Research On Fault Modeling And Protection Configuration Of Distributed Power Distribution Network

With the continuous growth of the world economy,the demand for energy by human beings is increasing day by day.New energy sources that are integrated into the distribution network in the form of distributed power sources are receiving increasing attention.However,access to a large number of distributed power sources makes the original single-radiation power distribution network a complex network that radiates from multiple power sources,resulting in problems such as difficult position of transmission line faults and poor economical efficiency of existing protection schemes.Therefore,it is particularly important to study the protection of distribution network with distributed power supply.Firstly,the distributed power source was integrated into the distribution network.The effect of different fault locations on the fault current of the line was analyzed.The instantaneous current direction before the fault was taken as the dynamic positive direction,and the input and output dynamic ports of the protection line were defined.The relationship between dynamic port interchange and current direction and the relationship between fault direction and current before and after fault was presented.A new criterion for pilot protection based on dynamic port swapping and positive sequence current vector ratio before and after fault was proposed,and the protection was given.In the range,the fault action information is sent at both ends,and the new rules for the single-end transmission of fault action information within the scope of protection are used as the main protection of the transmission line.Secondly,taking into account the possibility of failure of the main protection,an improved genetic algorithm using global fault information was proposed to locate faults in the distribution network.It was regarded as a backup protection for transmission lines.When main protection malfunctions,there is error correction capability.At the same time,when the main protection refused to move,there is the ability of backup protection.A new crossover mutation probability function is constructed based on the evolutionary properties of the genetic algorithm population.Combined with the individual characteristics of the population,an adjustment factor was introduced to adjust the similarity coefficient that reflects the similarity relationship between the parent and offspring,and a power distribution is provided.The new crossover operator for network fault location improves search capabilities and accelerates the convergence of the algorithm,making the positioning more reliable.Finally,PSCAD and Matlab simulations show that the main protection can determine the location of the fault and pass the action information according to the new rules.The wide area backup protection based on the improved genetic algorithm can correctly locate the fault when the signal was distorted.Compared with the traditional genetic algorithm,the correct rate was 98% higher and the average iteration number was 9 steps faster,which reduces communication costs and real-time requirements.