Research On Grid-connected Photovoltaic Power Generation System

With the rapid development of economic globalization,traditional fossil energy day by day consumption, energy supply condition increasingly severe, find new source of energy has become a common problem all conuntries. Solar has obtained much popularity with the advantages of abundant reserve and cleanness. As the constant development of power electronic technology and reducing price of photovoltaic power generation components, making the development of solar photovoltaic power generation grid-connected.The paper mainly research the grid-connected solar photovaltaic energy system, focused on the structure of PV grid-connected inverter system and control strategy. First, with the studies of fundamental principle and mathematic model in photovaltaic power generation, we analyzed the effects of external factors on output characteristics. On the base, we chose one simulation model of solar photovaltaic cell. Secondly, we analyzed several common maximun power point tracking algorithm, contrast to their advantages and disadvantages, we put forword a method of the variable step perturbation and observation. Next, we designed the overall structure of two levels of grid-connected photovaltaic power generation, and selected the DC/DC converter to Boost circuit, aiming to come ture the maximum power point tracking control. The stage DC/AC section for realizing a stable output DC voltage and grid current. The article based on the three-phase grid-connected photovoltaic inverter control system, using the closed-loop control of direct power replace the traditional current control, to achieve fast power control response.It presents a virtual flux oriented replace the traditional voltage oriented, to achieve grid voltage frequency and phase accurate orientation.,and it can achieve the inverter network operation of unity power factor. At the same time, the output current and grid voltage maintain the same frequency and phase.The last, the paper based on the TMS320F2812 sign the hardware circuit and the main software program flow chart of photovoltaic inverter, it builds the simulation model and makes the simulation verification, and demonstrated the rationality and reliability of design solution.