An aggregated model of wind farm composed of doubly fed induction generators

A single-unit equivalent modeling method for multi wind power generating units in a wind farm under different wind speeds is proposed. Under the same parameters of the generating units and based on the principle that the active and reactive power outputs of the wind farm, the kinetic energy change rate and the loss of the drive trains are kept constant, the equivalent transformation of wind wheel, drive train, generation system and main control system are performed and the computing methods for relevant parameters as well as that for the equivalent wind speed are given. Taking the equality of short-circuit impedances at the point of common coupling (PCC) as the principle, the single-impedance equivalence of power network within the wind farm is carried out. A detailed model of a wind farm composed of four double fed induction generators (DFIG) with rated capacity of 2 MW, which possess the same parameters, and corresponding equivalent model are built, and the output characteristics of the two models during stochastic wind speed and under power grid faults are respectively compared and analyzed by simulation results. Simulation results show that the equivalent aggregated model obtained by the proposed method possesses high accuracy and suits to the modeling of the wind farm composed of DFIG units with same parameters. ©, 2015, Power System Technology Press. All right reserved.