Reaserch On Two-stage Grid-connected Photovoltaic System And Decoupling Control

Solar power generation has gradually become one of the most promising renewable energy.Chinese government has made the "Twelfth Five-Year Plan" for the development of solar powergeneration. Researchers always focus on high-power photovoltaic generation currently, but smalland medium power inverters still have an important role in resisdent market. The two-stagephotovoltaic inverters occupy some market in small and medium-sized inverter market. PV arrayinput voltage is wide.The research is meaningful and has a brilliant prospect.Firstly, this paper reviewed the current situation and development of photovoltaic powergeneration. Different topologies of inverters are introduced and classified according to whether theycontain an isolation transformer. The various maximum power point tracking algorithm wasanalyzied and compared, the perturbation and observation method is mainly studyed inMatlab/Simulink, The simulation results proved the method. Passive soft-switching Boost converterwas designed, zero-voltage turn off and zero-current turn on circuit was finished.Secondly, the structure and working principle of system is analized completely in this paper.The power and control circuit based on DSP2812is designed.This paper presents the calculationmethods of components. A5KW single-phase two-stage grid-connected inverter prototype is builtup and debugged.Lastly, this paper presents a DC-link voltage control scheme of two-stage single-phase PVgrid-connected inverter. This is based on the energy-balance between DC input and the energystored in the DC-link capacitor and AC output. A high performance DC-link voltage controller withfast response is desirable to keep the voltage in a safe operating range even the DC-link capacity issmall. System model simulation verifies the feasibility and effectiveness of the proposed method.