Design of Electrical System for Offshore Wind Power Plant (OWPP)

Anotace: The paper proposes a novel Optimum Frequency AC (OFAC) transmission system for reducing investment and operational cost of Electric System (ES) - integrating Offshore Wind Farm (OWF) to the onshore grid. Optimum operational frequency for ES is an inherent characteristic of the trade-off between its investment and operational cost. The paper presents a comprehensive methodology for the design of ES based on Life Cost Analysis using a Generic Algorithm. For the given offshore wind farm, alternative designs for ES are generated for different operational frequencies. Power system components of standard ratings are used for the designs. All the designs are evaluated in terms of~Net Present Values (NPV) and the design with maximum NPV is selected as the optimum solution. For 200 MW OWF, optimum operational frequencies are obtained as 50, 35, 25, and 50/3 Hz for offshore distances of 50, 100, 150, and 200 km, respectively. The results show that for 200 MW the feasible range for OFAC is 100-150 km and provides the saving of 5-10% as compared to High Voltage AC (HVAC) and Low-Frequency AC (LFAC). The results further indicate that for large-scale wind farms the saving increases substantially and the feasible range is reduced. It concludes that OFAC is an economical alternative to HVAC and LFAC for integrating large-scale OWF to the onshore grid and provides a new dimension for promoting Offshore Wind Power Plant (OWPP).