Research On The Power Distribution Relay Protection With Distributed Generation

In recent years,Distributed Generation(DG)has been the most friendly way to develop new sources of energy.However,after the DG access distribution network,distribution network by the original single radiation power supply network into the double side or multiterminal power supply network,and with short circuit current size and direction of change,the more serious is that the original configuration of relay protection likely refusing action and error action and a series of problems.This paper presents a complete set of grid protection schemes,including primary protection and reserve protection,based on the minimum possible changes to the existing distribution network configuration.First,the mathematical model is established for the most widely used Inverter Interfaced Distributed Generation(IIDG),according to its control mode and the output characteristic of IIDG when the distribution network fails.When the two phases are short circuited,it is equivalent to the voltage controlling current source of the bus,which is equivalent to the current source controlled by the bus voltage in the three-phase short circuit.Second,Theoretical analysis the effect of relay protection and automatic reclosing after IIDG access to the original distribution network from IIDG access capacity with the point of failure in IIDG two sides of the different positions of the access point.In this paper,the model of 10 KV of IIDG is set up,and the simulation model of the model is simulated by MATLAB/Simulink,which analyzes the influence of IIDG access on the protection of the existing distribution network.Third,according to the different influence of IIDG access to distribution network relay protection,puts forward an improved adaptive current instantaneous fault protection is given priority to protection the protection scheme,so that the fault characteristic of distribution network is different with different setting value.When the fault occurs downstream of IIDG,the effect of introducing load current on protection increases the sensitivity of short circuit.When fault occurs in the upstream IIDG,according to two phase short circuit fault and three phase short circuit fault protection installation of positive sequence voltage of positive sequence current protection,and the relationship between the change of the existing adaptive current protection setting formula of certain parameters,the setting calculation more accurate.Finally put forward will be based on power balance of wide-area protection as backup protection introduced including IIDG distribution network,according to the size IIDG capacity and load forecast of distribution network containing IIDG area division,through information interaction to achieve fault area rapid positioning and IIDG island operation.