Analysis of Harmonic Propagation and Coupling among Wind Farm Groups

Although wind energy itself has the conditions of large-scale development and utilization, power quality has always been the focus and difficulty of wind power generation. Harmonics generated by power electronic equipment in doubly-fed generators may lead to overheating damage and faults of transmission lines and transformer equipment. To improve the safe operation and harmonic control ability of power grid and reduce the loss of electrical equipment, a model of double-fed wind farm group with voltage level of 690V/35kV/110kV was established in Matlab/Simulink. By analyzing the characteristics of harmonic propagation and coupling between wind farms under different conditions, it is found that when the harmonic source was on the fan side, the harmonic is transmitted from the fan side to the grid side. If the harmonic content of wind power station is large, it will have a greater impact on power quality. In addition, due to harmonic coupling, 110 kV bus current has the highest harmonic distortion rate and the highest harmonic content.