交流XLPE电缆线路改为直流运行时的载流量及绝缘层电场分析

发布时间：2018-04-18 00:07

本文选题：交流XLPE电缆 + 增容改造　；参考：《东北电力大学》2017年硕士论文

【摘要】：线路增容改造不仅可以充分利用原有输电走廊,而且还能大幅提高线路的输送能力。随着直流输电技术的成熟,将交流电缆线路改造为直流运行已成为线路增容改造的有效技术方案。交流电缆改为直流运行后,其直流载流量的计算以及绝缘电场分布的研究对电缆安全运行具有重要意义。本文以YJLW03-48/66kV-400mm2型单芯交流电缆为研究对象,分析改为直流运行后的载流量以及绝缘电场。首先从传热学角度分析了电缆的热特性;使用解析法、数值法和试验法分析了空气中敷设交流交联聚乙烯(XLPE)电缆的直流载流量。然后,采用解析法计算了三相交流直埋敷设交流电缆的交流载流量;结合实际增容改造工程,计算了直埋电缆改为双极直流运行时的载流量。最后,分析了交流电缆材料在直流电压下的电导率特性,建立了电导率-(温度、场强)数学模型;借助COMSOL多物理场软件对交流电缆改为直流运行时的绝缘电场进行仿真;开展了型式试验,对电缆进行全面校验,并对电缆线路改为直流运行的增容效果进行了评估。通过试验确定了空气中敷设交流XLPE电缆的直流载流量,且验证了解析法在计算高压电缆(66 kV)直流载流量的准确性;确定了土壤直埋敷设下交流电缆改为直流运行时的载流量(710 A);电缆在100%负荷时,绝缘层电场发生明显翻转;交流电缆通过电气型式试验的校验,计算了改造后的增容倍数。研究成果不仅能为东北地区城市电网66 kV电缆线路增容改造提供技术支持,而且还为未来交流电缆线路改为直流运行奠定基础。
[Abstract]:The line capacity increase can not only make full use of the original transmission corridor, but also greatly improve the transmission capacity of the line.With the maturity of HVDC transmission technology, transforming AC cable line into DC operation has become an effective technical scheme for line capacity increase and transformation.The calculation of DC current and the study of insulation electric field distribution are of great significance to the safe operation of AC cable.In this paper, YJLW03-48/66kV-400mm2 single core AC cable is taken as the research object, and the carrier current and insulation electric field after switching to DC operation are analyzed.The thermal characteristics of the cable are analyzed from the point of view of heat transfer, and the DC current of the AC XLPE cable laid in the air is analyzed by analytical method, numerical method and experimental method.Then, the AC load current of the three-phase AC direct-buried AC cable is calculated by analytical method, and the DC current when the buried cable is changed to bipolar DC operation is calculated.Finally, the electrical conductivity characteristics of AC cable materials under DC voltage are analyzed, and a mathematical model of conductivity (temperature, field strength) is established, and the insulation electric field of AC cable is simulated by COMSOL multi-physical field software.The type test was carried out, the cable was checked and the capacitive effect of the cable line changed to DC operation was evaluated.The DC current of AC XLPE cable laid in air is determined by experiments, and the accuracy of analytical method in calculating DC current of high voltage cable (66 kV) is verified.It is determined that the AC cable under direct buried soil is replaced by DC operation, the electric field of the insulation layer is obviously reversed when the cable is under 100% load, and the capacity increase multiple after modification is calculated by checking the electrical type test of the AC cable.The research results can not only provide technical support for the capacity increase and transformation of 66 kV cable lines in Northeast China urban power grid, but also lay a foundation for the conversion of AC cable lines to DC operation in the future.
【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

【参考文献】