基于级联变压器的二极管桥式固态故障电流限制器（英文）

目的:为控制故障电流,提出一种新型基于级联变压器的二极管桥式固态故障电流限制器(SSFCL)。创新点:所描述的SSFCL具有简单且易用的结构,能够将故障电流幅度限制于安全范围内。并能减少谐波畸变与开关电压过冲,调控公共耦合点电压。方法:将一串联RLC支路连接于隔离串联变压器的次级端,针对此RLC支路,提出两种限流模式。(1)放电模式:电阻R与电容C被并联的功率电子开关(IGBT)旁路,而电感L仍与变压器次级端相联,从而构成直流电抗器。(2)充电模式:若串联电抗器阻抗不足以限制故障电流,可以通过选择恰当的并联IGBT开关持续时间(on-off duration),将高阻抗的串联电阻R和电容C插入电路,从而限制故障电流。结论:通过控制直流电抗器电流幅度,可以降低故障电流并将公共耦合点(PCC)的电位限制于合理水平。此外,在本文所述的新型SSFCL中,与IGBT并联的RC支路可作为缓冲电路用于降低开关状态下IGBT的瞬态恢复电压(TRV)。因此,SSFCL可以提升电能质量。本文还给出了在已有的原型系统上的实验测量结果以支持理论和仿真研究。所述的SSFCL可以无延迟地限制故障电流并有效平滑故障电流波形。

Controllable reactor based hybrid HVDC breaker

Short circuit fault occurrence in high-voltage DC (HVDC) systems causes extremely high currents in a fast raising time that does not experience current zero-crossing. To protect HVDC systems/grids against fault current, fast HVDC breaker is an essential equipment. This study presents the design procedure of a novel HVDC breaker based on solid-state controllable reactor which is able to reduce the fault current's rate of rise and fault current amplitude to less than grid nominal current in the breaking process. The main achievement of the proposed HVDC breaker is that not only breaker does not encounter fault current, but also none of the series HVDC equipment is influenced by the fault. The designed breaker performance is studied by PSCAD/EMTPS, and then the simulation results are validated by the developed laboratory experimental setup.