Research On Grid Inverter System Control Method Of Photovoltaic Power Generation Based On NKMTOA

Solar power is becoming one of the most important energy sources.The research and improvement of photovoltaic power generation technologies and enhancing the performances of photovoltaic grid-connected power generation system have become an upsurge,and are of great significance.Employing the applicable MPPT technology and inverter control strategy can make the photovoltaic power generation system work in a high quality and efficiency way.Therefore,this paper mainly studies the pre MPPT control and post grid connected inverter control strategy of PV grid connected system.(1)The main frame design of photovoltaic grid-connected power generation system.According to the classification and comparative analysis of circuit topology of photovoltaic grid connected power generation system,the structure of two stages of nonisolation has been chosen finally,and its working principle is analysed.The front stage is DC/DC boost circuit,and the back stage is three-phase full bridge inverter with DC/AC.The principle of photovoltaic cells and the calculation method of various parameters are researched.Then,the simulation model of photovoltaic cell is built and its output characteristics are studied by running in different environments.(2)In the shadow environment,the global MPPT of PV is realized by using the improved Niche Kinetic Molecular Theory Optimization Algorithm.Aiming at the traditional MPPT method is difficult applied to track the maximum power point in the partial shadow condition,a MPPT technology based on intelligent algorithm are put forward.In order to strengthen the global search ability of Niche Kinetic Molecular Theory Optimization Algorithm,the niche principle is introduced to avoid felling into local optimum conditions.The MPPT simulation model of PV array based on NKMTOA algorithm is built in Simulink.The simulation results show that this method can find the maximum power point of pv array quickly and accurately under complex conditions,and the steady vibration is small.(3)By using the improved Niche Kinetic Molecular Theory Optimization Algorithm to adjust the PI parameters of double closed loop controller.The mathematical model of the three-phase photovoltaic grid connected inverter is analysed.Then,according to the actual demand,the dual loop grid voltage oriented vector control strategy is presented.According to design and analysis the PI control parameters of voltage and current double closed loop,and consider the fluctuate characteristics of photovoltaic power generation system which is easily affected by environmental changes,the method is proposed by using the improved Niche Kinetic Molecular Theory Optimization Algorithm to tuning the PI parameters of double closed loop controller,thereby,it can avoid the repeated trial and error of traditional PI control parameters and track the changes of photovoltaic grid-connected power generation system quickly.The simulation results show that this method can stabilize the DC bus voltage rapidly,at the same time,the grid connected current waveform is good,and its harmonic content is low.(4)A GUI simulation platform and hardware platform based on photovoltaic grid connected power generation control system.Several important GUI interface modules are introduced.The simulation experiment platform can set the basic parameters of the system and select the control mode more conveniently,and the simulation result data can be viewed and conpared.At the same time,through the hardware design and software design of PV grid connected inverter control system,the experimental prototype is built.Testing and debugging are carried out,and the test results meet the requirements of grid connection.The feasibility of the algorithm is verified.