城市地下电缆群载流量预测仿真研究

Simulation Study on the Prediction of Urban Underground Cable Group

对城市地下电缆群载流量数值的预测计算,能够有效的确定电力电缆在特定环境条件下的载流量。对电缆载流量的预测,需要对电缆的实际工况进行建模,并分析相关的热传递特性,进行迭代计算后得到预测结果。传统方法首先计算电缆不同部位的等效热阻和电缆的总损耗,基于热路计算电缆温升,但对于有多种热传递过程的计算对象预测精度较低。针对城市电网中排管敷设的电力电缆群,从热传导、热对流、热辐射三方面分析了热传递过程,结合一220k V电缆与35k V电缆同排管敷设的实际工况,建立二维温度场和流场有限元模型。利用多层圆筒结构对电缆薄层进行了电参数、热参数的折算,计算了一定条件下的220k V电缆的载流量,给出了电缆群温度场、流场的计算结果,并进一步从土壤导热系数、环境温度、邻近电缆负荷三方面进行了电缆载流量影响因子的定量计算。

In this paper, we analyzed heat transfer process from three aspects of heat conduction, heat convection, and heat radiation aiming at power cable system of duct laying in urban power grid. Firstly, integrating 220kV cable and 35kV cable with actual working condition of the duct laying, a finite element model of two- dimensional tempera- ture field and flow field was built. Then, structure of multi - layer cylinder was used to carry out amortized computa- tion of electrical parameter and heat parameter for thin layer of cable, and carrying capacity of the 220kV cable under certain condition was calculated. Moreover, calculation results of the temperature field and flow field was provided. Finally, quantitative calculation of influence factor of the cable carrying capacity was carried out from three aspects of heat conductivity coefficient of soil, environment temperature and neighbor cable load.