Stability Analysis of Wind Farm Connected to Hybrid HVDC Converter

The high-voltage direct current (HVDC) transmission has been the promising scheme for power transfer of large-scale long-distance offshore wind farms. Nowadays, the modular multilevel converter (MMC) is the mainstream topology for the HVDC converter. However, due to the large number of submodules, the conventional offshore MMC converter station has higher volume, weight and cost. To overcome the shortcomings, the hybrid converter scheme based on a diode rectifier and a small-scale MMC-based ancillary converter is a possible cost-efficient solution for the offshore HVDC converter. In this paper, the hybrid HVDC converter is designed for a practical small-scale wind farm with eleven 1.5 MW doubly-fed induction generator (DFIG)-based wind turbines. The interactive stability of the wind farm connected to the hybrid HVDC converter is analyzed using the impedance-based analysis method. Finally, the time-domain simulations confirm the stability analysis.