基于直流侧电容电压弱控制策略的UPFC二阶段控制器设计

在分析常用直流侧电容电压控制方法的基础上，确定了直流侧电容电压强控制的概念，并相应地提出了直流侧电容电压弱控制策略。该策略能够利用UPFC直流侧电容吸收部分暂态能量，从而加速故障后线路上潮流稳定过程。基于直流侧电容电压弱控制的概念，结合线性最优控制方法，给出了相应的弱-强二阶段控制器设计实例及仿真结果。仿真实验表明，在系统发生三相对称短路故障时，该控制策略能够迅速地稳定被控线路的潮流和UPFC接入点的母线电压。该文提出的直流侧电容电压弱控制方式可与任一成熟的UPFC控制策略共同工作，以达到进一步改善控制效果的目的。

DESIGN OF UPFC TWO-PHASE CONTROLLER BASED ON DC LINK CAPACITOR VOLTAGE SOFT CONTROL STRATEGY

Based on analyzing the normal control strategy to the DC link voltage, this paper defines the strong control concept of the DC link capacitor voltage and proposes the soft control strategy to the DC link voltage. The soft control strategy can accelerate the stability process by utilizing the fact that the DC link capacitor of unified power flow controller (UPFC) can absorb transient energy. Further, based on the soft control strategy and combining the linear optimal control strategy, this paper proposes the structures of soft-complete controller of UPFC and provides the simulation results, illustrating that the soft-complete controller can stabilize the power flow on the transmission line and the connection bus voltage of UPFC more efficiently.