Study On Thermal Characteristics And Current Carrying Capacity Under The Condition Of Heavy Load Of Aluminum Conductor Composite Core

The aluminum conductor composite core conductor is a new type of wire developed in recent years.It has the advantages of large current carrying capacity and small sag change.The line operation standard is based on the static value calculated under severe environmental conditions,while the actual operating conditions provide a good environment for current capacity of transmission lines.With the increase of the voltage level of the power grid,the requirements for current carrying capacity of transmission lines under high load conditions are getting higher and higher.However,the research on the current carrying capacity and thermal characteristics under heavy load conditions is still not sufficient and lacks experimental support.Taking this as a benchmark,aluminum conductor composite core conductor were chosen as the research object,and the types of JLRX1/F1B-240/30 and JLRX1/F1B-315/40 wires of different sizes were selected for the research on current carrying capacity and thermal characteristics of aluminum conductor composite core conductor under heavy load conditions.Firstly,a nonlinear mathematical model of the current carrying capacity of aluminum conductor composite core conductor under high load was established.According to the principle of temperature field heat balance and Fuhl and Ohm's law,three factors including ambient temperature,wind speed and time were introduced,and the mathematical relationship between ambient temperature,wind speed and time and synthetic temperature field is deduced.The mathematical formula under natural conditions and forced convection conditions is solved by the Runge-Kutta method.Secondly,in order to verify the correctness of the calculation results of the current carrying capacity mathematical model,ANSYS software was used to perform corresponding simulations.The simulations were performed under natural convection and forced convection conditions.First,consider the changes of wire surface temperature under the same current carrying capacity and different ambient temperatures;Second,consider the changes of wire surface temperature under the same ambient temperature and different current carrying capacities;The third thing to consider is the relationship between wire current carrying capacity and temperature change under the condition of wind speed.At the same time,compare the findings with the ASCR(Aluminum conductors steel reinforced cable)which has the same cross-sectional area,and the results show that the calculation results and the simulation results are fitted to the curve showing the relationship between the numerical values of the current carrying capacity and the temperature,and the relationship between the calculation results and the actual values can be reflected on the curve.Through data comparison and analysis,it is found that the wire carrying capacity ofcarbon fiber composite core is better than the ACSR.Besides,the surface temperature of aluminum conductor composite core conductor is lower under the same load carrying capacity,which fits the line capacity compatibilization requirements better.Finally,the experiment were conducted to test current carrying capacity and thermal characteristics of the two types of ACCC(Aluminum conductor composite core conductor)under heavy load conditions.In order to verify the calculation results of the current carrying capacity mathematical model,a current carrying test under large load condition was performed.By adjusting the ambient temperature,the current carrying capacity and the wind speed,and verifying the numerical results of the calculation and simulation,the results show that the calculation deviation is within the permissible range and meets the specification requirements.In addition,ACCC is often used under high temperature and high load conditions,therefore the thermal characteristics of link fitting needs to be analysed.First,the wedge clamp is used for grip strength test,and three groups of tests are conducted at normal temperature.After the test,the aluminum conductor composite core conductor is found to be broken,and the inspection found no slippage between the mandrel and the wedge clamps;The following aluminum tube temperature rise test is to heat the area of the aluminum tube drainage plates surrounded by screw holes.A temperature sensor is used to measure the temperature of the corresponding wedge-shaped clamp seat part of the aluminum tube,and it is found that the aluminum tube was broken at high temperature,the core rod is not broken,and the grip strength betweeen the aluminum conductor composite core conductor and the clamps has decreased at high temperature.