Abstract This article provides an in-depth analysis of the causes of overvoltage at the generator end and the existing overvoltage protection circuits. Due to the long cable connection between the generator and the converter, voltage reflection occurs during the power transmission process, resulting in overvoltage at the output end of the generator and the input end of the converter. A mathematical model and simulation model have been established to address this issue. Firstly, the transmission line theory is used to analyze the characteristics of PWM pulse transmission in long cables. The reasons for overvoltage at the generator end and the influence of cable distribution parameters on overvoltage are analyzed; Secondly, conduct theoretical calculations; Finally, establish a simulation model using Matlab/Simulink, and analyze the harm of motor terminal overvoltage to the wind power generation system through simulation.