Article | Proceedings of the 9th International MODELICA Conference; September 3-5; 2012; Munich; Germany | On the Formulation of Steady-State Initialization Problems in Object-Oriented Models of Closed Thermo-Hydraulic Systems

Title:
On the Formulation of Steady-State Initialization Problems in Object-Oriented Models of Closed Thermo-Hydraulic Systems
Author:
Francesco Casella: Dipartimento di Elettronica e Informazione, Politecnico di Milano, Milano, Italy
DOI:
10.3384/ecp12076215
Download:
Full text (pdf)
Year:
2012
Conference:
Proceedings of the 9th International MODELICA Conference; September 3-5; 2012; Munich; Germany
Issue:
076
Article no.:
021
Pages:
215-222
No. of pages:
8
Publication type:
Abstract and Fulltext
Published:
2012-11-19
ISBN:
978-91-7519-826-2
Series:
Linköping Electronic Conference Proceedings
ISSN (print):
1650-3686
ISSN (online):
1650-3740
Publisher:
Linköping University Electronic Press; Linköpings universitet


The object-oriented formulation of steady-state initialization for models of closed thermo-hydraulic systems yields singular problems; due to system-wide structural issues. The paper proposes how to solve this problem in an object-oriented fashion; by means of an additional component that helps to uniquely determine the initial conditions of the system. A method based on the analysis of the null space of the Jacobian of the initialization problem and on suitable annotations is also proposed to provide the end user with meaningful; high-level; context-relevant diagnostic messages; in case the singular problem arises. This diagnostic method can also be applied to other cases; such as closed systems with constant density fluid and electrical circuits lacking a ground connection.

Keywords: Thermo-hydraulic system modelling; Initialization; User-friendly error diagnostics

Proceedings of the 9th International MODELICA Conference; September 3-5; 2012; Munich; Germany

Author:
Francesco Casella
Title:
On the Formulation of Steady-State Initialization Problems in Object-Oriented Models of Closed Thermo-Hydraulic Systems
DOI:
10.3384/ecp12076215
References:
[1] F. Casella and P. Colonna. Development of a Modelica dynamic model of solar supercritical CO2 Brayton cycle power plants for control studies. In Proceedings of the Supercritical CO2 Power Cycle Symposium; pages 1–7; Boulder; Colorado; USA; May 24–25 2011.
[2] F. Casella and A. Leva. Modelica open library for power plant simulation: Design and experimental validation. In P. Fritzson; editor; Proceedings 3rd International Modelica Conference; pages 41–50; Linköping; Sweden; Nov. 3–4 2003. Modelica Association. http://www.elet.polimi.it/upload/casella/thermopower/.
[3] F. Casella and A. Leva. Modelling of thermohydraulic power generation processes using Modelica. Mathematical and Computer Modeling of Dynamical Systems; 12(1):19–33; Feb. 2006. doi: 10.1080/13873950500071082.
[4] F. Casella; M. Sielemann; and L. Savoldelli. Steady-state initialization of object-oriented thermo-fluid models by homotopy methods. In C. Clauss; editor; Proceedings 8th International Modelica Conference; pages 86–96; Dresden; Germany; Mar. 20–22 2011. Modelica Association.
[5] V. Dostal. A Supercritical Carbon Dioxide Cycle for Next Generation Nuclear Reactors. PhD thesis; MIT; 2004.
[6] R. Franke; F. Casella; M. Sielemann; K. Proelss; M. Otter; and M. Wetter. Standardization of thermo-fluid modeling in Modelica.Fluid. In F. Casella; editor; Proceedings 7th International Modelica Conference; pages 122–131; Como; Italy; Sep. 20–22 2009. The Modelica Association.
[7] M. Sielemann; F. Casella; M. Otter; C. Clauß; J. Eborn; S. E. Mattsson; and H. Olsson. Robust initialization of differential-algebraic equations using homotopy. In C. Clauss; editor; Proceedings 8th International Modelica Conference; pages 75–85; Dresden; Germany; Mar. 20–22 2011. Modelica Association.

Proceedings of the 9th International MODELICA Conference; September 3-5; 2012; Munich; Germany

Author:
Francesco Casella
Title:
On the Formulation of Steady-State Initialization Problems in Object-Oriented Models of Closed Thermo-Hydraulic Systems
DOI:
10.3384/ecp12076215
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Citations:
  • Pengfei Li, Yaoyu Li, John E. Seem, Hongtao Qiao, Xiao L & Jon Winkler (2014). Recent advances in dynamic modeling of HVAC equipment. Part 2: Modelica-based modeling. HVAC&R Research, 20(1): 150. DOI: 10.1080/10789669.2013.836876