| With the development of UHV transmission technology,GIL transmission technology,which is characterized by high-capacity transmission and environment-friendly,has been widely concerned and applied.However,it is facing the problem of metal particle pollution in the operation process,which may cause insulation flashover fault and bring immeasurable economic losses.Therefore,it is necessary to study the movement characteristics and detection methods for metal particle.In this paper,firstly,the mathematical model of electric-magnetic-thermal-fluid multi-physical coupling field and the mathematical model of motion of free metal particles in multi-physical field are established,and their correctness are verified by temperature rise experiment and particle observation experiment respectively.Then,based on the simulation,the mathematical model of the simplified external air region and the geometric model of the truncated GIL are analyzed to improve computing efficiency.Secondly,combined with the multi-physical field simulation of 500 kV GIL,the motion characteristics of free metal particles in GIL are studied.Finally,the acoustic signal excitation and propagation model is established based on particle impacting enclosure.The correctness of the model is verified by experiments,and the acoustic signal excited by free metal particles in 500 kV GIL impacting enclosure and the propagation characteristics of acoustic signal are studied.The conclusions below are drawn based on this research.In the process of metal particles moving in GIL,the main force is the normal Coulomb force,and its normal velocity has a very obvious power frequency correlation.With the increase of the diameter of metal particles,its maximum take-off height,maximum normal collision velocity and power frequency component of normal velocity decrease.When the metal particles collide with the GIL enclosure,a pulse sound pressure signal will be generated,and its amplitude is proportional to the impact force amplitude.The sound signal starts from the collision position,propagates along the GIL axis in the form of elastic wave,and then the pressure wave is excited on the enclosure surface and spreads around.With the increase of the diameter of the metal particles,the amplitude of sound signal increase.The detection effect of the acoustic signal is the best at the detection point directly below the collision position,and there are different degrees of exponential attenuation in the axial,radial and angular directions. |
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