Reserch On Hybrid Photovoltaic-grid System Based On Double Input Push-pull Converter

Energy crisis and environmental degradation are common challenges to human beings. The development of new clean energy is an effective way to solve these problems, but the disadvantages such as intermittence and labialization affect its separate use of photovoltaic. In order to solve this defect and design a system which can work stably and continuously, multiple energy, those mutually making up for each other’s deficiencies, are combined to form the hybrid renewable energy power system. The Grid-Photovoltaic system, relative to the Wind-Photovoltaic system, based on Multiple- input converter(MIC) can put the extra power back to Grid, eliminate energy storage device such as batteries, and reduce the cost and complexity; In addition, All-weather Grid is more reliable than new energy. Therefore, research on topology, energy management and parameter calculation of Grid-Photovoltaic system is the critical point of this article.Push-Pull converter is widely used in low or medium power system due to the advantages of simple structure, control. Traditional multiple input push-pull converter is high cost and complex. Through the analysis of the generating method of MIC, a family of simple and practical multiple input push pull converter is constituted by using Pulsating Voltage Source Cells(PVSCs) in series or Pulsating C urrent Source Cells(PCSCs) in parallel. Half bridge inverter is adopted to provide AC output. The details of smal-signal analysis, control method and mathematical model are provided also.The expounded system working mode, power management strategy and influence of different control method will help to understand the working principle of Grid-Photovoltaic system based on multiple input push pull converter. Photovoltaic maximum power point tracking(MPPT), photoelectric complementary and inverter control algorithms are adopted in the system software, they are also the critical point.The parameters design of power circuit, especially the push pull transformer and filter, affects the performance and index of system directly, so hardware parameter design step details are given. System software flow chart which can more clearly express the idea of software control is designed according to the software algorithm.Software parameter has an important influence in the speed and robustness of the system. In the foundation of hardware parameter design, software parameter calculation is also very necessary, simulation model in simulink will help to revise the error of software parameter. Finally, according to the energy management strategy, algorithm and simulation model proposed in this paper, using TI DSP chip TMS320F2809 as the main control chip, an experimental prototype is built and carried out the related experiments.