Reliability and economic analysis of offshore wind power systems- A comparison of internal grid topologies

Wind power has emerged the last decades as an important technology for low carbon emitting electricity production. The development was first onshore, but recently many wind farms have been developed offshore due to space availability, low noise and visual impacts. Offshore wind farms experiences higher winds resulting in higher production, but investment costs, and operation and maintenance costs are also much higher. More specifically, a failure may result in long downtime due to inaccessibility to the site during harsh conditions, and transportation costs are also higher since boats, and sometimes helicopters are necessary. This study consists of a reliability and economic analysis of the internal grid of offshore wind power system. Different topologies are evaluated and compared against each other with the aim of presenting alternative layouts with increased level of reliability at an acceptable cost. The different layouts are compared in additional income over the life time of the wind farm considering the energy not supplied. The results show that for the case study consisting of two arrays of ten 3MW wind turbines– three of the proposed alternative layouts presents a positive Net Present Value of the extra investment of 63k€, 165k€ and 201k€ respectively. It can be concluded that it can be beneficial to implement some degree of redundancy along with improvements in the protection system.