计及金属护套环流影响的高压电缆温度场及载流量的数值分析

Numerical study on temperature field and ampacity of high voltage cables considering effect of circulating current in metal sheaths

温升和载流量是电缆运行的重要参数,而金属护套环流是影响电缆温升及载流量的关键因素。在综合现有电缆金属护套环流计算理论及电缆温度场和载流量数值计算模型与计算方法的基础上,本文建立了电缆温度场和载流量计算的有限元模型。该模型充分考虑了实际电缆沟工程敷设工况。在此基础上,分析并计算了金属护套环流影响下的典型电缆温度场,讨论了维持三相电缆线芯(或金属护套)最高温度不变前提下金属护套环流影响下的线芯载流量,研究了不同大小环流对电缆温度场和载流量的定量影响规律。结果表明:金属护套环流的增大将导致电缆温度升高,线芯载流量降低;随着电缆金属护套环流的增大,电缆金属护套环流对电缆温度及载流量的影响作用显著增加;相比于维持三相电缆线芯最高温度不变,同一环流影响下维持三相电缆金属护套最高温度不变时计算出的线芯载流量更低。本文的研究成果为保障电缆在工程实际中长期安全高效运行提供了理论指导。

Temperature rise and ampacity are important parameters during cable operation,and circulating current is a key factor affecting cable temperature rise and ampacity.Based on the existing calculation theory of the metal sheath circulating current and the numerical calculation model and calculation method of the cable temperature field and ampacity,a finite element simulation model of the cable temperature field and ampacity is established in this paper.The model is fully simulating the actual laying condition of cable trench project.On this basis,the typical cable temperature field under the influence of metal sheath circulating current is simulated and calculated,and the ampacity under the influence of the metal sheath circulation current under the premise of maintaining the maximum temperature of the three-phase cable core(or metal sheath)is discussed,and the quantitative influence law of circulating current on the cable temperature field and ampacity is studied.The results show that the increase of the metal sheath circulation can lead to the increase of the cable temperature and the decrease of the ampacity;With the increase of the cable metal sheath circulating current,the influence of the metal sheath circulation on the cable temperature and ampacity will increase significantly.Compared with maintaining the maximum temperature of the three-phase cable core constant,under the influence of the same circulating current,the calculated core ampacity is lower when the maximum temperature of the three-phase cable metal sheath is maintained constant.The results provide theoretical guidance for ensuring the long-term safe and efficient operation of cables in engineering practice.