电力电缆暂态热路模型的优化分析

发布时间：2018-02-03 02:55

本文关键词： 电力电缆暂态热路模型热阻动态特性绝缘层优化分析采样频率　出处：《华南理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：电力电缆导体温度的在线监测是确切掌握电缆运行状态的重要手段，也是指导线路负荷调度、运行维护及提高线路利用率的有效方法。本文在广州供电局有限公司重点科技项目的支持下，开展了用于单芯电缆导体温度在线监测的暂态热路模型研究，主要工作如下： 1.电缆各层材料热阻的动态特性研究。提出了铝护套至导体间的热阻物理模型，分析了温度对热阻的影响，通过电缆载流温升实验得到实验热阻值随温度的变化曲线，定量分析了其变化规律，并对比热阻的理论计算值和实验值，为电缆载流量的计算和导体温度在线监测提供了依据。 2.电缆暂态热路模型的优化建模研究。详细论证了电缆暂态热路模型的构建及模型本身的误差，通过引入热扩散率得到电缆各层对传热的影响，然后重点针对绝缘层的建模进行优化分析，，构建了绝缘层按照等厚度、厚度比、等热容、热容比四种方法建模的暂态热路模型，编辑Matlab程序实现绝缘层在四种建模方法下的任意分层，并结合电缆载流温升实验，定量分析了绝缘层分层数对模型误差的影响规律，得到实验电缆的最优暂态热路模型。 3.采样频率和模型结构对误差的共同影响。在分析电缆热时间常数的基础上，通过实验得到不同采样频率下电缆导体温度的变化速率，论证了电缆暂态热路模型可以由积分解变换为差分解，并在上述四种暂态热路模型的基础上，重点研究工程应用中极其重要的采样频率对模型误差的影响，结合电缆载流温升实验得到采样频率和模型结构对误差的共同影响，为电缆暂态热路模型的工程应用打下基础。
[Abstract]:On-line monitoring of the conductor temperature of power cable is an important means to master the operating state of the cable, and it is also an important means to guide the load dispatching of the line. Under the support of the key science and technology project of Guangzhou Power supply Bureau Ltd, the transient heat path model for the on-line monitoring of conductor temperature of single core cable is studied in this paper. The main tasks are as follows: 1. Research on the dynamic characteristics of thermal resistance of different layers of cable. A physical model of thermal resistance between aluminum sheath and conductor is proposed, and the influence of temperature on thermal resistance is analyzed. The curves of experimental heat resistance with temperature are obtained by the experiment of cable current temperature rise. The variation law of thermal resistance is quantitatively analyzed, and the theoretical and experimental values of thermal resistance are compared. It provides the basis for the calculation of cable load current and the on-line monitoring of conductor temperature. 2. Research on the optimal modeling of cable transient thermal circuit model. The construction of cable transient thermal circuit model and the error of the model itself are demonstrated in detail, and the influence of each layer of cable on heat transfer is obtained by introducing thermal diffusivity. Then the optimization analysis is focused on the insulation layer modeling, and the transient heat path model is built according to the constant thickness, thickness ratio, equal heat capacity and heat capacity ratio. The arbitrary stratification of insulation layer under four modeling methods is realized by editing Matlab program, and the influence of insulation layer number on model error is quantitatively analyzed in combination with the experiment of cable current carrying temperature rise. The optimal transient thermal circuit model of experimental cable is obtained. 3. The influence of sampling frequency and model structure on the error. Based on the analysis of cable thermal time constant, the temperature change rate of cable conductor at different sampling frequencies is obtained by experiments. It is demonstrated that the cable transient thermal circuit model can be transformed from integral solution to differential decomposition. On the basis of the above four transient heat path models, the influence of sampling frequency on the model error is studied. The influence of sampling frequency and model structure on the error is obtained by combining the current carrying temperature rise experiment of cable, which lays a foundation for the engineering application of cable transient thermal circuit model.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM247

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