Research On Maximum Power Point Tracking Algorithm Of Compound Variable Step Size INC In Photovoltaic Power Generation

Maximum Power Point Tracking(MPPT))Control technology is one of the key technologies in photovoltaic power generation systems.The output characteristics of solar photovoltaic cells have a very obvious non-linear characteristic,which is vulnerable to light intensity,temperature,load and other external factors,and MPPT control technology is based on external factors to adjust the output of photovoltaic cells operating point which can make it work at the Maximum Power Point to maximize efficiency.Therefore,the research and application of MPPT control technology are of significant theoretical and practical value.Aiming at solving the problems existing in the present MPPT algorithm,a compound variable step size conductance increment method(hereinafter referred to as the compound variable step size INC algorithm)based on constant voltage method and variable step size incremental conductance method is proposed.The main contents of this paper are as follows:Firstly,the working principle,equivalent model and output characteristic of the photovoltaic cell are analyzed.Then,this paper introduced the basic principle and control technology of the DC / DC converter which is made of boost circuit.The photovoltaic cell and boost converter simulation models are built with MATLAB/Simulink software and the correctness of the models are verified.Then by using what was mentioned above the model of MPPT control system is simulated.Secondly,the traditional MPPT algorithms,such as the constant voltage method,the disturbance observation method and the incremental conductance method and the particle swarm algorithm,in the intelligent algorithm are respectively introduced,including the control mechanism,the pros and cons analysis and the simulation analysis.Then the energy loss of the commonly used MPPT algorithms in maximum power tracking process is analyzed.In order to solve the problem of the MPPT algorithm and the energy loss caused in the tracking process,a compound variable step size INC algorithm is proposed.First,the compound variable step size INC algorithm is analyzed and simulated in detail,and then the algorithm is compared with the commonly used MPPT algorithm.The simulation results show that the algorithm has obvious advantages.It combines the advantages of the constant voltage method and the variable step size incremental conductance method,which not only improves the response speed and steady state accuracy of the system,but also reduces the energy loss during the tracking process.Finally,this paper designs a hardware and software of photovoltaic MPPT control system,and builds a set of experimental platform of photovoltaic MPPT control system by using DSP28035 as the core of control.The traditional fixed step size conductance increment method is compared with the compound variable step size INC algorithm.The experimental results show that the compound variable step size INC algorithm has a good performance,which verifies the correctness and feasibility of the algorithm.The MPPT control system platform is helpful to study the performance of various MPPT control algorithms,and it has a certain practical value.