混合式直流断路器IGBT关断能力提升技术研究

混合式高压直流断路器主要由快速机械开关和电力电子器件构成,主要依靠快速机械开关承载电流,通过电力电子器件开断和关合电流,为基于MMC柔性直流输电提供直流侧短路保护。但是直流断路器分断电流大,远远高于IGBT常规分断能力。文中根据直流断路器IGBT的特殊工作条件和电气应力,分析影响IGBT关断能力提升的影响因素,分别从降低IGBT导通损耗、关断损耗和抑制IGBT关断过电压等3个方面提升IGBT的可关断电流能力。文中首先仿真不同回路参数对IGBT损耗的影响,通过优化IGBT退饱和能力和关断过程暂态特性,降低关断损耗,最终完成IGBT结温仿真校核。同时通过研究IGBT关断过电压的影响因素,仿真不同回路参数对IGBT过电压的影响,提出抑制IGBT的关断暂态过电压的具体方法。研制50 kV转移支路阀组,搭建试验平台,完成26 kA的大电流开断,IGBT稳态损耗和暂态损耗都得到有效控制,相关技术和研制设备已经应用张北工程±535 kV混合式高压直流断路器项目,具有十分重要的工程意义。

Research on IGBT Turning off Capacity Enhancement Technology of Hybrid DC Circuit Breaker

HHybrid HVDC circuit breaker is mainly composed of fast mechanical switch and power electronic de?vice,which mainly relies on fast mechanical switch to carry current and break and close current through power elec?tronic device.It provides DC side short circuit protection for flexible HVDC transmission.However,the breaking cur?rent of DC circuit breaker is larger than that of IGBT’s normal capacity.According to the special working conditions and electrical stress of the IGBT of the DC circuit breaker,this paper analyzes the factors that affect the improve?ment of the IGBT’s turning off capacity and improves the turning off current capacity of the IGBT from three aspects:reducing the turning on loss,turning off loss and restraining the IGBT turning off overvoltage.In this paper,the influ?ence of different circuit parameters on IGBT loss is firstly simulated.The IGBT’s turning off loss is reduced by opti?mizing the desaturation ability and the turning off transient characteristics of IGBT,and finally the junction tempera?ture simulation check of IGBT is completed.Meanwhile,by studying the influence factors of IGBT turning off over?voltage and simulating the influence of different circuit parameters on IGBT turning off overvoltage,the specific method of suppressing the turning off transient overvoltage of IGBT is proposed.Through the development of 50 kV transfer branch valve group and the establishment of test platform,this paper completes the large current breaking of 26 kA and the IGBT steady?state loss and transient loss are effectively controlled.The research results have been suc?cessfully applied to the±535 kV hybrid high?voltage DC circuit breaker project of Zhangbei project,which is of great engineering significance.