Abstract: With increasing wind power, the oscillation risk inside the wind farm is realistic. The existing modeling of the oscillation aggregates the wind farm to a wind turbine generator (WTG), ignoring the dynamic interaction among the WTGs. The existing theoretical method fails to explain the interaction process and the coupling among the WTGs. In this paper, an extended effective open-loop process (EEOP) is newly proposed to analyze the interaction paths among the doubly-fed induction generators (DFIGs) in the wind farm. At first, a linearized feedback connection model based on the transfer function matrix in the frequency domain is derived for multiple DFIGs. Based on the two-input two-output model of the DFIG, the transfer function of the wind farm is rearranged to newly extend the EOP theory. The open-loop transfer function of the DFIGs is derived to find analytical expression of the interaction among the DFIGs and draw the interaction paths to reveal the transfer process and coupling among the DFIGs. The indicators based on the 2-norm and generalized Nyquist theory are proposed to quantify the gain of the interaction paths and its effects on the oscillation of the wind farm. Finally, the simulation results validate the effect of the wind speed and the control parameters on the interaction and verify the correctness and effectiveness of the proposed interaction paths and the indicators.