基于可变虚拟阻抗的感性逆变器下垂控制

Droop control for parallel inverters using inductive output impedance based on variable virtual impedance

为解决并联逆变器功率分配差异,首先从逆变器并联的功率传输特性出发分析了线路阻抗差异对感性逆变器无功功率分配的影响;然后,通过选取合适的逆变器双环控制参数,将逆变器等效输出阻抗设计成感性,并在传统下垂控制的基础上引入虚拟阻抗,通过实时无功与给定无功的偏差调节虚拟阻抗补偿线路阻抗差异。随后的仿真结果证明:该方法能实现线路阻抗差异下逆变器并联功率均分。

For parallel multi-inverters in DC zonal electric distribution subsystem of shipboard integrated power system,the power distribution difference is mainly affected by the difference in line impedances between the inverter output terminal and the point of common coupling as long as the main circuit parameters and control parameters are the same.The influence of line impedance difference on reactive power sharing between inductive inverters is analyzed in the light of power transmission cha-racteristics of parallel inverters.By selecting the appropriate dual-loop control parameters,the equivalent output impedance of the inverter is designed to be inductive.Meanwhile,the virtual impedance is introduced on the basis of the traditional droop control,and the deviation between the real-time reactive power and the given reactive power adjusted to compensate the difference of the line impedance.Simulation results show that the proposed method can realize power sharing of parallel inverters under different line impedances.