| Metal particles are the most common defects in GIS.Free movement of metal particle is a major security threat to GIS,not only because the metal particle can move to the higher electric field area,but also the weak discharge can lead to complete breakdown of the insulation of GIS.In order to improve the effectiveness of detection of metal particle in GIS and reduce the harmfulness of metal particle,there have been many researches on metal particles.The current research mainly focuses on the movement law and partial discharge phenomena of single particle under the typical flat plate,and lacks the research on the movement behavior and discharge characteristics of metal particles in the actual GIS coaxial cavity under the operating voltage.The current research results are difficult to meet the practical application of the project.So this paper mainly investage the movement behavior,partial discharge and the harmful degree of different types of metal particles in actual GIS under operating voltage.In order to investage the effect of particle shape(sheet particle,linear particle,spherical particle and metal dust)on the movement behavior of particle,based on the calculation of the charge amount and coulomb force of particles with different shapes and sizes of metal particle,this paper obtains the effect of shape and size of particle on chshapearge amount and coulomb force of partic,proposes the initial condition of different types of metal particles under operating voltage,and researches the movement behavior of different kinds of metal particles.The initial condition of movement of linear particles : The linear particle radius of the aluminum material is less than 0.139 mm,the linear particle radius of the copper material is less than 0.044 mm,and the linear particle radius of the silver material is less than 0.036 mm.The initial condition of movement of sheet particles : the sheet thickness of the aluminum material is less than 0.069 mm,the sheet thickness of the copper material is less than 0.022 mm,and the sheet thickness of the silver material is less than 0.018 mm.The initial condition of movement of spherical particles: the spherical particle radius of the aluminum material is less than 0.175 mm,the spherical particle radius of the copper material is less than 0.052 mm,and the spherical particle radius of the silver material is less than 0.044 mm.The movement behavio of metal particle mainly includ es four kinds of state: static standing,jumping with small height,jumping with big height and jumping to high voltage electrode throug the gas.The linear particle and sheet particle will move to the shielding ring with strong electric field,which will attach to the insulator when the metal particle's velocity is slow and closes to the insulator.However,the spherical particles/ metal dust tend to move to the place with weak electric field and they are diffic ult to be attached to the insulator.In order to investage the effect of the number of particles on the movement behavior of metal particle,this paper researches the movement behavior of particles with different number.the linear particle will cause the electric distortion and adjacent linear particles can stand up at low voltage.With the increase of the number of adjacent linear particles,the initial jumping voltage of linear particles tends to decrease,but the number of particles has little effect on the spherical particles.In order to investage the effect of size of tip curvature radius on the movement behavior of metal particle,this paper compares the movement behavior of linear particles with different tip curvature radius,and reveals the reason of the effect of tip radius on the movement behavior of metal particle.With the increase of voltage,the metal particle without the corona of the end have four kinds of movement state: static standing,jumping with small height,jumping with big height and jumping to high voltage electrode throug the gas.However,the smal er end of the metal particle with corona of end will firstly stand up at the initial jumping voltage.With the increase of voltage,the metal particle will still jump with small height,and will not jump with big height.The influence of the impact force on the movement behavior of metal particle is studied,and the reason of the effect of the vibration of the GIS cavity on the movement of particle.Under the action of impact vibration,the linear particle is deflected upward at one end and the other end is in contact with the ground electrode,which can result in a sharp increase of discharge amount of linear particles,and the linear particle is deflected upwardly under the action of the Coulomb force until the particle stands vertically.The impact force makes harmless particles into harmful particles.In order to study the partial discharge characteristics of free metal particles,the partial discharge characteristics of metal particles in different motion states were analyzed based on the behavior of different types of metal particles(flaky metal particles,linear metal particles,spherical metal particles and metal dust),The relationship between the behavior of metal particles and the partial discharge was established.At the operating voltage,the difference of the charge amount,the velocity of jump,the frequency of jump and the height of jump can cause the difference of the discharge amplification,the width of discharge pulse cluster and the number of discharge pulse.The number of metal particles will cause the difference of the maximum number of ultrasonic in half of AC voltage.The tip curvature radius of metal particle can cause a difference in the phase correlation of the discharge pulse signal.The movement behavior of different types of metal particle can be determined based on the analysis of the above discharge characteristics.The breakdown characteristics of different types of metal particles(different shapes,different numbers and different sizes)in different positions of GIS cavity(high voltage busbar,shielding ring and insulator)were studied,and the types and characteristics of harmful particles under operating voltage were obtained.The results show that there is no necessary relationship between height of jump and the breakdown caused by the metal particle.The free jump of single linear particle or sheet particle under high voltage bus and shield ring is relatively less harmful to the GIS,but the harmfulness of linear particles or sheet particles increase greatly when the unmber of particles increases.When the linear particle or sheet particle is attached to the insulator,the deterioration of the insulator caused by discharge of particle along the insulator is harmful to GIS,but the harmfulness of spherical particle or metal dust is less harmful to GIS insulator becasuse the spherical particle or metal dust tend to move away from the insulator and gathers in the weaker electric field.The relationship between the movement behavior,the partial discharge and the harmful degree is established.The method of judging the shape,size,quantity and harmful degree of metal particles by partial discharge is put forward for the first time. |
PDF Full Text Request