Analyze The Influence Of Distribution Network Voltage Quality With High Penetration Of Distributed Generation

With the continuous progress and development of the society,the power supply mode of the traditional power grid,which has great limitations,has not satisfied the user's electricity demand,at this point,environmentally friendly and flexible distributed generation sources have been widely used.However,access to a large number of distributed generation sources will change the unique power flow direction and voltage distribution characteristics of traditional generation distribution networks.This article is based on the study of high-permeability distributed power access to distribution networks,in-depth analysis of the effect of distributed power grid-connected on the distribution of feeder voltages,and on this basis,clearing how to improve the quality of the voltage,it provides favorable suggestions for grid-connected planning of high-permeability distributed power sources and improvement of system voltage quality.This paper first studies two representative distributed generation systems: photovoltaic power generation system and wind power generation system;through analysis and introduction of their working principles,mathematical models and control strategies,two mathematical simulation models of distributed power supply were established in the power system simulation software PSCAD/EMTDC.Through Simulations,obtained standard three-phase voltage and current grid-connected waveforms,and the detected voltage and current total harmonic distortion rate and the various voltage and current harmonic distortion rates are in line with national standards.Secondly,the voltage distribution characteristics of the feeders were theoretical analysied after the distributed power is connected to the distribution network is carried out.on this basis,the typical distribution network simulation model with distributed power supply was established in PSCAD/EMTDC.Simulation results shows: Distributed power supplies have different effects on the distribution of feeder voltages in distribution networks when the access method,access capacity(permeability),and access location are differents.The same capacity of distributed power centralized access lines is better than decentralized access to voltage,but the distributed access mode makes the overall line voltage more stable.The higher the penetration rate of the distributed power source,the more obvious the effect of improving the line voltage is,and with the distributed power access location close to the end of the line,there will be line over-voltage phenomenon,the results obtained from this modeling simulation are consistent with the results of theoretical analysis.Finally,for the issue of voltage quality caused by distributed power grid connection,a voltage quality adjustment scheme,such as optimizing the distribution of distributed power sources,adjusting the transformer ratio,adjusting the power factor of distributed power sources,and adding additional reactive power compensation devices,was proposed,and use PSCAD for simulation verification.The results shows: Adjusting the distributed power source's own output power factor and additional reactive power compensation devices are simple and flexible.The adjustable parameters can be set on demand and the voltage regulation effect is good.The additional reactive power compensation device can also improve the phenomenon of low line voltage when no distributed power supply is connected.