Innovations in today’s energy grids are mainly driven by the need to reduce carbon emissions and the necessary integration of decentralized renewable energy sources. In this context, a transition ...towards hybrid distribution systems, which effectively couple thermal and electrical networks, promises to exploit hitherto unused synergies for increasing efficiency and flexibility. However, this transition poses practical challenges, starting already in the design phase where established design optimization approaches struggle to capture the technical details of control and operation of such systems. This work addresses these obstacles by introducing a design approach that enables the analysis and optimization of hybrid thermal-electrical distribution systems with explicit consideration of control. Based on a set of key prerequisites and modeling requirements, co-simulation is identified as the most appropriate method to facilitate the detailed analysis of such systems. Furthermore, a methodology is presented that links the design process with the implementation of different operational strategies. The approach is then successfully applied to two real-world applications, proving its suitability for design optimization under realistic conditions. This provides a significant extension of established tools for the design optimization of multi-energy systems.
Zusammenfassung
Aktuelle Trends, wie die zunehmende Verbreitung von Ladestationen für Elektrofahrzeuge (EVCSs) mit und ohne Batteriespeicher in Kombination mit Wärmepumpen (WP) und Klimaanlagen, ...stellen Niederspannungsnetze (NS-Netze) bzw. deren Betrieb vor neuartige Herausforderungen. Diese können beispielsweise in Form von nennenswerten Lastfluss- sowie Kurzschlussproblemen in deren traditionellen, meist radialen Strukturen bzw. Topologien auftreten. Ein wesentliches Beispiel dafür ist die Überlastung von Leitungssegmenten durch Lasten mit erheblicher Gleichzeitigkeit (EVCSs, WPs, Klimaanlagen etc.). Darüber hinaus können hohe lokale Einspeisungen durch dezentrale Stromerzeuger (z. B. Photovoltaikanlagen, Kleinwasserkraftwerke, Batterie-Energiespeichersysteme) zu Problemen der Spannungsqualität (bspw. Verletzung der Spannungsgrenzen, Spannungsabfall, schnelle Spannungsänderungen) führen. Das Projekt ,,Power System Cognification“ (PoSyCo) entwickelt Lösungsansätze, um diese eben genannten Herausforderungen zu bewältigen. Es zielt darauf ab, ein ,,SOFTprotection“-System zu implementieren, das zur Vermeidung von systemkritischen Zuständen des Niederspannungsnetzes bzw. von Fehlern beiträgt und als Ergänzung zur herkömmlichen ,,HARDprotection“ (u. a. Sicherungen, Leistungsschalter) dienen soll. Im Zuge dieses Beitrags wird einer der dafür entwickelten Methoden in Form eines Algorithmus zur automatisierten Netzrekonfiguration auf Ebene der Niederspannung (NS) näher beschrieben.
The need to limit climate change has led to policies that aim for the reduction of greenhouse gas emissions. Often, a trade-off exists between reducing emissions and associated costs. In this ...article, a multi-objective optimization framework is proposed to determine this trade-off when operating a Community Energy Storage (CES) system in a neighbourhood with high shares of photovoltaic (PV) electricity generation capacity. The Pareto frontier of costs and emissions objectives is established when the CES system would operate on the day-ahead spot market. The emission profile is constructed based on the marginal emissions. Results show that costs and emissions can simultaneously be decreased for a range of solutions compared to reference scenarios with no battery or a battery only focused on increasing self-consumption, for very attractive CO 2 abatement costs and without hampering self-consumption of PV-generated electricity. Results are robust for battery degradation, whereas battery efficiency is found to be an important determining factor for simultaneously decreasing costs and emissions. The operational schedules are tested against violating transformer, line and voltage limits through a load flow analysis. The proposed framework can be extended to employ a wide range of objectives and/or location-specific circumstances.
Integrated operation of distribution grids for multiple energy carriers promises hitherto unused synergies in terms of efficient generation, storage, and consumption. A major obstacle to the ...investment in such systems is their increased complexity, as conventional tools and methods were not designed to capture all relevant technical and economic aspects of hybrid grids. To address this obstacle, this work proposes a methodology to systematically assess multi-carrier energy grids under a holistic scope. By adopting a simulation-based approach that relies on detailed technical and economic models, an efficient and precise evaluation of both short-term (operational) and long-term (strategic) aspects is supported. The methodology enables the assessment of system configurations, control strategies, business models, and regulatory conditions in one coherent approach. As a proof-of-concept, the new methodology is applied to a real-world use case of a hybrid thermal-electrical distribution grid in a central European city. The results are comprehensively discussed to showcase how the various aspects of hybrid energy systems are addressed. The outcomes also demonstrate how this methodology aids the involved stakeholders in understanding the associated risks and potentials, paving the way for early adopters to realize multi-carrier energy distribution grids.
•A holistic methodology to study multi-carrier energy systems is presented.•Operational technical and strategic economic perspectives are considered.•Established tools for different domains are coupled in a co-simulation framework.•Multiple market participants and opposing objectives are taken into account.•The methodology is demonstrated by a comprehensive study in a central European city.
In this paper, a hierarchical iterative control algorithm is proposed to optimally balance grid load (both voltage drop and current load) while meeting consumers power demand. The proposed control ...architecture is based on the assumption that a certain proportion of the consumers can predict their consumption profile and adapt their control strategies to fulfill power consumption constraints. It is assumed that a simplified model of the power grid and a prediction based on historical data for the consumption profile of passive consumers are available. Based on the consumers' consumption profile predictions, the controller proposes constraints for predictively controlled buildings (PCBs) at critical times, so that these consumers can adapt their consumption strategies in advance. The control algorithm also deals with the case of noncompliant consumers. It has low-communication requirements and consumer information is only shared with the hierarchical controller. The method is verified by simulations of an existing power grid with two PCBs. For this purpose, a grid linearization method and a model predictive controller for a building are suggested.
We present two case studies on energy grid hybridization, where the distribution networks of multiple energy sectors are more tightly coupled together to increase their flexibility via mutual ...transfer of energy. The hybridization approaches were developed in cooperation with the local stakeholder in a northern European city, comprising of a short-term setup with a low adoption barrier as well as a long-term scenario with more involved grid coupling using more efficient devices. For a range of coupling device configurations, device locations, control algorithms, and assumptions on utility prices and energy demand, we investigate the influence of the hybridization on the energy mix, CO 2 emissions, and energy costs. The studies have been conducted using a co-simulation toolchain developed by the European Project OrPHEuS specifically for fine-grained technical simulation of multi-carrier grids. Our results confirm that the hybrid grid approach is an effective means to increase the share of renewable energies and reduce operational costs. It also turns out that precise forecasts of energy demand and utility prices are essential for appropriate dimensioning of the coupling points.
Improving distribution grid reliability is a major challenge for planning and operation of distribution systems having a high share of distributed generators (DGs). The rise of DGs share can lead to ...unplanned contingencies while on the other hand, they can provide flexibility in supporting grid operations after a contingency event. This paper presents an optimal energy interruption planning approach that dispatches the flexibility from DGs and performs a cost-optimal load shedding of flexible loads. The proposed approach is tested on a synthetic grid, representing typical urban and low voltage feeders in EU with distribution networks modeled in radial and meshed configurations. The study shows that the proposed optimization process can be successfully used to plan resources during contingency event and this can lead to a reduction in energy not supplied and improvement of reliability indices.
The need to limit climate change has led to policies that aim for the reduction of greenhouse gas emissions. Often, a trade-off exists between reducing emissions and associated costs. In this ...article, a multi-objective optimization framework is proposed to determine this trade-off when operating a Community Energy Storage (CES) system in a neighbourhood with high shares of photovoltaic (PV) electricity generation capacity. The Pareto frontier of costs and emissions objectives is established when the CES system would operate on the day-ahead spot market. The emission profile is constructed based on the marginal emissions. Results show that costs and emissions can simultaneously be decreased for a range of solutions compared to reference scenarios with no battery or a battery only focused on increasing self-consumption, for very attractive CO 2 abatement costs and without hampering self-consumption of PV-generated electricity. Results are robust for battery degradation, whereas battery efficiency is found to be an important determining factor for simultaneously decreasing costs and emissions. The operational schedules are tested against violating transformer, line and voltage limits through a load flow analysis. The proposed framework can be extended to employ a wide range of objectives and/or location-specific circumstances.
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