Research On Evaluation Method Of Insulator Pollution Status Based On UV Pulse Parameters

Pollution flashovers have a major impact on the safe and reliable operation of the power system.Along with the rapid development of China’s power construction,the scale of power grid coverage has been expanding,the operating environment is complex and diverse,and the pollution components on the surface of insulators are also different.At present,the artificial contamination test method usually uses pure sodium chloride to simulate the soluble part of the insulator accumulation component,which results in the low pollution flash voltage of most artificial pollution test,and the artificial contamination test and the natural pollution test vary.At the same time,it was found that the discharge intensity of the insulators of different fouling components under the same salt density is different,that is,the equivalent salt density has defects in the characterization of the fouling state.Therefore,it is necessary to study the influence of different contamination components on the surface of the insulator on the flashover characteristics of the insulator,and then propose a more reasonable and effective method for characterizing the fouling state of the insulator.The ultraviolet pulse method has been used for non-contact measurement of insulator discharge in recent years due to its high sensitivity and economy.In this paper,based on this method,the ultraviolet pulse detection device is built,and the ultraviolet light signal received by the ultraviolet photosensitive tube is converted into a pulse current signal by using the principle of photoelectric conversion,and the counting is realized by the peripheral circuit,thereby reacting the discharge strength of the insulator.Four typical soluble pollutant components were selected and tested in an artificial fog chamber to study the single soluble salt component and the mixed soluble salt component at different salt density levels,different relative humidity,different voltage levels,and mixed soluble salt components.The variation law of the number of discharge ultraviolet pulses under different mixing ratios is analyzed.The experiment found that when the other parameters are unchanged,the discharge conditions of different soluble salt components of the same salt density level are different.The discharge ultraviolet pulse number of pure NaCl is significantly higher than the ultraviolet pulse number of pure CaSO₄.The presence of CaSO₄in the mixed contamination reduces the intensity of the discharge of another soluble salt component in the mixed contamination,and the larger the proportion of the insoluble salt CaSO₄,the smaller the number of ultraviolet pulses emitted by the insulator.In addition,for any single soluble salt component,the number of ultraviolet pulses emitted by the insulator increases with the increase of the equivalent salt density,and increases with the increase of the ambient humidity which proves that the number of ultraviolet pulses has good followability and reliability for the discharge strength of the insulator.The action mechanism and influence law of different soluble salt components on the discharge characteristics of insulators are analyzed.The test also proves that the number of ultraviolet pulses has good followability and reliability for insulator discharge strength.Finally,in this paper,by selecting the factors affecting the contamination state of insulators（inherent factors,environmental factors,historical factors）,based on the knowledge and definition of fuzzy comprehensive evaluation method,the solution of the weights and membership functions of each factor is realized,and the evaluation model of insulator contamination status is established.The evaluation results serve as a characterization parameter for the contamination state of the insulator.The reliability of the constructed model was tested by experiments.