不同容量微源逆变器并联功率鲁棒控制

微网不同容量逆变器按照比例精确分配负荷有功功率和无功功率的条件是等效输出阻抗与容量成反比,但实际中由于参数漂移、谐波注入和采集误差很难精确设计等效输出阻抗。以感性输出阻抗为例,分析等效输出阻抗对功率分配的影响机理及传统下垂控制法的局限。针对一种包含电压电流环的功率下垂控制器,通过重新设计等效输出阻抗,提出一种功率分配鲁棒控制方法,使无功功率分配不受输出阻抗变化的影响,并使等效输出阻抗幅频特性在工频内输出呈感性,高频内呈阻性以满足下垂方程及实现谐波抑制。仿真和实验证明并联运行的微源逆变器能按容量比精确分配负荷有功和无功,设计的控制器具备较强的鲁棒性能。

Robust Power Control of Paralleled Micro-source Inverters With Different Power Ratings

On the basis of the power distribution mechanism of multi-inverters in paralleled micro grids,it is proved that the condition for ideal sharing of loads is their equivalent output impedances of parallel-operated inverters should be in inverse proportion to their power ratings.But this condition is difficult to meet in practice.For a power droop control structure with a voltage-current loop,an improved power droop robust control method based on redesigning the reactive power control and the equivalent output impedance is proposed which is robust against the parameter drifts,design errors and the voltage drop.Simulations and experimental results show that the improved drooping controller can make the paralleled multi-inverters to share the load power by the ratio of rated capacity accurately.