采用虚拟阻抗的逆变器并联运行均流控制

摘要

逆变器并联运行是提高UPS容量的一种有效方法,逆变器输出电压幅值、频率或相位的微小差异都会引起巨大的环流,因此需要进行均流.目前的均流方法中,无通信线的下垂控制和虚拟阻抗技术有较大发展潜力,引入相等的虚拟电抗和虚拟电阻,对功率进行线性组合,减小了功率之间的耦合,取得了很好效果.本文分析了这种方法在推理过程中存在的纰漏,给出了更准确的推理方法,提供了完整的论证过程,指出加入虚拟阻抗后电压需作相应修正并提供了修改方法,最后用Matlab进行了仿真研究,验证了方法的正确性.%Greater capacity of UPS is usually achieved by parallel operation of inverters.Minor difference between inverter voltage magnitude,frequency and phase will trigger great circulating current,which attaches great importance to current sharing.At present,lots of solution have been proposed.Droop control without communication connection and virtual impedance are promising method.In a paper,equal virtual resistance and inductance are introduced and by linear combination of power the coupling between active and reactive power is decreased,which leads to better performance.This paper analyzes the deficiency of this method and points out that voltage correction is essential.Correction method is also provided and Mtalab simulation is carried out to confirm the effectiveness.