Research On Grid-Connected Solar Photovoltaic Power Generation System

Global fossil energy increasingly consumption, energy supply situation increasingly nervous, all countries in the world have to step up looking for alternative energy and vigorously develop energy-saving technology. So abundant and clean solar energy undoubtedly is an ideal sustainable alternative energy of fossil energy; photovoltaic system as the main way of solar energy, can effectively relieve the fossil energy supply of nervous of the status quo. Photovoltaic system merges into conventional power grid, and undertakes the task of generate electricity, which forms a grid photovoltaic power generation system. Relative to the independent photovoltaic power generation, the grid-connected solar photovoltaic energy system with lots of advantages has got the praise highly of all countries and rapid development. Therefore, the grid-connected solar photovoltaic energy system will become a research hotspot in the field of the global green new energy.This paper mainly based on two levels of grid-connected solar photovoltaic energy system, and studies the key technologies such as maximum power tracing, grid-connected control and the contrary islanding effect, and on this basis of the above analyses, the thesis studies the factors affecting its power quality.First of all, this paper researched and analyzed the basic principle of photovoltaic cells and all kinds of equivalent model, chose one model suitable for the engineering research and analysis, used Matlab/simulink software platform, the photovoltaic cells simulation model was built, and output characteristics were simulated.The principles and its advantages and disadvantages of the DC-DC transform circuit were discussed, chose Boost booster circuit to realize the maximum power point tracking, analyzed some commonly used for maximum power point tracking control algorithm, and established DC-DC transform circuit simulation model (the power used the photovoltaic power), used incremental-conductance algorithm perturbation and observation method to implement the maximum power point tracking respectively, compared to the simulation results, the results prove conductivity incremental approach power tracking performance is superior to the disturbance of observation;Secondly, researched the topological structure and control method of the photovoltaic (pv) grid-connected inverter, and chose a suitable topology as the main circuit, build a grid inverter simulation model, and the simulation results show that, using the hysteresis current comparison method can well realize the network voltage of tracking. Furthermore, the principle and commonly used detection method of islanding effect were analyzed, analyzed the testing blind area of the active frequency shift (AFD) detection algorithm and the positive feedback active frequency shift method (AFDPF), and used S-Function function written island detection program, build the grid (pv) power system simulation model, used AFD, AFDPF and improving the positive feedback active frequency shift method for the island detection, verified the effectiveness of the algorithm, and the simulation results were compared, and showed that the improvement positive feedback initiative frequency shift method has better detection effect.Finally, based on the front analyses and simulations, researched and analyzed the factors that could affect the on the power quality among the grid (pv) power system DC-DC module, DC-AC module and the island of detecting various part, analyzed the influence of each parameter value and control methods of the on the power quality, provided basis for the reasonable selection of system parameters and the control method.