A novel topology design for integration of offshore wind farm via high-voltage DC transmission

A novel configuration for offshore wind farms based on variable-speed permanent magnet synchronous generator integration via high-voltage DC transmission is proposed. Each permanent magnet synchronous generator is equipped with a full-bridge diode rectifier and a DC/DC boost chopper, which constitutes a cascaded submodule. Quite a number of submodules are series-parallel connected to form a DC collector system for the offshore wind farm. Any unit that needs maintenance or that undergoes fault in a series-connected branch can be isolated from the system by the natural commutated process without influencing other normal units in the same branch. The proposed submodule has several prominent features, such as low cost, low power loss, and simple control strategy. A maximum power point tracking algorithm of each wind turbine is realized by controlling the current through the inductor of each DC/DC boost circuit in one submodule. The proposed topology and control strategy are verified by simulations in Power Systems Computer Aided Design/Electromagnetic Transients including Direct Current (PSCAD/EMTDC; Manitoba HVDC Research Centre, Manitoba, Canada).