| In the current situation of environmental pollution and energy shortage,all countries in the world are committed to solving the problem of harmonious development among environment,economy and energy.As a new energy with great potential,solar energy has become one of the focuses of research in the world.In the solar power generation system,the maximum power point tracking(MPPT)technology is considered as one of the key technologies to improve the conversion efficiency of photovoltaic cells,which is crucial to improve the utilization efficiency of solar energy.In order to improve the utilization rate of photovoltaic power generation,this paper firstly builds the model of photovoltaic cells,and simulates and analyzes their output characteristics in different external environments;Secondly,the status evaluation model of photovoltaic array is established,and the fuzzy comprehensive evaluation method is used to evaluate the status of photovoltaic array,laying the foundation for subsequent research;Then,aiming at MPPT technology,the optimized and improved Gray Wolf Algorithm(LGWO)is proposed on the basis of the Gray Wolf Algorithm(GWO),and compared and verified under different conditions set up in the built simulation model to determine the advantages of the LGWO algorithm.Finally,the hardware and software are combined to complete the physical design of the MPPT photovoltaic controller.At the same time,a test environment is set up in the laboratory,and the LGWO algorithm is verified by using the designed MPPT photovoltaic controller to determine the feasibility and superiority of the LGWO algorithm in the application of MPPT.The main research contents of this paper are as follows:(1)By studying the power generation principle of photovoltaic cells,the engineering and mathematical models of photovoltaic cells are established,and the photovoltaic cell model is constructed.The output characteristics of photovoltaic cells under different environmental conditions are tested,and the output characteristic curves are analyzed.(2)Through the analysis of the characteristics of the maximum power point voltage,current and power of the photovoltaic array under different operating conditions,the power ratio,voltage ratio,current ratio and filling factor are selected as the indicators of the photovoltaic array status evaluation model,and the value range of these indicators is determined.Then,the fuzzy comprehensive evaluation method is applied to evaluate the status of photovoltaic array,and the corresponding evaluation results are obtained.(3)By introducing the principle,control process and conventional control methods of MPPT technology,this paper analyzes the shortcomings of traditional MPPT algorithm and swarm intelligence algorithm,adopts the more advantageous GWO algorithm and optimizes and improves on the original GWO algorithm,and further proposes the optimized LGWO algorithm.Through simulation in Matlab/Simulink to simulate different lighting and temperatures,the traditional perturbation algorithm(P&O),particle swarm optimization algorithm(PSO),GWO algorithm,and improved and optimized LGWO algorithm,which are widely used in swarm intelligence algorithm,are compared and analyzed in three different modes.All of them reach the conclusion that LGWO algorithm has the shortest convergence time,small amplitude of oscillation,good stability,and the highest tracking accuracy.(4)With STM32 as the main control chip,the hardware and software of MPPT photovoltaic controller are designed.The hardware includes BUCK main circuit,control circuit,voltage and current sampling circuit and drive circuit.The software part includes the design of the main program and the subprograms of ADC interrupt and PWM interrupt.Then a photovoltaic experimental platform was built to test and verify the designed photovoltaic controller and MPPT algorithm.The results showed that the power tracking accuracy of MPPT photovoltaic controller under LGWO algorithm reached 97.8%. |
