Hybrid High Voltage AC/DC System Protection and Controls for Interfacing Off-shore Power Generations with On-shore Grid

Drs. Madhav Manjrekar and Badrul Chowdhury
Research Highlight

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.