Voltage Flicker Compensation through an HVDC Connected Offshore Wind Farm

Electric arc furnaces are one of the largest voltage flicker sources in the power system, which causes additional power losses in the grid and extra costs to the system operators. This paper investigates the potential for flicker mitigation via an offshore wind farm connected through a high voltage direct current transmission line and a modular multilevel converter, which serves as an active filter and provides dynamic compensation. The converter transforms the active power generated by the wind farm. The reactive current injected or absorbed by the converter is regulated by the flicker mitigation control, which computes the necessary reactive current reference to reduce ac voltage oscillations in the rotating reference frame. The effectiveness of this strategy is proven by means of time-domain simulations in MATLAB/Simulink environment, reaching flicker reduction of up to 82.67 % and 78.08 % for flicker frequencies of 5 Hz and 15 Hz, respectively.