Modelica extensions for Multi-Mode DAE Systems

Abstract

The paper proposes to extend the scope of Modelica and model and simulate systems with multiple operating modes. Examples: - Changing a controller from nominal operation to startup, shutdown or manual operation. - Structural changes of a physical model (e.g. modeling the seperation mechanism of a two or three stage rocket). - Describing failure situations where the model structure is changing (e.g. an electrical line or a mechanical shaft breaks). - Describing failure situations where the model is completely changing (e.g. the normal behavior of a pump is a 0D model. In case of cavitation, a 1D model is needed to describe physical, requiring to switch dynamically from a 0D to a 1D model when cavitation occurs). In general this means that the number of continous-time states of the model might change dynamically during the situation. Such models cannot be described with current Modelica, verseion 3.3, since in this case the basic requirement is that the number of continous-time states of a model is fixed during a simulation. [...]