Flexible, robust and resilient power systems (GreenGrids)

GreenGrids - an overarching research vision

GreenGrids is an overarching research vision for flexible, robust and resilient power systems, with power-system reliability as a central research perspective. The research addresses how future power systems can integrate new generation, storage and sector-coupled energy resources while maintaining reliability, stability and resilience.

The research combines reliability analysis and power-system engineering with flexibility, energy storage, sector coupling and system-supporting technologies. Applications include battery storage, hydrogen and Power-to-X, electromobility and nuclear power. The GreenGrids perspective connects technologies and energy sectors at system level and studies how they can jointly enable the transition towards a reliable and decarbonized energy system.

The research is aligned with the UN Sustainable Development Goals, particularly affordable and clean energy, resource efficiency, sustainable infrastructure and cities, and responsible use of natural resources.

Figure: The GreenGrids vision – flexible grid infrastructure enabling power grid evolution and decarbonization.

Power-system reliability as the scientific core

Power-system reliability provides a common scientific foundation across the GreenGrids research. Reliability analysis is used to understand how changes in generation, grid infrastructure, flexibility resources, and sector coupling affect the ability of the power system to deliver electricity securely and sustainably.

This creates a natural connection to the Reliability Centered Asset Management (RCAM) research area. RCAM approaches reliability from an asset and life-cycle perspective, including condition monitoring, predictive maintenance, maintenance optimization and lifetime extension. GreenGrids complements this with a system perspective: how assets, technologies and energy sectors interact to maintain reliability, robustness and resilience as the power system evolves.

Flexible resources, energy storage and grid services

Energy storage and flexible resources can provide both local and system-level services in future power systems. Research within GreenGrids has addressed energy-management systems for battery energy storage systems, virtual power plant concepts, forecasting and control, and the provision of ancillary services to transmission and distribution system operators.

The work includes methods for coordinating renewable energy resources and storage to improve resource efficiency, economic value, and grid support. Earlier GreenGrids-Flex research developed and tested energy-management approaches for battery storage and demonstrated their potential through Swedish case studies and collaboration with industry.

Hydrogen, Power-to-X and sector coupling

Hydrogen and Power-to-X provide opportunities to connect the electricity system with industry, transportation and heating while introducing new sources of flexibility for the power grid. Within GreenGrids, these interactions are studied from a system perspective, including how hydrogen production and storage can contribute to grid support while enabling decarbonization in other sectors.

One example is the completed Vinnova-funded research based on the hydrogen facility at Ovako Hofors, inaugurated in 2023. In collaboration with Ovako, Volvo Trucks and Hitachi Energy, two pre-studies investigated sector coupling between green hydrogen for steel production, electricity-grid flexibility, heavy transportation and district heating. The work explored how industrial hydrogen production can be combined with power-system services and sustainable mobility, including hydrogen refuelling for heavy transport.

This research direction continues through ongoing doctoral research on green hydrogen and electrolyser-based industrial systems, including their interaction with future power systems and their potential to provide flexibility and grid support.

Nuclear power, reliability and system-supporting technologies

Nuclear power is an active GreenGrids research area and provides a particularly important link between the system and asset perspectives. At system level, the research studies the potential role of small modular reactors (SMRs) and other nuclear technologies in renewable-rich power systems, including their contribution to system-bearing services, voltage and frequency support, and grid-forming capabilities.

A complementary research direction concerns reliability, ageing and lifetime extension of nuclear power assets. This connects directly to the RCAM perspective through reliability analysis, condition assessment, maintenance and life-cycle decision support. Together, these perspectives address both how nuclear assets can remain reliable over extended lifetimes and how nuclear power can contribute to the reliability and resilience of the future power system.

Current research includes ongoing projects on SMRs, reliability-centered asset management for nuclear applications and the role of nuclear power in future low-carbon power systems.

Robustness, resilience and nonlinear power-system dynamics

Future power systems with increasing shares of inverter-based and actively controlled resources introduce new dynamic interactions and operating conditions. GreenGrids therefore also includes research on robustness, resilience and nonlinear power-system behaviour.

Ongoing research investigates how nonlinear and complex dynamic phenomena can be understood and incorporated into analysis and decision support for future power systems. This complements conventional reliability analysis and contributes to a broader understanding of system robustness and resilience under changing operating conditions.

Selected publications

Selected publications illustrating the development of the GreenGrids research from smart grids and flexibility to sector coupling, nuclear power and the current overarching vision:

• C. J. Wallnerström and L. Bertling Tjernberg (2018), “Analysis of the future power system’s ability to enable sustainable energy - Using the case system of Smart Grid Gotland,” in Application of Smart Grid Technologies, Elsevier/Academic Press.
• H. Shafique, L. Bertling Tjernberg, D.-E. Archer and S. Wingstedt (2021), “Behind the Meter Strategies: Energy management system with a Swedish case study,” IEEE Electrification Magazine, 9(3), 112-119.
• L. Bertling Tjernberg and H. Shafique (2023), “The flexible grid infrastructure enabling power grid evolution and decarbonization,” in Handbook on Climate Change and Technology, Edward Elgar.
• T. Elmfeldt, Y. Arafat, L. Bertling Tjernberg, A. Lugnet and G. Nyström (2024), “Sector-coupling Green Hydrogen to Electrify Steel Production - A Case Study at Ovako Hofors,” PMAPS 2024, Auckland, New Zealand.
• J. K. Nøland, M. Hjelmeland, C. Hartmann, T. Øyvang, M. Korpås and L. B. Tjernberg (2024), “Running Renewable-Rich Power Grids With Small Modular Reactors: Their grid-forming role in the future power system,” IEEE Electrification Magazine, 12(4), 20-29.
• J. K. Nøland, M. N. Hjelmeland, C. Hartmann, L. B. Tjernberg and M. Korpås (2025), “Overview of Small Modular and Advanced Nuclear Reactors and Their Role in the Energy Transition,” IEEE Transactions on Energy Conversion.
• L. B. Tjernberg, A. A. López, Y. Arafat, J. K. Nøland and H. Shafique (2026), “The GreenGrids Vision and Case Studies From Sweden,” IEEE Energy Sustainability Magazine, 2(2), 128-138.

→ KTH | Complete List of Publications | Lina Margareta Bertling Tjernberg

GreenGrids - research development and collaboration

The GreenGrids vision has developed through research on smart grids, flexibility, storage, sector coupling and system-supporting technologies, in collaboration with academic and industrial partners. The research continues to evolve around the common challenge of maintaining power-system reliability while enabling decarbonization and increasing integration across energy sectors.

Figure:Lina Bertling Tjernberg and Hamza Shafique with the book chapter The flexible grid infrastructure enabling power grid evolution and decarbonization, 2023.