Coordination between DFIG-based wind farm and LCC-HVDC transmission considering limiting factors

For wind farms with thyristor-based line current commuting (LCC)-HVDC delivery systems, reactive power must be provided for the HVDC converters to ensure normal operation. When the wind speed increases, the capability to provide reactive power by a doubly-fed induction generator (DFIG) wind farm decreases. Meanwhile, there is increase in reactive power loss in the transformer and ac lines. As a consequence, the reactive power transmitted to the LCC-HVDC could be reduced. Coordination of the DFIG wind farm terminal voltage and HVDC rectifier voltage is necessary to make sure the required reactive power is supplied to the HVDC converters. The goal of this paper is to investigate the upper and lower limits for the rectifier ac bus voltage. An integrated DFIG-based 200 MW wind farm with a simplified HVDC-link connection is studied in Matlab/Simulink. Time-domain simulation results are given to confirm the analysis.