This paper introduces a novel design of an electric vehicle (EV) fast charging station, consisting of a battery energy storage system (BESS) with reconfigurable cell topology. The BESS comprises two battery strings that decouple the power flow between EV and grid, to enable charging powers above the grid capacity. The reconfigurable design is achieved by equipping the battery cells with semiconductor switches and serves two main purposes. First, it aims at solving cell unbalance issues to increase safety, reliability, and lifetime of the battery. Second, it enables the BESS to actively control the EV charging process by changing its cell configuration in a real-time fashion, making a DC-DC converter redundant. The paper presents a modelling approach that captures the reconfigurable design including the controlling algorithm used for cell engagement. The simulation results show that the BESS is able to fulfil the EV request with sufficient accuracy for most of the fast charging process. However, the switching of cells leads to variations in the charging current that can potentially exceed the tolerance band defined in IEC61851-23. Therefore, complementary measures are suggested to achieve a suitable current control during all phases of the charging process. The estimated BESS efficiency during the EV fast charging process is $93.3$%. The losses caused by the reconfigurable design amount to $1.2$% of the provided energy. It is demonstrated that the proposed design has a competitive efficiency compared to a battery buffered fast charging station with DC-DC converter.

Biogas plants may support the transformation towards renewable-based and integrated energy systems by providing dispatchable co-generation as well as opportunities for biogas upgrading or power-to-X conversion. In this paper, a simulation model that comprises the main dynamics of the internal processes of a biogas plant is developed. Based on first-order kinetics of the anaerobic digestion process, the biogas production of an input feeding schedule of raw material can be estimated. The output of the plant in terms of electrical and thermal energy is validated against empirical data from a 3-MW biogas plant on the Danish island of Bornholm. The results show that the model provides an accurate representation of the processes within a biogas plant. The paper further provides insights on the functioning of the biogas plant on Bornholm as well as discusses upgrading potentials of biogas to biomethane at the plant from an energy perspective.

Reconfigurable batteries can change their cell topology in real time, which enables them to adapt their voltage during operation. This unique capability makes interfacing power converters redundant in applications where batteries are directly coupled with other DC components or systems. The present paper characterizes a 104 kWh prototype of a reconfigurable battery for high power applications, and derives equations for calculating the battery efficiency for the complete operating area. The battery can adapt its voltage from 0 V up to 1200 V, and reaches power values of 240 kW for charging, and 280 kW for discharging. The results are presented in efficiency maps, showing the dependency on voltage, power, and state of charge. Moreover, the efficiency characteristic is compared to a conventional battery with fixed cell topology and DC-DC converter. The reconfigurable battery can operate at a wider voltage range and achieves better efficiency up to an average power of 44.6 kW during charging, and 46.7 kW during discharging. Conversely, the conventional system performs better above these thresholds. Finally, the presented model can be used to optimize the design of reconfigurable battery strings, and to accurately size such systems for specific applications and purposes.