基于可控电压源的高压直流输电换相失败抑制技术  

Commutation Failure Suppression Technology for HVDC Transmission Based on Controlled Voltage Source

作　　者：高凯 屈海涛 任茂鑫 刘寅迪 曾翔君[3] 曹均正 崔春艳 骆一萍[3] GAO Kai;QU Haitao;REN Maoxin;LIU Yindi;ZENG Xiangjun;CAO Junzheng;CUI Chunyan;LUO Yiping(Equipment Technology Center of Electric Power Research Institute,State Grid Shanghai Electric Power Company,Shanghai 200122,China;C-EPRI Electrical Power Engineering Co.,Ltd.,Beijing 102200,China;School of Electrical Engineering,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]国网上海市电力公司电力科学研究院设备技术中心,上海200122 [2]中电普瑞电力工程有限公司,北京102200 [3]西安交通大学电气工程学院,西安710049

出　　处：《高压电器》2023年第1期49-57,共9页High Voltage Apparatus

基　　金：国家电网公司总部科技项目(5500⁃201940124A⁃0⁃0⁃00)。

摘　　要：为解决传统高压直流输电系统换相失败的问题,文中提出一种在电网换相换流器(LCC)与换流变压器之间串联级联H桥构成柔性化LCC系统的方案。级联H桥作为可控电压源产生容性交流电压,可以实现对换流阀实际换相电压的调节,从而有利于降低换相失败发生的概率。文中根据换流变压器二次侧相位关系建立起柔性化LCC的准稳态模型,进而研究了系统直流母线电压和实际熄弧角的控制关系并证明了柔性化LCC具备可以实现电网功率因数调节的特性。之后,文中提出了针对不同电网状况的可控电压源和LCC协调控制策略,使得系统在故障条件下能够同时满足保障直流功率传输和抗逆变颠覆的要求。最后,利用PSCAD/EMTDC仿真证明了所提出的方案在交流电压跌落时相比传统LCC方案能够更有效的维持系统稳定、抑制换相失败发生。For solving the problem of commutation failure of the traditional HVDC transmission system,a kind of flexible LCC scheme with cascaded H⁃bridge connected in series between the line commutation converter(LCC)and the converter transformer is proposed.The cascaded H⁃bridge as a controllable voltage source generates capacitive al⁃ternating current voltage,can achieve adjustment of actual commutation voltage of converter valve,thus the probabili⁃ty of commutation failure is reduced.In this paper,the quasi steady⁃state model of the flexible LCC system is set up in accordance with the phase relationship of the secondary side of the converter transformer.The control relationship of DC busbar voltage of the system and the actual extinction angle is studied further,proving that the flexible LCC has characteristic which can achieve power factor adjustment of power grid.After that,a controllable voltage source and LCC coordinated control strategy under different power grid conditions angle is proposed so that the system can,in case of fault condition,meet simultaneously the requirements of DC power transmission and anti⁃commutation⁃fail⁃ure.Finally,it is proved by PSCAD/EMTDC simulation that the proposed scheme can,in case of AC voltage sag,ef⁃fectively maintain system stability and suppress the commutation failure more effectively over the traditional LCC scheme.

关 键 词：电网换相换流高压直流 换相失败 级联H桥 功率因数 电网电压跌落 

分 类 号：TM721.1[电气工程—电力系统及自动化]