Background Harmonic Suppression in Offshore Wind Power Systems Using Virtual Impedance Control of SVG

With the rapid development of offshore wind power, the issue of excessive background harmonics in offshore wind power grid-connection systems has become increasingly prominent, seriously affecting grid stability and power quality. Existing harmonic suppression measures primarily focus on passive and active resonance suppression techniques. However, effective suppression of background harmonics in offshore wind power systems under such conditions remains a challenge and warrants further investigation. In response to this issue, this paper takes a representative offshore wind farm in Zhejiang Province as a case study. By leveraging the already-installed power electronic equipment within the offshore wind system and improving its control strategy, an adaptive virtual impedance control strategy based on Static Var Generator (SVG) is proposed to manage background harmonic voltage. This strategy dynamically adjusts the equivalent impedance of the SVG in the fifth harmonic frequency band in real time, effectively reducing background harmonic voltage and significantly enhancing the system's operational stability and dynamic response. Simulation results based on MATLAB/Simulink validate the effectiveness of the proposed method, demonstrating a substantial reduction in the total harmonic distortion (THD) of the fifth-order harmonics. The findings offer a novel technical solution for the high-quality grid integration of offshore wind power systems under complex grid conditions.