7th International Hybrid Power Plants & Systems Workshop 2023

Faroe Islands, 23 – 24 May 2023

Hybrid Power/Energy Systems (Island Power Systems)

Optimization-Based Operation of Island Hybrid Power Systems: A Case Study in Suðuroy, Faroe Islands
Marco Alferink 1, Lucas Reus 2, Farshid Goudarzi 2, Lutz Hofmann 2, Kai Michels 1
1 University of Bremen, Germany
2 Leibniz University Hannover, Germany
An optimization-based energy management system (EMS) for the island hybrid power system of Suðuroy on the Faroe Islands is proposed in this paper. Next to balancing generation and load, the aim lies in reducing the operational costs while dealing with uncertainties from the intermittent nature of renewables. This is achieved by a two-layer model predictive control (MPC) approach solving a mixed-integer linear programming problem for unit commitment, as well as a non-linear programming optimal power flow problem for economic dispatch. The setpoints are transferred to the local controllers of the distributed energy resources. Simulations of the MPC strategy show that the utilization of renewables is preferred and, thus, decreasing operational costs are obtained while satisfying operational and security requirements. The proposed EMS is further investigated in quasi-stationary simulations using a simplified model of the Suðuroy power system. It can be observed that after changes of power setpoints and besides small deviations from the predicted values, no stability boundaries are violated.

The Evolution of Hybrid Systems: Insights from 30 years of Modeling
Peter Lilienthal
UL Solutions, United States
Hybrid systems have evolved from a research concept and various pilot project. They are now the most cost-effective source of power in a wide variety of settings. There are also a huge variety of types of hybrid systems depending on the application. This presentation will provide an overview of that history, starting with small systems for energy access in remote areas of developing countries without any pre-existing power infrastructure. Another promising early application were islanded systems, both geographic islands and electrical islands, such as the 200 remote indigenous communities in Alaska. The falling cost of solar PV and various forms of batteries, particularly lithium has dramatically changed the results of least cost design optimization. The lessons learned over these 30 years of modeling, pilot projects, and development experience are now being applied to very large grid-connected hybrid systems as continental-scale electric grids decarbonize. The ability of these large grids to absorb the levels of solar and wind that have become common for smaller grids depends on the hybridization of large wind farms and solar parks with utility-scale batteries. This presentation will conclude with descriptions of how the modeling requirements have evolved to respond to these new challenges.

Optimal Dispatch for the US Virgin Islands to Increase Renewable Rates in Saint Croix
Daniel Vazquez Pombo 1, 2, Vahan Gevorgian 3, Daniel Olis 3, Henrik W. Bindner 2
1 Vattenfall R&D, Sweden
2 Technical University of Denmark, Denmark
3 National Renewable Energy Laboratory, United States
Despite holding abundant renewable energy resources, most islands present extreme external energy dependency on fossil fuels, ultimately causing high energy costs. In order to remedy such situation, many island communities are targeting the abandoning imported fossil fuels in favour of local renewable resources. The U.S. Virgin Islands emerged in 2010 as front runners in reducing fossil fuel imports and stabilize electricity costs with energy efficiency schemes along with wind and solar power installation. They had significant progress over the years, hindered by relatively expected stability issues. Then, in 2017, Category 5 hurricanes Irma and Maria struck the islands, causing extensive damages, which, among other things, affected up to 90% of the transmission lines. After recovering the system, the focus of the local system operator is on increasing the reliability and resiliency of the grid.

In the case of Saint Croix, solar power covers around 10% of the peak demand and 2.5% of the overall energy needs in 2022, although this does not include installations at distribution level. Wind power is not yet present in the island, but its addition is already planned along with more solar PV, and battery systems. In this context, our work focused on developing optimal economic dispatch attending to the particular conditions of the island, paying special attention to positively contributing to reducing instability. While minimizing the stress on the batteries by limiting their cycling. The approach considers two different methods to provide asymmetric reserves. One simply by ensuring 25% of the present load, and the other attending to the N-1 contingency. Besides, the study will explore the effects of strengthening the renewable installed capacity.

On the usage of hybrid storage systems for the provision of services for local grids
Adolfo Anta , Diego Cifelli
Austrian Institute of Technology GmbH ((AIT), Austria
Hybrid power plants are emerging as an adequate solution to address emerging power system needs, since they can provide a wide palette of services by leveraging the capabilities of different technologies. At the same time, storage has been recognized as a critical component for the energy transition,
in order to deal with the new characteristics of inverter-based generation. In particular, it is becoming clear how a storage system can provide certain grid services, but how to extend these ideas to hybrid storage systems is not fully understood. In this work we present an optimization-based framework that is able to deal with the typical fast time scales associated with storage, at a reasonable computational cost. The approach relies on piecewise affine linear approximations, that can be reformulated as mixed integer linear programs. An example focused on peak shaving shows the benefits of the proposed approach.

Techno-Economic Effects of Electricity Market Conditions in the Optimal Operation of Hybrid Power Plants
Jon Martinez-Rico 1, 2, Ismael Ruiz de Argandoña 1, Ekaitz Zulueta 3, Mikel Armendia 1, Unai Fernandez-Gamiz 2
1 Automation and Control Unit, Tekniker, Basque Research and Technology Alliance, Eibar, Spain, Spain
2 Energy Engineering Department, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain, Spain
3 System Engineering and Automation Control Department, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain, Spain
Hybrid power plants (HyPPs) combining different renewable energy sources with battery energy storage systems (BESSs) present multiple advantages and might become a key part of the energy transition, but the still high price of BESSs and varying market conditions could slow down the investment on them. In this paper, the optimal operation of a HyPP consisting of wind, solar photovoltaic and a BESS operating in the Iberian Electricity Market is analysed under the market scenarios between 2018 and 2022. The study reveals the significant effects of the market conditions regarding the revenues obtained by installing BESSs, but claims the need for new market mechanisms to ensure their feasibility. Moreover, a closer market study indicates that price difference rates between markets have not varied significantly, resulting in similar optimal operation strategies in the studied years.

Optimizing a solar-battery-plant for peak-time (9AM-10PM) operation with constant power output
Bernhard Schropp , Isabella Caschetto
SMA Solar Technology AG, Germany
With increasing penetration of renewable energies in the electricity grid, baseload- and dispatchable power plants are pushed out of the market. When the capacity of flexibilities to balance load and generation is depleted, new renewable systems need to be able to operate just like the fossil fuelled powerplants they replace and provide a guaranteed output on demand. Hybrid powerplants combining a renewable energy source with storage can provide this constant power as well as associated grid services.

In the case studied here a constant power supply based on solar energy is necessary between 9AM and 10PM to support the island's energy demand. Because solar energy is only available from 6AM to 6PM this requires a fine balance between the size of the solar farm, the battery system, the converters, and the dimensioning of the point of common coupling. As the project is privately funded the goal was to find the most economic operation strategy that fulfills the requirements of the power purchase agreement, while avoiding penalties.

For this project, an analysis on how an energy management system can optimize the power levels selected for each day and how the applied strategies affect the sizing of the main cost factor: the battery capacity, was conducted. For this purpose, a greedy algorithm was employed to find the optimal sizing. The resulting strategy is then tested through a 25-year simulation based on one minute irradiance data derived from satellite images and state of the art site assessment methods to account for aging effects in the photovoltaic installations as well as in the battery system.

The result was that the operation mode orchestrated by the energy management system affects the sizing of all components as well as the total energy that can be provided to the grid over the 25-year lifetime of the project. For the specific system, the lifetime average size of the battery capacity should be slightly above 3 hours of the nominal plant capacity resulting in operating the system at around 70% of its nominal power output in most days.

In the paper, the method used will be described and exemplary results for different input parameters are presented.

Advanced Battery Energy Storage Systems for Optimal Hybrid Power and Energy Management
Francesco Baccino , Marina Santarelli
Hitachi Energy, Italy
Evolution of Battery Energy Storage Systems (BESS) made them a pivotal asset to successfully deal with hybrid power systems with high Renewable Energy Sources (RES) penetration.

The main objective is to achieve stable and secure operation of the electrical system. All services required to maintain system stability and security are traditionally provided by synchronous generators but can now also be provided by high power grid forming inverters (GFM), supported by batteries and the right control and automation to make them into Virtual Synchronous Machines (VSM). In addition, BESS allows to accumulate green energy excess to be released in time of need without fuel consumption or green house gas emissions.

Classic power systems unit commitment and optimal dispatch problems have to be industrialized and tailored to small/medium scale hybrid systems with large RES penetration in which leveraging forecasts and correctly capturing BESS-specific constraints, cost and efficiency items become key to improve the technical and economical performances of the whole system.

This paper provides insights on BESS value proposition in terms of both power and energy management. Real plant data as well as simulation results obtained with dedicated tools are discussed to explain and highlight how advanced BESS value can be fully exploited. The paper demonstrates and provides simulation and experimental evidence that advanced BESS bring to the system a unique combination of technical features and a pivotal additional degree of freedom key for successful operation of hybrid power systems.
These benefits come at the cost of increased complexity which can however be comfortably addressed with specialized control and management systems which are nowadays supported by viable and trustworthy technology solutions and products from industry players such as Hitachi Energy, rich with hybrid systems domain knowledge and expertise.

Fixed-Frequency Operation of an Island Grid with Multiple Grid-Forming Inverters and GPS-Based Synchronization
Robin Strunk 1, Lucas Reus 2, Lutz Hofmann 2, Axel Mertens 1
1 Leibniz University Hannover Institute for Drive Systems and Power Electronics, Germany
2 Leibniz University Hannover Institute of Electric Power Systems Electric Power Engineering Section, Germany
By using an external signal for the synchronisation, an island grid with grid-forming inverters (GFM) can be operated
with constant frequency. The global positioning system (GPS) provides a periodic pulse with suitable accuracy. It is used to
define the grid frequency and a reference for the voltage phase angle. A digital counter on the control hardware determines
the phase angle. The counter is reset with each pulse of the GPS. An active power - angle droop control leads to partial
power sharing between the GFM and reduces distortions due to non ideal synchronisation. Furthermore, the grid operator
can adjust the voltage reference phasors of the GFM to control the power flow in the grid. An island grid with two GFM
and a hydro power plant is studied in simulations. The investigated power system is an altered and simplified grid model
of Suðuroy, in the Faroe Islands. The effects of a load connection and a distorted GPS synchronisation are studied. The
stable operation of the power system with the fixed-frequency approach is demonstrated.

Development of a Software in the Loop environment to control a microgrid
Maximilian Mütherig 1, Giuseppe Puleo 1, Markus Zdrallek 1, Andrea Schönbauer 2
1 Bergische Universität Wuppertal, Germany
2 RheinEnergie AG, Germany
After a blackout, critical infrastructure can be resupplied through a microgrid on distribution grid level. In this way, considerable damage to society can be avoided. This microgrid must be separated from the higher-level grid and interconnected by switching operations in that way that as many critical infrastructures as possible can be resupplied. In this case, a controller with automated processes is important, because fast actions are necessary during a blackout. The controller must stepwise expand the microgrid to avoid high fluctuations. Since it is not trivial to test a microgrid on distribution level during daily grid operation, extensive simulation tests are necessary to validate such a controller. PowerFactory is ideal for this purpose, as it can be used to simulate the dynamic processes in microgrids. Furthermore, an interface is needed to connect the controller with the microgrid. This interface enables the exchange of control commands and measurement values between the controller and the microgrid. It must also ensure the independence of the controller so that it can be used in simulation and in the field. This paper presents an interface concept for an automated control of a microgrid simulation. Furthermore, its practical suitability is evaluated.
The first step in this publication is a description of the conceptual design to show the two software programs, MATLAB and PowerFactory, and their communication interfaces. In addition, the advantages of a control system programmed in MATLAB are explained to demonstrate the benefits of this software. Furthermore, the software PowerFactory is presented and analyzed to highlight its reliability and accuracy in calculating a dynamic simulation. Afterward, the data exchange and the developed program are presented to describe essential processes. Subsequently, the developed concept is evaluated using an exemplary microgrid and test scenarios with different switching operations. The results of these analyses provide the basis for the practical suitability of the concept.
Key results
The developed interface transmits control commands from a controller to a microgrid. Moreover, sensor measurements from the microgrid are sent to the controller. This concept is necessary to build up a microgrid after a blackout to resupply critical infrastructures. In addition, the interface allows the controller to be tested with a simulated grid and then used in the field.

Toward high levels of Renewable Energy Sources in the French Insular Systems
Gregoire PRIME 1, Jakub WITKOWSKI 2
1 EDF - R&D, France
2 EDF - SEI (Systèmes Electriques Insulaires), France
Isolated French power systems, such as the overseas departments and territories, are facing high ambitions for decarbonization of the energy mix. These systems encompass a wide variety of situations, with wide range of consumption levels and numerous decarbonization strategies, which include massive penetration of solar and wind generation. This paper provides an overview of the key technical challenges that EDF SEI (Systèmes Energétiques Insulaires) is currently solving to ensure a robust system operation with high shares of renewable electricity.

How to quickly transition from 0% to 100% renewable energy on an island in the northwest corner of Europe?
David Quirk 1, 2, John Boucher 3, Poul Østergaard 3, Henrik Lund 3, Felipe Camara 3, Filipe da Silva 3, Ralph Peake 2
1 DTU Offshore, Denmark
2 Energy & Sustainability Centre Isle of Man, Other
3 Aalborg University, Denmark
Like many nations, the Isle of Man is committed to net zero emissions by 2050. 75% of the island’s greenhouse gas footprint - 500,000 tonnes of CO2 per year - is related to energy use. The island is almost entirely reliant on gas & oil for electricity, heating & transport and there are currently no wind farms, solar parks or energy storage facilities.

The Isle of Man lies in the Irish Sea, situated midway between the UK and Ireland. The island has 85,000 residents, with a land area of 571 km2 and a shallow territorial sea of 4000 km2. In total, the island uses around 1300 GWh of energy per year, of which 360 GWh is electricity, most of which is generated from a gas-fueled (CCGT) power plant with diesel engines in reserve.

There has been some hesitation on utilising the island’s enviable natural resources of wind, water & mountainous terrain. There are worries around maintaining a stable & resilient electricity grid and the cost of upgrading & reinforcing the grid to accommodate intermittent renewables plus a 2-3 times increase in electricity demand. The solution promoted by the state grid operator is to buy a majority of its future power from green sources in the UK via an existing and a planned interconnector. However, the steep rise and unpredictability in prices, has changed the question to can the Isle of Man become self-sufficient in renewable energy and, if so, how? This is the reason for the research reported here.

We have used the dual approach of energy system simulation and power-flow modelling to start building two different pathways for an economic transition from gas & oil to an island powered entirely by wind & solar energies supported by varying amounts of storage. Other options such as biomass, nuclear, tidal, wave & geothermal energies were found to be either too expensive or not feasible based on the island’s geography & geology.

The first pathway is essentially a British Isles-style transition involving full electrification and has been completed. The second pathway, based on Denmark-style plans involving district heating & a certain amount of green hydrogen, is now underway. Both pathways lead to net zero emissions from power generation through broadly overlapping steps:

1) Phase in onshore renewables.
2) Develop energy storage schemes.
3) Phase out gas power from the CCGT plant, whilst keeping the diesel plants as back up.
4) Build a second interconnector & strengthen key parts of the grid.
5) Phase in electric vehicles with carbon pricing.
6) Phase in sustainable heating through incentives.

The CCGT plant could be converted to a synchronous condenser to stabilise electricity or, alternatively, a new hydrogen turbine would allow it to continue as a thermal power plant. In the Denmark-style model, new district heating schemes use heat from seawater-sourced communal heat pumps, concentrated solar & energy from waste.

Both pathways are economic, the main difference being up-front cost versus operating cost. The models also show that, up to a reasonable size of over-capacity in wind energy, the larger the interconnector, the greater the value from exports, particularly if stored energy can be used in arbitrage, which helps justify the cost of pumped hydro schemes. Ultimately, the island could serve as an energy hub for offshore wind farms, linked to markets in the UK & Ireland.

Developing Standardized Plant Controls and Sizing Methodologies - In the face of an Industry in Flux
Benjamin Joseph Braun , Björn Lang
Fluence Energy GmbH, Germany
Continual de-carbonization and de-centralization of electrical grids has highlighted the need for ever more advanced plant controls and design sizing. New technical requirements resulting from these market movements are developing faster than standards and grid codes can be adapted. Meanwhile, component suppliers offer various forms and implementations of grid-forming controls and customers request new applications to be delivered today as well as "tomorrow".

How can market players develop standardized plant controls and sizing methodologies in the face of an industry in flux?

Fluence Energy GmbH is in a unique position to advise and guide this discussion thanks to their breadth of project implementation (Island Microgrids, Industrial Black-start, Advanced Grid-Following, and On-Grid Grid-Forming BESS for TSOs) and depth of in-house product development (From battery pack to PCS to Hybrid Plant Controls) as well as integration utilizing various PCS suppliers.

This white-paper will address the design sizing methodologies, options, and plant controls development of BESS plants taking into consideration: Anonymized empirical results from past implemented projects and in-house testing will be presented and discussed to provide insight into the potential pitfalls of system design and to drive a broader industry discussion as to how future standards, regulations, and markets might be best structured to ensure the fullest implementation and optimization of hybrid power systems by leveraging the unique and advanced capabilities and controls of BESS plants.

Alternative and Combined Procedure for Parameter Identification and Validation of Governor and Automatic Voltage Regulator Dynamic Models
Helma Maria Tróndheim 1, Filipe Faria da Silva 2, Claus Leth Bak 2, Terji Nielsen 1, Bárður A. Niclasen 3, Rasmus Skov Nielsen 4, Nicolas Weikop 4
1 Electrical Power Company SEV, Faeroe Islands
2 Aalborg University – AAU, Denmark
3 University of the Faroe Islands, Faeroe Islands
4 AFRY, Denmark
The Faroe Islands are aiming for 100% renewable electricity generation. The complexity of operational power systems with a high level of renewable generation necessitates accurate dynamic models. Many power systems, including the Faroe Islands, do however consist of generation units with old governors and automatic voltage regulators, in which suitable models and parameters are unknown. Obtaining dynamic models with parameters that replicated measurements proved to be challenging using existing procedures. Therefore, this paper presents an alternative and combined procedure for identifying and validating the controllers and parameters. The procedure utilises measurement data from trip tests, standard controller models, and an optimisation algorithm. The procedure also combines hybrid simulations and system-wide simulations. A successful application of the proposed procedure on the power system of the Faroe Islands is presented. The proposed approach can be applied to other power systems and is especially suitable for other island power systems of similar size to the Faroese power system.

how to submit an abstract
Uta Betancourt
Energynautics GmbH, Germany
how to submit an abstract

Developing the Geo-Techno-Economic Analysis of Hydrogen Ecosystems
Friedrich Weise 1, 2, Barbara Koch 2, Christopher Voglstätter 1, Tom Smolinka 1, Christopher Hebling 1
1 Fraunhofer-Institut für Solare Energiesysteme ISE, Germany
2 Freiburg University, Germany
While it is consensus that hydrogen will play a key role in climate neutral energy systems, the where,
when, and how of many hydrogen applications remains unclear. Techno-economic modelling of
potential hydrogen ecosystems at Fraunhofer ISE aims to addresses these questions by reproducing
realistic technical behaviour of plants and systems with nonlinear mathematical and physical
correlations. The goal is to optimise the system’s setup and operation towards economic and other
Geographic conditions determine the use of hydrogen. Renewable energies are necessary to produce
hydrogen, transport distances influence optimal transportation technologies and costs, and different
infrastructure needs to be available respectively installed. Therefore, my dissertation analyses
possibilities to combine geo-information analyses with techno-economic modelling to create a “geo-
techno-economic analysis”. This includes the identification, creation, and transformation of necessary
geodata and the development and integration of methods for spatially resolved modelling in the
techno-economic optimisation process.
This paper gives insights in the methodology, application, and potential of the geo-techno-economic
analysis. First preliminary results are presented, including: (1) costs and important locations for the
production and distribution of hydrogen, (2) transformation pathways for potential hydrogen
applications, (3) geographic, economic, and infrastructural preconditions that enable hydrogen
ecosystems and (4) optimal transportation technologies. A special focus lies on the analysis of autarkic
energy system and the relevance of import possibilities for electricity or hydrogen.

Coupling Wind Power and Heating with a Thermal Grid: Simulation Case Study Isle of Barra
Markus Auer
Lucerne University of Applied Sciences and Arts, Switzerland
Decarbonisation of heat is a crucial step in the process of mitigating climate change. If the electrical power system supplies mainly renewable energy, heat pumps are a viable low carbon heating system. Heat pumps can either be installed for individual properties or in central district heating (and cooling) schemes.
To proof viability and identify benefits of renewable heating solutions on a community energy approach, I analysed an area in Castlebay on the Isle of Barra. Heating of residential, public and commercial properties was assessed in two-steps: Firstly, individual heating solutions were evaluated and compared to a low-temperature district heating system. Secondly, the district heating system was designed in more technical detail.
My proposed district heating scheme includes 119 properties with a total heat demand of 2.1 GWh/y, resulting in a distribution grid length of 2.3 km. Seawater as a source for the heat pump was found as most suitable, with an average seasonal performance factor of 3.8. Equipment was sized using a 1h timestep model, resulting in: heat pump 500 kW, thermal store 70 m³, electric heater 100 kW, backup fuel oil boiler 600 kW. Investment cost of £2.7 million is higher than individual heating units. This results in moderate cost of delivered heat of 8.7 p/kWh. The district heating allowed integration of further wind power into an otherwise constrained grid. A turbine with 180 kW capacity was selected. District heating in combination with wind power can reduce emissions by 634t CO2-eq/y.
These results are based on my master thesis from 2019 (publicly available) and were indicating that district heating has high potential for decarbonisation but also high investment cost. The recent rise of fossil fuel prices changes these boundary conditions and makes heat pumps even more viable.

Transforming Small Island Power Systems
Gayathri Nair
IRENA, Germany

IRENA Grid Assessment and Modelling- Case studies
Gayathri Nair
IRENA, Germany
Case studies- IRENA grid assessment studies for

7th International Hybrid Power Plants & Systems Workshop 2023

7th International Hybrid Power Plants & Systems Workshop 2023

Faroe Islands, 23 – 24 May 2023

Hybrid Power Plants (Combined Wind &Solar plus may be storage as a power plant connected to a grid)

Design of Wind-Solar Hybrid Power Plant by Minimizing Need For Energy Storage
Erik Jonasson 1, Oskar Lindberg 2, David Lingfors 2, Irina Temiz 1
1 Department of Electrical Engineering, Sweden
2 Department of Civil and Industrial engineering, Sweden
An important aspect in designing co-located wind and solar photovoltaic hybrid power plants is the sizing of the energy converters to achieve as efficient power smoothening as possible. In this study, the ratio of wind- and photovoltaic energy converters in a hybrid power plant is determined by minimizing the overall stored energy that is needed to facilitate constant power output. Using Fourier transform the variability is isolated at predefined time scales that are relevant for grid integration. For the investigated time scales, energy and power ratings for energy storages are determined to counteract the variability. The resulting configuration is the one that is able to achieve constant power output with minimum stored energy. It is shown that co-locating wind- and photovoltaic energy converters smoothen seasonal energy generation, and reduce the energy storage need in both the diurnal and seasonal time scales. A case study for south-eastern Sweden is presented where the wind- & solar hybrid plant configuration that minimizes the energy storage need and therefore most closely resembles constant output power is determined. It is found that a ratio of approximately 40-45% wind power in the hybrid power plant yields the lowest need for energy storage. The presented method is valid for any number of co-located energy sources, and can also be extended to sizing of hybrid power systems.

Coordinated Control of Hydrogen Production Based on Wind Power Generation
George Alin Raducu 1, Stoyan Kanev 1, Ozan Sahin 2, Bashar Alahmad 2, Nicolas Espinoza 2, Daniel Vazquez Pombo 2
1 Vattenfall Wind Power, Denmark
2 Vattenfall R&D, Sweden
Combining different energy sources as a hybrid power plant (HyPP) is gaining interest due to their advantages compared to traditional renewable plants at the expense of requiring more complex control. This paper focuses on the promising coupling of wind farms and electrolyzers for the combined production of electricity and hydrogen. A modelling and control framework is presented employing model-based design capable of coordinating the different technologies in order to minimize curtailment needs while considering operational limitations. The developed control platform considers different sources of variability in wind power generation and provides a sophisticated control strategy to produce green hydrogen. This framework provides a promising avenue to integrate hydrogen production with HyPP and enable more efficient utilization of renewable energy resources. Specifically, simulation results are presented with the HyPP operating in different scenarios focusing on: producing hydrogen at will, turn excess wind power into hydrogen production and synergies allowing the provision of frequency services without curtailment. The simulation results demonstrate the robustness and flexibility of the developed solution, paving the way towards future validation in real-time hardware-in-the-loop and, later, in the field.

Techno-economic modeling of stationary energy storage systems with focus on temperature’s influence on aging
Corina Theresa Schwarz 1, 2, Judith Kapeller 1, Yannick Wimmer 1
1 AIT Austrian Institute of Technology, Austria
2 TU Technical University of Vienna, Austria
With the accelerating implementation and large-scale rollout of intermittent renewable energy into the electric power grid to compensate for terminating fossil fuel-based power plants, large-scale storage technologies are becoming increasingly important. However, depending on the particular application and electricity market in which a battery energy storage system (BESS) operates, many of the potential applications of large-scale BESS are not yet economically viable, making optimal economic operation crucial for accelerated deployment. Especially frequent replacements and thus rapid aging is to be avoided. Among other influencing factors, thermal management plays an important role in minimizing the aging of the battery. However, keeping a large-scale storage containment within a narrow temperature range leads to additional energy costs for cooling and/or heating. To weigh these two economically vital factors, this paper, based on a master’s thesis, introduces a techno-economic model which enables the determination of an optimal temperature range customized for each BESS. Additionally, a simulation study is conducted, performing an exemplary application of the model tool. The main results of the study show the dependency of the net present values (NPV) on various allowed temperature ranges within the BESS containment. The simulation study also finds that for optimal operation, the thermal management needs to be designed individually for each use case and cannot be set to a specific temperature range by considering BESS aging only.

Optimal Operation of Hybrid Power Plants: A Case Study of an Operation Park in Sweden
Oskar Lindberg 1, Rujie Zhu 2, David Lingfors 1, Kaushik Das 2, Poul E. Sørensen 2
1 Uppsala University, Sweden
2 Technical University of Denmark, Denmark
Hybrid power parks (HPPs) that combined renewable power sources and storage can improve generation flexibility compared to single-resource parks, making HPPs able to participate in different electricity markets, e.g., regulating markets. Despite the foreseen advantages with HPPs, a challenging aspect relate to coordination of the included assets due to the stochastic nature of wind production, solar production and electricity prices. In this work, we utilize an energy management system (EMS) that optimally coordinate the power output from the included generation units with the objective to maximize the profit. More specifically, the EMS is multi-time scale rolling optimization framework including spot market optimization and balancing market optimization, where bids in the spot market and balancing market are updated sequentially. Besides, a detailed battery degradation model is included to quantify the non-linear degradation cost of battery storage system. The EMS is implemented using data from an operational 3.7 MW co-located wind and solar park on the west coast of Sweden. Results show that a battery with a size of up to 2 MWh will increase the unit profit when trading in the day-ahead and regulating market compared to having no battery. Higher energy capacity will result in degradation costs that are too high compared to the additional incomes.
Oversizing the park, i.e., installing more capacity than stipulated in the connection agreement with the system operator, impacts the amount traded electricity in the regulating market. At the same time, curtailment losses are increased in a non-linear manner while the unit profit is not much impacted by the different grid connection capacities. When adding the opportunity for the park to trade in the regulating market, as compared to solely the day-ahead market, profits are increased by 3.9%.

How Efficient Can Hydrogen Be? - Hydrogen Technologies and Their Limits of Optimizability
Natascha Eggers 1, 2, 3, Torsten Birth 1, 2, Marcel Scheffler 1, Sebastian Jentsch 1, Antonio Hurtado 3
1 Fraunhofer Institute for Factory Operation and Automation IFF, Germany
2 University of Applied Life Sciences Hamburg, Germany
3 Technische Universität Dresden, Germany
Energy from renewable sources is usually available in a volatile manner (primarily wind and solar energy). For a self-sufficient power supply, these fluctuations must be balanced out. Green hydrogen from electrolysis offers a solution to this problem. Green hydrogen can be used as a storage medium for energy supply or as a green fuel. In addition, through sector coupling, hydrogen offers the possibility of decarbonizing those sectors that cannot be electrified.
In this approach, it is essential to convert the available energy as efficiently as possible. However, to holistically optimize a process, the optimum must be known. In addition, the cause of effects that reduce efficiency must be identified so that it can be fixed in the first place.
At Fraunhofer IFF, we integrate hydrogen technologies into existing infrastructures. Among other things, we investigate the limit of optimizability based on modeling and can thus identify the most efficient storage technology.
Based on physical laws, the limit of optimizability can be modeled using the method of the Physical Optimum. This way, optimization potentials can be identified and exploited both during the planning and in the subsequent operation of the plant.
We have developed a model for polymer electrolyte membrane electrolyzers and validated it using a test plant. The efficiency can be monitored in real time by comparing the model with the actual measured values of the electrolysis cell. This serves to monitor the optimal operating conditions and track degradation effects in real time. The causes of these effects can be identified and systematically eliminated based on changes in the model parameters.
The planned presentation will provide an overview of opportunities for integrating hydrogen technologies into existing infrastructures. Furthermore, we will show the limit of optimizability of hydrogen technologies using the example of electrolyzers. Besides the basic model, the first results of validation will be presented. Recommendations for action derived from the efficiency evaluation to improve the operation of the sample plant will be provided.

Techno-Economic Viability of Pumped Hydropower Plants in Germany, with Focus on Battery Hybridization
Øyvind Klyve 1, Ville Olkkonen 1, Andreas Hensel 2
1 Institute for Energy Technology (IFE), Norway
2 Fraunhofer ISE, Germany
In order to reach Germany's climate goals, large shares of variable renewable energies (VREs) need to be added to the energy mix, and additional storage capacity is crucial to ensure a continuous secure inclusion of these VREs. Adding new or expanding existing pumped hydropower energy storage (PHES) can be a cost optimal solution to achieve this goal. PHES technology can store excess electricity during periods of low demand and low prices, and release it during periods of high demand and high prices, ensuring both reliability in the energy system, as well as income for the PHES operator.

This study aims to investigate the techno-economical potential of investing in a PHES planned by a regional utility in Germany. Three operating strategies, forecast error correction, energy arbitrage and Frequency Containment Reserve (FCR) provision, are compared in terms of the profits each product could provide using market data from 2021. The results indicate that performing energy arbitrage in the day-ahead market at the same time as providing FCR services likely would maximize the profits for the analysed time period. For this operation, installing the most flexible PHES topology might be unnecessary, if the PHES could achieve flexibility through being hybridized with a battery system instead.

Load Shifting to Increase the Match of Consumption and Renewable Generation by Means of Added Thermal Storage, Analysed for the Case of Domestic Heating on the Faroe Islands
Torstein Balle , Hans-Georg Beyer
University of the Faroe Islands, Faeroe Islands
Load shifting is an element of Demand-Side-Management (DSM) that aims to move parts of the load on the electrical grid to another schedule with more desired features, e.g., showing better correlation of consumption with fossil free generation. One way to achieve load shifting is through energy storage, creating the ability to store energy in times of abundant electricity generation, and draw from the storage in times of scarce generation. The aim of this paper is to examine the possibilities of added thermal storage for heating in the Faroe Islands, using renewable power generation. This will be done by examining historical data of heat consumption for buildings using heat pumps, coupled with wind power production, to see if added storage can increase the share of load covered by power stemming from renewable generation, and in turn, reduce consumption generated by oil. So, in times with large wind power production and low heating consumption, and subsequent periods with no wind and large heating need, the prospect of added storage may be highly desirable for both the avoidance of non-renewable generation and reduced variability in the generation to consumption balance. A wind turbine was sized to match the annual electricity consumption of a heat pump, a month of equal wind generation and heat consumption was used to calculate a storage need of 6.51 average days of heat load. This was enough to cover many of the storage needs for the winter, spring and autumn months, but was insufficient in summer, where there was a larger storage requirement.

Critical Assessment of the German Innovation Tender for the Promotion of Hybrid Energy Systems on the Basis of a Revenue Model for Photovoltaics Plus Storage Hybrid Power Plant
Franca Mendler
BayWa r.e. AG, Germany

Utility Scale PV Plant OPEX Optimization with BESS
Dina Jaber
BayWa r.e. Solar Projects GmbH, Germany
This presentation investigates the economic use of battery storage systems in combination with large-scale PV plants in order to economically optimise their own power demand. In other words, to reduce the amount of electricity drawn from the grid, in order to save costs.
Focus is on Sizing, profitability and feasibility, practised on a real project example.