高压直流输电晶闸管阀开关过程的影响因素

Influencing Factors for the Switching Process of Thyristor Valve in HVDC Transmission

当晶闸管阀导通时,交流系统、杂散电容、阻尼回路、阀避雷器等的电流相互耦合,共同决定了晶闸管的开通过程。晶闸管阀关断时,反向恢复过程、换流变短路阻抗、阻尼回路参数等共同决定了晶闸管的关断电压。本文基于PSCAD/EMTDC搭建了晶闸管阀电磁暂态仿真模型,研究晶闸管阀开通暂态、关断暂态中电压电流的影响因素和时变机理,得出饱和电抗器和阻尼电阻对抑制端间电容和阻尼电容引起的开通过电流有重要作用,换流变压器短路阻抗对关断过程换相过冲影响较大。晶闸管阀开关过程的影响因素的研究成果对工程设计中的参数选型和器件设计具有一定的指导意义。

When turning on a thyristor valve,the AC system current,stray capacitance current,damping branch current,valve arrester current,and other currents are coupled to each other,which determines the opening process of the thyristor together.When turning off a thyristor valve,the reverse recovery process,short-circuit impedance of transformer,and damping branch parameters determine the thyristor turn-off voltage together.Based on PSCAD/EMTCD,this paper builds a thyristor valve electromagnetic transient simulation model to study the influencing factors and time-varying mechanism of the voltage and current of switching process of thyristor valve.The result shows the saturation reactor and damping resistance play important roles in suppressing the open current of capacitor,and the short-circuit impedance has a greater effect on the commutation overshoot.Studying the influencing factors of the switching process of the thyristor valve has certain guiding significance for parameter selection and device design in engineering design.