摘要
普通晶闸管换流阀无关断电流的能力,需要借助电网电压完成换相,不适用于没有交流电网的无源逆变电路。为了将晶闸管换流阀应用于柔性交直流电网,以并联十二脉动晶闸管换流器为前级,以七电平直流电流分配单元为后级构成级联型电流源逆变器。七电平直流电流分配单元不仅实现了对直流母线电流的动态平均分配,而且形成了周期性的直流电流过零点,为十二脉动晶闸管换流器提供零电流换相条件,从而实现晶闸管换流阀的强迫换相。实现强迫换相的晶闸管换流阀外特性相当于全控型逆阻器件,因此换流器可实现无源逆变。在对电路拓扑、调制方法进行详细分析的基础上,设计了额定功率为0.5 MW的七电平柔性直流换流器试验装置,以三相电阻为负载,进行了无源逆变试验。试验结果验证了大电流工况下,晶闸管换流阀与多电平直流电流分配单元协同作用实现晶闸管换流阀受控关断的可行性和可靠性。
Common thyristor converter valve is unable to turn off currents by itself and commutates with the help of the grid voltage,so it is not suitable for the passive inverter circuit without AC grid.In order to apply the thyristor valve in flexible AC/DC grid,the cascaded current source inverter is constituted by using the parallel twelve-pulse thyristor converter as the front stage and the seven-level DC current distribution unit as the back stage.The seven-level DC current distribution unit not only realizes the dynamic average distribution of the DC bus current,but also forms the periodic DC current zero crossing section,which provides the zero current switching condition for the twelve-pulse thyristor converter,so as to realize the forced commutation of thyristor converter valve.The external characteristics of the thyristor converter valve which realizes forced commutation are equivalent to the fully controlled reverse voltage-blocking device,so the converter can realize passive inversion.Based on the detailed analysis of the circuit topology and modulation method,an experimental device of seven-level flexible DC converter with rated power of 0.5 MW is designed,which employs the three-phase resistance as the load to carry out the passive inversion experiment.The test results verify that,under the high current condition,the controlled shutoff of thyristor converter valve under the cooperation of multi-level DC current distribution unit is feasible and reliable.
作者
杨宝峰
王志文
罗振鹏
王志和
韩俊飞
YANG Baofeng;WANG Zhiwen;LUO Zhenpeng;WANG Zhihe;HAN Junfei(Electric Power Institute,Inner Mongolia University of Technology,Hohhot 010080,China;Inner Mongolia Power Research Institute,Hohhot 010020,China)
出处
《电力自动化设备》
EI
CSCD
北大核心
2021年第7期130-134,共5页
Electric Power Automation Equipment
基金
内蒙古自治区科技重大专项(2019ZD027)
内蒙古自治区高等学校技术研究项目(NYZY19077)。
关键词
晶闸管换流阀
七电平
强迫换流
电流源换流器
无源逆变
级联
thyristor converter valve
seven-level
forced commutated
current source converter
passive inversion
cascade
