基于微分平滑理论的MMC电容电压波动无源一致性控制方法

Passivity-Consensus Based Control Method for Capacitor Voltage Fluctuation Suppression of Modular Multilevel Converter Based on Differential Flatness Theory

以模块化多电平换流器(MMC)电容电压波动抑制为目标,设计了微分平滑控制律,通过构建电容电压波动与注入环流间的非线性平滑映射关系,实现存在不确定性输入干扰或未建模误差情况下注入环流期望轨迹的快速准确求取,解决了数值解析法计算复杂的问题。为实现注入环流期望轨迹快速跟踪,设计了形式简单的无源性控制律,以最小内部能耗满足子模块电容电压波动抑制需求;为提升三相电容电压跟踪同步性,将相邻相的注入环流期望轨迹跟踪误差作为状态误差引入无源性控制律,提出了无源一致性控制方法,实现MMC电容电压波动抑制和三相电容电压均衡双目标,同时确保闭环控制系统全局渐近稳定。基于MATLAB/Simulink仿真结果和基于dSPACE的实验结果验证了所提方法具有计算量小、稳定域宽、鲁棒性强、同步性好的特点。

In order to suppress the capacitor voltage fluctuation of the modular multilevel converter(MMC),the differential flatness based control law is designed.The nonlinear flatness mapping relationship between the capacitor voltage fluctuation and the injected circulating current is constructed to achieve the fast and accurate desired trajectories of the injected circulating currents with the uncertain input interference and unmodeled errors,which solves the complicated calculation problem of the numerical analysis method.The simple passivity-based control law is adopted to realize the fast tracking of the desired trajectories of the injected circulating current.The requirement of submodule capacitor voltage fluctuation suppression can be met with the minimum internal energy consumption.To improve the synchronization of three-phase capacitor voltages,the desired trajectory tracking error of the injected circulating current of adjacent phase is introduced in the passivity-based control law as a state error.The passivity-consensus based control method is proposed to simultaneously achieve two goals of capacitor voltage fluctuation suppression and the balance of three-phase capacitor voltages of the MMC,while the global gradual stability of the closed-loop control system is guaranteed.The simulation results based on MATLAB/Simulink and the experimental results based on d SPACE verify that the proposed method has the characteristics of small calculation amount,wide stability domain,strong robustness and good synchronization.