计及晶闸管最小关断角变化的动态关断角控制

为了在实际工程中减小换相失败的概率,在PSCAD 中建立了晶闸管最小关断角动态模型,通过确定动态最小关断角得到换相失败的实际判据。然后,将晶闸管阀关断角的变化量引入控制系统中,提出了一种动态关断角控制方法。在PSCAD/EMTDC上进行仿真验证,仿真结果表明,换相失败实际判据能有效提高换相失败识别的精准性,关断角动态控制方法能较好地抑制单相及三相短路故障导致的换相失败,有利于直流输电控制保护系统调整关断角控制裕度,具有工程实际意义。

Dynamic Turn-off Angle Control Considering the Change of Minimum Turn-off Angle of Thyristor

To reduce the probability of commutation failure in practical engineering, the dynamic turn-off angle model of thyristor is established in PSCAD, and the actual criterion of commutation failure is obtained by determining the dynamic minimum turn-off angle. Then, the variation of turn-off angle of the thyristor valve is introduced into the control system, and a dynamic control method for turn-off angle is proposed. The proposed control method was improved on the CIGRE standard test model and realized by PSCAD/EMTDC simulation. The simulation results show that the actual criterion of commutation failure can effectively improve the accuracy of commutation failure identification. The dynamic control method for turn-off angle can mitigate the commutation failure caused by single-phase or three-phase short-circuit faults better. It can be beneficial for the control and protection system of DC transmission to adjust the control margin of turn-off angle of converters, which has practical engineering significance.