VSG Control for DFIG-based Islanded Wind Farm with LCC-HVDC Integration

Doubly-fed induction generator (DFIG)-based islanded wind farms cannot be directly integrated by line-commutated converter (LCC)-HVDC through conventional vector control algorithms, due to the lack of a voltage source support in the sending end bus of HVDC. This paper proposes a novel system topology and a corresponding virtual synchronous generator (VSG) based control algorithm of islanded DFIG-based wind farms with LCC-HVDC integration. In the system topology, batteries are installed in the back-to-back converters of the DFIGs to generate the terminal voltage and then supply energy for rotor excitation, therefore provide a prerequisite of the system startup. After the startup, synchronous generator characteristics are exhibited by the DFIGs based on the VSG control algorithm. In order to achieve active power balance and frequency stability of the sending end bus, the frequency control is realized in the rectifier of HVDC. Simulations performed on PSCAD/EMTDC verify the proposed control algorithm.