Optimal Design and Operation of Long-Distance Deep-Water HVAC Transmission for Offshore WECS Integration with FPSO Unit

This paper evaluates the technical feasibility of integrating an offshore Wind Energy Conversion System (WECS) to a Floating Production Storage and Offloading (FPSO) unit. The WECS is situated closer to the Brazilian mainland, requiring a 150 km long subsea umbilical cable for the integration with the FPSO unit. Given the substantial water depths, High Voltage Alternating Current (HVAC) transmission becomes mandatory, which introduces challenges such as power losses and high reactive capacitive current generated by the cable. To address these challenges, the paper proposes a comprehensive approach. Firstly, the umbilical cable section is sized based on ampacity and maximum current under short-circuit conditions. Subsequently, a power flow optimization technique is employed to determine the optimal transmission voltage that minimizes power loss. Such an optimization process also requires that the WECS absorbs reactive power according to the active power being processed. These power values obtained from the optimization are thus used for a lookup table control to optimize the efficiency of the entire transmission system. To validate the proposal, each component of the system is modeled, and a complete simulation is conducted using MATLAB-Simulink.