Coordinated active/reactive power control for flicker mitigation in distributed wind power

Flicker mitigation in variable-speed wind generators can be approached by reactive power control utilizing the power-electronic converter of the machine, a technique that is bound by several factors including the network X/R ratio, line current limits and the instantaneous output of the machine. The highest flicker level is observed as the machine approaches its rated output, under such conditions in sites with favorable wind resource, sole reactive power compensation would necessitate overrated operation for long periods and increased line currents or otherwise the reactive power margin narrows possibly resulting in impaired capability in reducing flicker to compatible levels. This paper proposes coordinated power curtailment and reactive power control and assesses the feasibility of its implementation in reducing variable-speed wind generators flicker emission under high wind speed conditions. The amount of active power to be curtailed is quantified based on the observed decrease in short-term flicker Pst with respect to power factor settings.