Optimized Sizing of BESS for Primary Frequency Control in a Hybrid O&G FPSO Unit

Abstract

The need to reduce emissions in the oil and gas (O&G) sector is boosting studies aiming to integrate renewable energy sources (RES) and replace fossil fuel generation. Several studies address the frequency control in isolated grids. Still, there's a lack of studies focused on frequency support in O&G facilities, where high demand, space, and weight restrictions bring additional challenges. This study proposes an optimization problem based on a penalty cost function to determine the optimal sizing of a battery energy storage system (BESS) for primary frequency support in an floating production and storage offloading (FPSO) unit. A complete and simplified FPSO model is developed, with the latter used in the optimization to reduce simulation time. The results show that the simplified model provides a frequency response similar to the more robust one but with some disparity due to the absence of voltage influence in the system dynamics. This discrepancy between the two systems' response in terms of voltage led to optimized BESS requiring a minimum 7.5% safety margin to ensure frequency stability within established limits during the steady-state period when considering the complete model to validate the results. The BESS power determined through the optimization process shows a 20% reduction in size compared to the value obtained using an analytical methodology.