Research On The Ultraviolet Imageing Detection Method Of External Insulation Discharge On Power Transmission And Transformation Equipment

The external insulation discharges take a serioussecurity risk to power transmission and transformation equipment,therefore,the necessary safeguard to ensure the safe and reliable operation of power transmission and transformation equipments is to find the discharge position and confirm the discharge type in time.Ultraviolet(UV)imaging method is one of the effective methodsto detect the external insulation discharge,but up to now,it lacks a consensus about detecting the fault and type of external insulation discharge by UV imaging in national and international,up to now.Based on the classical theory of gas discharge and the plasma radiation theory,this paper analyzes the UV detection principle of the external insulation discharge on power transmission and transformation equipment.And the feasibility and availabilityof UV imaging to detect and identify the external insulation discharge are analyzed and proved by UV photon and facular area from corona discharge of the needle-plate model.Multiple UV imager is used to detect the discharge characteristics of power transmission and transformation equipment in the fied and laboratory tests,and the results shows:UV detection is influenced by many factors.The first is the inherent characteristics of UV imager,like the gain.The second is the environment,such as the wind direction and speed,observation angle.The third is the observation distance,and the fourth is the discharge type,the discharges of different equipment have significant differences.Combine with the fied and laboratory tests of power transmission and transformation equipment,the differences of UV detection by some factors without the equipment faults are analyzed,and the correction of detection results are also researched.The reslut shows:wind direction and speed,observation angle have little effect on UV detection,they can be ignored in practical detection.The imager gain has important effect on UV detection,and the detection results under different gain could be corrected by correction formula of gain.The UV detection results decrease with the increase of observation distance,and the detection results under different observation distances could be corrected to reference distance by correction formula.Based on these researches,the correction formula of different UV imager is obtained.Based on the discharge characteristics and discharge rules of insulators under different environments,the methods to distinguish operating environments and discharge intensity are proposed.Researches show: the discharge positions and forms are different under different environments,the discharge position of polluted insulator is dispersive,butthe discharge position is relative centralization in the rain,and the discharge position of icing is the iciclesnearbyhigh voltage terminal.Because of the refraction of water,UV detection is infeasible in moderate and heavy rain.Based on the UV imaging,this paper proposes the method to distinguish and position the faulty insulator.The new UV characteristics(SPN,MPN,CPN)are also proposed by the discharge characteristics of icing insulator,and these UV characteristics are combined with fuzzy theory to build an evaluation model of the icing degree,furthermore,the validity of the model is verified.Based on the discharge characteristics and discharge rules of conductor and joint under different faults,and combine with the engineering practice,the methods to distinguish different faluts are proposed.Results show: the inception voltage of corona decrease with the increase of fault level,burry conductor and broken conductor could be detected by UV imager,but protuberant conductor is hard to be detected.The normal conductor joint also discharges,and the fault types of joint could reflect by pn% mentioned in this paper..According to the field and laboratory detection of external insulation discharges on power transmission and transformation equipment,the UV photon characteristic and information of UV image are analyzed,and the UV imager characteristic of external insulation discharges are acquired,furthermore,the identification method of external insulation discharge types are proposed by facular area.Because of a mass of the field and laboratory detection of external insulation discharges on power transmission and transformation equipment,the evaluation method of discharge types and equipment defects are proposed by the UV characteristics of external insulation discharges,and the relevant standard is formulated,it provides the theoretical support and technical guidance to the engineering application of UV detection.