Research On PV Grid Power System Control Strategy

After entering the 21st century, the energy crisis caused by global economic growth and ecological deterioration of the environment has reached an unprecedented degree, and a grave threat to human survival. The development and use of green energy is imperative, solar energy is one of the concerns of the new green energy, photovoltaic power generation has become the mainstream of the current human use of green energy, and has attracted national attention.In recent years, governments have invested a lot of money on research in the control system of grid-connected PV and the core component of its power generation systems-grid-connected inverter has been study as a key object.This thesis mainly focuses on two photovoltaic grid-connected inverter topology, the MPPT algorithm, the three-level SVPWM algorithm,and network control strategy, the software phase-locked loop, low voltage ride through and other key technical problems in a detailed theoretical analysis, Finally, the MATLAB simulation and prototype experiments verify.First introduced the status of the composition of the photovoltaic power generation system, development in the world, as well as grid-connected inverter technology, based on the current state of technology leads to the main contents of this subject; Secondly, for the two-stage three-level and network inverse change control system, the main circuit topology selection, first class using the boost circuit, the last stage, the T-type three-level inverter circuit, introduced the working principle of the circuit topology before and after class, and to determin the overall system control program. Then, the analysis of the mathematical model and electrical characteristics of photovoltaic cells, P&O to improve the algorithm-three-point method to overcome the power oscillation and misjudgment phenomenon, and through MATLAB simulation:in a different light intensity and ambient temperature, the system can quickly, stability to ensure that the output voltag at maximum power point.Then create a mathematical model of the grid-connected inverter, a PI current decoupling double-loop control and software phase-locked loop for grid point of view, the active current and reactive current to achieve decoupling control, and the net output current and grid voltage to achieve same frequency and phase, and dynamic reactive current support program to address the LVRT the key technical problems. Finally, based on TMS320F28335+CPLD controller, the 15KW prototype has been designed,do study on photovoltaic grid-connected inverter control system and its associated control technology.Program in this subject can improve system power efficiency, reduce system cost; the future will be large-scale applications, which greatly promoted the development of photovoltaic power generation.