Research On Suppression Measures Of Transformer Magnetizing Inrush Current

With the increasing scale of China's power grid,the number of ultra-high voltage lines and substations is also increasing.As an important electrical equipment in the power system,the transformer can work reliably and directly affect the normal operation of the entire large power grid.In recent years,China's transformer manufacturing industry has been at the world's leading level,and the transformer capacity of R&D and manufacturing is getting larger and larger.The commissioning of large-capacity transformers puts forward higher requirements for transformer relay protection.Through research,it is found that in the process of transformer relay protection,the occurrence of magnetizing inrush current will affect the normal operation of circuit breakers,transformers and other electrical equipment.In severe cases,it may cause a wide range of power failures.Therefore,how to suppress the transformer magnetizing inrush current Become an important direction to study transformer relay protection.This paper first analyzes the cause of the magnetizing inrush current in the power system,establishes the function model of the magnetizing inrush current,and combines the simulation model in MATLAB to analyze the characteristics of the magnetizing inrush current.On this basis,the methods of dealing with the phenomenon of magnetizing inrush current are summarized.A method based on controlling the closing angle of the transformer to suppress the inrush current is proposed.Subsequently,the traditional lumped parameter model and magnetic circuit model can not accurately characterize the magnetic saturation and hysteresis characteristics of transformers.A magnetic hysteresis model of transformer core is proposed based on Preisach principle.The hybrid time-colored colored Petri net(HTCPN)is used to transform the transformer.Modeling.Through the model,a more accurate estimation of the residual magnetism of the transformer is realized.When the system performs the excitation inrush current suppression scheme based on the mutual remanence of the transformer and the biasing,the better suppression effect is achieved.Finally,a simulation model based on the control closing angle to suppress the magnetizing inrush current of the transformer is established in the simulation software.The common situation in the four power grids is the planned split-closing,fixed-off corner closing,three-phase linkage closing and automatic reclosing.The simulation is carried out to verify that the magnetizing inrush current suppression scheme has good effects in various situations of grid operation.In order to compare with the traditional inrush current suppression method,this paper builds a model for suppressing the magnetizing inrush current in the low-voltage side parallel capacitor of the transformer,and compares the characteristics,effects and feasibility of the two types of magnetizing inrush current suppression schemes,further embodying the advantages of the former.Figure [55] table [7] reference [62]...