Research On Intelligent Optimization Reconstruction System Of PV Array Under Partial Shading Conditions

The increasing consumption of traditional energy and the deteriorating environmental problems have posed a great threat to the future survival and development of mankind.Therefore,the application of renewable energy has been paid more and more attention by the government and the general public.China is rich in solar energy resources.According to statistics,67% of the country's areas are located in exploitable areas.The utilization of solar energy,including solar thermal and photovoltaic power generation,will play an important role in the future energy structure.Photovoltaic systems rely on sunlight to generate electricity.In the process of power generation,they often encounter partial shading occlusions result from buildings,trees,birds and etc.Cloudy weather,surface dust,circuit damage and some other situation will cause panels fail to generate electricity normally at some time,which will not only cause energy loss of photoelectric conversion but also reduce the total output power of the whole system.The circuit structure will be changed to form 'internal circulation' because of partial shaded,which will transform the shaded photovoltaic panels into load and cause local overheating and permanent damage of the panel.In this paper,the output power of photovoltaic power generation system is improved through the optimization of photovoltaic array circuit structure,and the following work is completed:1.The various circuit structures of the PV array are analyzed,concluded that the TCT(TotalCross-Tied)structure has the advantages of stable output power,good anti-interference of the system and easy installation.It is the direction of design and research of large and mediumsized photovoltaic systems.Through the data acquisition of the distributed photovoltaic power generation system,the basis of using the output current as a reference variable for judging whether the PV Module is shaded;2.A new PV Module branch circuit is designed based on TCT structure.When the illumination is blocked,the PV module is identified as being too low to automatically isolate it.After the light turn to normal,the PV module voltage is recovered and switched back to the PV array.Power generation lines and restore power generation to ensure the safety of each PV Module;3.Electric quantity detection and analysis circuit is established,mainly to establish the adjacency matrix of branch switches in the photovoltaic array.According to the total output voltage and current of the photovoltaic array,a circuit dynamic topology reflecting the on-off state of the photovoltaic panel and the change of power generation capacity is formed.4.Apply PLC power optimization logic module,calculate the total current,voltage and power through the PV array output,judge the specific column of the PV module to be isolated according to the power maximization logic,using PLC to generate switch signals and reconstruct the circuit structure,realizing intelligent optimization and reconstruction of the photovoltaic array.5.Using MATLAB/Simulink,realized the 9×9 TCT structure PV array's output characteristics simulation after using intelligent optimization reconstruction,and the reliability of the control algorithm is verified.Through the above intelligent optimization of the photovoltaic array,the automatic switching on and off of the photovoltaic components under local shadow is realized,and the output power of the photovoltaic power generation system is optimized on the basis of ensuring the safety of the components.