Longitudinal direction protection of distance based on a Fourier algorithm and applied to the access system of a double-fed wind generator is influenced by frequency deviation characteristics. This paper analyzes the influence of short-circuit current characteristics of such a generator on the directional element of conventional distance. Given the frequency deviation characteristics of a double-fed wind farm, it adopts the principle of a time domain protective device. That is, it collects the time domain information of voltage and current at the protective device of each terminal of the outgoing line of a double-fed wind farm, recognizes the resistance and inductance at the protective device of each terminal by means of a recursive least squares method, takes time domain distance protection section II as the element to distinguish direction, so as to realize longitudinal direction protection of time domain distance. The simulation result indicates that this method will not be influenced by frequency deviation characteristics of short-circuit current at the wind power plant, and can identify the fault direction accurately and quickly. It is well able to resist transition resistance and improves the reliability of protection operation of the longitudinal direction of the outgoing line at the double-fed wind farm. This work is supported by the Key Project of National Natural Science Foundation of China (No. 52037003) and Major Special Project of Yunan Province (No. 202002AF080001).