引入自抗扰控制的MMC均压环流简化控制策略

Simplified control strategy for MMC voltage balancing circulation base on active disturbance rejection control

针对模块化多电平换流器(MMC)正常工作时,子模块电容电压不平衡和三相桥臂间存在环流分量的问题,通过引入自抗扰控制,提出一种新的均压环流控制策略。分析子模块电容电压波动以及环流机理,提出基于自抗扰控制的单环子模块均压控制;结合二阶广义积分器滤波环节提取交流分量,使用准PR控制对环流二倍频分量进行抑制。在稳态、动态条件下进行实验,结果表明:在稳态条件下,基于ADRC的单环控制波动系数降低0.5%,环流抑制降低19%,输出电流畸变率降低0.46%;在动态条件下,可以快速达到新的稳定状态,对电容电压脉动有良好的抑制作用。

To address the problem of unbalanced capacitor voltage of sub-module and circulating current component between three-phase bridge arms during the operation of MMC,this paper proposes a new equalizing circulating current control strategy by introducing active disturbance rejection control.First,the sub-module capacitor voltage fluctuation and the circulating current mechanism are analyzed.Then,the single-loop sub-module voltage equalization control based on active disturbance rejection control is proposed.Second,the AC component is extracted by combining the second-order generalized integrator filtering link,and the circulating current doubling component is suppressed by quasi-PR control.Finally,experimental verification is conducted under steady state and dynamic conditions.Our results show under steady state conditions,the ADRC-based single-loop control reduces the fluctuation coefficient by 0.5%,the circulating current suppression by 19%,and the output current distortion rate by 0.46%;and under dynamic conditions,it reaches the new stabilization faster and effectively suppresses capacitor voltage pulsation.