Research On Insulation Performance Diagnosis Technology And Aging Evaluation Method Of Distribution Power Cables

As the development of economy,the power grid load is growing.Constrained by corridors and electromagnetic environment and due to reliability of power supply and urban beautification requirements,cable lines increased rapidly.Therefore,XLPE cables get larger applications with its many advantages.Research on partial discharge of the power cable,discusses the causes of the insulation ability decrease and puts forward a scientific evaluation method of aging to provide guidance for fault diagnosis and tracking the working status of cables in real time so as to reduce the possibility of cable accidents and ensure the good operation of the power system.In this context,this paper conducts an in-depth research on the diagnostic techniques and aging assessment methods for the insulation performance of distribution network power cables.First of all,this paper analyzes the main causes of power cable fault in distribution network under the influence of many factors such as cable manufacturing quality,operating environment and operation and maintenance.Then the aging mechanism of power cable insulation is deeply analyzed from two aspects of thermal aging and electrical aging.The partial discharge capacity was selected as the characteristic quantity to study the insulation performance of the cable,which provided the theoretical basis for the following laboratory research.Secondly,aiming at the analysis method of cable insulation ability,this paper establishes AE-UHF joint model for detection and identification,set up a PD test platform and constructs a differentiated insulation defect in the laboratory.Through AE-UHF joint detection of PD test,it proved the system is effective.Principal component analysis(PCA)was used to collect the PD results of all kinds of insulation defects.Support vector machine(SVM)was used to identify the specific discharge types.The feasibility of the experimental scheme and diagnostic system was verified.Finally,aiming at the aging problem of power cables,the relationship between insulation characteristic parameters and aging time is analyzed.The aging loss of low frequency band(0.01 ~ 1Hz)and the total amount of space charge are selected to analyze the aging condition.Explore and analyze the aging of cable insulation from the three parameters of electric field,temperature and humidity.At the same time,the test method is used to determine the cable aging correction function that includes the above three parameters and their relations with each other.In this paper,the study of partial discharge on line testing and the aging mechanism of power cable insulation for power cable body and its accessories provide an important basis for the safe and economical operation of distribution network cable,and provide ideas and basis for early identification of cable insulation level and power cable fault assessment.