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

Abstract

The paper proposes a novel Optimum Fre- quency AC (OFAC) transmission system for reduc- ing investment and operational cost of Electric Sys- tem (ES) - integrating Offshore Wind Farm (OWF) to the onshore grid. Optimum operational frequency for ES is an inherent characteristic of the trade-off be- tween its investment and operational cost. The paper presents a comprehensive methodology for the design of ES based on Life Cost Analysis using a Generic Al- gorithm. For the given offshore wind farm, alternative designs for ES are generated for different operational frequencies. Power system components of standard rat- ings are used for the designs. All the designs are evalu- ated in terms of Net Present Values (NPV) and the de- sign with maximum NPV is selected as the optimum solution. For 200 MW OWF, optimum operational fre- quencies are obtained as 50, 35, 25, and 50/3 Hz for offshore distances of 50, 100, 150, and 200 km, respec- tively. 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 in- creases 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)