A Study on Using VSC-HVDC for Fast Restoring Loads after System Contingencies

The full-controlled voltage-source-converter (VSC) HVDC has been an effective and flexible technology and applied in practical projects and is potential to restore loads after system contingencies. In this paper, the method of restoring loads by the remote hydro power plants through VSC-HVDC transmission system is studied. On this basis, this paper further identifies the advantages of employing VSC-HVDC to restore a passive system, through the comparisons to the black-starting and loaded performances of conventional steam generators. The fast response ability of VSC-HVDC can dramatically reduce the restoration time and system frequency deviations when picking up the cold loads after contingencies. In order to achieve this target, the control strategy of VSC-HVDC entails to be slightly modified to implement the function of black starting and safely loading. The proposed operating strategy can be switched back to the normal strategy when the disturbances caused by contingencies are eliminated. The resilience of DC/AC interconnected power system can be enhanced by increasing the restoration reliability. The verification of the proposed strategy and the contrastive results are conducted in the simulation tests.