基于逆阻IGCT的可控关断电流源型高压直流换流器电气应力和损耗特性分析

Analysis of Electrical Stress and Loss Characteristics of Turning-off Current Source HVDC Converter Based on Reverse Blocking IGCT

逆阻型集成门极换流晶闸管(reverse blocking integrated gate-commutated thyristor,RB-IGCT)的出现,为可控关断的电流源型换流器(current source converter,CSC)的研究奠定了基础。为了推动器件在高压直流输电领域的应用,文中首先介绍最新研制的4500V/3000A逆阻IGCT的技术参数;其次,介绍CSC拓扑方案,提出子模块缓冲电路,能够实现器件的动态均压和IGCT取能的要求;接着,以换流阀电压和电阻损耗最低为约束条件,给出子模块串联数、缓冲电路参数设计和损耗分析等综合优化方法;然后,搭建250kV/750MW的LCC-CSC混合输电系统模型,给出缓冲电路和主要杂散参数的范围;最后,基于研制的4500V/3000A的逆阻IGCT子模块,验证所提缓冲电路的有效性,并对比分析在该参数下CSC、传统直流和柔性直流的损耗情况。结果表明,由逆阻IGCT串联构成的CSC,相对于传统直流换流阀具有可控关断的技术优势,相对于柔直换流阀,具有器件少、损耗低等优势。

The appearance of reverse blocking IGCT(RB-IGCT)sets the foundation for the research of current source converter(CSC).In order to enhance the application of RB-IGBT in HVDC,the recently developed 4500V/3000A IGCT and its parameters are introduced,then a CSC topology is introduced and its damping circuit is proposed,and they are capable of balancing the dynamic voltage and obtain energy.Secondly,the minimum converter voltage and loss are taken as the constraint condition to optimize the number of submodules,the parameters of damping circuit and the loss analysis.Then,a 250k V/750MW LCC-CSC hybrid HVDC model is established to study the buffer and stray circuit parameters.Finally,a 4500V/3000A module based on RB-IGCT is developed and tested to verify damping effects for IGCT during breaking current.Based on this,the overall losses of CSC,LCC and VSC are compared and analyzed.It demonstrates that CSC based on RB-IGCT is feasible.CSC has the controllable turning-off advantages compared with LCC,and less devices and series structure compared with the VSC.