Research on LCC-MTDC and STATCOM technology for wind farms integration

This paper proposed the line-commutated converter based multi-terminal HVDC(LCC-MTDC) combining with the static synchronous compensator (STATCOM) for doubly-fed induction generator (DFIG) based wind farms integration in the context of Northwest Grid (NG) in China. The control strategies design was approached from two aspects. One was aimed to the ac system on the rectifier side. To coordinate the wind farm, STATCOM and rectifier, the inverse system method was introduced to design the controller in view of the nonlinear characteristic of STATCOM. Meanwhile, the control strategy for the rectifier was proposed to balance the active power in the subsystem and ensure the dc link voltage of STATCOM constant. On the other hand, the single-point voltage control strategy suitable for LCC-MTDC was conceived to guarantee the stable operation of the system by considering the control characteristics of both rectifiers and inverters Simulations carried out in PSCAD/EMTDC have proven that the proposed control strategies possess favorable control performance and fast response speed.