Bernt Nilsson

On the Architecture Of Cace Environments

Abstract This paper discusses the objectives of an integrated interactive environment for simulation and computer aided control systems design. An integrated environment must support the userʼs work strategies and must not be based on normative work procedures. To make it easy to build such environments with customized user interface and flexible integrated tools some basic architectural issues have to be considered. The paper focuses on these issues and discusses model representation, tool integration and modularization of user interfaces. An object-oriented model representation is presented briefly and a model for tool integration is outlined

Object-Oriented Modelling of Thermal Power Plants

This paper presents a set of model libraries, called K2, for modelling of thermal power plants. The models are based on first principles and describe mainly the dynamic mass and energy properties of the modelled system. The K2 models are described in the object-oriented modelling language OMOLA and the libraries are organized in an OMOLA model database. The libraries are grouped into three different sets, namely unit libraries, subunit libraries and model component libraries. The unit models are used to build up plant system models, which are application dependent. The units are composed of subunits. The subunits describe different physical phenomena and a set of subunits build up the behaviour of the unit model. Model components are used to facilitate the development of new units and subunits. OMOLA models can be simulated in the OMSIM simulation environment and the K2 model database has been used in a case study of the dynamics in an HRSG plant.

Object-Oriented Modelling of a Controlled Chemical Process

Abstract In this paper we discuss the benefits using an object-oriented approach to modelling. Models and modelling are gaining more and more interest in process industry due to the development of knowledge-based systems. The basic elements in object-oriented modelling methodology are modularization, model encapsulation, hierarchical submodel decomposition, model parameterization and inheritance. Models have an internal structure of model components, like terminals, parameters and behaviour descriptions. The model behavior can be described with equations or as a structure of submodels. Models and model components are represented as objects in single inheritance object class hierarchies. Chemical processes and control systems can be described with the same basic concepts. Tasks that are facilitated in object-oriented modelling are model reuse, model development, model refinement and model maintenance. They are all of major importance for multi purpose process modelling.