This paper proposes a new adaptive perturb and observe (AD-PO) algorithm for maximum power point tracking (MPPT) of DFIG based Wind Energy Conversion Systems (WECSs).The proposed algorithm is able to solve the limitations of conventional fixed step-size perturb and observe (PO) algorithm. It is able to achieve the optimum power with small time and oscillations compared with the conventional P&O techniques. This algorithm is mainly based on dividing the power-speed curve into four sectors by comparing the power-speed curve and a special synthesize curve. Hence, the selection of appropriate dynamic perturbation step-size (DPSS) of rotor speed is changed related to the operating sector. For the two sectors far from the maximum power point (MPP), a large DPSS is applied. Otherwise, the controller utilizes a small DPSS. Theproposed algorithm is validated using a large-scale 1.5 MW double-fed induction generator (DFIG); where the stator terminals of DFIG are connected directly to the grid and the rotor terminals of DFIG are connected to the electric gridvia a back-to-back converter (BTBC). The proposed algorithm has been implemented using MATLAB/SIMULINK. The results prove the efficient operation of the proposed algorithm in term of the fast system response compared with traditional P&O techniques.