Study On The Mechanism Of Dynamic Contamination Accumulating And Its On-line Monitoring Of External Insulation Of High Voltage Transmission Line

According to statistics, during the80s and90s in the twentieth century, the number ofcontamination flashover accidents is the second of the total number of the power systemaccidents, and it is second to the number of lightning accidents. However, contaminationflashover accident interrupts the power system's regular supply for a long time over a largearea. The loss caused by contamination flashover accident is10times as much as the losscaused by lightning accidents. In the last few years, with the wide use of composite insulators,the anti-contamination ability of power system was generally improved. The contaminationflashover accident of transmission line whose voltage level is more than500kV wascontained. But the contamination flashover accident of transmission line whose voltage levelis less than500kV was still happened occasionally.This paper studies the dynamic contamination accumulating mechanism, establishes thedynamic contamination accumulating model. In order to validate and correct the model, thewind tunnel experiments platform was designed and built innovatively, and the artificialrainfall rushing experiment platform was designed and built creatively. And the dynamiccontamination accumulating model was validated and corrected by experiments. After that,the contamination on-line monitoring system based on the conductivity of insulator surfacewas established to correct dynamic contamination accumulating result. At last, based on thedynamic contamination accumulating model and the contamination on-line monitoring systembased on the conductivity of insulator surface, dynamic contamination accumulatingprediction software system of porcelain and glass insulator was developed. The main researchcontents of this paper are shown as follows.1. From the study of dynamic contamination accumulating progress and the top andbottom surface's contamination accumulating difference of porcelain and glass insulator, thedynamic contamination accumulating mechanism of natural contamination was studied. Fromthe micro perspective, the stress analysis and motion analysis of contamination particles,whose particle size is1~50μm, in the air, in the boundary layer of insulation surface and aftercolliding on the insulation surface were studied. Based on that, the criterion of contaminationparticles adsorping on insulation surface is studied. And from the wind rushing effect and rainfall rushing effect on contamination particles, the dynamic contamination rushingmechanism was studied.2. According to the dynamic contamination accumulating mechanism, dynamiccontamination accumulating progress can be stated by dynamic contamination accumulatingcoefficient and dynamic contamination rushing coefficient. Thus, dynamic contaminationaccumulating overall model was established. Then, the air flow field, the contaminationparticle equivalent model based on fluid dynamics, and the contamination particle sizedistribution model were studied. Therefore, the dynamic contamination accumulatingcoefficient model was established. At last, from the study of natural rainfall characteristicparameters and influence factors of natural rainfall rushing effect, the dynamic contaminationrushing coefficient model was established.3. In order to validate and correct the above model, the wind tunnel experimentsplatform was designed and built innovatively. It can control the relative humidity,contamination concentration, wind field turbulence. And the dynamic contaminationaccumulating model was validated and corrected. Then, the artificial rainfall rushingexperiment platform was designed and built creatively. It can control the rainfall intensity,rainfall erosion angle, rainfall time, rainfall homogeneous degree. And the dynamiccontamination rushing model was validated and corrected.4. In order to realize the monitoring and prediction of contamination degree, thecontamination on-line monitoring system based on the conductivity of insulator surface wasstudied, which is used to correct the result of dynamic contamination accumulating prediction.And dynamic contamination accumulating prediction software system was developed torealize dynamic contamination accumulating prediction.This research work was supported by National Key Basic Research and DevelopmentProgram(973Program)(2009CB724507).