面向电网互联串联型低压隔离光伏微逆变器的自主控制方案

This paper proposes and analyses an autonomous and decentralized control scheme for the series-connected low-voltage microinverter (LVM) operation. Due to the absence of a high-voltage gain stage, series-connected LVMs can use low-voltage and cost-effective Si MOSFETs with better characteristics. However, as the LVM's output is series-connected, implementing current control in all modules will violate the circuit laws. For this purpose, the work aims to develop a control scheme that dynamically decides which module in the string needs to operate as a current controller, thereby achieving maximum power point tracking (MPPT) for all modules. This scheme will also be valid if one of the modules in the string fails due to any faults in the module, as the selection of the current controlling element in the string is dynamically decided. To achieve MPPT, the output voltage of each module varies according to their respective maximum power points (MPPs). The variation can cause some modules' output to saturate during heavy partial shading. For this purpose, a novel anti-windup scheme is suggested for the proportional resonant (PR) controllers. All these schemes have been validated through simulation and experimental results on the developed hardware.