高压直流换流阀晶闸管控制单元保护特性与晶闸管级仿真建模

Protection Characteristics of Thyristor Control Unit and Simulation Model of Thyristor-level for HVDC Converter Valve

晶闸管级是组成高压直流换流阀的最小结构单元,晶闸管控制单元(TCU)是晶闸管级的关键元件。研究晶闸管级TCU的保护特性对于改进TCU保护逻辑功能设计以及晶闸管换流阀精细化仿真建模具有重要意义。以此为出发点,搭建了晶闸管级TCU保护特性的实验研究平台,研究了晶闸管级在断态和反向恢复期内不同时刻承受高幅值、高陡度侵入电压时TCU的保护特性。实验结果表明,断态下TCU的保护阈值在侵入低陡度电压时基本保持不变,而侵入高陡度电压时随陡度升高而降低;反向恢复期内TCU的保护阈值与电压侵入的时刻无关而随侵入电压陡度的升高而增大。在此基础上建立了一种考虑TCU保护功能的晶闸管级仿真宏模型,仿真结果表明此模型不仅能够反映晶闸管的基本动、静态特性,也能准确反映TCU保护特性,仿真结果与实验结果相吻合。

Thyristor-level is the fundamental unit constituting a HVDC converter valve. Thyristor control unit(TCU) is the key component of the thyristor-level. It can provide a basis for improving and perfecting the logic function design of TCU protection to study TCU protection characteristics, and expand existing thyristor simulation model. Based on this, this paper establishes an experimental research platform for the protection characteristics of thyristor-level TCU, and studies TCU protection characteristics when the thyristor is subjected to the intrusive voltage with high amplitude and high steepness during off-state and at different moments in reverse recovery period. Experimental results show that the protection threshold value of the TCU in the off-state is basically unchanged when the steepness of the intrusive voltage is low, and decreases with the steepness when the steepness is high. The protection threshold value of the TCU during the reverse recovery period is independent of the moment of voltage intrusion when the steepness of the intrusive voltage increases synchronously. On this basis, a thyristor-level macro model considering TCU protection function is built. Simulation results show that the model can reflect the basic dynamic and static characteristics of the thyristor, and accurately reflect the protection characteristics of the thyristor-level TCU.