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  <doc>
    <id>561</id>
    <completedYear/>
    <publishedYear/>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>preprint</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>2024-10-01</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Strategic Retailers in the Energy Sector</title>
    <abstract language="eng">We propose a general framework which allows to analyze the strategic interaction of retail companies, where customers choose retail contracts over a longer period of time based on price and non-price characteristics of retail contracts. We allow for many, possibly asymmetric retailers which can offer fixed price tariffs or dynamic prices, as typically observed in energy&#13;
markets. Our framework considers uncertainties and allows for price-responsive consumption choices of customers. We analytically characterize all resulting market equilibria for the general asymmetric setting. Based on those results we then propose a solution algorithm which is capable to determine all resulting equilibria. For the case of symmetric retailers we provide analytical comparisons of the different tariff structures. To show the applicability of our framework and our algorithm to real-world instances, we calibrate it to data of the German retail electricity market.&#13;
Our results show, that firms profits remain unchanged but consumer surplus and welfare increase when switching from fixed price tariffs to real-time pricing. This effect is more pronounced under higher wholesale price fluctuations. Finally we also propose a surrogate, reduced order model, which is shown to be equivalently capable to quantify the welfare difference of the different tariffs.</abstract>
    <enrichment key="opus.source">publish</enrichment>
    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Ann-Kathrin Wiertz</author>
    <author>Andrea Walther</author>
    <author>Gregor Zöttl</author>
    <collection role="subprojects" number="">B09</collection>
    <collection role="subprojects" number="">B10</collection>
    <file>https://opus4.kobv.de/opus4-trr154/files/561/StrategicRetailersInTheEnergySector.pdf</file>
  </doc>
  <doc>
    <id>527</id>
    <completedYear>2023</completedYear>
    <publishedYear/>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber>31</pageNumber>
    <edition/>
    <issue/>
    <volume/>
    <type>preprint</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>2023-11-13</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">On a Tractable Single-Level Reformulation of a Multilevel Model of the European Entry-Exit Gas Market with Market Power</title>
    <abstract language="eng">We propose a framework that allows to quantitatively analyze the interplay of the different agents involved in gas trade and transport in the context of the European entry-exit system. Previous contributions have focused on the case of perfectly competitive buyers and sellers of gas, which allows to replace the respective market equilibrium problem by a single welfare maximization problem. Our novel framework considers the mathematically more challenging case of a monopolistic and thus strategic gas seller. In this framework, the objective functions of the gas sellers and buyers cannot be aggregated into a common objective function, which is why a multilevel formulation is necessary to accurately capture the sequential nature of the decisions taken. For this setup, we derive sufficient conditions that allow for reformulating the challenging four-level model as a computationally tractable single-level reformulation. We prove the correctness of this reformulation and use it for solving several test instances to illustrate the applicability of our approach.</abstract>
    <enrichment key="SubmissionStatus">under review</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Veronika Grimm</author>
    <author>Julia Grübel</author>
    <author>Martin Schmidt</author>
    <author>Alexandra Schwartz</author>
    <author>Ann-Kathrin Wiertz</author>
    <author>Gregor Zöttl</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Multilevel optimization</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Reformulations</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Gas markets</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Market power</value>
    </subject>
    <collection role="institutes" number="">Friedrich-Alexander-Universität Erlangen-Nürnberg</collection>
    <collection role="subprojects" number="">B08</collection>
    <collection role="institutes" number="">Universität Trier</collection>
    <collection role="subprojects" number="">B09</collection>
    <file>https://opus4.kobv.de/opus4-trr154/files/527/document.pdf</file>
  </doc>
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