Research Of The Condition Assessment And Monitoring System For Single Core Cable Connectors In 10 KV Switchgear

As more and more power cables are pushed for large-scale application in the city distribution network,the cable faults also are into multiple.And the proportion of the cable heating fault cause in 10 kV high voltage switchgears is high.Once the faults were occurred,the cable terminal will be deflagrated in the extreme cases,even leading to large-scale blackout accidents.However,it is still lack condition monitoring and evaluation methods for the switchgear cable terminal currently.So,this paper uses the single core cable terminal in 10 kV switchgears as the object to study its operation evaluation states and on-line monitoring system.On the one hand,this paper makes use of the confidence level to assess operation states of the cable terminal.Firstly,a 3D model of single core cable terminal is established in ANSYS,which is based on the theory of finite element and the model is obtained by the IEC standard;secondly,under various conditions the model calculates a large number of cable terminal data in the electric and thermal coupling field.Then,this data are used as many samples,these samples are analyzed by statistics,and it can be obtained a series of the reasonable confidence intervals.Estimating the measured operating temperature value is or not in these reasonable confidence intervals,and determining the running states of the cable terminal.A large number of simulation data and some field measured data verify that the proposed method is feasible.On the other hand,an on-line monitoring system for the cable terminal is studied,and the power system of the monitoring nodes and the upper computer software are mainly studied.The power system solutions choose a combination of a large capacity lithium battery and induction,through optimizing power management,reasonable switch function mode to ensure power supply reliability and durability;the power system is tested on the experimental platform,its comprehensive performance meets the energy demand of the on-line monitoring system.This paper designs an upper computer software based on the LabVIEW,the utility algorithms of the data pretreatment,the trend forecasting and early warning are embedded in the upper computer software.This software achieves the functions of real-time display of the monitoring data,prediction terminal temperature change and risk alarm in the friendly man-machine interface.A large number of experimental tests show that the monitoring system which is including a power system hardware and a PC software is effective to monitor the cable terminal.The research and design of this paper provides a practical scheme for the state evaluation and monitoring of the single core cable terminal in 10 kV switchgears,which is conducive to develop the on-line condition based maintenance technology of the power equipment in the smart grid.