Research On Efficiency Of Photovoltaic Power Generation System

ABSTRACT:Due to the increasingly serious energy crisis and environmental degradation, the solar photovoltaic power generation has been rapidly developed with its unique advantages. However, compared with other renewable energy, the issues of higher cost and lower efficiency are presented in the photovoltaic power generation, whose research will greatly promote the promotion of photovoltaic power generation.In this paper, in order to evaluate and optimize the efficiency of photovoltaic power generation system, a photovoltaic power generation model has been established, with the solar radiation module, photovoltaic array module under different tracking device, inverter efficiency module, junction box and transformer losses module included.In practice, the main factors affecting the generation capacity of photovoltaic array include the mounting angle of photovoltaic array, occlusion, cable mismatch and low radiation. This paper studies the effects of the module building’s surface inclination and orientation on the radiation received by the PV, and an engineering application model that can simulate the reverse characteristics of photovoltaic modules was established in MATLAB. Based on the modified model of PV cells, the output characteristics of PV module, PV string, PV array under partial occlusion were analyzed. Besides, the power generation losses resulting from cable mismatch and low-radiation were analyzed. The conlusion of optimal shadow distribution rule under different array scale and the applicable condition of string-MPPT was obtained by simulation, which has established the theoretical basis for PV generation system optimization.In this paper, ah optimization scheme of PV array under partial occlusion and a new topology of group-control have been proposed. PV array configuration optimization scheme can reduce the impact of shadow on the array power output under the condition without any difficulty increased. The modified group-control topology optimization scheme can not only improve the power generation efficiency under low radiation, effectively widen array output power range, but also ensure PV array cell operate independently, narrow the scope of the partial shading.Finally a photovoltaic power generation efficiency evaluation system was established in LabVIEW, which can evaluate the annual generation capacity of PV system effectively, the output datas of the model such as the solar elevation angle, azimuth angle and the tracking angle of tracking device are important for the further research, with interface and modular achieved and the advantages such as faster solver and stronger applicability make it more outstanding. Based on the evaluation system mentioned above, the case of Shanshan20MW PV generation system was studied, comes the conclusion of the optimum tracking angle range of single-axis tracking, oblique single-axis tracking, vertical single-axis tracking and dual-axis tracking was obtained. Finally, the best tracking method applied to shanshan region is determined according to the comparision of different track ways’increased years of cost recovery.