A sequential design and global optimization method is proposed to coordinately design local and widearea controllers to enhance the overall stability of largescale power system.The sequential design is used to assign the distributed local power system stabilizer (LPSS) and high-voltage direct current (HVDC) wide-area stabilizing controller (HVDC-WASC) to the concerned damping modes.The global optimization is used to simultaneously optimize all the overall control gains of LPSSs and HVDCWASC.Moreover,the optimization model,which has an adaptive ability of searching and updating dominant oscillation modes,is established.Both the linear analysis and nonlinear simulation results verify the effectiveness of the proposed design method in enhancing the stability of large-scale power systems.
针对现有固态变压器拓扑结构存在的局限性及控制方法的不足,本文提出了一种模块化多电平型固态变压器(MMC solid state transformer,MMC-SST),并相应介绍了一种内模控制(internal model control,IMC)实现方法.首先分析了MMC-SST系统拓扑与运行特性,建立了同步旋转坐标系下MMC-SST输入级和输出级的数学模型;然后根据内模控制的特性,将内模电流内环与PI电压外环相结合,构造出新的双闭环控制结构,实现对MMC-SST输入级和输出级的控制;最后,基于Matlab/Simulink建立了MMC-SST系统仿真模型,在网侧电压波动、负荷突变和网侧功率因数变化多种工况进行了性能测试,结果表明,本文提出的基于内模控制的MMC-SST能够按照给定的功率因数运行,并且具有电压、电流动态响应快、抗负载扰动能力强等特点.
