Analysis of Post Fault Oscillation Damping by VSC-HVDC in an Offshore Wind Farm Connected System

The dynamic nature of power system creates the post fault voltage and frequency oscillations for a small period of time, which may further exaggerate due to inadequate controller settings. Large wind farms consisting of variable speed double fed induction generator (VS-DFIG) with proper control settings can contribute to the damping of such oscillations. At present offshore wind farms are becoming popular. As these farms are situated far from the main grid, connecting them to the main grid using a high voltage direct current (HVDC) system is more economical. Among the two principal types of converters in HVDC, the Voltage Source Converter (VSC) has several advantages over the Line Commutated Converter (LCC). In this study, the impact of an offshore VS-DFIG wind farm connected by VSC HVDC on the post fault voltage and frequency oscillation is analyzed. Studies show that the inclusion of VSC HVDC connected offshore wind farm instead of conventional generators reduces the damping time of post fault oscillations for both voltage and frequency significantly. IEEE 9 bus transmission network has been used as the test system. This initiative of connecting offshore wind farm aligns with the objectives of mitigating carbon emissions and fostering sustainable economic development.