Study Optimal Policy On Output Power Of PV Systems Under Shading Conditions

Solar energy as a clean and green energy, because its environmental pollutionis extremely small, and has a wide distribution of resources and great potential, iseasy for developing and utilizing nearby, so it has attract more and more attention ofscientists. Photovoltaic power generation is an important way to use solar energy,photovoltaic systems are generally installed in the flat and open place, wheresunshine is enough. however the clouds,or the differences between PV arrays, forexample, surface fouling, surface cracks, edge or other conditions can cause a shortcircuit partially shaded PV array. then the battery which is partially shadowed willabsorb the rest energy that the normal cells give, the output power of the system willbe reduced greatly, even lead to severe hot spot effect, cause fire on the PV array,destroying the photovoltaic cell insulated gate line. How to weaken the impact ofshading phenomenon, has become a hot issue in the photovoltaic power generationtechnology research.Shading system will lead to a sharp decrease on the output power, in order toavoid harm of hot spot effect, the usual method is connected bypass diode in parallelat ends of the PV module, but it will bring multi-peak phenomenon in the outputgraph, cause the traditional maximum power point tracking algorithm loseeffectiveness. The experiment results show that different topologies, under the sameconditions, their output system is also different, therefore it is necessary to study astructure that has minimal impact when shading happened, and how to track theglobal maximum power when the system’s output curve has multi-peak, and not towaste energy, is currently need to study in urgent.In this paper, the main target is photovoltaic power generation system, in orderto maximize the system output power. By studying comparative photovoltaic arrayphotovoltaic system under uniform radiation and partial shading in two cases theoutput, and further refine the study of different topologies, different external circuit, the output system under different environmental conditions,find a best topology thathas minimal impact on this situation. PSO is used to track photovoltaic maximumpower point, to maximize the output power of the system.The results show that the best topology has minimal impact in partial shadingenvironment,it can obtain the maximum output power, PSO can quickly track themaximum power point and improve the output power of photovoltaic systems, andprovide a basis to photovoltaic modules designers.