Ultra-high-voltage direct current wall bushings are critical components in direct current transmission systems.Temperature variations and abnormal distributions can signal potential equipment failures that threaten sy...Ultra-high-voltage direct current wall bushings are critical components in direct current transmission systems.Temperature variations and abnormal distributions can signal potential equipment failures that threaten system stability.Therefore,monitoring these critical multi-point temperature variations is essential.However,the unique design of the bushings,featuring insulation sheds of periodic shape,distorts infrared temperature measurements by introducing interference points.These interference points,dependent on the measurement's angle and distance,appear irregularly in infrared images,severely impacting the accuracy of multi-point temperature distribution assessments.To address this challenge,an anomaly detection method is proposed that adaptively identifies interference points.The method identifies interference points by comparing pixels and uses a voting mechanism to improve identification accuracy.Compared with traditional methods,this approach presents two main advantages:adaptive identification capability,which enables it to recognise interference points and adapt to changing conditions,and unsupervised learning,which enables it to work effectively without requiring manually labelled data.Experimental tests on 161 bushing infrared images demonstrate the effectiveness of the method,achieving a 100%success rate in identifying localised overheating issues.The method has been integrated into high-voltage direct current transmission anomaly systems and can be used to monitor critical equipment,enhancing system reliability and safety.展开更多
As an important component of oil-immersed transformers,the bushing's internal insu-lation ageing and dampness after the long-term operation can cause changes in the in-ternal electric and temperature fields,seriou...As an important component of oil-immersed transformers,the bushing's internal insu-lation ageing and dampness after the long-term operation can cause changes in the in-ternal electric and temperature fields,seriously threatening its safe operation.This paper tested the power frequency permittivity and direct current conductivity of aged and damp oil-paper insulation samples at different testing temperatures,and constructed a dynamic dielectric parameter calculation model.Meanwhile,a simulation model was established based on the actual structure of the 252 kV/1250 A bushing which is mainly used for the oil-immersed high-voltage bushings of 110 kV and above.The electric-magnetic-thermal multi-physical fields were used for simulation analysis.The influence of ageing/moisture(different degrees of dampness in the upper and lower regions)on the electric field distribution in the bushing was obtained.During the initial to steady-state process,the electric field distribution at the zero and end shield shows a reversal phenomenon.When the capacitor core has different degrees of dampness in the upper and lower regions,the impedance distribution of the capacitor core is non-uniform.This phenomenon will lead to an increase in the radial electric field gradient at the end shield of the capacitor core,which is prone to the risk of slip-flashing discharge.In summary,this paper adopts the field-induced dynamic parameters method to analyse the changes of multi-physical fields in the bushing.This can provide theoretical guidance for optimising the bushing structure and on-site maintenance.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:62106033,42367066。
文摘Ultra-high-voltage direct current wall bushings are critical components in direct current transmission systems.Temperature variations and abnormal distributions can signal potential equipment failures that threaten system stability.Therefore,monitoring these critical multi-point temperature variations is essential.However,the unique design of the bushings,featuring insulation sheds of periodic shape,distorts infrared temperature measurements by introducing interference points.These interference points,dependent on the measurement's angle and distance,appear irregularly in infrared images,severely impacting the accuracy of multi-point temperature distribution assessments.To address this challenge,an anomaly detection method is proposed that adaptively identifies interference points.The method identifies interference points by comparing pixels and uses a voting mechanism to improve identification accuracy.Compared with traditional methods,this approach presents two main advantages:adaptive identification capability,which enables it to recognise interference points and adapt to changing conditions,and unsupervised learning,which enables it to work effectively without requiring manually labelled data.Experimental tests on 161 bushing infrared images demonstrate the effectiveness of the method,achieving a 100%success rate in identifying localised overheating issues.The method has been integrated into high-voltage direct current transmission anomaly systems and can be used to monitor critical equipment,enhancing system reliability and safety.
基金National Natural Science Foundation of China,Grant/Award Number:52307164Heilongjiang Provincial Natural Science Foundation of China,Grant/Award Number:YQ2024E044。
文摘As an important component of oil-immersed transformers,the bushing's internal insu-lation ageing and dampness after the long-term operation can cause changes in the in-ternal electric and temperature fields,seriously threatening its safe operation.This paper tested the power frequency permittivity and direct current conductivity of aged and damp oil-paper insulation samples at different testing temperatures,and constructed a dynamic dielectric parameter calculation model.Meanwhile,a simulation model was established based on the actual structure of the 252 kV/1250 A bushing which is mainly used for the oil-immersed high-voltage bushings of 110 kV and above.The electric-magnetic-thermal multi-physical fields were used for simulation analysis.The influence of ageing/moisture(different degrees of dampness in the upper and lower regions)on the electric field distribution in the bushing was obtained.During the initial to steady-state process,the electric field distribution at the zero and end shield shows a reversal phenomenon.When the capacitor core has different degrees of dampness in the upper and lower regions,the impedance distribution of the capacitor core is non-uniform.This phenomenon will lead to an increase in the radial electric field gradient at the end shield of the capacitor core,which is prone to the risk of slip-flashing discharge.In summary,this paper adopts the field-induced dynamic parameters method to analyse the changes of multi-physical fields in the bushing.This can provide theoretical guidance for optimising the bushing structure and on-site maintenance.
