The Detection Method Of Coil Dislocation For Coupled Reactor Based On Spatial Magnetic Field Analysis

With the continuous development of China's power grid,how to ensure the good operation of power equipment and timely detection of equipment fault,to avoid the expansion of fault has become one of the important issues of China's power development.Tightly coupled reactors play an important role in automatic current sharing/current limiting.However,there is the possibility of coil dislocation in the tightly coupled reactors operated for a long time,which will cause changes in the coupling coefficient and the spatial magnetic field and affect the normal operation of the equipment.Even if the conductor coil and insulating material of the tightly coupled reactor are fixed,plastic deformation may still occur,and the mechanical properties of the equipment will gradually decrease under maximum electrical power,eventually causing equipment failure.Therefore,it is of great significance to study the coil dislocation of tight coupling reactor and put forward the detection method to ensure the safe and reliable operation of tight coupling reactor.This paper in view of the tight coupling reactor axial displacement and radial coil winding displacement study,content includes three parts:tight coupling reactor working principle and its finite element model,the tight coupling reactor coil displacement analysis of the influence of coupling coefficient,and based on the tight coupling of reactor coil magnetic field distribution in the displacement detection method research.Firstly,the basic working principle of the tightly coupled reactor is introduced,and the definition of axial coil dislocation and radial coil dislocation of the tightly coupled reactor is given,the self-inductance and mutual inductance are calculated,and the calculation formula of the coupling coefficient is obtained.The finite element model of the tightly coupled reactor was established,and three different cases of wireless coil dislocation,axial coil dislocation and radial coil dislocation were considered,respectively.The magnetic field distribution of the tightly coupled reactor in the axial plane and the central plane was analyzed,and the magnetic field variation rule of the distal and proximal ends of the reactor was obtained.Secondly,the coupling coefficient,as a key parameter of the tightly coupled reactor,is one of the important factors affecting the performance of the tightly coupled reactor.The value of the coupling coefficient changes with the change of self-inductance and mutual inductance of the coil,and the coil dislocation of the tightly coupled reactor will cause obvious change of the mutual inductance of the coil,which will change the size of the coupling coefficient,thus affecting the performance of the reactor.In this paper,simulation,calculation and fitting of multiple finite element models of radial dislocation and axial dislocation of tightly coupled reactor are carried out,and a calculation method of coupling coefficient is proposed and verified by an example.Finally,because it is difficult to measure the tightly coupled reactor manually or mechanically in operation,this paper proposes a method of coil dislocation detection.Since the self-inductance and mutual inductance of the tightly coupled reactor are closely related to the size of the magnetic field,the dislocation degree of the coil,the size of the magnetic field and the value of the coupling coefficient are inseparable.Based on this,this paper analyzes the relationship between magnetic field and axial coil dislocation degree and radial coil dislocation degree respectively through finite element model,and carries out curve fitting to them,so as to obtain the detection function of coil dislocation degree.Based on the coil dislocation detection function,the coefficient variation of the detection function is studied for the tightly coupled reactor with different aspect ratios.The results show that the tightly coupled reactor can reflect the change of self-inductance and mutual inductance through the change of magnetic field,and a method is proposed to calculate the dislocation degree of the coil by measuring the change of magnetic field.This paper focuses on the key issues of structural parameters of tightly coupled reactors.The research results will further promote the effective application of tightly coupled reactors in power grid and have practical guiding significance for the future development of tightly coupled reactors.