Christian Schallert

Towards a Model-Based Energy System Design Process

Advanced modeling and simulation techniques are becoming more important in todays industrial design processes and for aircraft energy systems in specific. They enable early and integrated design as well as validation of finalized system and component designs. This paper describes the main methods and tools that can be applied for different phases of the energy design process. For demonstration, the object-oriented modeling language Modelica was chosen, since it enables convenient modeling of multi-physical systems. Based on this standard, common modeling guidelines, a modeling library template, and common interfaces have been provided. A common modeling infrastructure is proposed with considerations on additional libraries needed for local tasks in the energy design process. The developed methods and tools have been tested by means of some predefined use cases, which are performed in cooperation with diverse aircraft industrial partners. Each use case represents a specific modeling, simulation, or design task. This use case approach covers a wide range of the overall energy system design process.

Automated Safety Analysis by Minimal Path Set Detection for Multi-Domain Object-Oriented Models

ABSTRACT A method called DMP for Detection of the Minimal Path set of any fault-tolerant technical system, the system being represented as a multi-domain object-oriented model, is described, exemplified and substantiated in this article. Thus, by use of DMP, a safety analysis of the system is automatically performed. DMP employs simulation of normal behaviour, degradation and failure of a system. In essence, it is a state space simulation. The state space, in this context, denotes the set of combinations of intact and failed components of a system to be examined for detection of its minimal path set. Without any reduction technique, the size of a system’s state space grows exponentially with the number of its components. In order to render the DMP method feasible, the object structure of the system model is represented as a graph. Evaluation of the graph reduces the size of the state space and hence the number of simulations required.