Study On Numeric Analysis Of Streamer Growing In Vegetable Insulating Oils

Insulating oil is widely used in electric power equipment insulation. Its insulationperformance has very important significance for the safe operation of power equipment.Vegetable insulating oil was used in the transmission equipment for its high ignitionpoint and environmentally friendly performance. Operating experience at home andabroad show that under the action of various kinds of impulse voltage, insulation oildischarge may occur and lead to breakdown failure, a serious threat to the safe operationof power grid. At the same time, with the development of super/uhv power transmission,insulation performance of insulating oil is becoming more and more important, thedischarge characteristics and discharge mechanism of insulating oil research work isbecoming more and more attention. Insulating oil discharge process is very short and ismore than a multi-scale coupling nonlinear dynamic process, and its test and theoreticalanalysis were extremely difficult. In this background, this article first studied thestreamer discharge characteristics in vegetable insulating oil, and compared it withmineral insulating oil, and then through the way of mathematical modeling andnumerical calculation, the insulating oil discharge process and influence factors arestudied, to explain the experimental rules and conclusions. Its main contents are asfollows:â‘ Establish platform to test vegetable insulating oil and mineral insulating oilstreamer characteristics under lightning impulse voltage. The discharge process invegetable insulating oil and mineral insulating oil are recorded with a high-speedcamera, the discharge voltage and time are recorded with a voltage divider and anoscilloscope, and the discharge speed are calculated.â‘¡The physical process of streamer growing in insulating oil are discussed,determine the physical mechanism of insulating oil discharge; Using gauss equation andcurrent continuity equation modeling the discharge process in insulating oil, and usingheat transfer equation coupling with them to observe the temperature change indischarge process; Through theoretical analysis calculate and determine the chargesource term in current continuity equation under different carrier generation mechanism;The carrier mobility is calculated, and compared with the literature results, select theappropriate carrier mobility; Determine the recombination rate in the model and otherparameters such as adsorption time constant; Using COMSOL Multiphysics calculating the discharge model in insulating oil; Discussed in elimination methods of the numericaloscillation in the calculating process.â‘¢From the electric field intensity, electric potential distribution, space charge,carrier density and the temperature to discuss the typical calculation results. From theelectric field distribution, space charge distribution to discuss the calculating results ofdifferent voltages, ionization potential and carrier mobility of the transformer dischargemodel, and explain them, discusses their effect on the discharge of insulating oil.