Technical and Commercial Comparison of AC- and DC-Coupled Battery Energy Storage Systems
Matikainen, Konsta (2024)
2024
Sähkötekniikan DI-ohjelma - Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2024-09-03
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202408298417
https://urn.fi/URN:NBN:fi:tuni-202408298417
Tiivistelmä
The integration of renewable energy sources (RESs) and the retirement of conventional power plants have increased the importance of battery energy storage systems (BESSs) for stabilizing the grid and managing the intermittent nature of RESs. BESS configurations can be categorized into AC-coupled and DC-coupled, depending on whether the BESS is connected to other systems on the AC (alternating current) or the DC side (direct current).
AC-coupled BESSs can function as standalone systems to provide grid services like frequency regulation or be co-located with RESs to support both the power plant and the grid, with options for shared or separate grid connections. DC-coupled BESSs are always connected to another system on the DC-side, sharing components such as the DC/AC converter, transformer, and interconnection with that system.
The thesis presents the power train configurations and components of BESSs, in addition to applications and key differences between AC- and DC-coupled BESSs. To provide a basic understanding of the subject, different battery technologies and general system architecture of BESSs are reviewed. It further evaluates the economic and technical considerations of AC- and DC-coupled BESSs through comparative analysis, presenting real-world examples of operational systems and commercial products.
Key findings revealed significant differences between AC- and DC-coupled BESSs in terms of installation layout, hardware sharing and costs. AC-coupled systems are found to have typically simpler design with separate components and lower operational costs due to component centralization. In contrast, DC-coupled systems, typically integrated with photovoltaic (PV) power plants, offer more efficient solar energy capture but have higher operational costs because of decentralized layout and more complex design caused by shared converters.
The thesis concludes that the choice between AC- and DC-coupled configurations depends on specific project needs, market conditions and regulatory frameworks, highlighting the importance of system design specific to the application. Future technological advancements and cost reductions are expected to balance the commercial attractiveness of these configurations.
AC-coupled BESSs can function as standalone systems to provide grid services like frequency regulation or be co-located with RESs to support both the power plant and the grid, with options for shared or separate grid connections. DC-coupled BESSs are always connected to another system on the DC-side, sharing components such as the DC/AC converter, transformer, and interconnection with that system.
The thesis presents the power train configurations and components of BESSs, in addition to applications and key differences between AC- and DC-coupled BESSs. To provide a basic understanding of the subject, different battery technologies and general system architecture of BESSs are reviewed. It further evaluates the economic and technical considerations of AC- and DC-coupled BESSs through comparative analysis, presenting real-world examples of operational systems and commercial products.
Key findings revealed significant differences between AC- and DC-coupled BESSs in terms of installation layout, hardware sharing and costs. AC-coupled systems are found to have typically simpler design with separate components and lower operational costs due to component centralization. In contrast, DC-coupled systems, typically integrated with photovoltaic (PV) power plants, offer more efficient solar energy capture but have higher operational costs because of decentralized layout and more complex design caused by shared converters.
The thesis concludes that the choice between AC- and DC-coupled configurations depends on specific project needs, market conditions and regulatory frameworks, highlighting the importance of system design specific to the application. Future technological advancements and cost reductions are expected to balance the commercial attractiveness of these configurations.