1. College of Electrical Engineering, Shanghai University of Electric Power, Shanghai 200090, China;2. Electric Power Research Institute of State Grid Shanghai Municipal Electric Power Company, Shanghai 200437, China;3. State Grid East Inner Mongolia Electric Power Co. Ltd., Hohhot 010020, China;4. Shanghai Donghai Wind Power Co. Ltd., Shanghai 200433, China

Because of the bad environment of wind farms in the far-reaching sea, the cost of power collector system is high. The contradiction between economy and reliability of the power collector system planning is particularly prominent. According to the particularity of the wind farm in the far-reaching sea and the demand of the power collector system on higher reliability, this paper proposes the definition of topological redundancy of the power collector system and develops a multi-objective optimization model based on the topological redundancy. Thus, the contradictory variables of economy and reliability are optimized. Taking a large-scale offshore wind farm as an example, based on the topological redundancy assessment, the topology of its power collector system is optimized from the perspective of life cycle cost. The results show that, although the initial cost of the optimal redundancy topology is slightly higher than that of the radial structure, the advantage of life cycle cost after 8 years of operation is obvious, which can meet the actual engineering requirements of the power collector system for the wind farm in the far-reaching sea.