Turhan Hilmi Demiray


Last Name

Demiray

First Name

Turhan Hilmi

ORCID

0000-0002-0923-6891

Organisational unit

02279 - Forschungsstelle Energienetze-ETH Zürich / Research Center for Energy Networks

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2022 - 20258
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Publications 1 - 8 of 8
  • Flexibility provision from electromobility and buildings - Synthesis Report
    Item type: Report
    PATHFNDR Consortium; Aliana, Arnau; Bellizio, Federica; et al. (2025)
    Switzerland’s energy transition relies on electrifying transportation and heating while keeping electricity generation low in greenhouse gas emissions and ensuring grid stability. The required energy system flexibility will still be provided mainly by hydropower. However, additional valuable demand-side flexibility could be provided by electric vehicles and heat pumps by shifting their consumption to align with renewable energy generation. This report evaluates the role of electric vehicle and heat pump flexibility by synthesizing research from across the PATHFNDR project consortium. The report thus quantifies these technologies' potential flexibility and value in supporting both the transmission and distribution systems and assesses existing and required market and policy mechanisms to unlock their full benefits. New scenario-based modelling results show that flexibility provision from electric vehicles and heat pumps can reduce system costs, defer network upgrade investments, lower electricity prices and imports, and reduce curtailment of renewable energy by better aligning demand with surplus generation. Electric vehicle smart charging and vehicle-to-grid can act as energy storage, which shift or discharge electricity to support the grid. Heat pump demand can be shifted using thermal inertia and thermal energy storage to reduce peak demand and stabilize the grid. At distribution level, flexibility-aware planning can reduce or defer low- and medium-voltage grid upgrades with minimal PV energy loss. Our research also finds that enabling flexibility-readiness through supportive policy and market mechanisms are critical for effective demand-side management. Some mechanisms are already in place, such as contracts with dynamic pricing, direct load control, and subsidies for smart charging and vehicle-to-grid infrastructure. However, further policies, changes to regulation, and owner/user acceptance are needed. Surveys of the Swiss public show that support for flexible EV charging and heat pump operation is high, indicating readiness for further policy and market changes supporting flexibility and renewable energy integration. Unlocking this flexibility will improve Switzerland’s energy resilience and sustainability while empowering consumers to participate actively in grid management. Future research should focus on scalable implementation and deployment: exploring business models for flexibility provision, evaluating new policy incentives, and demonstrating the use of flexibility at scale.
  • Aggregated models of active distribution networks for stability studies of large transmission systems
    Item type: Journal Article
    Fuchs, Alexander; Demiray, Turhan Hilmi; Larsson, Mats (2022)
    Electric Power Systems Research
    The paper presents a new framework to quantify the amount of dynamic grid support that should be provided from converter-based energy resources replacing generation from synchronous machines. A tuning approach for local stability issues in active distribution networks (ADN) is presented, followed by an aggregation procedure to derive adequate low-order ADN models. The resulting models from benchmark systems with varying shares of grid-forming converter-based generation up to 100% of the distribution grid load are published along with the paper. They allow an adequate representation of ADNs for the assessment of voltage and frequency performance in large-scale transmission grid simulations. A quantitative study of the full continental ENTSO-E system investigates a large disturbance in the form of a system split for multiple development paths of converters replacing synchronous machines. It is found that about 10%–20% of the new converters should have grid-support capabilities to maintain the dynamic power system performance at today's level.
  • FLEXHUB - Optimal and flexible operation of EV charging hubs
    Item type: Conference Poster
    Savvopoulos, Nikolaos; Bellè, Andrea; Fuchs, Alexander; et al. (2025)
  • Probabilistic Assessment of EV Charging Impacts on Distribution Grid Planning
    Item type: Conference Paper
    Savvopoulos, Nikolaos; Fuchs, Alexander; Demiray, Turhan Hilmi (2025)
    IET Conference Proceedings
    As global Electric Vehicle (EV) adoption accelerates, the integration of EV charging infrastructure into distribution grids presents substantial challenges. Traditional grid planning methods, based primarily on deterministic models, are increasingly insufficient due to the unpredictable nature of EV charging demands. This paper introduces a probabilistic planning approach that incorpo rates various stochastic uncertainties such as charger location, arrival times, and energy demands to enhance grid management. By simulating realistic EV charging profiles and their impacts on the grid, this methodology facilitates more accurate predictions of potential grid violations. This approach allows grid operators to explore flexible grid integration strategies and make informed decisions about infrastructure investments and EV demand response requirements. The results highlight the value of flexibility in mitigating grid upgrade decisions and suggest that future grid planning should incorporate adaptive strategies and demand-side management measures to accommodate growing EV loads efficiently.
  • SGEN Project: Distribution system in 2050
    Item type: Report
    Evrenosoglu, Cansin Yaman; Demiray, Turhan Hilmi (2024)
    The overall objective of this study is to quantify the CHF value of flexibility of distributed energy resources (DER) such as electrified demand (e.g. heat pump, EV charging), solar PV generation and distributed battery energy storage systems (BESS) at low voltage level to minimize or defer infrastructure investments in distribution grids while considering the impact of the technical capability and availability (reliability) of such resources, including the reliability of the ICT infrastructure. In order to achieve the objective, a framework is designed containing (i) data preparation including importing grid topology (urban and rural) from a commercial software, and creating/estimating reasonable synthetic demand, generation and storage profiles for each proliferation pathway, (ii) flexibility analysis by means of successive power flows in selected time resolution, including identification of temporal and spatial flexibility needs, and approximating the costs of meaningful flexibility providers, and (iii) demonstrating the potential of flexibility utilization for asset investment deferral, by comparing traditional approach, relying on worst case simultaneity factors. In this study central optimization of all resources for low voltage grid operation by means of optimal power flow is not used. It is assumed that the DER-owners (i.e., end customers) control their own resources according to their local objectives. The flexibility utilization is primarily based on shifting or reducing the demand locally either through established remuneration or bonus programs or through bilateral long-term contracts, which are not within the scope of this study. The implemented local strategies of delaying EV charging and shifting HP operation help reducing the simultaneity factors of these types, while the implemented local strategy for delaying BESS charging and discharging helps reducing the peak excess solar generation.
  • DFlex: Distribution system in 2050
    Item type: Report
    Evrenosoglu, Cansin Yaman; Demiray, Turhan Hilmi; Fuchs, Alexander (2024)
    The overall objective of this study is to quantify the CHF value of flexibility of distributed energy resources (DER) such as electrified demand (e.g. heat pump, EV charging), solar PV generation and distributed battery energy storage systems (BESS) at low voltage level to minimize or defer infrastructure investments in distribution grids while considering the impact of the technical capability and availability (reliability) of such resources, including the reliability of the ICT infrastructure. In order to achieve the objective, a framework is designed containing (i) data preparation including importing grid topology (urban and rural) from a commercial software, and creating/estimating reasonable synthetic demand, generation and storage profiles for each proliferation pathway, (ii) flexibility analysis by means of successive power flows in selected time resolution, including identification of temporal and spatial flexibility needs, and approximating the costs of meaningful flexibility providers, and (iii) demonstrating the potential of flexibility utilization for asset investment deferral, by comparing traditional approach, relying on worst case simultaneity factors. In this study central optimization of all resources for low voltage grid operation by means of optimal power flow is not used. It is assumed that the DER-owners (i.e., end customers) control their own resources according to their local objectives. The flexibility utilization is primarily based on shifting or reducing the demand locally either through established remuneration or bonus programs or through bilateral long-term contracts, which are not within the scope of this study. The implemented local strategies of delaying EV charging and shifting HP operation help reducing the simultaneity factors of these types, while the implemented local strategy for delaying BESS charging and discharging helps reducing the peak excess solar generation.
  • PVPUMP - Versorgungssicherheit und Integration von Schweizer Photovoltaik mit Pumpspeicherkraftwerken
    Item type: Report
    Fuchs, Alexander; Demiray, Turhan Hilmi (2025)
    Dieses Projekt befasst sich mit dem Wert eines neuen Pumpspeicherkraftwerks für die Unterstützung der Schweizer Energiewende. Dabei werden die drei Aspekte Versorgungssicherheit, Integration von Photovoltaik und Wirtschaftlichkeit betrachtet. Die Frage der Versorgungssicherheit stellt sich vor dem Hintergrund der Schweizer Importabhängigkeit. Auch bei massivem Ausbau der Erneuerbaren verbleiben vor allem im Winter kritische Stunden, in denen die Schweiz Importe zwingend benötigt. Dabei werden die Höhe der Importmöglichkeiten unabhängig vom Erfolg eines Stromabkommens begrenzt sein. Die Frage der zukünftigen Integration von Schweizer erneuerbarer Energie stellt sich vor dem Hintergrund der erklärten Ausbauziele für die Produktion aus Photovoltaik und Wind. Diese liegen für 2035 bei 35 TWh und für 2050 bei 45 TWh. Stunden, in denen die Stromnachfrage durch die erneuerbare Energie mehr als gedeckt ist und diese abgeregelt werden muss, stehen Stunden mit hoher Stromnachfrage gegenüber, welche durch flexible Kraftwerke gedeckt werden muss. Die Frage der Wirtschaftlichkeit stellt sich vor dem Hintergrund der zunehmend volatilen Preise, welche eine Herausforderung für die Bewirtschaftung und Investitionsplanung von Kraftwerken darstellen. Für alle drei Aspekte wäre eine Verschiebung des produzierten Stroms von Stunden mit Überschuss hin zu wertvolleren Stunden wünschenswert, wofür Pumpspeicherkraftwerke prinzipiell gut geeignet sind. Allerdings ist offen, wie hoch der Beitrag zu Versorgungssicherheit und Integration von Photovoltaik ausfällt, und ob der Markt diesen volkswirtschaftlichen Mehrwert auch belohnt, um die benötigte Investition zu rechtfertigen. Das Projekt schafft die quantitative Grundlage für so eine Bewertung am Beispiel des geplanten Pumpspeicherkraftwerks Lagobianco mit 1050 MW neuer Turbinen- und Pumpenleistung. Die Untersuchungen kombinieren eine detaillierte Modellierung des heutigen und zukünftigen Kraftwerkskomplexes sowie langjährige Preisprognosen auf Basis gesamteuropäischer Strommarktsimulationen. Für die Simulationen wurde die installierte Schweizer PV-Kapazität zwischen 10 und 40 GW und die Schweizer jährliche Gesamtlast zwischen 60 und 90 TWh variiert. Im Ergebnis können durch das Projekt Lagobianco zum Beispiel bei 30 GW installierter PV-Kapazität bis zu 1.14 TWh weniger zwingender Importbedarf im Winter und bis zu 2.7 TWh mehr Integration von Schweizer PV-Energie erreicht werden. Konservativ geschätzt entspricht das einem volkswirtschaftlichen Mehrwert von 180 Millionen CHF pro Jahr. Allerdings kann nur etwa die Hälfte dieses Mehrwerts als Erlös durch die Kraftwerksbetreiberin erzielt werden, wobei Erlöse aus Grosshandel sowie Regelleistung und -energie berücksichtigt wurden. Als Konsequenz ist das Projekt ohne Förderung nicht wirtschaftlich. In allen Szenariovarianten und Sensitivitätsanalysen mit einer Inbetriebnahme des Pumpspeicherkraftwerks im Jahr 2035 ist der Kapitalwert ohne Förderung deutlich negativ und erreicht im Basisszenario erst bei einer Förderung von etwa 2’200 Millionen CHF die Wirtschaftlichkeit. Als Variante wurde auch eine Inbetriebnahme im Jahr 2050 untersucht. Dabei wird die Wirtschaftlichkeit für das Basisszenario ab einer Förderung von etwa 1’760 Millionen CHF erreicht. Als Variante wurde ausserdem ein hypothetischer dauerhafter Grosshandelspreis wie im Jahr 2024 untersucht, der über die gesamte Lebensdauer der Anlage besteht. Dabei wird die Wirtschaftlichkeit für das Basisszenario ab einer Förderung von etwa 980 Millionen CHF erreicht. Zusammenfassend hat das geplante neue Pumpspeicherkraftwerk einen hohen systemischen und strategischen Mehrwert für die kritischsten Punkte der Schweizer Energiewende. Durch die zu geringe Wirtschaftlichkeit entsteht aber ein Förderbedarf, der sich volkswirtschaftlich bezahlt machen würde. In den Analysen wurde als Förderform ein Investitionsbeitrag untersucht. Die Wirtschaftlichkeit kann aber auch mit einer Marktprämie, einer Mischform oder anderen Fördermodellen erzielt werden.
  • INTERCHARGE - Probabilistic Assessment of EV Charging Impacts on Distribution Grid Planning
    Item type: Conference Poster
    Savvopoulos, Nikolaos; Fuchs, Alexander; Demiray, Turhan Hilmi (2025)
Publications 1 - 8 of 8