Research On The Maximum Power Point Tracking And Grid-connected Current Control Strategy Of Photovoltaic Power Generation

With the rapid development of new energy power generation technology in recent years,photovoltaic power generation with the characteristics of environmental protection,renewable,and easy installation has become a research hotspot in the field of new energy.In order to reduce the power loss of the photovoltaic system and improve its power transmission efficiency,a maximum power point tracking(MPPT)controller is applied in the photovoltaic system.This paper establishes the photovoltaic cell and Boost circuit models,respectively analyzes the improved MPPT controller based on dual-mode power prediction temperature compensation disturbance observation method and linear auto disturbance rejection technology,and makes improvements to the traditional current controller.The specific research content of this paper is as follows:(1)A photovoltaic cell model are establish,and change the temperature and light intensity are changed to obtain a dynamic output power curve.According to its output characteristic curve,the relationship between the output of the photovoltaic cell can be seen.The principle of the traditional Boost circuit is analyzed and compared with the simulation results of the Boost circuit with startup shock suppression function.(2)Aiming at the shortcomings of the traditional disturbance observation method,a dual-mode power prediction temperature compensation disturbance observation method is proposed,which takes into account the influence of temperature changes on the open circuit voltage,introduces temperature compensation,and uses constant voltage method and variable step disturbance observation at the same time Method,adding the prediction of the change trend of environmental factors,and comparing and analyzing the results of the photovoltaic system simulation and experiment based on the traditional constant voltage method and the disturbance observation method.(3)Aiming at the problem that the photovoltaic system is vulnerable to external interference,in order to ensure the stable operation of the photovoltaic system,a MPPT controller based on Linear Active Disturbance Rejection Control(LADRC)technology is proposed.Based on the temperature compensation disturbance observation method,LADRC technology is added to reduce the impact of interference on the system by predicting the total interference of the system and giving interference compensation in advance.Ud is used as the feedback voltage and LADRC is the controller to construct a voltage closed loop,which enhances the photovoltaic system.The anti-interference ability of the system.(4)The traditional grid-connected current control method has a weak ability to suppress the DC component and cannot eliminate the high-order harmonics in the grid-connected process,and the gain near the fundamental frequency is low,the fading speed is too fast,and the grid frequency fluctuates.The adaptability is not enough.Therefore,a multi-frequency resonant QPCI+PI current controller is proposed.The multi-frequency resonant QPCI controller can eliminate the high-order harmonics in the grid connection process,and the gain fading is slower near the fundamental frequency.The PI controller further eliminates the DC component to the fault tolerance of grid frequency fluctuations,and combines the two controllers to achieve no static error control of the grid-connected current.(5)The software/hardware design of the photovoltaic system with DSPTMS320F28335 as the control core is analyzed in detail,and a 200 W low-power MPPT controller experimental platform is developed in the laboratory.The proposed dual-mode power prediction temperature compensation disturbance observation method and LADRC based the technical MPPT controller was tested by experiments,and a3 k W experimental prototype was designed and manufactured to verify the multi-frequency resonant QPCI+PI current controller.