两级式光伏并网系统建模与控制研究

Research on modeling and control strategy for two-stage photovoltaic grid-connected system

建立了由Boost DC/DC电路和LCL滤波器的逆变电路组成的两级式单相光伏并网系统数学模型。前级Boost DC/DC电路采用变步长的扰动观察法调节占空比改变光伏阵列的输出电压,实现最大功率点的跟踪;后级LCL滤波器逆变电路采用电网电压前馈和电流跟踪控制技术,利用前馈补偿有效抑制电网波动,具有很好的跟随性能和抗干扰性能;改善系统的动态性能,有效减少系统产生的高次谐波。最后用Matlab软件对该模型进行了仿真,证明了建模和控制方法的有效性和可行性。

A mathematic model of single-phase two-stage photovohaic （PV） grid-connected systemhas been built, which consists of a boost DC/DC converter and a DC/AC inverter with LCL filter. Basedon the variable step perturbation and observation method （P＆O）, the boost converter changes the out-put voltage of PV array by adjusting duty cycle to realize the PV maximum power point tracking（MPPT）. The inverter system restrains the voltage fluctuation effectively with feed-forward of the gridvoltage and current tracking control technology, which has the high performance in both the sinusoidalreference tracking and the disturbance rejection. LCL filter improves the dynamic performance and re-strains the high harmonics efficiently. The simulation with Matlab confirms the effectiveness of themodel and control strategy.