Analysis of Transient Stability in Wind Power Grid Integration Systems

After a fault occurs in a wind farm, the output current of the multilevel converter is generally determined by the AC voltage control, and there is a significant transient process, which has a significant impact on the transient response of the phase-locked loop. However, in the transient synchronization stability analysis of existing wind power grid connected systems, it is assumed that the output current of the multi-level converter on the wind farm side reaches the limit value instantaneously after a fault, and the multi-level converter on the wind farm side is equivalent to a constant current source. The results of the transient synchronization stability analysis may be overly optimistic. In response to this issue, this article analyzes the transient synchronous stability of wind power grid connected systems. Firstly, a fourth-order synchronous stability model considering the dynamic AC voltage control of multi-level converters on the wind farm side is proposed. Then, using the equivalent swing equation to reveal the transient synchronization stability mechanism of the system, analyze and improve the transient synchronization stability of the system. Finally, the correctness of the theoretical analysis is verified through electromagnetic transient simulation.