Floating, Production, Storage, and Offloading Unit: A Case Study Using Variable Frequency Drives

The use of variable frequency drives (VFD) in floating, production, storage, and offloading (FPSO) units provides well-known benefits to the power system, such as: soft-starting of motors, increase of energy-efficiency, reduction of short-circuit currents, and enhancement of the load shedding capability. The VFDs with passive front-end rectifiers are the most commonly used for these applications due to their wider commercial availability and lower cost compared to VFDs with active front-end rectifiers. However, the latter can control the exchange of reactive power with the grid, which may contribute to voltage support and power factor regulation at the electrical system. This paper presents a case study considering the Production operating mode of an FPSO unit with two VFDs connected to the largest motors (i.e., water injection pumps). Simulations of the FPSO power system are evaluated using both active and passive VFDs, considering scenarios with analysis of steady-state, start of largest motors and symmetrical three-phase short-circuit.