The commutation overshoot is an important reference index for the insulation coordination of the converter station as well as the thyristor voltage capacity. Although the dispersity of reverse recovery charges of series thyristors may affect commutation overshoots, especially those at the thyristor level, little literature has tried to analyse it in detail. Firstly, this study compares the turn-off models of independent thyristor and elaborates their applicability to series thyristors. Then, a novel model for series thyristors during the turn-off process is proposed, based on which the turn-off model of converter valve is also established. Subsequently, the validity and efficiency of the proposed model are discussed by simulations and it is applied to the analysis of commutation overshoots. The analysis shows that though the average model can be used to estimate the valve voltage stresses, it may lead to large errors in the thyristor voltage stress. And selecting the 1:n − 1 distribution as the distribution mode of reverse recovery charge in series thyristors will result in very conservative results.

换流过冲是换流站绝缘配合以及晶闸管电压容量的重要参考指标。尽管串联晶闸管反向恢复电荷的分散性可能会影响换向过冲，尤其是晶闸管级的换向过冲，但很少有文献试图对其进行详细分析。首先，本研究比较了独立晶闸管的关断模型，并阐述了其在串联晶闸管中的适用性。然后，提出了一种新型的串联晶闸管关断过程模型，并在此基础上建立了换流阀的关断模型。随后，通过仿真讨论了所提模型的有效性和有效性，并将其应用于换向过冲的分析。分析表明，尽管可以使用平均模型来估算阀电压应力，但它可能会导致晶闸管电压应力的较大误差。并选择1：n  -1分布作为串联晶闸管中反向恢复电荷的分布模式将导致非常保守的结果。