Theoretical Analysis And Experimental Research Of Current-carrying Hot Spot In 110kV Cable Line

In order to ensure the safety of capacity-increasing,it is necessary to evaluate the thermal condition of cable line.At present,IEC60287 is primary reference to determine the current capacity of cable line.Current capacity of cable in specific laying environment is used.When the cable line is running with the current capacity of cable,cable accessories and many local points with mutational environment can be overheated,then become hot spots.With the support of Guangzhou Power Supply Bureau Co.Ltd.,Based on the available experimental conditions,research of current-carrying hot spot in 110 kV cable Line is carried out : 1.The possible overheating spot and its causes is analyzed from heat production,heat conduction and heat dissipation;2.The resistance of sleeve crimping connector in cable joint is discussed.The total resistance in connecting part consists of surface contact resistance and the overlapping body resistance,and it is affected by contact surface condition,contact pressure and contact area.Referring to manufacturing process of stranded conductor,the actual contact area between stranded conductor and crimping sleeve is calculated.Then,the actual contact area is used to calculate the total resistance of sleeve crimping connector.In this part,electrical contact theory and the effect of stream-line distortion are cited.Later,relevant experiment is done and the accuracy of theoretical calculation is obtained;3.By means of thermal circuit method,thermal conductivity difference along the radial direction between cable and cable joint is analyzed.The influence of longitudinal heat transfer to cable joint is emphasized.630mm2-110 kV cable joint is researched.Simulation and experimental results show that cable joint is current-carrying hot spot in 110 kV cable Line,the overheating condition gets worse with the use of FRP protective shell;4.Current capacity match between110 kV cable and overhead line is discussed.Then,thermal circuit method is used to analyze the heat dissipation ability in both radial and longitudinal direction of 110 kV porcelain oil-filled outdoor cable terminal.Simulation and high-current experiment are done,results show that porcelain oil-filled outdoor cable terminal is not current-carrying hot spot in 110 kV cable Line,and its current capacity is higher than cable.