Abstract: Reactive power assignment has not been considered seriously in wind power because many system owners manage real power output firstly and maintain the required voltage for each wind turbine. However, renewable resources penetration is being continuously increased and power system operator might ask additional service to improve the reliability and stability issues. Owing to the system loss by the extensive area, the uncertainty of transferred power from large-scale wind farm is considerable. Counterbalancing the gap between expected and real output quantity is available with additional control design but reducing the occurred error is more effectual to not only the system efficiency but also the system stability. In this paper, a reactive power assignment strategy based on the relative distance of each wind turbine in farm, and realistic assignment processes to verify the positive effect are performed by PSCAD/EMTDC. The strategy is considering voltage fluctuation and system loss by two distinguished assignment processes that regarding array and turbines.