In this paper, the coupling mechanism of phase-locked loop (PLL)-synchronized multiparalleled wind farms under grid faults is analyzed in detail. First, the coupling effects of the currents and the equivalent power angles (EPAs) among wind farms are identified by analyzing the voltage characteristics during low voltage ride-through (LVRT). Subsequently, a transient stability assessment method is proposed for multiparalleled wind farms to evaluate the effect of output currents of multiple wind farms on the EPA distribution characteristics. This method can be applied to evaluate whether each wind farm in the system has equilibrium points as well as evaluate the transient instability risk of the system during LVRT. In addition, the dominant wind farms for the system transient instability can be identified. Due to the coupling effects, any inappropriate current in the wind farm may deteriorate the EPA distribution characteristics and even cause loss of synchronism. Consequently, the current distribution method to minimize transient instability risk can ensure that each wind farm in the system has equilibrium points and effectively improve the multiparalleled wind farms stability during LVRT. Finally, the simulations results validate the effectiveness of the theoretical analysis and proposed method.

中文翻译：

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多并联风电场低电压穿越耦合机理分析及暂态稳定评估


本文详细分析了电网故障下锁相环（PLL）同步多并联风电场的耦合机制。首先，通过分析低电压穿越（LVRT）期间的电压特性，识别风电场之间电流和等效功率角（EPA）的耦合效应。随后，提出了多并联风电场暂态稳定评估方法，以评估多个风电场输出电流对EPA分布特性的影响。该方法可用于评估系统中各风电场是否存在平衡点以及评估系统在低电压穿越过程中的暂态失稳风险。此外，还可以识别系统暂态不稳定的主导风电场。由于耦合效应，风电场中任何不适当的电流都可能使EPA分配特性恶化，甚至造成失同步。因此，当前暂态失稳风险最小化的分配方法可以保证系统中各风电场均存在平衡点，有效提高多并联风电场低电压穿越过程中的稳定性。最后，仿真结果验证了理论分析和所提出方法的有效性。