一种限流式混合直流断路器方案

直流输电与交流输电相比,具有线损低、不存在系统同步运行稳定性问题等一系列优点。近年来,随着电压源型高压变流器等技术的迅速发展,柔性多端高压直流输电系统、直流输配电网以及直流断路器等关键技术与装备的研究受到了国内外的高度重视。文中简要阐述了机械式、全固态与混合式3类直流断路器的拓扑结构、工作原理、优缺点及国内外研究现状,指出高压直流断路器应以混合式为主要发展方向;提出一种限流式混合直流断路器方案并仿真验证了其可行性,该方案采用全/半控器件串联构成固态开关再与机械开关并联的混合开关结构及故障限流技术,可有效抑制直流短路电流上升率,降低故障判断灵敏性与机械开关速动性的要求,减少高压应用场合下固态开关器件的串联数量(特别是绝缘栅双极型晶体管等价格昂贵的全控型器件),从而降低装置工程化实现的技术难度及其体积与成本。

A Scheme for Current-limiting Hybrid DC Circuit Breaker

In contrast to alternating current (AC) power transmission, direct current (DC) power transmission has a series of advantages, such as low line loss and nonexistence of the problem of system synchronous operation stability. In recent years, with the rapid development of voltage source converter technology with higher voltage, the study on flexible multi-terminal high voltage direct current transmission (HVDC) system, DC transmission and distribution power net, as well as the related key technologies and equipments such as the high-voltage DC circuit breaker (DC-breaker) has captured great attention from the community at home and abroad. The research status of three types of DC-breakers (spoken of as the mechanical type, all-solid-state and hybrid type DC-breakers) and their topologies, working principles, advantages as well as disadvantages are briefly treated. It is concluded that the hybrid type should be the main trend of development for high-voltage DC-breakers. Furthermore, a scheme of hybrid DC-breakers with fault current limiting is proposed, its feasibility verified through simulation. In this scheme the DC-breaker adopts the hybrid solid-state switch (composed of half and full gate-controlled devices in series connection) which is paralleled with a mechanical breaker involving the fault-current-limiting technology. Therefore the rising rate of short-circuit current can be effectively restrained, relieving the requirement on fault diagnosis sensitivity and mechanical breaker speed. Moreover, the series quantities of solid-state switching devices (especially the expensive full gate-controlled devices such as the insulated gate bipolar transistor) in high voltage application, and the technical difficulty and production costs etc will be reduced.