宽输入范围光伏并网逆变器控制方法

为适应光伏阵列的输出特性,光伏并网逆变器通常要具有很宽的直流输入电压范围,这使得其系统特性随直流电压的变化而改变,导致参数选择及优化设计比较困难.本文研制的单相并网逆变器采用三角载波PI控制器进行电流闭环控制,直流电压相对于额定电压变化时,采用同比改变载波的幅值或者同比改变PI控制器的比例、积分系数的方法,可使系统传递函数保持固定不变,这有利于系统稳定性和优化设计.文中给出了1 kW并网逆变器数字控制的设计和实现方法,实验结果表明该方法具有良好的稳定性和动态电流跟踪性能.

Control of Photovoltaic Grid-Connected Inverter with Wide Input Range

The grid-connected inverter in a photovoltaic generation system is often supposed to work with a wide DC input voltage range. The inverter has a varying characteristic with the change of the input voltage, thus it is difficult to choose the system parameters to keep the system operate in an optimum mode. A grid-connected inverter with triangular carrier and PI controller is researched. By changing the peak value of the triangle carrier, or by changing the proportional and integral parameters of the PI regulator, the system can keep fixed loop transfer function when the input voltage varies. It benefits the system loop stability and the optimum design of the grid-connected inverter. The design and the implementation of the discrete-time control system of a 1 kW grid connected inverter are given. The result shows that the inverter has optimum stability performances and transient current tracking ability.