Research On The Saturation Characteristics Of Current Transformer In Power System And Its Influence On Relay Protection And Countermeasures

Current transformer as current signal transmission devices in the power system,which uses the principle of electromagnetic induction to make the current change proportionally,so as to obtain the small current on the secondary side.But in the process of running,if the flux is saturated,the excitation current will increase,this will change the ratio of the current on the second side of the current transformer and lead to the distortion of the current on the second side.In recent years,our country electric power system's capacity continues to increase,if the low voltage side of transformer substation outlet near fault,the current transformer saturation phenomenon is likely to happen,so as to make the protection relay refusing action,on the level of protection of main transformer was great action,expanding the scope of the power outage.Therefore,how to avoid the shock of the electrical current transformer saturation in the power system,it has very important research significanceIn this paper,the characteristics of the current transformer and its influence on relay protection are studied in detail in connection with the current state of a power grid.Firstly,the current research status of current transformers is analyzed.According to different types of current transformers,the main parameters of current transformers and the selection principle of current transformers are explained.Secondly,the simulation model of current transformer is established,electric power system are analyzed in a series of parameters on the impact of current transformer saturation characteristics,such as short circuit current,aperiodic component,a side time constant and the size of the secondary side load remanence and nature as well as the core,etc.the causes of the current transformer are analyzed.Again,the authors analyze the use of the current transformer of a grid and the impact of its effects on the relay protection,the saturation characteristics of current transformer with different load and different power factor are analyzed,and the influence of current transformer saturation on protection action.Finally,according to the current situation of a power grid,the concrete measures to prevent relay misoperation and current transformer saturation are proposed,and a detailed summary of the achievements obtained by the subject,and further elaboration on the future direction of development.