Improving Performance of Multi-Infeed HVDC Systems Using Grid Dynamic Segmentation Technique Based on Fault Current Limiters

A grid dynamic segmentation technique based on fault current limiter (FCL) is presented in this paper. The basic concept of this technique is to install the FCLs on appropriate ac lines according to network structure and segment multi-infeed HVDC systems into a number of sectors interconnected by these FCLs. Under normal conditions, the equivalent impedence of the FCLs is zero and does not affect power flow and bus voltage of the system. When short-circuit faults occur in the ac system, the FCLs are activated to limit the short-circuit current and obstruct the propagation of the faults among the sectors. As a result, for the dc systems, the commutation failure duration of the dc links is reduced, and the recovery of the dc systems is speeded, while, for the ac system, the power imbalance and the power flow transfer caused by the simultaneous commutation failure of the dc links are relieved. The transient stability of the whole ac/dc system is thus improved. The effectiveness of the proposed grid dynamic segmentation technique is demonstrated on two representative multi-infeed HVDC systems.