采用Laplace方法的单芯电缆线芯温度动态计算

Dynamic Calculation of Core Temperature of Single Core Cables Using Laplace Method

电缆线芯温度是电缆安全运行的重要参数。针对电缆线芯温度难于实时监测的问题,结合电缆传热学原理,提出基于电缆实际运行电流和表面温度计算电缆线芯温度的方法。首先建立电缆线芯温度动态计算的热路模型,进一步推导出计算电缆线芯温度的Laplace热路模型;然后剖分连续运行电流为阶跃输入值,并代入基于集中参数法所建立的Laplace热路模型,从而实现连续变化电流作为电缆线芯温度计算的实时输入量。通过试验研究和误差分析,基于电缆表面温度和实际运行电流实时计算线芯温度方法可以满足线芯温度实时监测,进一步研究分析能够实现载流量预测。

In order to achieve the real-time calculation of cable core temperature,according to principles of heat transfer,we proposed a way of calculating cable core temperature based on the actual operating current and the cable surface temperature,and studied the dynamic response of cable core temperature based on the core temperature.Changes of actual running currents result in dynamic response of cable core temperature.In order to input the actual continuously changing real-time current into real-time calculation model of cable core temperature,we set up an equivalent Laplace thermal model of single-core cable according to cable core thermal circuit model.A reference and theoretical support for real-time calculations model of cable continuously are provided by changing current in the actual operating into the step input current,so as to achieve a continuously changing current as the input parameters in calculating the cable core real-time temperature.The thermal circuit model which is able to calculate the core real-time temperature is established by the above analysis.The test and operation data can prove effectiveness and feasibility of cable core real-time temperature model,which can calculate core temperature and cable temperature field by the actual cable surface temperature and the actual running real-time current.