Impact Analysis And Control Strategy Of Distributed Photovoltaic Power Grid Interconnection

With the development of the electric power industry in China,the energy structure has been improved and optimized step by step,and the research and development of new energy has made great achievements.Compared with the traditional energy structure,distributed photovoltaic power generation has developed rapidly by virtue of its green environment,flexible installation position,high energy utilization,decentralized access to the power grid,relatively low investment costs,and so on.Gradually become one of the development trends of distribution network.On the basis of forecasting the power consumption and maximum load in Yangzhong area,the detailed model of district power grid is established in DIGSILENT Power factory software.The security level of distribution photovoltaic power supply and the load capacity of power grid are analyzed.The influence of short circuit current and power quality are analyzed,and the countermeasures of voltage deviation and voltage fluctuation in power quality are put forward.The main elements as follows:(1)Based on the original data of electricity quantity and load over the years,the natural growth rate and large user method are used to predict the electricity consumption and maximum load in Yangzhong area,and the absorption capacity of distributed power generation is analyzed.According to the capacity of load side grid-connected,the technical requirements of grid-connected are put forward.(2)Through N-1 analysis of main transformer and line,check whether the system has overload or voltage overrun,and analyze the influence of photovoltaic connection on the security level of power supply of the system.The load capacity of the power network is analyzed by analyzing the load ratio of the main transformer and the line under the operation modes of high load,large load and weak radiation,small load and weak radiation.By calculating the maximum short circuit current,the problem of short circuit current exceeding the standard is analyzed.Through the calculation of voltage deviation and voltage fluctuation index after access to photovoltaic power station,it is concluded that voltage deviation in power quality and voltage fluctuation have influence on grid connection of distributed power generation.(3)The problems of voltage deviation and voltage fluctuation are dealt with by adjusting transformer tap,changing power factor,installing energy storage position and changing access position of photovoltaic power station.Based on the grid-connected model of photovoltaic power supply in Yangzhong area,this paper studies the influence analysis and control strategy of grid-connected distributed photovoltaic power supply,and explores the problems of voltage deviation and voltage fluctuation control in distributed photovoltaic grid connection,it is of great practical significance and practical value to improve the power quality and reliability of distributed photovoltaic power supply.