Bennewitz 25 MWh
Battery Energy Storage System (BESS)
With the good experiences in the context of implementation and operation of the storage facility in Langenreichenbach, there was no doubt for Upside Group that they would also rely on the specially developed concept in the second 16.4MW battery storage project in Bennewitz. The innovative battery concept for the provision of primary control reserve is based on operating data carefully evaluated since 2014, which are used to relate the state of the transmission and distribution networks as well as the activity and load of the battery storage at each moment of operation. This enabled components to be selected and precisely dimensioned in order to be used in the battery system in a future-proof manner. The result is a battery energy storage system with exceptional functional properties. The interaction of power components and battery cells is ensured by the superior and tailor-made energy management system. This provides optimum support for the battery management, which is of particular importance for the service life of the battery. With this project, Upside Group continues to invest intensively in the expansion of the German storage infrastructure and between September and November 2018 realized a reproduction of the storage facility previously built in Langenreichenbach.
Location
The Central German region in the Leipzig area is traditionally known for its energy production. In addition to lignite, sun and wind, but also biomass, are used to generate electricity. This means, however, that the existing power lines are already heavily used, so that two 380 kV extra-high voltage lines are currently being planned/built here. Upside developed the Bennewitz project in 2017/18 in the 20kV distribution network of the network operator Mitnetz in the district of Leipzig in the direct vicinity of generation and industry. The open space created by the dismantling of an old transformer station building on the substation station site was used to install the battery storage in the immediate vicinity and integrate it into the medium voltage of the transformer station so that it is ready for operation 24/7, 365 days a year. The connection, quasi at the heart of the distribution network, enables not only the integration into the control power network for the output of the PRL, but also the direct provision of further network services. In this way, the Bennewitz battery storage facility contributes to grid relief in the entire region.
Performance
With the frequency-controlled power output of primary control reserve (PCR), it is important to follow the fluctuating frequency to the second. This is done by the Bennewitz energy storage system using 9 SMA 1.8MVA inverters, each equipped with its own frequency control. Since November 2018, the plant has been fully functional and was initially prequalified for the provision of PCR exclusively. Since 2022, the battery storage system has also been prequalified for automatic frequency restauration reserve (aFRR), operates on intraday and day-ahead markets and provides other grid-serving services.
Technology
After evaluating various storage technologies, the Bennewitz energy storage system relies on proven technologies from renowned manufacturers. The power electronics and the inverters come from Siemens and SMA, one of the world’s three largest manufacturers of battery inverters. The battery cells used are lead-carbon dry accumulators in which the electrolyte is bound in a glass fiber nonwoven. Combined with a firmly welded ABS plastic housing with an outgassing valve, the battery cells can therefore be installed horizontally and could even be flooded without any substances escaping. The typical oversizing of the electrical and chemical components in Upside Group projects and the low fire load inherent in the technology make the Bennewitz energy storage system, like its predecessor in Langenreichenbach, one of the safest and most reliable systems in the world. Apart from that, it was also one of the largest battery storage systems installed in Europe.