混合式直流断路器中快速真空开关的弧后介质恢复特性研究

The multi-terminal high voltage direct current (HVDC) system based on the voltage-sourced converter HVDC (VSC-HVDC) is one of the valid approaches to integrate distant renewable energy sources into AC networks. The hybrid direct current circuit breaker (DCCB) is the key device used for short-circuit fault isolation in multi-terminal HVDC system. In this project, a hybrid DCCB prototype will be developed based on the ultra-fast vacuum switch (VS) actuated by the electromagnetic repulsion mechanism. A new measurement method for the post-arc dielectric recovery strength of the VS in the hybrid DCCB after arc extinction is proposed in this project. So the post-arc dielectric recovery curves of the ultra-fast VS in the prototype can be obtained based on the proposed measurement method. By experiments and simulations, the influences of various factors on the post-arc dielectric recovery curves will be investigated, and the measures to promote the recovery of the ultra-fast VS in the hybrid DCCB will be investigated. Based on the post-arc dielectric recovery curves of the ultra-fast VS in the hybrid DCCB, the time sequences of the mechanical switches branch and the static DCCB branch, the strategy of turning off the static DCCB branch will be studies by experiments and simulations. The application of this technology studied in this project can provided theory basis for the determination of the time sequences of the components and the turn-off strategy of the static DCCB branch in the hybrid DCCB. In addition, the research results to be obtained in this project can ensure the reliability of the hybrid DCCB and promote the recovery of the multi-terminal HVDC system from the short-circuit faults. In conclusion, the researches in this project can provide technical foundation for the construction of the multi-terminal HVDC system.

发展基于电压源型换流站的多端直流系统是解决中国新能源并网的有效技术手段，混合式直流断路器是保证多端直流系统可靠运行的关键设备。本项目拟应用电磁斥力机构驱动的快速真空开关实现混合式高压直流断路器试验样机，研究一种快速真空开关弧后动态介质强度测量方法，用于测量试验样机中快速真空开关的弧后介质恢复曲线。结合试验与仿真手段，研究各种因素对快速真空开关弧后介质恢复曲线的影响规律，探索提高其弧后介质恢复速度的方法。以快速真空开关弧后介质恢复曲线为基础，通过试验及仿真，研究混合式直流断路器中机械开关支路与电力电子支路的时序配合方法，并制定电力电子支路的最优关断策略。本项技术的应用，可为确定混合式直流断路器中各组件之间的时序配合、制定电力电子支路的最优关断策略等提供理论依据，提高混合式直流断路器运行的可靠性，加速直流系统故障后的恢复过程，为直流电网建设奠定技术基础。

在混合式直流断路器的开断短路电流的控制过程中，快速机械开关和大功率电力电子器件支路的控制时序是保证可靠关断短路电流的关键技术。本项目研究了一种快速真空开关弧后动态介质强度测量方法，通过样机试验，研究了快速真空开关的介质恢复特性，研究了多种因素对快速真空开关介质恢复曲线的影响规律，总结了提高其介质恢复速度的方法。设计了基于耦合负压式混合式直流断路器中机械开关支路与电力电子支路的时序配合方法，并制定电力电子支路的最优关断策略。基于本项目研究的快速机械真空开关介质恢复特性，为张北500kV直流电网的耦合负压换流535kV混合式直流断路器的操作时序和控制策略提供了技术支持。设计了基于耦合负压换流的混合式直流断路器中各组件之间的时序配合方法，制定了实际断路器产品的最优关断策略，在张北500kV直流电网中的直流断路器中得到了实际应用。