Rummeny, Silvan: Emergency Island Operation of a Medium-Voltage Utility Grid with a Large Battery

Abstract:

To achieve a future secure and fully renewable electricity supply, the authors suggest renewable-powered subsystems, which balance demand and supply within their local grid and, in emergency, run in an island operation. The utility of Versorgungsbetriebe Bordesholm (VBB) usually operate their battery energy storage system (BESS) of 15 MWh/12,5 MW realised by RES Deutschland GmbH on the frequency containment reserve (FCR) market. This study shows how the BESS’s power converter bank made by SMA is able to control grid voltage and frequency while switching into island operation without interruption. In addition, it can balance distributed renewable generators (PV and biomass) and the demand of up to 4 MW in Bordesholm during island operation. In preliminary experiments the BESS was able to manage artificial load steps of up to 4 MW without significant disturbances. The final real-word experiment showed that the transition into islanding operation and back is smoothly possible without any voltage disturbances noticed by the customers of VBB. It is a milestone in the energy transition process to be able to uninterruptedly supply the customers of such a utility as VBB only with renewable energy sources and even in case of an upstream grid outage