准Z源级联光伏并网逆变器功率平衡控制

提出一种基于准Z源级联逆变器功率平衡控制的调制波分配方法，该方法的核心是将系统所需无功功率由某一个级联单元提供，并网有功功率由所有级联单元平均分配，然后按这一功率分配原则生成各级联单元调制波；由于准Z源级联逆变器结构特点，在应用时直通占空比存在一定约束条件，因此基于调制波分配方法，推导出实现功率平衡控制的准Z源级联逆变器的直通占空比约束条件；最后通过载波移相调制控制各级联单元逆变实现并网。仿真与实验结果验证级联单元输入功率不平衡时，该策略能有效保障直流母线电压的稳定和光伏模块最大功率输出，实现单位功率因数并网。

POWER BALANCE CONTROL OF QUASI-Z SOURCE CASCADED PHOTOVOLTAIC GRID-CONNECTED INVERTER

This paper proposes a modulation wave distribution method based on the power balance control of the quasi-Z-source cascaded inverter. The reactive power required by the system is provided by a certain cascaded unit,and the grid-connected active power is equally distributed by all cascaded units; According to this power allocation principle, all levels of connected units are generated. Unit modulation wave. At the same time, the constraint conditions of the pass-through duty cycle of the quasi-Z-source cascaded inverter to achieve power balance control are derived. Finally, through the carrier phase shift modulation to control the inversion of the connected units at all levels to achieve grid connection.Simulation and experiment results verify that this strategy can effectively guarantee the stability of the DC bus voltage and the maximum power output of the photovoltaic cell module when the input power of the cascade unit is unbalanced, and achieve unity power factor grid connection.