Research On Performance Of Intelligent Grid - Connected Photovoltaic Power Generation System Based On Micro - Inverter

Grid-connected Photovoltaic Systems(GCPVSs) has becoming the most promising application, and the total installed capacity is sharply increasing. At present, the central Maximum Power Point Tracking(CMPPT) is the common scheme for PV array due to the advantages of simple system design, cost-effective, and easy maintenance. However, under the mismatch conditions, such as partial shading, hotspot and the differences of PV module parameters, because the Power vs. Voltage(P-V) characteristic of the PV array appears multi-peaks, the CMPPT technique cannot track the MPP exactly, causing huge damage of annual power generation. Besides, for the topology of the PV array with the CMPPT scheme, the electronica measurement modules are usually located in the inverter to achieve the monitor of the input and output running data, leading to high cost of the communication system and the complexity of the system installation. What’s more, the monitoring and control center cannot detect and diagnose the failure point among the whole PV array precisely. To solve these problems, smart GCPVSs are the main trend of the development as the emerging of Smart Grid(SG). This paper is aiming to realize the smart GCPVS, which adopts the micro inverters and is integrated with the Narrowband Power Line Communication(NB-PLC). A theoretical, simulation and experimental study has been conducted in detail.First of all, according to the theoretical analysis, it has been derived that the PV array with the microinverters can effectively reduce the losses caused by the mismatch of PV components or partial shading. And the monitoring and controlling can be at module level. The simulation results shows the annual power yield of the system is effected by the tilt and azimuth of PV module, as well as the partial shading on the PV array. The changes of the tilt may lead to the highest rate of change of 43.75%, while the changes of the azimuth may lead to the highest rate of change of 11.78%. Furthermore, compared to the PV array with the central inverter, the system performance of the PV array with the microinverter optimized about 9.2%. In general, the smart GCPVS prompt the system performance under the mismatch condition. Furthermore, the system not only reduces the fittings, but also facilitates a real-time, reliable and decentralized control.