地下管道群中安装电缆的热状态及载流量评估

为了保证地下电缆可靠运行，电力部门通常的做法是在电缆表面安装温度传感器，对电缆的热状态进行直接监测。但是对于管道群中安装的电缆，如在安装时打碎已有管道既不安全也不经济，使温度传感器不得不安装在管道群的外表面，带来如何从远离电缆安装的温度传感器的数据中推测出电缆绝缘温度的问题。对此，提出了一种通过土壤热参数的估算来评估电缆绝缘热状态的方法，主要涉及有限元法和优化方法。通过实际应用于220 kV变电站入线的3条220 kV／250 MVA地下管道群电缆线路，对热状态进行精确评估，预测结果与实际测量值具有很好的一致性，证明了所提方法的有效性。

Assessment of Thermal Condition and Current Rating of Underground Power Cables Installed in Duct Banks

For reliable operation of underground power cables, it has been a common practice that power utili- ties mount thermal sensors on cable surface to directly measure temperature and then assess the thermal condi- tions and ratings. However, this method could not be applied readily to those cables installed in duct banks due to the inconvenience in mounting sensors on cable surface. To solve the problem, an alternative manner of mounting sensors outside the duct banks is proposed and a technique is developed to assess the cable thermal condition by matching the computed temperature to that measured with sensors in this paper. The matching process involves two methods： the finite element method （FEM） and an optimization method. Good consisten- cy between prediction results and the actual measured values of network application proves its effectiveness in accurate assessment of thermal condition of three 220 kV/250 MVA underground cable circuits installed in duct banks entering a 220 kV substation.