Electromagnetic Transient Modeling of Large-Capacity Offshore Full-Converter Wind Turbines

Modeling the wind turbine, consisting with on-site fault ride-through response characteristics, is the premise to analyze the safety and stability of the power system with highpenetration wind power. Existing methods are mostly aimed at the simulations of small-capacity units under typical conditions, and rarely take the considerations of comprehensive simulation and verification of different voltage sags at various operating points simultaneously. To overcome this problem, based on the "black box" model of a certain-type offshore wind turbine, the model is divided into two parts: the main and control circuits. And thus, a general electromagnetic transient modeling method is proposed for large-capacity offshore wind turbines, under various operating conditions. For the main circuit, a general topology of a large-capacity full-power wind turbine, consisting of a typical half direct-drive rotary system, a neutral-point clamped parallel three-level converter and a protection circuit module, is constructed; for the control circuit, the neutral point potential balance controller and low-voltage ride-through controller in symmetry and asymmetry conditions are constructed. Through comparisons with the response characteristics of the actual wind turbine in whole fault ride-through process, it is found that they are consistent, which proves the effectiveness of the proposed modeling method.