Study On The Characteristics Of Pressure-controlled Materials For Current Transfer

Fault current limiter is responsible for quickly handling fault current in powertransmission and distribution systems.Its core function is to use different current transfer forms to force the fault current to quickly transfer to the current-limiting branch,and limit the fault current to a safe range.The evolution of the current transfer form has an important impact on the current limiting capability of the fault current limiter.The current forms of fault current transfer all need to be transferred at the natural zero-crossing point of the current,which gradually cannot meet the current demand for rapid current transfer in the power industry,and the controllability of the impedance of the pressure-controlled material can solve the problem of transfer time lag.In this paper,a new pressure-controlled material for rapid current transfer is taken as the research object.The electrical characteristics of the material are regularly studied through experiments and simulations.The new pressure-controlled material is a kind of granular material whose material resistance value changes with the external pressure.This article uses Ti B2 as the main research object.In the current transfer circuit,the line impedance affects the speed of current transfer,so the controllable impedance of the pressure-controlled and the fast switching speed of the resistance state are the core of the smooth transfer of current;Because the material itself needs to pass a large current,its heat generation will affect the quality of the current transfer and the service life of the device.Stable heat generation is the basis for applying the material to the field of current transfer;When a fault occurs,the impedance of the material increases,and the two ends of the material will withstand a huge overvoltage.The ability of the material to withstand a large voltage is a guarantee for the smooth transfer of current.Therefore,before it is used for the rapid transfer of fault current,it is indispensable to study the electrical characteristics such as impedance characteristics,temperature characteristics,and voltage characteristics.In this paper,a container containing material is made of insulating material,the pressure-resistance relationship of the material under different parameters is tested by a laboratory pressure tester and a digital bridge.After analyzing a lot of test data,an optimization model is designed and made,the dynamic impedance characteristics of the material were tested with permanent magnet repulsion mechanism,and the dynamic response relationship between the resistance value and the pressure was obtained;A thermoelectriccoupling simulation analysis of the pressure-controlled materials is carried out in this paper in ANSYS Workbench.to ensure the correctness of the simulation,the flow-through experiments of the materials under the same conditions are carried out by using a high-current generator,and the temperature rise performance of the materials under different current grades and short-time on-off flows is studied.After optimizing the parameters of the simulation model,the test results have high consistency with the simulation;In this paper,a high voltage pulse voltage apparatus is used to build a voltage test platform to measure and record the pressure resistance performance of the material under different conditions,the influence of the parameters such as material itself,container diameter,material type,material height,parallel series on its voltage tolerance is compared,and some reasonable suggestions are put forward to enhance the voltage resistance characteristics.Through the simulation and experimental research on the electrical properties of pressure-controlled materials,Ti B2 has better resistance characteristics than Ti C,a wider range of resistance,and a faster response to pressure.It also meets the temperature rise and voltage tolerance of materials in practical applications.The requirements are conducive to transferring the fault current in a very short time and limited to a reasonable range,and have the feasibility of application in the field of fault current transfer.