海上风电低频输电系统低频侧不对称故障控制策略  

Control strategies of offshore wind power low frequency transmission system under asymmetric fault of low-frequency side

作　　者：高校平 张晨浩 宋国兵[1,2] 蒋嘉桁 吕艺超 GAO Xiaoping;ZHANG Chenhao;SONG Guobing;JIANG Jiaheng;LÜYichao(Shaanxi Key Laboratory of Smart Grid,Xi’an Jiaotong University,Xi’an 710049,China;School of Electrical Engineering,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学陕西省智能电网重点实验室,陕西西安710049 [2]西安交通大学电气工程学院,陕西西安710049

出　　处：《电力自动化设备》2023年第10期160-166,共7页Electric Power Automation Equipment

基　　金：国家重点研发计划项目(2021YFB2401100)。

摘　　要：低频海底电缆发生不对称故障时存在模块化多电平矩阵换流器(M3C)功率器件电流越限、非故障相过电压风险,严重影响海上风电低频输电系统(LFTS)的安全运行。针对上述问题,在充分发挥M3C高可控性的基础上,提出了一种适用于海底电缆不对称故障的控制策略:根据故障严重程度动态调整M3C低频侧电压,防止非故障相过电压;各子换流器通过抑制负序电流限制短路电流上升,保护功率器件免受过电流危害;计及控制策略的影响,通过建立系统故障等值模型进行故障分析。在PSCAD/EMTDC中搭建了海上风电LFTS模型,仿真结果验证了所提控制策略和故障分析方法的有效性,其能够实现低频侧不对称故障下系统的稳定运行。Asymmetric faults of low-frequency submarine cable will lead to risks of overcurrent of power electronic devices in modular multilevel matrix converter(M3C)and overvoltage in the non-fault phase,which brings great challenges to offshore wind power low frequency transmission system(LFTS).To solve the above problems,a control strategy for asymmetric fault of submarine cable is proposed based on excel⁃lent controllability of power electronic equipment in M3C.The low-frequency side voltage of M3C is adjusted dynamically according to the fault severity to avoid overvoltage in the healthy phase.Meanwhile,to limit the amplitude of short circuit current and protect power devices from overcurrent,the negative-sequence current is suppressed by sub-converters.Then the fault equivalent model is derived for fault analysis with taking the influence of control strategy into account.The model of offshore wind power LFTS is built in PSCAD/EMTDC.The simulative results validate the effectiveness of the proposed control strategy and fault analysis method.The strategy can realize stable operation of the system under asymmetric fault of low-frequency side.

关 键 词：模块化多电平矩阵换流器 海上风电低频输电系统 不对称故障 V/f降压控制 负序电流控制 故障分析 

分 类 号：TM713[电气工程—电力系统及自动化] TM46TM614