Process monitoring• Plant-wide control• Process control systems• Control techniques and algorithms• Process modelling and simulation• Design methods
Advanced design methods exclude well established and widely studied traditional design techniques such as PID tuning and its many variants. Applications in fields such as control of automotive engines, machinery and robotics are not deemed suitable unless a clear motivation for the relevance to process control is provided.