| Distribution lines have the characteristics of wide distribution,difficult maintenance,complex line models and equipment,difficult to locate and find fault points,low insulation levels,they are extremely vulnerable to lightning damage,cause serious consequences such as damage to electrical equipment,line trips,and large-scale blackouts.Although "blocking","dredging" and "combined" lightning protection methods have reduced lightning disaster accidents to a certain extent,they are still restricted by factors,such as high lightning intensity,high probability of lightning strikes and uncontrollable lightning strikes.In order to solve the shortcomings of the existing lightning protection methods,reduce the lightning trip rate of the line and improve the lightning resistance level of the line,this thesis proposes a lightning protection method for pressure explosion airflow arc extinguishing and develops a compressed explosive airflow pipeline arc extinguishing device for 10 k V and 35 k V lines.This thesis mainly analyzes and researchs from arc characteristics,arc extinguishing mechanism,simulation simulation,test verification and practical application,etc.The specific content is as follows:(1)Start with the change law of arc physical characteristics and energy balance characteristics under the action of air flow,and analyze the conditions that are conducive to arc extinguishment.The ionization characteristics of the arc particles,the arc length and the critical value of the temperature are studied to provide a basis for judging whether the arc is extinguished.(2)The internal arc extinguishing mechanism of the device is analyzed from two perspectives: the development process of compressed explosion gas flow coupled arc and longitudinal air flow blowing the arc model.First,Step by step analysis of the "compression-suction-heat exchange" effect between the arc and the air medium in the arc extinguishing pipeline.Research shows that arc characteristics change after compression effect,then the suction effect causes a large amount of air to be sucked into the pipe.At the same time,the energy accumulated by the arc is transferred to the air medium to form a heat exchange effect,the resulting compressed explosive air flow extinguishes the arc.Then study the established model,among them,the basic equations of the boundary layer provide control equations for subsequent simulations to build mathematical models.Finally,the advantages of the arc extinguishing method of compressed explosion airflow are summarized.(3)Use COMSOL Multiphysics software to simulate the coupling effect of compressed explosive air flow and arc in the arc extinguishing pipeline.It is concluded that the pressure explosion air flow is extremely fast,the arc is extinguished within 0.48 ms without reigniting.(4)The device is tested to verify the operation and lightning protection ability.1)The impulse current discharge comparison test is carried out for unit pipelines and compressed explosion airflow pipeline lightning protection gap.Verify the unit pipeline structure,the withstand performance and arc extinguishing ability of the main body of the device.2)Through the impulse voltage volt-second characteristic test,the lightning 50% impulse voltage of10 k V and 35 k V devices is 110.2k V and 319.7k V.The test results show that the volt-second characteristic curve of the device meets the requirements of protecting insulators and can take priority over insulator breakdown.3)In the power frequency continuous current interruption test,the 10 k V and 35 k V devices successfully interrupted the power frequency current of about 1.6k A and2 k A respectively.And the action speed is extremely fast.After testing and verifying the effectiveness of the device,analyze the actual operating data of10 k V and 35 k V lines,the results show that the lightning trip rate before and after the installation of the device is greatly reduced,and the device has a good lightning protection effect. |
PDF Full Text Request