Lightning Overvoltage Simulation and Design of a Novel Surge Protective Device for High-Power Offshore Wind Farms

Wind power converters in high-power offshore wind farms (OWFs) are exposed to complex overvoltage environments. In particular, the effects of lightning overvoltage on OWFs have not been adequately studied. Therefore, the effectiveness of conventional surge protective devices (SPDs) in overvoltage protection systems faces great challenges, which poses a significant threat to the stability of high-power converters in OWFs. To address this issue, a typical OWF transient simulation model is developed, and the lightning overvoltage on the converter side is quantitatively evaluated. Based on the simulation results, we propose a novel surge protection scheme based on controllable V-I characteristics. Furthermore, a novel controlled SPD prototype based on this concept is designed and includes a fast response controlled trigger switch, an active energy coupling trigger circuit, and a metal oxide varistor unit. The performance of the SPD prototype is validated. Experimental results show that its response time is only approximately 130 ns under high-frequency overvoltage conditions, with a residual voltage 32% lower than that of the existing SPDs (at the same nominal voltage). This novel SPD module is able to meet the strict requirements of overvoltage protection for high-power OWFs, which is highly important for their safe and stable operation.