System Restoration using VSC-HVDC connected Offshore Wind Power Plant as Black-Start Unit

This paper presents the possibility of using a point-to-point voltage source converter - high voltage direct current (VSC-HVDC) transmission system connecting offshore wind power plant (WPP) to the onshore grid as black start unit to initiate the restoration process for an interconnected electrical system after a large area system blackout. The onshore converter station (CS) provides voltage in order to establish an electrical island within the integrated grid after offshore CS's and WPP's black-start. Electric loads on the mainland can be resupplied and auxiliary power for the start-up process of a thermal power plant can be provided. Possible fundamental control structures for the VSC-HVDC CSs and for the WPP are proposed, with which a fast communication channel to the Wind Energy Generators (WEG) is not needed to ensure load balancing. The overall control strategy is shown as well as the appropriate control structures and the dynamic descriptions of the WPP, HVDC-CSs and the load. The proposed strategy is verified by simulating relevant study cases using PowerFactory.