Application Research Of Multi-fracture Self-arc Extinguishing Device On The Collecting Line Of Wind Farm

With the transition of the energy structure to green and low-carbon,the proportion of the wind power industry in the newly installed capacity of renewable energy in the country is increasing year by year.Wind farms are mostly located in high mountains,and lightning activities are frequent.Lightning hazards are transmitted from the power supply side to the power demand side,and the security of the national economy will be seriously threatened.Based on the technology of gas extinguish arc,this paper proposes to use the multi-fracture structure to extinguish the arc to solve the problem of lightning tripping on the collector line.First of all,this paper reveals the characteristics of multiple lightning strikes and the harm of multiple lightning strikes to the line insulation.Taking the lightning resistance level as the measurement scale,the laws of high soil resistance counterattack and center shielding strikes in the span are explained.The paper points out the weaknesses and blind spots of traditional lightning protection,and proposes a new mode of lightning protection that integrates impact dredging,rapid arc extinguishing and power frequency blocking.Then,the paper establishes a channel model of arc column.Combining the theories of wall compression,fluid compression and self-magnetic compression to study the formation mechanism of arc column jet.The arc column jet will be accompanied by the effect of magnetic suction.The phenomenon of self-expanding air blowing arc causes multiple fractures in the arc,which causes the arc to self-annihilate.Combining with the theory of gas blowing arc,the model of improved mayr arc is established.A simple circuit of 35 k V system is built by using MATLAB.It is concluded that if the power frequency transient arc is to be destroyed within 10 ms,the velocity of airflow must not be lower than 550 m/s.The software of COMSOL Multiphysics is used to simulate the arc extinguishing and strength recovery of the medium.Lightning and power frequency are applied simultaneously in the test.The results show that the velocity of airflow triggered by the arc can reach 700 m/s.The arc is basically extinguished in about 4 ms.In order to improve the capacity of extinguishing arc,the structure of triple tortuous compression with recoil tube at the top is finally determined.The tests of impulse discharge voltage and the volt-second characteristic have determined insulation coordination parameters between the device and insulator.The test of high-current impulse verified that the device successfully withstands 25 k A lightning current.It can weaken the amplitude of current and delay the discharge time.The test of interrupting power frequency continuous current verified that the device interrupted the continuous current of about 1.2k A within 1/4 cycle.The amplitude and frequency of voltage returned to normal within 1/2 cycle.Finally,based on the operating conditions of the 35 k V collector line,this paper designs matching installation fittings.It is recommended to adopt the method of three-phase installation on the whole line.The power collection line in the area of high lightning damage was selected for the trial operation of the device.After installation,the rate of annual average lightning trip has dropped by more than 80%.It is proved that the device has the value of promotion and application.