换相失败引发送端混合级联直流系统换流母线暂态电压波动机理及抑制策略  

Mechanism of and suppression strategy for transient voltage fluctuation in the commutator bus of a hybrid cascaded DC system caused by commutation failure

作　　者：刘江山 李凤婷[1] 尹纯亚 苏常胜[1,2] 韩璐 宋伟[3] LIU Jiangshan;LI Fengting;YIN Chunya;SU Changsheng;HAN Lu;SONG Wei(College of Electrical Engineering,Xinjiang University,Urumqi 830047,China;State Grid Xinjiang Electric Power Co.,Ltd.,Urumqi 830036,China;Xinjiang Special Equipment Inspection and Research Institute,Urumqi 830000,China)

机构地区：[1]新疆大学电气工程学院,新疆乌鲁木齐830047 [2]国网新疆电力有限公司,新疆乌鲁木齐830036 [3]新疆维吾尔自治区特种设备检验研究院,新疆乌鲁木齐830000

出　　处：《电力系统保护与控制》2023年第20期36-46,共11页Power System Protection and Control

基　　金：国家重点研发计划项目资助(2021YFB1507001)。

摘　　要：与电网换相高压直流输电(line commutated converter HVDC,LCC-HVDC)相比,送端混合级联直流系统具有灵活性高、弱网适应性强等优势,但其换相失败后交流系统暂态电压波动机理尚不明晰。为此,首先建立了暂态电压与系统强度、功率不平衡量之间的定量关系。考虑有功、无功不平衡量对暂态电压的影响,推导了暂态电压变化率表达式。明确了换相失败及其恢复期间换流母线暂态电压特性。其次,为抑制换流母线暂态过电压,推导了LCC直流电流指令值与模块化多电平换流器(modular multilevel converter,MMC)无功指令值表达式,提出了基于多换流器的协同抑制策略。最后,基于PSCAD/EMTDC仿真平台搭建仿真模型,验证了机理分析的正确性及抑制策略的有效性。Compared with a line commuted converter HVDC(LCC-HVDC),a hybrid cascade DC system at the sending end has advantages such as high flexibility and strong adaptability to weak networks.However,the mechanism of transient voltage fluctuations in the AC system after commutation failure is still unclear.To this end,a quantitative relationship between transient voltage and system strength,as well as power imbalance,is established.The influence of active and reactive power imbalance on transient voltage is considered,and the expression for transient voltage change rate is derived.The transient voltage characteristics of the commutation bus during commutation failure and recovery are clarified.Secondly,in order to suppress transient overvoltage of the converter bus,the expressions of LCC DC current command value and modular multilevel converter(MMC)reactive power command value are derived,and a collaborative suppression strategy based on multiple inverters is proposed.Finally,a simulation model is built based on the PSCAD/EMTDC simulation platform to verify the correctness of the mechanism analysis and the effectiveness of the suppression strategy.

关 键 词：混合级联型直流系统 换相失败 暂态电压 无功功率 有功功率 

分 类 号：TM721.1[电气工程—电力系统及自动化]