Control Method for the Valve-side Single-phase-to-ground Faults on the Transmission Side of Symmetrical Bipolar Offshore Wind Power Based on System Parameter Optimization

In order to address the problem of coexistence of overvoltage, overcurrent, and voltage drop at the wind farm grid connection point caused by single-phase grounding faults on the transformer side of the offshore wind power system, we put forward a stress control method for symmetrical bipolar offshore wind power system faults based on system parameter optimization. Firstly, we constructed a mathematical model for the converter valve and a control model for wind turbines, and revealed the overvoltage, overcurrent and the voltage drop characteristics of the converter valve after faults and their impact on the wind farm grid connection points. Secondly, on the basis of the impact mechanism of system key parameters on post fault voltage and current, we proposed a fault stress control scheme based on system parameter optimization. By optimizing the configuration of system key parameters, the control of overvoltage, overcurrent, and low voltage can be realized, significantly extending the safe operation time after system faults and improving the voltage at the wind farm grid connection point. Finally, we verified the effectiveness of the proposed method in regulating system fault stress through simulation analysis of a flexible DC system for symmetrical bipolar offshore wind power. This method can provide support for the optimization design of offshore wind power. © 2024 Science Press. All rights reserved.