Robust Voltage Security Regions with VSC-HVDC Connections

Large scale wind powers transmitted through voltage source converter based high voltage direct current (VSC-HVDC) links represents one of the major ways to use the renewable energy resources. However, several voltage-related challenges exist in large-scale wind integration area with VSC-HVDCs such as the cascading trip faults. To efficiently prevent the large-scale tripping faults, this paper proposes a robust voltage security region (RVSR) computation method to determine a secure operational range for wind automatic voltage control (AVC) for each wind station and VSC station. The RVSR computation is applied using a hierarchical iteration method between wind farm side and system side, which only needs at most 4~5 times under most conditions. The computation efficiency and accuracy are validated using a modified IEEE9 system with two VSC-HVDC links.