级联H桥光伏逆变器的功率自适应控制策略

A Power Adaptive Control Strategy of Cascaded H-bridge Photovoltaic Inverter

当光伏(PV)组件间的输出功率严重不均衡时,单相级联H桥(CHB)PV并网逆变器的部分H桥单元的调制度将大于4/π,超过H桥变换器最大线性调制范围,使得PV组件的输出功率与相应的H桥变换器实际传输的功率不匹配,导致系统不能稳定运行。为此,基于方波补偿提出一种CHB PV并网逆变器的功率自适应控制策略,能够根据H桥的调制度自适应地控制PV组件的输出功率。即使PV组件间的最大输出功率严重不均衡,系统依然能够以单位功率因数稳定运行。相比现有的控制策略,能够进一步扩大单相CHB PV并网逆变器的运行范围。实验结果验证了所提控制策略的有效性。

When the output power among photovoltaic(PV) panels are seriously unbalanced,the modulation indexes of some H-bridges in single-phase cascaded H-bridge(CHB) PV grid-connected inverter will be greater than 4/π,exceeding the maximum linear modulation range of the H-bridge converter,so that the output power of PV panels do not match the actual transmission power of corresponding H-bridge converter,resulting in the unstable operation of the system.Therefore,based on square wave compensation,a power adaptive control strategy of CHB PV grid-connected inverter is proposed,which can adaptively control the output power of PV panels according to the modulation index of H-bridge.Even if the maximum output power among PV panels are seriously unbalanced,the system can still operate stably at unit power factor.Compared with the existing control strategies,it can expand the operation range of singlephase CHB PV grid-connected inverter.The experimental results verify the effectiveness of the proposed control strategy.