The key control technologies in the direct drive PMSG offshore wind turbine system

For improving the efficiency of offshore wind energy, control technologies develop rapidly in the direction of high-power, variable speed, individual pitch and direct drive permanent magnet generator (PMSG). Because offshore wind loads and control objectives are more complex than those of onshore, the widely existing control methods of the entire offshore wind turbine system, including pitch control, machine-side and grid-side control and transmission control, etc are described in this paper. Their advantages and disadvantages are summed up by comparing these control methods, and the improvement of corresponding control methods are proposed, which provides the theoretical foundation for improving the large-scale offshore wind farms and developing their control technologies.