The Design And Implementation Of Single Phase Photovoltaic Grid Connected System

The progress of science and technology has made people's living standards improve,which also leads to the increasing demand for energy.The energy crisis caused by the rapid consumption of traditional petrochemical energy,but also caused serious environmental pollution problems.Therefore,the effective development and utilization of renewable energy is the only way for future development.In many new energy sources,solar energy has been widely concerned because of its rich resources,clean and harmless,easy access and use.In recent years,the rapid development of solar panels,power electronic devices and grid connected technology makes the use of solar energy more efficient and safe.Therefore,the research and design of grid connected photovoltaic system is of great practical significance.In this paper,the single-phase grid connected system is taken as the research object,and the control system design of photovoltaic grid connected system is analyzed.Firstly,this paper analyzes the related technologies of single phase photovoltaic grid connected generation system and the principle and mode of photovoltaic power generation.It discusses the topology of photovoltaic power generation system.This paper analyzes the structure,performance and advantages and disadvantages of power frequency isolated grid connected inverter,high frequency isolated grid connected inverter,single stage non isolated grid connected system and multi stage non isolated grid connected system.It introduces the structure of DC/DC converter and DC/AC converter.Secondly,it analyzes the demand analysis and the overall design of the grid connected control system.It draws the overall structure of the grid connected photovoltaic control system.It describes the functional structure of each part in detail.It discusses the overall structure of the main controller and the analog signal conditioning circuit.This paper focuses on the design of the software and hardware of the photovoltaic grid connected controller.In the design of the hardware unit,it analyzes the design of the external interface configuration circuit of DSP controller.This paper analyzes the design of analog signal conditioning circuit,which realizes the detection of current and voltage of each node of the grid connected system,and the detection of the voltage frequency and phase of the power system.It discusses the schematic design of the signal amplification,isolation and drive of the drive unit.It introduces the design of power supply system and the design of relay driver circuit.In the aspect of software design,this paper analyzes the design of the maximum power point tracking control method,and determines the tracking algorithm based on the variable step perturbation as the maximum power point of the system.The closed loop control method of inverter is analyzed.It uses the current and voltage double closed loop control strategy to ensure the output AC frequency and phase stability.It discusses the frequency and phase locking method,analyzes the program control flow,and gives the phase loop control program flow chart.