柔性直流输电系统三维度控制  

Three-degree Control of MMC Based High Voltage Direct Current Transmission System

作　　者：向往[1] 文劲宇[1] 张浩博 贺永杰 XIANG Wang;WEN Jinyu;ZHANG Haobo;HE Yongjie(State Key Laboratory of Advanced Electromagnetic Engineering and Technology(Huazhong University of Science and Technology),Wuhan 430074,Hubei Province,China)

机构地区：[1]强电磁工程与新技术国家重点实验室(华中科技大学),湖北省武汉市430074

出　　处：《电网技术》2023年第8期3385-3395,共11页Power System Technology

基　　金：国家自然科学基金项目(52237004)。

摘　　要：现有柔性直流输电工程均采用双闭环矢量控制,通过交流调制比生成桥臂电压调制信号。此种方式下,子模块电容电压与直流输出电压耦合,控制灵活性差。该文基于混合型模块化多电平换流器(modular multilevel converter,MMC)交直流对偶控制框架,提出了一种适用于半桥型MMC-HVDC系统的三维度控制架构,包含交直流对偶控制、子模块电容能量控制与可变最近电平调制,使得MMC子模块电容电压与直流输出电压解耦,极大提高了控制灵活性。文章首先分析了柔直常规控制的设计特点,给出了三维度控制的设计思路;然后基于三维度控制,分析了MMC的直流电压运行域、主动能量利用与直流故障限流等能力,建立了包含三维度控制的MMC小信号模型分析了其稳定性。最后,通过PSCAD/EMTDC仿真验证了所提控制方法的有效性。The existing modular multilevel converter-based high voltage direct current(MMC-HVDC)transmission projects adopt the double closed-loop vector control,which generates the AC modulation index to regulate the arm voltage.However,under this control scheme,the sub-module capacitor voltage and the DC output voltage are coupled,resulting in poor control flexibility.Based on the AC-DC dual control framework in the hybrid modular multilevel converter,a three-degree control architecture consisting of the AC-DC dual control,the sub-module energy control and the variable nearest level modulation is proposed for a half-bridge MMC-HVDC system in this paper.This control architecture decouples the sub-module capacitor voltage from the DC output voltage,greatly improving the control flexibility.Firstly,this paper analyzes the design characteristics of the conventional MMC-HVDC control schemes,putting forward the design idea of the three-degree control.Based on the three-degree control,then the DC voltage operating region,the capabilities of active energy control and the DC fault current limiting of the MMC are analyzed.In addition,the small-signal model adopting the three-degree control is built and its stability is discussed.Finally,the effectiveness of the proposed control is verified by the PSCAD/EMTDC simulations.

关 键 词：柔性直流输电 模块化多电平换流器 三维度控制 主动能量利用 故障限流 小信号模型 

分 类 号：TM721[电气工程—电力系统及自动化]