Abstract
Deep voltage sags represent a critical challenge in power-from-shore supply to offshore platforms, as they can cause variable-speed drives to trip and interrupt essential processes. This paper investigates energy-storage-integrated flexible AC transmission solutions (FACTS) for voltage sag mitigation, with a focus on comparing active series and active shunt compensation. The analysis is performed on the LEOGO reference model representative of an offshore oil and gas installation on the Norwegian Continental Shelf of 62 MVA with 100 kV AC export system and 33/11 kV distribution. The required converter power rating is determined as a function of voltage sag depth and the short-circuit ratio at the PCC, assuming commercially available converter modules suitable for offshore deployment. Numerical simulations show that a series FACTS device enables variable speed drive ride-through for a 0.25 p.u., 100 ms three-phase volt-age sag on a platform with a converter rating of approximately 25 MVA, whereas an equivalent shunt compensator requires about 150 MVA, which is impractical for offshore applications. Thus, the results indicate that series energy-storage-integrated FACTS solutions provide a more compact and effective approach for mitigating deep voltage sags than shunt-based configurations.