海上风电柔直系统送端电网故障过电压机理分析及抑制策略  

Mechanism and Restraining Strategy of the Sending-end Grid Overvoltage in Offshore Wind Farm-flexible HVDC Transmission System Under Grid Faults

作　　者：王霄鹤 杨林刚 林斌 宋伟宏 林磊[3] WANG Xiaohe;YANG Lingang;LIN Bin;SONG Weihong;LIN Lei(Key Laboratory of Far-shore Wind Power Technology of Zhejiang Province,Hangzhou 311122,China;Power China Huadong Engineering Corporation Limited,Hangzhou 311122,China;State Key Laboratory of Advanced Electromagnetic Engineering and Technology,School of Electrical and Electronic Engineering,Huazhong University of Science and Technology,Wuhan 430074,China)

机构地区：[1]浙江省深远海风电技术研究重点实验室,杭州311122 [2]中国电建集团华东勘测设计研究院有限公司,杭州311122 [3]华中科技大学电气与电子工程学院强电磁与新技术国家重点实验室,武汉430074

出　　处：《高电压技术》2021年第8期2688-2697,共10页High Voltage Engineering

基　　金：中国博士后科学基金(2020M681800)。

摘　　要：为应对送端交流电网故障时的过电压问题,分析了风场-柔性直流输电系统送端交流电网故障过电压产生机理,并提出了过电压抑制策略。首先,建立了不同电网故障下换流变压器网侧及阀侧电压的数学模型,研究了模块化多电平换流器(modular multilevel converter,MMC)控制策略对于电网电压的影响机理,及电网过电压导致MMC出现的过调制问题对于系统控制性能的影响;在此基础上,提出了一种过电压抑制策略,能够在不引入负序电流的条件下有效抑制系统的过电压水平,且能够在故障线路切除后加快电网电压的恢复速度;最后,基于PSCAD/EMTDC仿真平台构建了风场-柔性直流输电系统模型并进行了仿真研究。研究结果表明:所提出的送端交流电网电压数学模型能够准确反映系统的故障特性,所提出的过电压抑制策略能够实现预期控制效果,有利于系统在故障发生及恢复过程中的稳定运行。To deal with the overvoltage,the mechanism and restraining strategy of the sending-end overvoltage in offshore wind farm-flexible HVDC transmission system under grid fault are studied.Firstly,the mathematical model of the grid-side and valve-side voltage under grid faults is established.The influence mechanism of MMC control strategy to the grid voltage is analyzed,and the influence of the over-modulation problem caused by the overvoltage on the control performance is studied.On this basis,an overvoltage restraining strategy is proposed,which can restrain the overvoltage without introducing negative sequence currents,and can accelerate the voltage recovery speed after the faulty line is cut off.Finally,the offshore wind farm-HVDC transmission system is established in the PSCAD/EMTDC environment,and simulation studies are conducted.The research results show that the mathematical model proposed in this paper can reflect the fault characteristics accurately.In addition,the proposed overvoltage restraining strategy can achieve the desired performance,which can benefit the system stable operation during the grid fault and recovery periods.

关 键 词：海上风电 柔性直流输电 电网故障 过电压 模块化多电平换流器 送端电网 

分 类 号：TM721.1[电气工程—电力系统及自动化] TM614