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Your search keyword '"Karl Worthmann"' showing total 186 results
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186 results on '"Karl Worthmann"'

1. Adjustable Robust Energy Operation Planning under Uncertain Renewable Energy Production

Author

Anna Eingartner, Steffi Naumann, Philipp Schmitz, and Karl Worthmann

Subjects
adjustable robust optimization, uncertainties, renewable energy, imbalance energy, energy system operation, day-ahead planning, Technology
Abstract

In this paper, the application of the method of affinely adjustable robust optimization to a planning model of an energy system under uncertain parameters is presented, and the total scheduling costs in comparison with the deterministic model are evaluated. First, the basics of optimization under uncertain data are recapped, and it is described how these methods can be used in different applications for energy systems. This is followed by the methodology of adjustable robust optimization by defining the affinely adjustable robust counterpart. Finally, a numerical case study is conducted to compare the adjustable robust method with a rolling deterministic scheduling method. Both are implemented on a model of an energy system and compared with each other by simulation using real-world data. By calculating the total operating costs for both methods, it can be concluded that the adjustable robust optimization provides a significantly more cost-effective solution to the scheduling problem.

Published
2024
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2. Aggregation of Demand-Side Flexibilities: A Comparative Study of Approximation Algorithms

Author

Emrah Öztürk, Klaus Rheinberger, Timm Faulwasser, Karl Worthmann, and Markus Preißinger

Subjects
demand-side management, flexibility aggregation, Minkowski sum, energy storage, smart grids, Technology
Abstract

Traditional power grids are mainly based on centralized power generation and subsequent distribution. The increasing penetration of distributed renewable energy sources and the growing number of electrical loads is creating difficulties in balancing supply and demand and threatens the secure and efficient operation of power grids. At the same time, households hold an increasing amount of flexibility, which can be exploited by demand-side management to decrease customer cost and support grid operation. Compared to the collection of individual flexibilities, aggregation reduces optimization complexity, protects households’ privacy, and lowers the communication effort. In mathematical terms, each flexibility is modeled by a set of power profiles, and the aggregated flexibility is modeled by the Minkowski sum of individual flexibilities. As the exact Minkowski sum calculation is generally computationally prohibitive, various approximations can be found in the literature. The main contribution of this paper is a comparative evaluation of several approximation algorithms in terms of novel quality criteria, computational complexity, and communication effort using realistic data. Furthermore, we investigate the dependence of selected comparison criteria on the time horizon length and on the number of households. Our results indicate that none of the algorithms perform satisfactorily in all categories. Hence, we provide guidelines on the application-dependent algorithm choice. Moreover, we demonstrate a major drawback of some inner approximations, namely that they may lead to situations in which not using the flexibility is impossible, which may be suboptimal in certain situations.

Published
2022
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3. Towards dynamic contract extension in supplier development

Author

Karl Worthmann, Michael Proch, Philipp Braun, Jörg Schlüchtermann, and Jürgen Pannek

Subjects
Supply chain management, Supplier development, Optimal control, Receding horizon scheme, Dynamic systems, Industries. Land use. Labor, HD28-9999, Transportation and communications, HE1-9990
Abstract

We consider supplier development within a supply chain consisting of a single manufacturer and a single supplier. Because investments in supplier development are usually relationship-specific, safeguard mechanisms against the hazards of partner opportunism have to be installed. Here, formal contracts are considered as the primary measure to safeguard investments. However, formal contracts entail certain risks, e.g., a lack of flexibility, particular in an ambiguous environment. We propose a receding horizon control scheme to mitigate possible contractual drawbacks while significantly enhancing the supplier development process and, thus, to increase the overall supply chain profit. Our findings are validated by a numerical case study.

Published
2016
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