Analysis And Implementation Of Micro-grid Based AC Photovoltaic Module

Energy and environment have become more and more importantissues in the whole world today. People are looking forward to seek clean,efficient and renewable energy that can be used instead of oil, coal andother conventional fossil fuels. Development and utilization of renewableenergy has become the basic choices of the energy development strategy inthis century. Solar photovoltaic energy has aroused more and more people’s attention as a new kind of green pollution. A reasonable idea of usingsolar energy is also gradually penetrated into every household. Family andusers that use photovoltaic products become mainstream. In this trend,micro-grid based AC photovoltaic modules emerged. As a micro-inverterdevice, AC module has a modular structure, and integrates inverter deviceand PV modules seamlessly together. It can reduce the losses, improve thestability of the system, with a strong extended, and improve the conversionefficiency. And also greatly facilitates the small users. In this thesis, basedon PV grid background, the design of a micro-grid based AC photovoltaicmodule is presented:1. According to the characteristics of the AC PV modulemicrominiaturization, this thesis presents a miniature inverter system basedon micro power grid. This system has the characteristics of generalinverter， In addition, it has the advantages of modular and highlyintegrated. AC module inverter system is given in this thesis, including theoverall design principle, the analysis of the related parameters, and thefinal design.2. This thesis proposes a two-stage high frequency isolation inverter system, including push-pull DC/DC booster circuit and full bridge invertercircuit, then detailed studies the working principle, the whole circuittopology structure and the solution of realization. After those, verified thecorrectness of the system working principle and parameter by usingSimulink platform.3. For the control model of AC module which is based on single pieceof photovoltaic panels, the design in this thesis improved the algorithm ofmaximum power tracking algorithm. A maximum power trackingalgorithm which has the power had voltage feedforward was given in thisthesis. The proposed algorithm improved the tracking progress, and thestability of the system.4. Considering the miniaturization characteristics of AC module, andthe need to reduce the wastage of the system. So in this thesis, the invertermodulation method based on hardware implementation of single frequencydoubling polarity SPWM modulation, so that we can output frequencymultiplication by the same switching frequency. To some extent, it reducedthe loss of the system and also reduced the size of the system.5. Considering the characteristics of the AC photovoltaic modules forhome users, this thesis design a set of perfect protective measures to ensurethe good-working state of the system and life safety of the user. Includingthe protection for input and output by hardware and software, and alsoimplements software based active testing and passive testing combiningisolated island detection and protection technology. Practice proved thatthe scheme is practical and effective; greatly improve the reliability andsecurity of the system.