Power Cables Ampacity Calculation Based On The Finite Element Method

For the cable line’s long-term and stable operation and fully takingadvantage of its transmission capacity, it is of crucial importance to accuratelycalculate its ampacity. There are lots of factors that affect the cable ampacity,especially the laying of cable cluster in the multi-loop. According to theinternational electrotechnical commission (IEC) and national standard, theanalytical method that applies to calculate power cables ampacity will produce anobvious error. For this reason, the research of new method that based oncomputer technology to determine power cables ampacity is of great significance.In this thesis, the model of the electromagnetic field and temperature field ofpower cable is established, which is based on the finite element method.Considering that the conductor resistivity is cared about the temperature, on thebasis of the calculating of loss of volume power density, this thesis establishesthe two-dimensional finite element model that indirectly couples "electricity-hot",and simulates the power cables ampacity. First, the ampacity of single-loopcables laying in different conditions is caculated. Compared with the analyticalmethod (according to IEC60287standard), the finite element method is moreeffective and feasible to calculate the ampacity of power cables, and thesimulation results are of greater accuracy. On this basis, the simulation analyseshow the factors, such as air temperature, soil temperature, soil thermal resistivity,cable burial depth and space between the neighboring cable axis, to influence thetemperature field distribution and ampacity of cables. Then, with the two-loopcables and three-loop cables laying in the cluster as the reaserch object, thisthesis simulates and calculates the ampacity of multi-loop cables in flatarrangement and vertically arrangement, contrasts the differences of ampacity between each other and single-loop laying cables, and analyzes the relatedmechanism.Applying the finite element method to simulate the ampacity of cables, manycomplex factors affecting the calculation will be taken into consideration. Theresults are of practical significance to ensure the safety and economic operationof cable.