基于桥臂调制波调整的多端柔直系统直流过电压抑制策略  

DC Overvoltage Suppression Strategy for MMC-MTDC Based on Bridge Arm Modulated Wave Adjustment

作　　者：彭茂兰 冯雷 王宇 徐李清 赵薇 郭春义 PENG Maolan;FENG Lei;WANG Yu;XU Liqing;ZHAO Wei;GUO Chunyi(China Southern Power Grid Joint Laboratory of DC Transmission Equipment and Submarine Cable Safety Operation(CSG EHV Electric Power Research Institute),Guangzhou 510663,China;State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University),Beijing 102206,China)

机构地区：[1]南方电网公司直流输电装备与海底电缆安全运行联合实验室(超高压输电公司电力科研院),广东广州510663 [2]新能源电力系统全国重点实验室(华北电力大学),北京102206

出　　处：《中国电力》2024年第4期171-181,共11页Electric Power

基　　金：南方电网公司直流输电装备与海底电缆安全运行联合实验室科技项目(提升柔性直流输电系统消纳新能源能力的关键技术研究,0120002022030301SJ00046)。

摘　　要：基于模块化多电平换流器(modular multilevel converter,MMC)的多端柔性直流输电系统能够实现多电源供电和多落点受电,运行方式灵活,是解决清洁能源并网和消纳问题的有效技术手段。然而当系统受端交流侧发生故障时将出现盈余功率,导致直流过电压问题。对此,提出一种基于桥臂调制波动态调整的多端柔直系统直流过电压抑制策略。所提策略通过在换流阀桥臂调制波中引入直流电压偏差控制,动态调整暂态期间桥臂调制波的直流电压参考值,从而减少桥臂投入的子模块数量,最终达到抑制直流过电压的目的。为验证所提控制策略的有效性,在PSCAD/EMTDC中搭建了送端光水打捆经四端柔性直流输电的外送系统,给出了所提控制策略的参数设计方法。通过设置受端交流系统不同工况,对比研究了所提控制策略投入后的系统直流过电压特性,结果表明所提控制策略可以有效抑制因受端交流侧故障引起的多端柔性直流输电系统的直流过电压。Modular multilevel converter based multi-terminal DC transmission(MMC-MTDC)system can realize multi-source power supplies and multi-terminal power-receiving.Flexible in operation modes,it is thus an effective technical means to solve the problem of grid-access and accommodation of clean energy.However,when AC fault occurs at the AC side of the receiving-end system,the created surplus power of the system will lead to serious DC overvoltage.In view of this,this paper proposes a DC overvoltage suppression strategy for multi-terminal flexible HVDC system based on bridge arm modulated wave dynamic adjustment.The proposed strategy introduces DC voltage deviation control into the modulation wave of the converter valve bridge arm,dynamically adjusting the DC voltage reference value of the bridge arm modulation wave during transient periods,thereby reducing the number of sub modules invested in the bridge arm,and ultimately achieving the goal of suppressing DC overvoltage.In order to verify the effectiveness of the proposed control strategy,a four-terminal flexible HVDC transmission system for photovoltaic and hydropower transmission is built in PSCAD/EMTDC,and the parameter design method of the proposed control strategy is given.Finally,by setting different operating conditions for the receiving-end AC system,a comparative study is made on the DC overvoltage characteristics of the system after implementation of the proposed control strategy.The results show that the proposed control strategy can effectively suppress the DC overvoltage of the MMC-HVDC transmission system caused by the receiving-end AC-side fault.

关 键 词：多端柔性直流输电系统 盈余功率 直流过电压 桥臂调制波动态调整 直流电压偏差控制 

分 类 号：TM721.1[电气工程—电力系统及自动化]