Research On Maximum Power Tracking And Grid-connected Operation Control Strategy Of Photovoltaic Power Generation

With the rapid increase of energy demand,photovoltaic power generation,as an inexhaustible green renewable energy,is an important part of China’s sustainable development strategy.Annual photovoltaic installed capacity is increasing,but photovoltaic power generation is greatly affected by the environment,and the generated power can not be directly connected to the grid,so the corresponding photovoltaic power generation needs to be in-depth studied.Two aspects studied by this paper,the first is maximum power tracking,the second is the design of control strategy of grid connected inverter.Firstly,the research background,current situation and significance of photovoltaic power generation are introduced,and the photovoltaic cell model,output characteristic equation,inverter model and characteristic equation are established accordingly.Secondly,aiming at the problem of low efficiency under partial shading of photovoltaic cells,this paper simulates the multi peak phenomenon of partial shading of photovoltaic cells on the MATLAB simulation platform,studies the mechanism of P& O and the interaction of simulation from the traditional disturbance observation method,and deduces the disadvantage of the traditional P & O method-the contradiction between rising speed and steady-state oscillation amplitude,and there are steady-state errors.Therefore,a new intelligent algorithm particle swarm optimization is introduced to solve the above problems,and the advantages of the new algorithm are verified and analyzed through simulation.Then,in order to solve the problem of small oscillation in steady state of particle swarm optimization(PSO),this paper takes it as a disturbance on the DC bus and introduces the active disturbance rejection control(ADRC)technology to suppress it.By analyzing the mathematical model of inverter and combining the LADRC technology with filter,an improved LADRC-RL technology based on filter function is constructed.The core of this method is to expand the filtered voltage into a new state variable,estimate the filtered voltage by using the linear extended state observer(LESO),and use it as a feedback quantity,so as to improve the ability of LADRC technology to suppress high frequency noise.Then,the frequency domain characteristics of LADRC-RL are analyzed theoretically and verified by Bode diagram simulation under the premise that the system output contains disturbance.Finally,the feasibility and effectiveness of the control strategy proposed in this paper are verified by building a simulation platform of grid-connected photovoltaic system inverter.