Fault Section Locating Of Distribution Network With Distributed Generation

As an important part of the power system,the distribution network is directly connected to the customer side and plays the role of distributing power and balancing the load.The vast majority of faults in the power system occur in the distribution network,which is a key factor affecting the stability,reliability and security of power supply.After a fault occurs in the distribution network,fast and accurate location of the fault section is helpful to isolate the fault,restore power supply to the non-fault section and improve power supply reliability.A lot of Distributed Generation(DG)is connected to the distribution network,which changes the structure of the distribution network from a single source radial network to a complex multi-source network.Factors such as bidirectional power flow,dynamic switching of DG,and incomplete fault information reported by Feeder Terminal Unit(FTU)make the traditional fault location methods ineffective.Therefore,this thesis studies the fault section locating of the distributed generation connecting to the distribution network.Firstly,this thesis introduces the basic concept of DG and access criteria,analyzes the fault current characteristics when various short-circuit faults occur in the distribution network,and discusses the influence of DG access on the fault location of the distribution network.Through Matlab/Simulink simulation and analysis,DG access location,DG access capacity and fault type occurrence are changed to verify the impact of DG access on the fault current characteristics of distribution network,and the rectification principles of FTU uploading various fault current codes suitable for DG access distribution network are given,which provide the basis and foundation for the fault section locating of distribution network with DG access below.Secondly,due to load transfer,fault isolation and other factors,the structure of distribution network often changes,and accurate fault location needs to obtain real-time topology structure,so this thesis studies a method based on smart FTU automatic recognition of feeder topology.By using the static topology information of the smart FTU and the information of the adjacent smart FTU,the real-time topology identification of the distribution network is finally completed.The scheme has the advantages of high flexibility and fast response.Then,to address the problem of more complex distribution network topology after DG access,fault current codes,switching functions and adaptation functions for distribution network fault location applicable to DG access are constructed.In order to solve the problem that the traditional intelligent algorithm is easy to fall into the local optimal,this thesis studies the immune particle swarm optimization algorithm which is suitable for the fault section locating of the distributed generation access network,and expounds the main idea and implementation process of this algorithm.Taking the IEEE-33 node distribution network as an example,the accuracy of location was verified in the cases of single fault,multiple faults,and incorrect fault information reported by FTU,respectively.Finally,the algorithm comparison shows that the immune particle swarm optimization algorithm has the advantages of high fault tolerance,operation efficiency and accuracy in distribution network fault section locating.Finally,the distribution network fault location system is designed by combining the immune particle swarm optimization algorithm with the distribution network operation mechanism.On the basis of determining the design principles and basic functions of the system,the hardware,software and human-computer interaction parts of the system are designed respectively.The system not only realizes the fault section locating of distribution network based on immune particle swarm optimization algorithm,but also reports the location results to the operator in real time,which improves the efficiency and ensures the stability and reliability of power system operation.This thesis has 59 formulas,76 figures,11 tables,and 86 references.