基于反馈解耦控制的链式STATCOM研究

Research on the feedback decoupling control of cascaded STATCOM

链式STATCOM在高压大容量无功补偿中具有良好的应用前景,控制策略的选取将直接决定STATCOM设备能否快速、准确地响应电力系统无功功率的变化。分析了链式STATCOM的工作原理和数学模型,通过PARK坐标变换,将三相交流量转变为两相直流量,以此建立了链式STATCOM的有功_无功状态反馈解耦控制模型。针对此模型,利用PI控制,实现了有功电流和无功电流的解耦和线性化控制;并运用单极倍频CPS-SPWM调制技术,使级联H桥STATCOM系统能够在较低的开关频率下实现较好的补偿效果,系统动态响应迅速,稳态无静差。通过仿真分析,验证了该控制策略在H桥级联型STATCOM系统中应用的可行性。

The cascade STATCOM had a good prospect in the high-voltage and large-capacity reactive power compensation. Whether the STATCOM device could be quickly and accurately in response to the changes of reactive power in power system were determined by the selecting control strategies. Therefore, aiming at electric power system was a strongly coupled and nonlinear systems, the use of appropriate control strategies was particularly important to ensure the linear control objective of entire control systems. The working principle and mathematical model of the cascaded STATCOM was analyzed, the three-phase AC value was changed to two-phase DC after PARK coordinate transformation. Based on this, the active-reactive state feedback decoupled control model of the H-bridge cascade STATCOM for this model was established. The active current and react^ve current decoupling and lineadzation control by using the PI control were realized. The cascaded H-bridge STATCOM system was with better compensation effect in lower switching frequency by the applying of the monopole multiplier CPS-SPWM modulation technique. System dynamic response was rapid and without static error in steady-state. The feasibility of applying the control strategy to the H-bridge cascaded STATCOM system was verified by the simulation.