On the Formulation of Steady-State Initialization Problems in Object-Oriented Models of Closed Thermo-Hydraulic Systems

Francesco Casella
Dipartimento di Elettronica e Informazione, Politecnico di Milano, Milano, Italy

Ladda ner artikelhttp://dx.doi.org/10.3384/ecp12076215

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

Linköping Electronic Conference Proceedings 76:21, s. 215-222

Visa mer +

Publicerad: 2012-11-19

ISBN: 978-91-7519-826-2

ISSN: 1650-3686 (tryckt), 1650-3740 (online)


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.


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


[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.

Citeringar i Crossref