基于三次谐波注入的桥臂交替换流器子模块电容优化方法  

Submodule Capacitance Optimization Method for Alternate Arm Converter Based on Third Harmonic Injection

作　　者：王顺亮 廖鑫 张芮[1] 马俊鹏 李金铭 刘天琪[1] WANG Shunliang;LIAO Xin;ZHANG Rui;MA Junpeng;LI Jinming;LIU Tianqi(College of Electrical Engineering,Sichuan University,Chengdu 610065,China)

机构地区：[1]四川大学电气工程学院,四川省成都市610065

出　　处：《电力系统自动化》2024年第12期165-176,共12页Automation of Electric Power Systems

基　　金：四川省自然科学基金资助项目(2023NSFSC0301)。

摘　　要：桥臂交替换流器(AAC)具有子模块数目少和电容小等优点,在交直流系统功率互联和柔性直流输电中具备广阔应用前景。针对AAC存在的固定调制度运行缺陷和工程应用子模块电容经济性问题,提出了一种基于三次谐波注入的AAC子模块电容优化方法和闭环控制策略。文中首先介绍了AAC的拓扑结构和运行原理,根据换流器能量平衡方程给出注入三次谐波后AAC的宽调制度运行条件,并设计了AAC的闭环控制策略;然后,基于子模块电压波动数学模型,建立了AAC的能量波动方程,能够精确生成不同调制度和功率因数角下的能量波动模型,定量分析了注入三次谐波后能够降低的能量波动峰值和子模块电容优化率,所提出的子模块电容优化方法和闭环控制策略在实现AAC宽调制度稳定运行的同时,注入的三次谐波不改变AAC能量平衡条件,最高能够降低AAC子模块电容大小为传统控制方式下的12.1%;最后,在电磁暂态仿真软件和StarSim半实物平台中搭建模型,验证了所提分析方法和控制策略的有效性。The alternate arm converter(AAC)has the advantages of a small number of submodules and low capacitance,which shows great potential for applications in AC/DC system power-interconnection and flexible DC transmission.Aiming at the operation defects of the AAC with fixed modulation degree and the economics of the submodule capacitance of AAC in engineering,this paper proposes a submodule capacitance optimization method and a closed-loop control strategy for AAC based on the third harmonic injection.The topology and operation principle of AAC are introduced in this paper.According to the energy balance equation of the converter,the extended modulation degree operation condition of AAC after the third harmonic injection is given,and a closed-loop control strategy for AAC is designed.Then,the energy fluctuation equation of AAC is established based on the mathematical model of submodule voltage fluctuation,which can obtain energy fluctuation models with different modulation degrees and power factor angles.The reduced energy fluctuation peak value and the submodule capacitance optimization rate after the third harmonic injection are quantitatively analyzed.The proposed submodule capacitance optimization method and closed-loop control strategy achieve stable operation of AAC in a wide modulation degree range,while the injected third harmonic does not change the AAC energy balance condition.The proposed method could reduce the capacitance of AAC submodule to 12.1%of the conventional method.Finally,the model is built in the electromagnetic transient simulation software and the StarSim semi-physical platform to verify the effectiveness of the proposed analysis method and the control strategy.

关 键 词：高压直流输电 桥臂交替换流器 电容优化 能量波动方程 能量平衡 移相导通 

分 类 号：TM721.1[电气工程—电力系统及自动化] TM46