With the development of the ship industry, the power quality of the ship power system is getting worse and worse. More scholars turn to the detection and improvement of the power system. However, most of the current research focuses on the study of the whole power system, few people pay attention to the source of the power quality problem. The nonlinear load is one of the most important factors to affect the quality of the ship's power. This paper does some study on the power quality of the frequency conversion system introduces the harm caused by the electric power quality of the frequency...