Research On The Planning And Operation Of Photovoltaic Power Generation Integration Into Low-voltage Distribution Network Based On DIgSILENT

In recent years,with the adjustment of energy structure and the maturity of photovoltaic generation(PVG)technology,the installed capacity of PVG is increasing day by day,but the problems are gradually prominent,especially voltage rise caused by the reverse flow of power due to PV generation connected to low-voltage distribution network,which is a threat to the stability of grid voltage.Therefore,in order to ensure the safe and stable operation of the power grid,the influence of PVG on the power grid should be taken into account in the planning and operation stages of the power grid.Firstly,the development of PVG at home and abroad is reviewed.The installed capacity of PVG have been growing rapidly in recent years.At present,China is the largest and fastest growing PVG market in the world.The main problems caused by PVG system are pointed out.The basic theory of PVG system,the basic functions of DIgSILENT software and DPL custom method for the local controller of PV inverter are briefly introduced.Secondly,for the potential problem of out of limit of voltage due to high penetration of PVG in low voltage distribution networks,a simplified analytical approach for calculating the maximum capacity of the PVG is studied in depth.With the help of DIgSILENT simulation software,case analysis is carried out in an IEEE-33 node system,and the results show the effectiveness of the analytical algorithm.Thirdly,on the basis of the analytical calculation of PVG access capacity,In order to solve the problem that permitted capacity of PVG may be conservative or optimistic due to the traditional approach based on estimated value of the daily minimum load,this paper proposes a method for calculating the permitted capacity of the PV generation connected to any bus using the daily minimum load with confidence interval.The case study has been carried on an IEEE 69-node system.Comparing the results calculated by the proposed method and DIgSILENT platform,it shows the validity of the proposed method.Finally,combined with the advantages of active and reactive power control of PV inverter,a voltage management strategy based on Q(V)&P(V)control for High-penetration PV to low-voltage distribution network is studied.Using DIgSILENT programming language DPL,several main local controllers of PV inverter are customized.The quasi-dynamic simulation of one month in DPL script is carried out,and the characteristics of each local controller are analyzed.The simulated results show the studied control strategy can not only effectively control the system voltage,but also reduce the active power loss compared with the traditional local control.