Selected Publications

2022

• Wanapinit N, Thomsen J, Weidlich A
  Find the balance: how do electricity tariffs incentivize different system services from demand response?
  2022 Sustainable Energy, Grids and Networks
• Wanapinit N, Thomsen J, Weidlich A
  Integrating flexibility provision into operation planning: A generic framework to assess potentials and bid prices of end-users
  2022 Energy, volume: 261, issue: B, supplement: 125261, pages: 1 - 14
  
   
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2021

• Wanapinit N, Thomsen J, Kost C, Weidlich A
  An MILP model for evaluating the optimal operation and flexibility potential of end-users
  2021 Appl Energ, volume: 282, issue: Part B
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  Abstract

  It is expected that end-users from all sectors should participate in providing system flexibility, as variablerenewable energy is increasingly integrated into electricity systems. The ability of end-users to shift theirelectricity profiles has considerable potentials and can serve many purposes, e.g. to curb the peak loador to increase self-consumption. However, evaluation methods designed for flexibility from conventionalpower plants may be inadequate for flexibility from end-users due to the diverse constraints of underlyingprocesses and limitations related to individual needs. This work presents a comprehensive and modularflexibility model developed from common operational characteristics of flexible processes as an alternativemethod.The model is applied to two examples: First, the operation of a combined heat-and-power plant includinginput and output storage is optimized with the objective to increase profits from electricity sales on the spotmarket. Second, a steel rod production line consisting of melting, casting, and milling processes is scheduled sothat operating costs, including peak power costs, are minimized. Moreover, potentials of flexibility as externalservices and related costs are analysed. In this paper, the model is used to calculate the optimal costs (e),time-dependent flexibility potentials (kWh) and costs of flexibility provision (e/kWh). Thus, the adaptabilityand versatility of the model are demonstrated. As a modelling template, the model can ease the efforts ofstakeholders in the characterization and evaluation of various flexible processes, especially those from smalland medium-sized users.
  
  
   
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• Klobasa M, Kühnbach M, Pelka S, Stute J, Sarfarazi S, Nienhaus K, Bruckmeier A, Springmann E, Köppl S, Guthoff F, Qussous R, Ritter D, Flachsbarth F, Heinemann C
  Bewertung der systemischen Auswirkungen der C/sells-Anwendungsfälle: Gesamtbericht der Arbeiten in Arbeitspaket 2.6 des SINTEG-Forschungsprojekts C/sells
  Fraunhofer ISI, 2021
• Wanapinit N, Thomsen J
  Synergies between Renewable Energy and Flexibility Investments: A Case of a Medium-Sized Industry
  2021 Energies, volume: 14, issue: 22, page: 7753
  
   
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2020

• Harder N, Qussous R, Weidlich A
  The cost of providing operational flexibility from distributed energy resources
  2020 Appl Energ, volume: 279, pages: 1 - 16
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  Abstract

  Flexible household devices, such as heat pumps combined with thermal energy storage or battery energy storage units, can provide flexibility to the electricity sector. However, to make flexibility available to the market, it has to be correctly quantified, and its cost has to be estimated. In this work, a methodology for generic flexibility quantification is proposed and developed in a Python environment using model predictive control. The chosen methodology allows to quantify the adjustable power, and also to determine the corresponding cost of the flexibility provision. It was observed that the available flexibility and its cost is influenced by many factors such as system components, human behavior, building thermal parameters, and price signals. Also, the inclusion of even a low share of households with batteries or electric vehicles smoothens the aggregated flexibility profile, and a considerable amount of flexibility is available at almost any point in time.
  
  
   
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2019

• Weidlich A, Zaidi A
  Operational Flexibility of Small-Scale Electricity-Coupled Heat Generating Units
  2019 Technology and Economics of Smart Grids and Sustainable Energy, volume: 4, issue: 8, pages: 1 - 16
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  Abstract

  Heat generation that is coupled with electricity usage, like combined heat and power generators or heat pumps, can provide operational flexibility to the electricity sector. In order to make use of this in an optimized way, the flexibility that can be provided by such plants needs to be properly quantified. This paper proposes a method for quantifying the flexibility provided through a cluster of such heat generators. It takes into account minimum operational time and minimum down-time of heat generating units. Flexibility is defined here as the time period over which plant operation can be either delayed or forced into operation, thus providing upward or downward regulation to the power system on demand. Results for one case study show that a cluster of several smaller heat generation units does not provide much more delayed operation flexibility than one large unit with the same power, while it more than doubles the forced operation flexibility. Considering minimum operational time and minimum down-time of the units considerably limits the available forced and delayed operation flexibility, especially in the case of one large unit.
  
  
   
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• Wanapinit N, Weidlich A, Thomsen J
  Promoting flexibility from prosumers through a generic characteristic flexibility model
  2019 11. Internationale Energiewirtschaftstagung an der TU Wien
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  Abstract

  Energy systems require flexibility - an ability to respond to changes - to integrate higher shares of variable renewable energy. On the whole, flexibility potential from prosumers is significant and stems from various processes. As each flexibility option is unique, before utilization, its potential first must be assessed. This paper presents a universal flexibility model, so called generic characteristic flexibility model (GCM), as tool to characterize and assess most, if not all, flexibility options from prosumers. GCM establishes a generic flexible process with components representing physical parts, e.g. machine and storage, and various administrative decisions, e.g. changes in output delivery or operating hours. Each component is described with essential characteristics and constraints. As demonstrations, three flexible systems representing various sectors – a district heating system, a household appliance, and a production process - are characterized and modelled using GCM. Flexibility in these systems is utilized to minimize costs under time-varying electricity prices and subject to operational constraints. This in turn proves the concept of a universal flexibility model. GCM eases burdens of actors - flexibility providers and users - to develop assessment tools for each flexibility options. Its pre-defined structure and characteristics also support identification of flexible processes and communication between actors. Thus, it helps promoting the utilization of flexibility from prosumers.
  
  
   
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2017

• Künzel T, Klumpp F, Weidlich A
  Methodische Quantifizierung der Bereitstellungskosten flexibler Systemkomponenten im deutschen Stromsystem
  2017 Zeitschrift für Energiewirtschaft, volume: 41, issue: 1, pages: 33 - 55

2016

• Weidlich A, Schmidt M
  C/sells – ein Schaufenster in die zukünftige Energieversorgung
  Campus Magazin der Hochschule Offenburg, volume: 40, pages: 36 - 37, 2016
• Künzel T, Klumpp F, Weidlich A, Stuible A
  Flexibility Options for Integrating Renewable Energy and Grid Stability
  2016 10th International Renewable Energy Storage Conference IRES, Düsseldorf
• Künzel T, Weidlich A
  Methodik zur Quantifizierung der Grenzkosten flexibler Systemkomponenten
  2016 3. Konferenz Zukünftige Stromnetze für Erneuerbare Energien, Berlin , pages: 110 - 114
• Bolivar Jaramillo L, Weidlich A
  Optimal microgrid scheduling with peak load reduction involving an electrolyzer and flexible loads
  2016 Applied Energy, volume: 169, pages: 857 - 865
  
   
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