A large number of power sources with complex fault characteristics are connected to the collecting line of wind farms so that fault localization for the line is difficult. This problem has been plaguing wind power operators. Therefore, this paper presents a zero-sequence component-based fault localization scheme for asymmetric phase-to-ground faults of collecting lines. Starting by defining the branch-free area and fully considering the special relationship between wind turbines (WTs) and zero-sequence components of wind farms, the WT-independent identification and fault distance calculation for the faulty branch-free area can be realized hierarchically. First, the concept of status information of branch-free areas is introduced to reflect the main flow path of zero-sequence current. Then the faulty branch-free area can be identified by using optimization to match the status information. Second, a fault distance calculation model of the faulty branch-free area is derived from zero-sequence impedance, and the solution problem of this model is transformed into an optimization problem to obtain the fault distance. The proposed localization scheme can completely eliminate the effect of WTs with only a few measuring points and effectively adapt to the collecting line with branches. In addition, strictly synchronous data is not necessary for this scheme and multiple solutions are avoided. Finally, in order to deal with line parameter variation, online calculation of line parameters is also designed. Simulation results verify that this localization scheme is accurate and not affected by WTs, fault locations, fault types, fault resistance and asynchronous data, and the overall performance is better than that of existing schemes. The effectiveness of online calculation of line parameters is also proved. This work is supported by the National Natural Science Foundation of China (No. 51677072).