Single-stage Photovoltaic (pv) Grid Inverter Control Technology Research And Implementation

With the increasing depletion of traditional fossil energy sources, the research of renewable energy in recent years becomes a hot spot. As one kind of inexhaustible regenerate energy source, solar energy has become one of the most ideal new energy resources. Because of the practical value, Photovoltaic power generation is the focus of current research and developmen.The key work of the paper is the research and design of a control method suitable for single-stage photovoltaic grid inverter, including maximum power point tracking (MPPT), grid-connected algorithm and island detection method. First of all, the paper analysed the photovoltaic grid power generation system, including the the solar panels configuration method and grid index. Compared the topology structure, the system decide to use single-stage circuit because of the security and simplicity. Secondly, this paper summarized and compared several common method of MPPT, and analysed the bus crash in the single-stage inverter, therefore a kind of variable step interference observation method was designed to undertake the problem and improved the efficiency of MPPT. Thirdly, the paper analysed the grid-connected principle and the inherent zero concussion phenomenon caused by the unipolarity.The control model of the inverter was build and analysed, then a kind of independen point PI algorithm wad designed to keep the grid electric current the same frequency and phase with the voltage and small harmonic. At last, the active and passive island detection method was designed to prevent the damage to the machine and staff.The control algorithm was realized in the DSP platform according to the above analysis. The1700W sample inverter was designed and tested. The experimental results, such as:Peak Efficiency add up to92.4%, THD is1.2%, Power Factor reaches1, verify the validity of the algorithm.