中文摘要：

下垂控制逆变器在大扰动下存在类似于传统同步发电机的暂态失稳现象,且受到逆变器输出电流限幅环节的影响使其电压控制环失去作用,因而工作于饱和电流源模式。文中进一步分析了在暂态过程中由于电压非理想跟踪特性而导致虚拟功角曲线发生偏移、并使逆变器暂态稳定裕度下降的机理。在此基础上,提出一种估计逆变器输出电流并用于前馈控制的方法,以提高逆变器的电压跟踪性能,从而提高逆变器的暂态稳定性。此外,针对逆变器暂态过程中无稳定平衡点的问题,提出一种暂态同步控制策略。当逆变器电压控制环饱和失控时,将逆变器控制在合适的平衡点,以防止其发生暂态失稳,同时为系统提供无功支持。最后,采用单机无穷大系统验证了所提出方法的有效性。

英文摘要：

Like synchronous generators,transient instability also occurs to droop-controlled inverters when subjected to large disturbances.Owing to the current limitation,the voltage loop of the inverter is out of work during the disturbance and the inverter turns to operating in the current source mode.The mechanism of the virtual power angle curves deviating during the transient process because of the limited voltage tracking performance,which reduces the stability margin,is further analyzed.To this end,a current feed-forward control method based on estimating the output current is proposed to improve the voltage tracking performance so that the transient stability is improved.Besides,to deal with the loss of equilibrium points during the transient process,a transient synchronous control method is proposed.It helps the inverter to reach a proper equilibrium point when the voltage loop is out of commission and prevents the inverter from transient instability.Finally,simulations on a singlemachine-infinite-bus system verify the effectiveness of the proposed control methods.