配电系统三芯电缆应急时间计算方法

Calculation Method for Emergency Time of Three-core Cable in Distribution System

当配电系统三芯电缆因其他线路故障或电力抢修而需施加较大的应急负荷时,其线芯温度达到最高限值前,允许过载的时间是电缆运行监测部门亟待解决的问题。文中以10 k V三芯电缆为研究对象,首先建立电缆暂态热路模型,并将应急负荷作用下电缆暂态温升分为稳态分量和五个热时间常数不同的暂态分量。其次借助数据拟合的方法确定不同暂态分量的参数,得到应急负荷作用下电缆应急时间的计算表达式。最后设计了加载不同应急负荷时三芯电缆的暂态温升实验。实验结果表明,本方法能够准确地计算电缆的应急时间,为三芯电缆的应急能力评估和电力应急调度提供依据。

When three-core cable in distribution system needs to load larger emergency loads for other line fault or power repair,the time the cable can resist the overload is an urgent issue for cable running and monitoring depart- ment.The 10kV three-core cable is taken as the research object in this paper.Firstly,a cable transient thermal cir- cuit model is established,and the transient temperature rise of the cable is divided into two parts,the steady state component and five transient components including different thermal time constant.Secondly,by means of the meth- od of data fitting,the parameters of different transient components are determined,then the calculation formula of cable emergency time is obtained under the action of emergency loads.Finally,the transient temperature rising ex- periments aredesigned under different emergency loads.The experimental results show that,using the proposed method the emergency time of cable can be calculated accurately,which provides the basis for the emergency capa- bility evaluation of the three-core cable and power emergency dispatching.