Research On Line Protection Of Distribution Network With Distributed Generation

Renewable energy generation has been more and more widely used in recent years.When the renewable energy is connected to the distribution network in the form of distributed generation,the distribution network changes from the original single power supply to multiple power supply at the same time.This change changes substantially electrical characteristics of the original distribution network.When the distribution network fails,the protection of the original line will misoperate or refuse to operate.Therefore,it is of theoretical and practical significance to study the line protection of distribution network with distributed generation(DG).In this paper,based on the operating principle and control strategy of distributed generation(DG),the current output characteristics of DG in the case of distribution network failure are studied,and the equivalent model of DG is obtained,and the accuracy of the equivalent model is verified by simulation.Then on this basis,according to the typical operation mode of the 10 kV distribution network and current protection configuration,10 kV distribution network including DG model is established,this paper analyzed the failure occurs in different type line,DG on the current distribution and the impact of current protection movement situation,and has carried on the simulation,the results show that the DG interconnection will change the current distribution,and cause the original current protection misoperation.Then,based on the impact analysis,and in order to solve the problem of current protection maloperation,put forward the improvement project of current protection,the power distribution network containing DG partition,pick a DG at the end of the line and the end of the first are attached to the ends of the line for that DG power supply area,the first termination of DG line and there were no DG at the end of the first line of the single power supply area.The two ends of the power supply area adopts the longitudinal differential main protection and the fixed time current backup protection,while the single end of the power supply area still adopts the original current protection,and the simulation proves that the improved scheme can solve the current protection misoperation problem.Finally,in order to further improve the protection performance,a wide-area protection method using multi-point information is proposed.The principle of the method is simple,the calculation is small,and the fault area can be identified quickly.The reliability of the method is verified by an example.