针对独立光伏逆变器输入电压较低且波动的问题, 提出一种采用双闭环控制策略且抗输入电压扰动的光伏逆变器系统。在阐述其工作原理基础上, 对光伏逆变器主要部件进行建模, 得到总体数学模型, 并举例设计了输入电压为24 V、输出为311 V、输出频率为50 Hz、输出功率为6 kW的光伏逆变器。设计中采用极点配置进行控制器参数计算, 定量描述了输入电压波动对逆变器跟踪误差的影响。仿真结果表明, 设计的逆变器具有稳定性好、抗扰动性强和稳态误差低等特点, 其电压变化率为0.03%, 输出电压总谐波失真(THD)为1.03%, 最高单次谐波含量小于3%, 可以满足性能指标要求。所建模型和设计方法具有一定通用性和理论指导意义, 可用于特殊光伏发电领域中大功率光伏逆变器的研究与设计。

For lower voltages and fluctuated inputs of a standalone Photovoltaic (PV) inverter, a disturbance-rejection system with a double-closed-loop control was proposed. On the basis of the working principle of the system, the main parts of the inverter were modeled and a overall mathematical model was obtained. The inverter with an input voltage of 24 V, an output voltage of 311 V, a frequency of 50 Hz and an output power of 6 kW was illustrated as an example. In the design, the pole assignment method was used to calculate the controller parameters and the relation between fluctuation input and steady state error was described quantitatively. The simulation result indicates that the system with good stability and low steady state error can reject the disturbance. Its voltage change is 0.03%, total Harmonic Distortion(THD) is 1.03%, and the highest single harmonic content is less than 3%, which meets the requirements as well. The model and design method with theoretical guidance meaning is universal and can support the applications and design of high power inverters in other special fields of PV generation.