直埋电力电缆载流量的有限元数值计算

发布时间：2018-08-13 12:19

【摘要】：电力电缆是输送电能的重要途径,准确计算电力电缆温度场与额定载流量对工程实际意义重大。现阶段,电缆的额定载流量根据IEC标准计算,但运行中的电缆敷设方式多样,影响载流量的可变因素众多,仅参照IEC标准计算载流量会造成一定误差,且IEC标准无法计算电缆的暂态温度。本文以有限元法为基础,分析了电缆载流量与其影响因素之间的关系,并对应急负荷下电缆的温升响应进行研究,实现对现行电缆的合理利用。首先,介绍了基于有限元法计算电力电缆温度场的基本原理。结合电力电缆的散热特性,给出了电力电缆的温度场控制方程、电缆热源和边界条件,推导了电缆温度场的计算过程,进而得到电缆稳态、暂态温度场。其次,搭建了空气中敷设的单根66kV含光纤电力电缆试验平台,在恒定负荷和变负荷的条件下开展温升试验,通过试验验证有限元法计算电缆温度场的正确性和分布式光纤测温系统测温的可靠性。最后,建立了单、双回直埋电力电缆温度场模型。对于单回直埋电力电缆,分析了空气温度、空气对流换热系数、土壤温度、土壤导热系数、电缆间距、电缆埋深与载流量之间的关系,对于双回直埋电力电缆,分析了水平一字型、上下一字形、水平三角形三种排列方式下的载流量,给出了提高和改善电力电缆载流量的合理建议。计算单线增容允许增容时间,绘制应急负荷-允许增容时间的曲线,供电力调度参考;双线增容时有双线同时增容、单线轮流增容两种方案可供选择,计算并比较两种方案所能提供的增容时间,结果表明双线同时增容可提供更长的增容时间。
[Abstract]:Power cable is an important way to transmit electric energy. It is of great significance to calculate accurately the temperature field and rated load current of power cable. At present, the rated capacity of the cable is calculated according to the IEC standard, but the cable laying mode in operation is various, and there are many variable factors that affect the carrier discharge. Only referring to the IEC standard, the calculation of the current carrying capacity will cause certain errors. And the IEC standard can not calculate the transient temperature of the cable. On the basis of finite element method, this paper analyzes the relationship between cable load and its influencing factors, and studies the response of cable temperature rise under emergency load, so as to realize the reasonable utilization of current cable. Firstly, the basic principle of calculating the temperature field of power cable based on finite element method is introduced. Combined with the heat dissipation characteristics of power cable, the control equation of temperature field, the heat source and boundary conditions of power cable are given. The calculation process of cable temperature field is deduced, and the steady and transient temperature field of power cable is obtained. Secondly, a test platform of single 66kV power cable with optical fiber was set up in the air, and the temperature rise test was carried out under the condition of constant load and variable load. The correctness of the finite element method for calculating cable temperature field and the reliability of distributed optical fiber temperature measurement system are verified by experiments. Finally, the temperature field model of single and double direct buried power cable is established. The relationship between air temperature, air convection heat transfer coefficient, soil temperature, soil thermal conductivity, cable spacing, buried depth of cable and load current is analyzed for single-circuit direct-buried power cable. This paper analyzes the load current of three kinds of arrangement modes: horizontal type, upper and lower glyph, and horizontal triangle, and gives some reasonable suggestions for increasing and improving the load current of power cable. To calculate the capacity increase time of single line, draw the curve of emergency load and allowable capacity time for the reference of electric power dispatching; when adding capacity on two lines, there are two lines to increase capacity at the same time, and the two schemes of single line alternate capacity increase can be chosen. The results show that both lines can provide longer compatibilization time.
【学位授予单位】：东北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM75

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