Simulation Research On MPPT Algorithm And Hybrid Energy Storage Of Independent Photovoltaic System

With the continuous development of countries around the world,the problem of energy shortage has become increasingly serious,especially with the huge pollution brought about by fossil fuels.The search for alternative clean energy has become a top priority.Among renewable energies,photovoltaic power generation has received worldwide attention because photovoltaic material can be easily obtained and the solar energy is abundant.As part of the use of solar energy,stand-alone photovoltaic power generation systems have become increasingly popular in people’s daily lives.In an independent photovoltaic power generation system,the PV array will suffer from mismatch loss due to external shadow obstruction and aging of its own components,so its P-V output curve will show a multi-peak phenomenon.Due to the instability of the external environment,the power output of the independent photovoltaic system is in an unstable state and is not suitable for the direct use of the direct current load.In order to solve the above problems,this article studies from the following aspects.This thesis first introduced the research background and research significance of photovoltaic power generation,and introduced the application form of photovoltaic power generation system and the research status of independent photovoltaic power generation at home and abroad.Secondly,the equivalent circuit model of photovoltaic cell is introduced in detail,and the dominant PV cell I-V relationship is given.The specific formulae of the model parameters are given.The photovoltaic arrays in complex environments were modeled,and the Newton–Raphson method for solving the equations was optimized for the non-convergence of the modeled nonlinear equations,and the program was verified under the matlab.Finally,the simulation of the different connection modes of the PV array under the same environment proves that changing the connection mode of the PV array can reduce the mismatch loss.Then introduced the circuit structure applied to photovoltaic power MPPT,and analyzed the working principle of Boost circuit and Buck circuit.The operating principles of the perturbation observation method,conductance increment method and fuzzy control algorithm in the traditional MPPT algorithm are introduced.This three MPPT algorithms are simulated and analyzed.Then,the particle swarm algorithm applied to the multi-peak MPPT of photovoltaic array is introduced.An improved ordered particle swarm algorithm is proposed for the voltage overshoot of the particle swarm algorithm in practical applications.Finally,simulation and hardware experiments verify the effectiveness of the improved particle swarm optimization algorithm.Finally,the control strategy of the hybrid photovoltaic system with independent photovoltaic power generation was studied.First introduced the battery and super capacitor used in the independent photovoltaic power generation system.the advantages of the battery and super capacitor parallel structure used are analyzed.Then,the control strategies for regulating DC load using energy storage device and Boost circuit were introduced respectively,and the latter was simulated.For the four cases of sudden changes in load and changes in the external environment of the PV array,the use of the energy storage device to regulate the DC load and the MPPT of the PV array were simultaneously achieved by adjusting the PI parameters.Finally,the energy management strategy of the independent photovoltaic hybrid energy storage system is proposed.