Small Capacity Single-phase Grid-connected PV System Design And Research

Nowadays the national economy is in the stage of fast development with a rapidgrowth of the social demand for electricity. Meanwhile, our nature resources arerelatively scarce and the traditional energy source has caused serious environmentalpollutions. So the new energy generation is widespread concerned now. While, in thisnew field, the grid-connected photovoltaic system is expected to become one of themain directions of the applications of new energy in the future as for its uniqueadvantages. Closely contacted with the needs for the practical engineering, this paperwill analyze the design and application technology of the typical small capacitysingle-phase grid-connected photovoltaic power generation system which includes thecomparison analysis research of different system topologies, the selection of the maincircuit parameters, the control method of single-phase full-bridge inverter, themaximum power point tracking, system hardware and software optimum designs,applied technologies for the engineering and so on.First, this paper summarized the present research situation of photovoltaictechnology.The definition, characteristics and research status of the small capacitygrid-connected photovoltaic system has been presented. On that basis, by illustratingthe typical Boost circuit and Luo converter, the difference between photovoltaicsystems of different topologies has been analyzed. Then, direct at the common the keycomponents in different topology systems such as photovoltaic array, energy storageinductor and DC capacitor, corresponding parameters designation and research havebeen done. All this work will help choose the correct and reasonable parameters andtopologies while designing a specific system.After determine system topology, this paper presents a thorough study of thecontrol strategy. First, the advantage and shortage of variety kinds of traditionalcurrent control methods of single-phase bridge inverter circuits have been analyzedand summarized. By comparing the simulation results of before and after using Powerfeed forward control in the deadbeat current control, the characteristic of Power feedforward control method is stated. On that basis, the paper presents a new feed forwardpower prediction control method, and its superiority is proved by computation andsimulation. Second, several classic photovoltaic maximum power tracking controlstrategies are analyzed and summarized. Combining with the new feed forward power prediction control method presented above, the paper introduces a brand new MPPTcontrol conception and realizing method by theoretical analysis and derivation.In actual product development, hardware and software design of the system isvery important. This paper has briefly introduced the thoughts and methods ofhardware optimal design when developing a typical small capacity single-phasephotovoltaic grid-connected generation system, taking signal acquisition andconditioning and system electromagnetic compatibility design for examples;meanwhile, it also has described common methods of software optimal design inactual product development, from three angles: optimal configuration of datatransmission, optimal selection of program algorithm and code refining and aidedoptimization design of system software. Finally, some concrete questions indevelopment and debugging of actual system are summarized and analyzed, andpractical solutions and methods are put forward.