Fault current limiters: a case study of protection and operational continuity for FPSOs

The Floating Production Storage Offloading offshore (FPSO) has been employed in the oil and gas exploration at the Brazilian pre-salt fields. Due to the increasing production capacity of process plants and consequently its power demands, FPSO power systems are experiencing higher fault current levels, which can present peak values of almost 200 kA in the medium voltage circuit. One solution to keep fault currents within safe values for the new electrical installations is to split the main switchgear busbar in two parts interconnecting them with a pyrotechnic device (PD). However, this typical fault current limiter (FCL) imposes operational restrictions to the FPSO; when the PD is triggered, the production of barrels is severely reduced. This work proposes two alternative FCLs to mitigate this problem: a Pyrotechnic Device (PD) associated with a parallel Air-Core Reactor (ACR) and a resistive Superconducting Fault Current Limiter (r-SFCL). As described in this manuscript, both alternatives allow full operation of the FPSO even after its actuation. The simulation model used to reproduce the transient behavior of two FCLs and the power system of typical FPSO was developed in the software Alternative Transients Program. The results show that the alternatives can limit the fault current below the main switchgear supportability limit, improving the reliability of FPSO’s production.