| The dry-type air-core shunt reactor is important reactive-load compensationequipment in the electrical power system. Its stability directly related to the powerquality in system. The electromagnetic force of dry-type air-core shunt reactor maycause insulation cracking, and then break the reactor. The magnetic field could beused to monitor the running state of reactor. The destruction of the electromagneticforce and the distribution characteristics of the magnetic field under all kinds ofrunning state had been not researched in this voltage, so it had academic value andengineering significance to research this problem.Taking a35kV,20000kvar dry-type air-core shunt reactor for calculationexample, this paper analysis the distribution regularities of the magnetic field andelectromagnetic force under all kinds of running state. The field-circuit couplingmodel have been set up by the large finite element analysis software ANSYS. Bycomparing the result of numerical analysis and finite element analysis, the validityof the field-circuit coupling model has been proved. And on this basis, using theharmonic analysis method, the magnetic field and electromagnetic force have beencalculated under different running state: normal use, number of turns deviation,wire-to-wire short circuit and turn-to-turn short circuit. In order to explore theimpact of inputting transient electromagnetic force on the insulation, this article hasanalyzed the inputting transient process under normal use and number of turnsdeviation. By the transient analysis of ANSYS, some physical quantities’transient process has been calculated, including current, magnetic field andelectromagnetic force. At the same time, comparing the largest electromagneticforce and the mechanical property, the possibility of insulation failure caused bytransient electromagnetic force has been discussed.According the calculation results, some conclusion could be drawn. It is extremely uneven that the electromagnetic force produced by the reactor undernormal use. If the number of turns has deviation, the impedance angle changes. Theregular change of electromagnetic force has been happened with theimpedance angle. In the process of investment, the maximum transientelectromagnetic force can reach4times of the steady state. But if good impregnated,generally the envelopment insulation does not be damaged by the electromagneticforce. When wire-to-wire short circuit has been happened on the reactor, the shortcircuit electromagnetic force is related to the fault location. At the same time, themagnetic field distorts with different degrees. When short circuit happened on theend of the reactor, the fault location has the most obvious magnetic field distortionand the maximum electromagnetic force. So envelopment insulation should havecertain thickness. When turn-to-turn short circuit has been happened on the reactor,the magnetic field distorts obviously. The electromagnetic force is also related to thefault location. The short circuit positions nearer the center height in the outermostlayers, the greater the electromagnetic force is. If the insulation thickness is notenough, envelopment cracking will be happened. This study is available for thestudying of damage mechanism of reactor and monitoring the short circuit fault. |
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