Optimization of photovoltaic systems along railways
Off-grid solar photovoltaic system is an innovative way to supply power for electrified operations and maintenance of facilities along railways.The provisions or recommendations of specifications such as the Code for Design of Photovoltaic Power Station(GB 50797-2012)and other relevant standards generally target the maximum annual power generation capacity,which is mainly oriented to balanced loads and grid-connected power generation,and there is a blindness when it is directly used for railroad lines.In this paper,for the special power scenario and load demand along the railroad line,the component matching principle and design process of an off-grid photovoltaic storage system along the railroad line was proposed,the optimal design model of photovoltaic power supply system for any period was constructed,and the calculation program was compiled based on Python language.The model included a solar irradiation model,PV array tilt angle and spacing model,power generation model,PV module quantity and series-parallel connection scheme model,battery model,controller model,and inverter model.The calculation program realized the automatic search for the optimal tilt angle of the PV array,which can complete the design selection and installation scheme optimization of the optical storage system according to the load demand of different geographic locations,power consumption,and power consumption period(month,season,year,etc.),as well as considering the influence of meteorological conditions,module performance degradation and other factors.The practical application in the Junchi Railway shows that there is a significant difference in the optimum inclination angle of photovoltaic arrays at different months of the year.More specifically,the minimum and maximum angles are 16° and 69°,which occurs in June and December,respectively.To absorb maximum radiation throughout the whole year,summer half-year and winter half-year,the optimum inclination angles are 46°,25°,and 61°,respectively.For the winter-type load,the optimized scheme can save 8.8%of investment compared with the scheme recommended by the specification.The research results can provide a guideline for designing photovoltaic power systems along the railway.
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