Abstract: The three-phase unbalanced current of the wind farm is one of the causes of the zero-sequence current generated inside the wind farm. In this paper, the actual zero-sequence protection action case in the wind farm field is taken as an example to analyze the three-phase current imbalance caused by the single-phase ground fault resection process. In the event of the fault, the static var generator（SVG） is connected to the wind farm, and the zero-sequence current in the line will oscillate greatly, which leads to the problem of zero-sequence current oscillation in the field. A wind farm simulation model was established to systematically analyze the cause of the unbalanced current generated when a single-phase earth fault occurred. Aiming at the oscillation problem of zero-sequence current, the wind farm zero-sequence protection tuning is proposed and the simulation analysis is carried out. The results show that the two solutions which are to increase the damping of the system and reduce the zero-sequence protection action time of SVG can reduce the amplitude and oscillation time of the zero-sequence current and also reduce the occurrence of malfunction of the relay protection device.