风电机组多物理系统与交流电网间的功率传播及频率耦合特性

Industrial field reports show that wind turbine (WT)-based energy systems are prone to result in power grids suffering from oscillating problems. One of the main differences between the WT system and the photovoltaic system is the property of their primary energy, the former is rotating and the latter is static. Hence, in this paper, the multi-physical domain modeling of a doubly-fed induction generator (DFIG)-based wind turbine system, composed of aerodynamics, mechanics, electromagnetism, power electronics and control system, is derived to study the power propagation and frequency coupling characteristics from wind energy to electricity grids, showing the impacts of the WT system on electricity grid performances. Theoretical analysis shows that the ${\mathbf 3}n$p Hz distortion in wind energy can be converted to ${\mathbf 50\pm 3}n$p Hz oscillations in AC grids. The impacts of different control schemes (power control and speed control) of DFIG are studied in detail to show that the control schemes of the back-to-back converter play a significant role in influencing the power propagation characteristics. The results of PLECS-based simulation and OPAL-RT-based test clearly validate the correctness of the theoretical analyzes.