Simulation Analysis Of Electrical Tree Growth Based On WZ Model

Electrical tree was of interest to the electrical generation, transmission anddistribution industries as it was one of the causes of insulation failure inelectrical machines, switchgear and transformer bushings. Although electricaltree phenomenon was usually studied by experiment, the test results wereaffected by many external factors that makes it maybe couldn’t accurately reflectthe correlation of the micro-nature of polymer. Therefore, it’s necessary to studythe actual situation by physical modeling and mathematical analysis. So as to laythe foundation for revealing the microscopic nature of the development ofelectrical tree.Discharge in the insulation medium was rendered as the irregular branchesof the discharge channel，as it had inherent regularity and self-similarity that itwas consistent with the research ideas of fractal geometry. So studying it via thetheory of fractal was feasible.This paper was based on fractal theory and makes use of MATLAB as aplatform for modeling and simulation analysis. In this paper, simulation wasbased on WZ model. It accomplished the simulation for needle-plane electrodedischarge. This paper respectively studied the influence to electrical tree growthas variation of the growth index η, the critical field strength Emcand electric fieldwithin the discharge structure Es. As η decreased, the branches fractal dimensiongradually increased and the number of branches branching increased. As Emcincreased, the fractal dimension gradually decreased and the number of branchesbranching reduced. As Esincreased, branches length decreased and the dense oftree increased. Afterwards based on the prior simulation, making use of theMATLAB PDE unit electrode was improved. This paper explored the influence tothe growth of electrical trees when the radius of curvature of the needle-planeand the needle-plane space changed. When curvature radius were small, the time branches began to grow was short. The growth trend of branches in the tip waslarger. Tree growth length was longer. Branches branched trend was larger. Whencurvature radius were larger, the time branches began to grow was long. Butthere were more growing point around the tip. Tree growth length was shorter.Branches branched trend was larger. The plexiform trend was larger. For theneedle-plane model when the space of needle and plate was small, the length ofthe tree was longer. Branches branched trend was larger. With the increased ofthe needle plate space, braches length gradually decreased. The plexiform trendwas larger. In this paper, finally poly methacrylate was used as experimentalmaterials. Electrical tree experiment was done under different needle tipcurvature radius and different space of needle-plane. The test results andsimulation results were consistent.