Research On Identification Method And Simulation Software Module Of Inrush Current In Distribution Network

With the increment of the power load in the distribution network,the distribution transformer quantity increase,and the phenomenon of magnetizing inrush current is easy to occur in the distribution line when the breaker closing,which usually cause the problem of line protection malfunction?failure closing and the distribution automation failure,and seriously affect the reliability of power supply reliability.Therefore,the research of the mechanism and identification method of inrush current has a significant engineering value and theoretical meaning.Firstly,this paper analyzes the mechanism of inrush current in the distribution network,and then analyzes the current waveform characteristics of the distribution network at different switching angles and different remanence by building a simulation model.According to the significant difference between inrush current and fault current in the fundamental wave,this paper puts forward a new method to identify inrush current and fault current which is based on the attenuation factor of the current fundamental wave,and the attenuation factor is obtained by the Prony algorithm.If the attenuation factor of the fundamental wave is greater than the setting value,the line current is inrush current,otherwise it is fault current.Finally,test results of the simulation data and actual data of the inrush current and fault current testify the validity and feasibility of the proposed approach.On the other hand,a typical transient calculation model of the distribution network which includes more than one distribution transformer on the basis of UMEC(Unified Magnetic Equivalent Circuit)model and combined with JA hysteresis theory and piecewise linear theory is built.Then a distribution network inrush current simulation software modules for simulating inrush current of the distribution line in different conditions is built by using the C++ builder 6.0 and Visual C++ 6.0.Finally,transient calculation model of distribution network inrush current by using piecewise linear theory to obtain core magnetization curve has been tested,to compare with the authoritative software PSCAD,the developed computational models and software modules can calculate the inrush current correctly,and the development requirement is achieved.