To the power flow modeling of the brushless doubly-fed induction generators (BDFMs), it is found that their active output under the maximum power point tracking (MPPT) mode is related to the power system operation condition, thus simultaneous solution to power flow constraints of the BDFMs and the power system is newly proposed. For the BDFMs under power dispatch, it is found that the reference power may not be satisfied by low wind speed, yielding divergence of power flow solution. A two-stage power flow model is newly proposed. Effectiveness of power dispatch object is judged to choose the power constraints and solution procedure for the BDFMs. To improve power flow convergence, the initial setting to the BDFMs set by the rotor slips or branch powers is newly proposed. The numerical results on IEEE RTS test system are provided, which validate the feasibility and accuracy of the proposed models.