Study On Theory And Power System Of Magnetic Saturable Switch Fault Current Limiter

With the expansion of the power system scale and capacity,capacity of short circuit and short-circuit current level is also rising,the demand of limiting the short circuit current is becoming more and more urgent.Magnetic Saturable Switch Fault Current Limiter,as a kind of SFCL,has the advantages of small size,light weight,fast response and easy to match with the auto-recloser,which has a very wide range of applications.Firstly,the research status of superconducting material and superconducting fault current limiter are discussed in this paper.The basic physical properties of superconducting materials are introduced,the topology and operating principle of various types of superconducting fault current limiter are studied.Unlike the kind of SFCL which is based on the transition of physical properties,MSS-FCL is quite the opposite.The theory it utilized makes it quite suitable to achieve the requirements of a ideal FCL.Then he theory of MSS-FCL is illustrated in details.The principle of MSS-FCL is based on the change in magnetic state from saturation to unsaturation to offer low impedance during normal operation and high impedance during fault.And the change in magnetic state is dependent significantly on the relation between flux density and magnetic field intensity of the core which is a nonlinear magnetic phenomenon.Most of the cases which involve this complicated nolinear phenomenon have consider a simplified B-H curve or even a more approximated linearized representation of it.Since the change of the magnetic state of the core plays a very significant role in operation of the device,inclusion of the effects of hysteresis in the model will definitely come up with a more accurate modeling for the sake of the reliability of the in facility.So Jiles-Atherton's(J-A)Hysteresis Model is used to solve the problem.The equations that can be used to represent the magnetic core and the whole equipment installed in the power system.The next chapter of this paper illustrates every part of the DC current control system in every details.Finally,this paper has designed the experimental platform based on DSP of TMS320F28335 and the current limiting performance of current limiter are studied in the paper.In this paper,the theoretical study of the MSS-FCL is carried out and the equations based on Jiles-Atherton's hysteresis model that can be used to represent the magnetic core and the whole equipment installed in the power system is presented.Through MATLAB simulation analysis and experimental research,the things this paper put forward has been verified.