Drs. Madhav Manjrekar and Badrul Chowdhury have received funding from the NC Coastal Studies Institute to investigate the use of Multi-terminal High Voltage DC (MT-HVDC) transmission link based on Voltage Source Converter (VSC) technology for transferring power generated in off-shore wind farms. These MT-HVDC systems suffer from poor protection and control issues which stems from an inadequate understanding of the system-level power flow mechanisms and operation of such systems under fault and abnormal conditions. Furthermore stability aspects of such systems when subject to wind/tidal current variation and transient faults has not been fully addressed. Although, the US has very limited off-shore wind power production, there are a number of studies being funded by the US Department of Energy (see https://energy.gov/eere/wind/offshore-wind-research-and-development).
The principal objective of this project is to model and simulate an off-shore multi-terminal HVDC system along with the on-shore HVAC system and investigate system-wide power flow scenarios along with response of such system during abnormal operating circumstances and post-fault conditions in both ac and dc sections. Rather than employing a separate AC system protection scheme that gets patched with a DC system protection scheme, a combined model that includes power converters, power system controls and AC/DC protection methodology will be developed. This alternative offers advantages of adopting a holistic approach thereby accounting for interdependencies between the off-shore power production, the high voltage DC link between off-shore and on-shore, and the traditional high voltage AC grid that is on-shore.