The Research And Application Assessment Of Cable Capacity And Operating Temperature On-line Monitoring Technology

In recent years, as China's rapid economic growth, electricity demand was rapidlyincreasing. However, due to the increasing tension of the cable line corridor resources and theexpanding lack of the land, a dozen or even dozens of cables are often set up in a corridor, thenew transmission lines has become increasingly difficult. The cable insulation material toallow maximum operating temperature of long term is a decisive factor of the cable carryingcapacity, conductor temperature cannot exceed the temperature tolerance of insulatingmaterial to ensure the life of the cable. However, if we only pursue the lower operatingconductor temperature, then it will make the cables under long term low load operation,causing the cable cross section not used effectively, not giving full play to the cabletransmission capacity, resulting in wasted investment. Therefore, we need to be able toaccurately grasp the real time cable conductor temperature to increase the potential capacityof the conductor, so the actual cable current carrying capacity will be increased. However,currently cable carrying capacity calculations are based on IEC 60287, the calculationsassume that the cable is 100% load and at the worst environmental conditions, so the result ofthe calculation often has too large margin, the calculations is so low that could not beaccepted. But, this rare adverse weather conditions, which resulted in the vast majority ofcases, we can't really get efficient use of potential transmission capacity of transmission lines.So over rated cable load carrying capacity is still safe to run, but also will not cause theequipment failure and system damaged. Therefore, it is necessary to analyze the presentcalculations of the cable conductor temperature and study a method of real time calculationso that cable operation can be gained in real time.The content of this thesis is as follow: the research background and object of the projectis shown, the conductor temperature calculation methods in and out abroad containIEC60287,IEC60853,heat circuit model,finite element,boundary element;a method ofcalculating in real time conductor temperature based on heat circuit model is given, includingin steady and transient. Moreover, how to get physical parameters about the method is given;A finite element model is constructed, and through the finite element method conductortemperature is calculated in real time, and to verify the accuracy of the model in second part. And this part specific introduces how to use finite element real time to calculate cableconductor temperature in real time; temperature rising test for step current is designed toverify the accuracy of heat circuit model and finite element model.In this paper, to calculate the conductor temperature in real time comes true, and whichgive references to use the cable capacity fully, improve the reliability of power supply.