基于六阶动态模型的MMC多回路控制策略

MMC Multi-loop Control Strategy Based on Six-order Dynamic Model

针对负载和模块化多电平换流器(MMC)参数变化引起MMC输出电压不稳定问题,提出一种基于六阶动态模型的MMC多回路控制技术。首先建立了 MMC六阶动力学模型,基于此给出MMC有功功率和无功功率能力曲线;在此基础上,提出MMC三回路控制技术,即外部回路控制(OLC)、中央回路控制(CLC)和内部回路控制(ILC)。其中,OLC基于无源控制理论设计,保证负载变化下的运行稳定性,CLC基于滑模控制理论设计,保证MMC参数变化情况下的动态稳定性;ILC根据实际运行状态实时提供OLC和CLC的电流参考值;理论证明3个控制环均具备Lyapunov稳定性。最后进行实验验证,结果表明所提MMC控制技术具有较强电压稳定能力。

In order to solve the problem of voltage instability of modular multilevel converter(MMC)caused by load and MMC parameter changes,a multi-loop control strategy of MMC based on six-order dynamic model is proposed.First of all,the six-order dynamic model of MMC is established,based on which the active power and reactive power capability curves of MMC are given.On this basis,the three loop control strategy of MMC,external loop control(OLC),central loop control(CLC)and internal loop control(ILC),is proposed.Among them,OLC is designed based on passive control theory to ensure the operation stability under load changes,CLC is designed based on sliding mode control theory to ensure the dynamic stability of MMC when the parameters change,and ILC provides the current reference value of OLC and CLC in real time according to the actual operation state.And the Lyapunov stability of the three control loops is proved.Finally,the experimental results show that the proposed MMC control technology has strong voltage stability.