基于热路模型的架空导线暂态载流量研究

Research of Transient Allowed Current of Overhead Lines Based on Thermal Circuit Model

架空导线允许载流量是线路安全运行的重要参数,深入分析了稳态载流量及暂态载流量的计算原理。由于导线自身热容的缘故,外界条件(环境条件或者加载电流)发生跃变时,导线温度处于暂态过程。以热电比拟为基础,通过监测导线温度及环境温度建立了架空导线暂态热路模型,得出了导线暂态允许电流-允许时间-允许温升数学模型。根据暂态热路模型可以实现暂态允许电流的实时计算,为确保线路出现N-1故障或者短时过负荷时的正常运行提供方便,并提出了预先调度的概念。最后,对暂态载流量计算模型进行了试验验证,试验结果与理论计算基本一致,且理论计算允许时间偏于保守。

The allowed current of overhead lines is an important parameter to safe operation of lines. The calculation principle of steady ampacity and transient ampacity were analyzed deeply. When the external conditions （environmental condition or load current） changed, the temperature of overhead lines was in transient state because of the heat capacity of conductors. The transient thermal circuit model of overhead lines was built by monitoring the conductor temperature and environmental temperature based on thermoelectrical analogy, and the mathematical model of transient allowed current-allowed time-allowed rising temperature was obtained. The transient allowed current can be calculated timely based on the transient thermal circuit mode, which was able to provide help for the normal operation of overhead lines when the lines appeared N-1 fault or short time overload. The transient allowed currents were compared under different initial temperatures of overhead lines, and the concept of pre-schedule was proposed. Finally, the calculation model of transient allowed current was proved by experiment, the experimental result was consistent with the theory calculated value, and the theory calculated value was conservative.