三相级联H桥光伏逆变器的功率均衡控制策略

Power Balance Control Strategy of Three-phase Cascaded H-bridge Photovoltaic Inverter

故障冗余运行条件下,三相共直流母线级联H桥(CHB)光伏并网逆变器中的每一相所包含的模块数目可能不同,导致模块间传输的有功功率存在差异,进而导致模块间的散热需求不同,不利于系统的模块化设计。为此,提出一种三相共直流母线CHB光伏并网逆变器的功率均衡控制策略,当三相所包含的模块数目存在差异时,即使电网发生不对称故障且逆变器非单位功率因数运行,依然能够确保所有模块传输相同的有功功率。实验结果验证了所提控制策略的有效性。

Under the condition of fault redundancy operation,the number of modules in each phase of three-phase common DC-bus cascaded H-bridge(CHB)photovoltaic grid-connected inverter may be different,resulting in the dif-ference of active power transmission between modules and the difference of heat dissipation requirements between modules,which is not conducive to the modular design of the system.Therefore,a power balance control strategy of threephase common DC-bus CHB photovoltage grid-connected inverter is proposed.When the number of modules in three-phases is different,even if the grid has asymmetric fault and the inverter operates at non-unit power factor,it can still ensure that all modules transmit the same active power.The effectiveness of the proposed control strategy is.verified by experimental results.