高压架空导线电流与轴向温度关系计算的热路模型

Thermal Circuit Modeling of the Relationship between Current and Axial Temperature for High Voltage Overhead Conductor

不同电流时的高压架空导线轴向温度分布对输电系统安全运行具有重要意义。根据热平衡原理,提出了基于状态方程形式的轴向热路模型。为验证模型精度,设计了导线温度测量实验平台,利用接续管使实验导线轴向产生温度分布,在自然对流条件下对不同电流时的LGJ—400导线和LJG—240导线轴向温度进行了实测。利用线性回归方法,对模型中导热热阻和对流热阻进行了灰箱辨识。热阻辨识结果表明在环境条件相对稳定时,随着导线电流及平均实验数据所用时间窗长度的增加,导线导热热阻呈增大趋势,对流热阻呈减小趋势。通过求解轴向热路模型时域响应,得到了导线温度分布计算值。与实验结果对比表明,热路模型计算结果平均误差在3%以内,精度高于IEEE标准模型,能够用于计算自然对流下LGJ—400导线和LJG—240导线的轴向温度分布。

High voltage overhead conductor axial temperature distribution with various current is significant for the safe operation of electricity transmission system. An axial thermal circuit model in the form of state equation was proposed based on thermal equilibrium principle. The overhead conductor temperature measurement experiment platform which fitted with a connecting tube to generate axial temperature distribution was set up for verification of model accuracy. The LGJ--400 and LGJ--240 overhead conductor axial temperature with various current were measured under the condition of natural convection. The thermal conduction resistance and thermal convection resistance in the thermal circuit model were identified by grey box identification based on linear regression. The identification result of thermal resistance show that with the increasing current level arid length of time window for experimental result average calculating operation, the thermal conduction resistance trends to be larger and the thermal convection resistance moves toward smaller under relatively stable environmental condition. The calculation results of overhead conductor axial temperature distribution with various current were obtained by solving time response of proposed model. Comparison of calculation results and experimental results shows that the average calculation error of proposed model is less than 3%. The accuracy of proposed model is better than IEEE standard model, and it earl be used to calculate LGJ-400 and LGJ-240 overhead conductor axial temperature distribution with various current under the condition of natural convection.