Power Quality Research Of Distributed Photovoltaic Power Generation System

Due to the rapid development of the global economy,the problem of energy crisis and environmental pollution is urgent.The distributed photovoltaic power generation has attracted wide attention because of its clean,renewable and flexible layout.Because of the unique natural conditions,on the basis of the development of large capacity and large scale photovoltaic power stations,the co-nstruction of distributed photovoltaic power generation is popularized so as to make the photovoltaic power generation into the ordinary people's home.However,with the increasing penetration of distributed photovoltaic power generation,the impact of distributed photovoltaic power generation on power quality is also growing.In this paper,the distributed photovoltaic power generation system is modeled and analyzed,including the mathematical model of the photovoltaic cell,the mathematical model of the photovoltaic inverter,the maximum power tracking and the control model of the photovoltaic inverter.On the basis of the mathematical models of each component,the simulation model of the distributed photovoltaic grid connected is set up and its output is given.The influence of external conditions on the output characteristics of photovoltaic is analyzed,and a platform for subsequent research on power quality problems is obtained.On this basis,the harmonic clustering algorithm is used to analyze the characteristics of the distributed photovoltaic power generation system,and the existence of characteristic harmonics,non characteristic harmonics,high frequency harmonics,direct current components and circulation harmonics in distributed photovoltaic output and its mechanism cause and influence factors are clarified.At the same time,by changing the location of distributed photovoltaic,this paper analyzes the distribution law of the distributed PV as a harmonic source after the grid connection.It is found that most of the distributed photovoltaic harmonic current is before the access point to the photovoltaic access point,and it is remitted to the public grid through the distribution line.Near the end of the line,the harmonic voltage distortion level of the whole line is higher.At the end of this paper,the influence of distributed PV grid on line voltage and loss is analyzed.The connection of PV will change the distribution of power flow,and can improve the voltage of the photovoltaic access point,and will lead to the voltage fluctuation of the photovoltaic access point.In this paper,the influence of distributed PV access on line voltage distribution and line loss is analyzed by changing the different access location and different access capacity of distributed photovoltaic,which provides a reference for the selection of distributed PV access position and access capacity.