Entity

Time filter

Source Type


Voll P.,RWTH Aachen | Kirschbaum S.,Society for the Promotion of Applied Computer Science | Bardow A.,RWTH Aachen
Proceedings of the 23rd International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, ECOS 2010 | Year: 2010

The analysis and optimization of industrial energy systems pose non-trivial, multi-criteria problems. Today, solving these problems can be supported by system simulation. A simulation's applicability to practical problems, however, is strongly depending on the level of detail of the physical models employed. This paper evaluates quasi-stationary simulation based on rather simple models with regard to its applicability to industrial energy consultancy. For this purpose, a simplified quasi-stationary and a full dynamic model of an actual heating system are developed. Simulation is used to quantify the impact of two measures forthe reduction of the heating system's energy use. Both models are compared with regard to time and effort to perform the system modeling, the quality of their simulation results, and necessary computing time. It is shown that the simplified quasi-stationary approach minimizes time and effort to perform the system modeling and simulation. Moreover, it yields sufficiently accurate results when integral values are of main interest. This is demonstrated for the case studies investigated within this paper and applies to most tasks within the scope of industrial energy consultancy.


Meyer B.,RWTH Aachen | Voll P.,RWTH Aachen | Kirschbaum S.,Society for the Promotion of Applied Computer Science | Bardow A.,RWTH Aachen
Proceedings of the 26th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2013 | Year: 2013

This work presents a methodological framework for MILP modeling and optimization of distributed energy supply systems (DESS) with nonlinear system characteristics. The required MILP linearization is based on a multivariate piecewise-affine (PWA) surrogate modeling approach. A machine learning algorithm using Model Trees is employed to enable adjustments of model accuracy and to ensure an efficient discretization. The MILP component models are assembled to a DESS superstructure, which is optimized with respect to system structure, equipment sizing and load dispatch. During optimization, an iterative model refinement procedure is used to adapt the multivariate linear discretization to realize a prescribed prediction accuracy. The features of the presented modeling framework are demonstrated for the optimal synthesis of a refrigeration system.


Voll P.,RWTH Aachen | Lampe M.,RWTH Aachen | Wrobel G.,Society for the Promotion of Applied Computer Science | Bardow A.,RWTH Aachen
Proceedings of the 24th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2011 | Year: 2011

A novel approach for the model-based superstructure-free synthesis and optimization of distributed energy supply systems is proposed. While current methods request the designer to define a superstructure which subsequently is optimized, the presented approach exploits the nature of evolutionary algorithms to allow for a superstructure-free synthesis and optimization. A mutation operator replaces parts of energy supply structures by alternative designs. Thereby, the a priori specification of a superstructure can be avoided. The mutation operator chooses alternative designs based on a set of replacement rules. To minimize both the number of replacement rules and meaningless design alternatives generated by this operator, all considered energy conversion technologies are classified into a hierarchically-structured graph, the so-called energy conversion hierarchy. This hierarchy allows for an efficient definition of all reasonable connections between the regarded components through a minimal set of generic replacement rules. The presented approach balances richness of the available design space and computational efficiency. The method is applied to the synthesis of a heating and cooling system, which is optimized with respect to the net present value. It is shown that the presented method can be used to tackle both retrofit and grassroots design problems.


Voll P.,RWTH Aachen | Lampe M.,RWTH Aachen | Wrobel G.,Society for the Promotion of Applied Computer Science | Bardow A.,RWTH Aachen
Energy | Year: 2012

A novel approach is proposed for the superstructure-free synthesis and optimization of distributed energy supply systems (DESS) by exploiting the nature of evolutionary algorithms. Current approaches require the designer to define a superstructure, which subsequently is optimized. In the presented method, the a priori specification of a superstructure is avoided: A mutation operator employs generic replacement rules to replace parts of energy supply systems by alternative designs. To minimize both the number of replacement rules and meaningless design alternatives generated during mutation, all energy conversion technologies are classified into the so-called energy conversion hierarchy (ECH). The ECH allows for an efficient definition of all reasonable connections between the regarded components, and the definition of generic replacement rules. Thereby, the hierarchy-supported approach balances richness of the available design space and computational efficiency. In addition, the convenient description of the design space allows for an easy addition of technologies into the optimization problem. The proposed approach thus provides an expandable framework for optimizing DESS. The method is applied to the synthesis of a heating and cooling system. The presented approach efficiently solves retrofit and grassroots design problems. It automatically identifies complex solutions such as trigeneration demonstrating the power of the suggested optimization framework. © 2012 Elsevier Ltd.


Almeroth T.,Thuringian State Authority of Metrology and Verification | Kuhn O.,Thuringian State Authority of Metrology and Verification | Linss G.,TU Ilmenau | Lemke A.,Society for the Promotion of Applied Computer Science | Kramny J.,EnBW
14th Joint International IMEKO TC1, TC7, TC13 Symposium on Intelligent Quality Measurements - Theory, Education and Training 2011, Held in Conj. with the 56th IWK Ilmenau University of Technology | Year: 2011

This paper deals with various methods to estimate the lifetime of smart meters regarding its measurement features. Shorter innovation cycles lead to additional and/or exchangeable functional components resulting in a change of the reliability. The procedure presented in this paper is a new methodical approach. It combines well-known approaches of technical reliability with a consideration of a priori knowledge. In particular, the state of measuring characteristic on several points of time is observed. The observation leads to prediction of a realistic period of utilization.

Discover hidden collaborations