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基于量纲分析的电网防冰临界电流研究

发布时间:2018-09-14 20:28  文章来源:笔耕文化传播
【摘要】:覆冰威胁电网的安全运行,影响电力的安全输送,扰乱人民的日常生活,我国是世界上架空线路遭受冰灾较严重的国家之一,覆冰事故频发给电力系统带来巨大的经济损失。随着西电东送、超高压输电等建设的进行,我国电网覆盖面积越来越大,经过的恶劣地理环境越来越多,越来越容易受到覆冰事故的影响,加之全球气候愈加恶劣,覆冰带来的威胁越来越严峻。解决架空输电线路覆冰问题,具有重要的工程应用意义。本文对线路覆冰的影响因素、形成条件,飞机、铁路接触网、输电线路覆冰的危害,输电线路覆冰的特点,覆冰在线监测和除冰方法进行了介绍,概述了国内外防冰技术研究进展,总结了现有研究的不足,介绍了国内外专家学者提出的防冰临界电流理论模型,简述了计算临界电流时需要用到的几种较为经典的对流换热准则公式与实验关联式,由此提出了本文的主要研究内容。本文根据量纲分析建模理论,首次运用量纲分析法,在对影响防冰临界电流的主要因素进行全面分析的基础上,根据Π定理,得出了与之相关的一系列无量纲量(5个),这些无量纲量是气象参数(气温、风速、空气中液态水含量、液滴直径)与导线参数等的组合,经过进一步推导得出了与临界电流有关的无量纲量,分析了各无量纲量的物理意义。介绍了冰风洞实验,并运用导线覆冰临界状态热平衡方程,导出了对流换热系数的计算模型,利用冰风洞实验数据得出一定条件下的对流换热系数,使用数据分析软件拟合得到努谢尔数与对应的雷诺数的关联式,分析了与其他较经典的经验公式的区别与联系,分析了实验误差。在此基础上,利用实验所得无量纲数据分析了无量纲量的变化规律,根据非线性回归分析方法,分别运用主成分分析法、多项式拟合法和指数乘积拟合法对得到的无量纲量进行了拟合,得到了计算临界电流的理论模型,并计算了相对误差和平均相对误差,与热平衡模型计算结果进行了比较,验证了实验的准确性,结果表明,运用量纲分析建模结合指数乘积拟合法进行防冰临界电流研究是可行的。本文提出的防冰临界电流量纲分析建模方法,在国内首次使用,得到的防冰临界电流准则公式为电网进行临界电流防冰提供了理论支撑,具有一定的工程应用意义。
[Abstract]:Icing threatens the safe operation of power grid, affects the safe transmission of electric power, and disturbs the daily life of people. China is one of the countries with serious ice disasters on overhead lines in the world, and the frequent occurrence of icing accidents brings huge economic losses to the power system. With the construction of power transmission from west to east and ultra-high voltage transmission, the area of power grid in our country is more and more large, the bad geographical environment is more and more, more and more vulnerable to the influence of icing accidents, and the global climate is becoming more and more bad. The threat of icing is becoming more and more serious. It is of great significance to solve the icing problem of overhead transmission lines. In this paper, the influence factors, forming conditions, aircraft, railway catenary, transmission line ice, the characteristics of transmission line icing, the on-line monitoring and deicing methods are introduced. This paper summarizes the research progress of anti-ice technology at home and abroad, summarizes the shortcomings of existing research, and introduces the theoretical model of anti-ice critical current put forward by experts and scholars at home and abroad. In this paper, several classical formulas of convection heat transfer criterion used in calculating critical current and their experimental correlations are briefly described, and the main research contents of this paper are put forward. In this paper, based on dimensional analysis modeling theory, dimensionality analysis method is used for the first time. Based on the comprehensive analysis of the main factors affecting the critical current of anti-ice, and according to the 蟺 theorem, A series of dimensionless quantities (5) are obtained, which are the combination of meteorological parameters (temperature, wind speed, liquid water content in air, droplet diameter) and traverse parameters, etc. The dimensionless quantities related to the critical current are derived and the physical meaning of the dimensionless quantities is analyzed. The ice wind tunnel experiment is introduced, and the calculation model of convective heat transfer coefficient is derived by using the heat balance equation of the critical state of conductor icing. The convection heat transfer coefficient under certain conditions is obtained by using the ice wind tunnel experimental data. The correlation between the Nuschel number and the corresponding Reynolds number is obtained by using the data analysis software. The difference and relation between the Nuschel number and the other classical empirical formulas are analyzed, and the experimental errors are analyzed. On this basis, using the dimensionless data obtained from the experiment to analyze the change of dimensionless quantity, according to the method of nonlinear regression analysis, the principal component analysis method is used respectively. The polynomial fitting method and exponential product fitting method are used to fit the dimensionless quantities, and the theoretical model for calculating critical current is obtained. The relative error and average relative error are calculated, and the results are compared with those of the thermal equilibrium model. The accuracy of the experiment is verified. The results show that it is feasible to use dimension analysis modeling and exponential product fitting to study the critical current of anti-ice. For the first time in our country, the critical current dimensionality analysis method proposed in this paper is used for the first time in China. The formula of anti-ice critical current criterion has provided the theoretical support for the critical current anti-ice of the power network, and has certain engineering application significance.
【学位授予单位】:长沙理工大学
【学位级别】:硕士
【学位授予年份】:2014
【分类号】:TM752

【参考文献】

相关期刊论文 前1条

1 魏慧玲;王闪闪;普洁;马春旺;;Origin软件多自变量多参数曲线拟合功能探究[J];河南师范大学学报(自然科学版);2012年03期



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