Integrated control of offshore wind farms and HVDC links with MML converters

摘要

This thesis analyzes the integration of large quantities of offshore wind power into power systems through point-to-point or multiterminal HVdc grids that use modular multilevel converters (MMC). Firstly, a simplified method to simulate MMCs is developed with the objective of reducing the simulation times. Secondly, a new control strategy for offshore wind power plants connected through MMC-HVDC links is developed in order to meet the requirements of the new ENTSO-E grid codes (for instance, island operation or black-start). Next, a mathematical study is carried out to estimate the values of the DC fault currents in HVDC grids and the response of several wind power plant control strategies are analyzed in the event of DC faults. Finally, a new DC-DC MMC topology is proposed for HVDC grids.