描述高压直流电缆绝缘材料电导率的公式比较

以高压直流交联聚乙烯(cross-linked polymeric,XLPE)电缆为研究对象,研究讨论了现阶段描述直流电压下绝缘材料电导率公式对XLPE材料的适用情况。首先基于两种不同电导率公式推导了稳态下高压直流电缆中电场反转的临界温差、绝缘层温度分布、电场、电导率和距离电缆中心的乘积以及绝缘层电场分布,并通过比较有限元仿真结果和公式计算结果证明了所推公式的可靠性。然后通过对不同电导率公式计算值的比较,以及不同公式在相同条件下引起的绝缘材料热电特性,证明了公式互换的可能性。

Comparison Between Electrical Conductivity Equations in Describing HVDC Cable Insulating Materials

Aiming at the HVDC cross linked polymeric (XLPE) cables, the applicability of equations describing electrical conductivity of insulating materials under DC voltage to the XLPE material is discussed and studied. Based on two conductivity expressions, the critical temperature difference for field reversal, the temperature difference across insulation, the product value of local electric field, the electrical conductivity and the associated distance from the cable centre, and the field distribution across insulation at steady state are deduced and proposed. Simulation results from the finite elements analysis and the calculation results according to equations are compared, and these equations are proved reliable. The values calculated from the conductivities are compared, as well as the comparison in corresponding thermal and electrical characteristics, both forms of equations describing conductivity are proved exchangeable for the HVDC XLPE cable.