电缆导体温度及过负荷能力的研究

Study on Cable Conductor Temperature and Overload Capacity

导体温度是反应电力电缆运行状态的重要参数,对于含有内置光纤的电力电缆,通过建立光纤到电缆导体的热路模型,推导出导体温度变化表达式,利用光纤所测得温度和实时负荷计算电缆导体的温度,并搭载了实验平台,实际测试电缆导体温度与电缆导体温度计算结果相比较。研究发现:本文提出的计算电缆导体温度的方法满足工程需要,误差来源于光纤测量系统、电缆自身热物性参数和土壤热阻系数,其中土壤热阻系数越大误差越大;实际运行中的电缆线路具有很大的裕度,对于2 200mm^2和1 400mm^2电力电缆而言,以60%额定载流量能持续运行8 h为基准,2 200mm^2的电缆可以施加1.45倍的过负荷,1 400mm^2电力电缆可以施加1.28倍的过负荷。

Conductor temperature is the important parameters of characterization of power cable running state.For the power cable with built-in optical fiber,on the basis of the thermal path model of optical fiber to cable conductor,the expression of conductor temperature change under constant load could be derived.The temperature of cable conductors is calculated by using the measured temperature and real-time load of optical fibers,and a test platform is set up.The measured and calculated values of conductor temperature are compared.It is found that the method for calculating the temperature of the cable conductor proposed in this paper meets the needs of engineering.The error comes from the optical fiber measurement system,the thermal physical parameters of the cable itself and the soil thermal resistance coefficient.The larger the soil thermal resistance coefficient is,the greater the error will be.For power cables of 2 200mm^2 and 1 400 mm 2,the initial load is 60%of the rated current,and the continuous operation for 8 hours is the benchmark.The cable of 2 200mm^2 can be overloaded by 1.45 times,and the power cable of 1 400mm^2 can be overloaded by 1.28 times.