A co-ordinated recovery strategy of multi-infeed HVDC systems

In this paper, a coordinated recovery strategy for multi-infeed HVDC system is proposed. A nonlinear feedforward loop is used to realize the coordinated control between the two controlled variables at the two control ends at first. Secondly, a constant AC voltage control was implemented for a short period after the AC fault removal. Finally, a staggered recovery strategy for different HVDC subsystems with the restart time interval optimized using the steepest descent method is developed. The simulation results show, with the proposed coordinated recovery strategy, the recovery performance of the tested multi-infeed HVDC system has been improved a lot when compared with the conventional control strategy.