空气湿度对直流电晕放电影响的研究

发布时间：2018-02-16 11:49

本文关键词： 直流电晕放电相对湿度放电参数电流密度电晕起始场强电晕效应　出处：《山东大学》2014年博士论文　论文类型：学位论文

【摘要】：实施我国西电东送的能源战略,国家已经投运了多条不同等级的高压和特高压直流输电线路。特高压直流输电需要考虑输电过程中电晕放电的产生。电晕放电不但增加线路的功率损耗,还会导致无线电干扰、可听噪声等一系列的环境问题。随着经济的不断发展,环境问题越来越受到人们的关注,并受到环保法规的严格制约。这就使得电晕放电成为决定直流输电线路结构,影响建设费用的重要因素。我国特高压直流输电线路的输送距离远,工程沿线地形、地貌与气象条件复杂,不可避免地需要经过高湿度地区。因此,研究空气湿度对直流电晕放电的影响具有重要的理论意义和实际意义。本文针对空气湿度对导体电晕放电的影响进行了深入研究。系统地计算分析了空气湿度对支配电晕放电性质的参数,如电离系数、附着系数、光子吸收系数、电子和离子漂移系数以及电离层半径等的影响。基于对导体电晕起始场强的分解、对考虑湿度的电晕起始场强构成的理论分析和电晕起始场强的模拟计算,研究了Peek公式的修正。结合本文给出的修正的Peek公式,系统地计算分析了湿度对电晕效应的影响。本论文主要包含以下方面的内容和结果： (1)介绍了环境空气的组成和特性以及电晕放电中的电离、附着等物理过程。在此基础上,描述了正、负极性导体电晕放电机理,描述了正、负极性导体电离层中电荷数量密度分布的一维数学模型。 (2)电晕放电的性质与多个参数相关,即电离系数、附着系数、光子吸收系数、电子漂移速度和正离子漂移速度等。因此,空气湿度对电晕放电性质的影响将通过对这些参数的影响来产生。基于对湿空气下的各放电参数相应于干空气和水蒸气的分解,系统地计算分析了空气湿度对各放电参数的影响,得到了这些参数随空气湿度变化的规律,这就是：电离系数随湿度增大,较大的电场强度使这一影响更为显著；低场强下附着系数随湿度增大,高场强下随湿度减小；光子吸收系数随湿度增大；电子和正离子漂移速度分别随湿度增大和减小,大的电场强度使这一效应减小。此外,计算分析了湿度对导体外电离层的影响。结果表明,电离层半径随着湿度的增大而减小。 (3)基于电离层内电荷数量密度一维数学模型,计算分析了湿度对电离层内电流密度的影响,得到以下结果：对于大半径正极性导体,电流密度均随湿度减小,导体表面电场强度的增加使这一效应增强；对于小半径正极性导体,电流密度随湿度的变化基本上呈现先减小后增大的特征。电流密度随湿度减小时,导体表面电场强度的增大使这一效应减弱。电流密度随湿度增大时,导体表面电场强度的增大使这一效应增强。对于负极性导体,电流密度均随湿度增大,且这一效应随导体表面电场强度增大而增大。 (4)汤生第二电离系数是描述负直流电晕放电的一个关键参数。本文研究了不同湿度下,导体表面水分子的吸附对导体逸出功的影响,在此基础上给出了一个考虑空气湿度的汤生第二电离系数的计算方法,应用该方法计算的结果与实验符合很好。这一方法对于考虑导体表面水分子吸附时导体放电的研究具有重要的理论意义。 (5)Peek公式由于它的简单和解析的特点,长期以来一直被用来估计导体电晕起始场强。然而,该公式的局限是未考虑空气湿度的影响。目前,尚未有一个较好地估计考虑空气湿度影响的电晕起始场强的解析表达式。基于对导体电晕起始场强的分解,对考虑湿度的电晕起始场强的构成作了理论分析和推导,结合应用导体电晕起始判据的不同湿度下的电晕起始场强的系统的数值计算,对Peek公式作了修正,分别给出了考虑空气湿度的正极性和负极性导体电晕起始场强计算的修正的Peek公式。基于修正的Peek公式计算的不同湿度电晕起始场强与报道的实验结果符合很好。因此,本文给出的修正的Peek公式为不同空气湿度下的导体电晕起始场强提供了一个有效可行的理论估计。 (6)基于本文给出的修正的Peek公式,系统地计算分析了空气湿度对电晕可听噪声、电晕损耗以及无线电干扰等电晕效应的影响,得到了如下结果。湿度对电晕可听噪声的影响：对于不同半径正极性导体,大的半径和小的半径下A声计声功率级(PWL)分别随湿度减小和增大。对于不同半径负极性导体,PWL基本上随湿度增加,只是与大半径导体相比,对于小半径导体湿度对PWL的影响更为显著。对于不同半径和不同极性的导体,湿度对Lso声级(SLA)的影响基本一致,即SLA随湿度的增加而增加。湿度对电晕损耗的影响：对正极性导体,大半径和小半径导体的电晕损耗分别随湿度减小和增大。对于负极性导体,大半径导体的电晕损耗随湿度的增加先减小后增大,小半径导体的电晕损耗随湿度增大。湿度对电晕无线电干扰水平的影响：正极性导体电晕产生的无线电干扰水平随湿度减小。对于大半径导体以及大的导体表面电场强度,湿度对无线电干扰水平的影响显著。对于小半径导体,这一变化很小,且几乎不受导体表面电场强度的影响。
[Abstract]:The implementation of power transmission from west to east energy strategy of our country, the country has been put into operation of high pressure and ultra high voltage DC transmission lines and a plurality of different levels. The need to consider the UHVDC corona discharge of transmission process. The corona discharge will not only increase the loss of power lines, can cause radio interference, audible noise of a series of environmental problems. With the continuous development of economy, environmental problems have attracted more and more attention, and is restricted by the strict environmental regulations. This makes the corona discharge become DC transmission line structure, factors that influence the construction cost. The transportation distance of UHVDC transmission lines in China, along the terrain, topography and meteorology the condition is complex, inevitably requires high humidity areas. Therefore, study on the influence of air humidity on DC corona discharge has important theoretical significance and practical significance.
This paper studies the effects of air humidity on conductor corona discharge were analyzed systematically. The parameters of air humidity on corona discharge control properties, such as ionization coefficient, friction coefficient, photon absorption coefficient, influence of electron and ion drift coefficient and ionospheric radius. The decomposition of conductor corona onset electric field based on simulation the theoretical analysis and field considering corona onset corona inception of the humidity field, correction of Peek formula. Combined with the modified Peek formula is given in this paper, systematically analyzed influence of humidity on corona effect. This paper mainly contains the following contents and results:
(1) the composition and characteristics of ambient air and the physical processes such as ionization and adhesion in the corona discharge are introduced. On this basis, the corona discharge mechanism of positive and negative conductor is described, and the one-dimensional mathematical model of the number density distribution of positive and negative conductor ionosphere is described.
(2) the nature of the corona discharge associated with multiple parameters, namely the ionization coefficient, friction coefficient, photon absorption coefficient, electron drift velocity and positive ion drift velocity. Therefore, effects of air humidity on corona discharge properties by the influence of these parameters to generate various discharge parameters on the wet air. Based on the corresponding in the dry air and water vapor decomposition, systematic calculation and Analysis on influence of air humidity on the discharge parameters, obtained the law of these parameters with the variation of air humidity: the ionization coefficient with increasing humidity, electric field intensity of the larger the effect is more significant; low field strength adhesion coefficient with increasing humidity. Under high electric field with the humidity decreases with increasing humidity; photon absorption coefficient; electron and positive ion drift velocity respectively with increasing humidity and reduced electric field strength large this effect decreases. In addition, calculation analysis The effect of humidity on the outer ionosphere of the conductor shows that the radius of the ionosphere decreases with the increase of humidity.
(3) the charge number density of one dimensional mathematical model based on the analysis of the influence of humidity on the ionospheric current density calculation, get the following results: for large radius positive conductor current density increased with the increase of humidity decreases, the surface electric field strength of conductor makes this effect enhancement; for small radius anode conductor, current density with the change of moisture basically characterized first decrease and then increase. The current density decreases with increasing humidity, electric field intensity on the surface of the conductor. The current density effect decreases with increasing humidity, increase the surface electric field strength of conductor makes this effect enhanced. For the negative conductor, the current density increases with increasing humidity. The effect with the conductor surface field strength increases.
(4) second students ionization coefficient is a key parameter to describe the decoction of negative DC corona discharge. This paper studied the effects of different humidity, the adsorption of water molecules on the surface of conductor conductor work, on the basis of this gives a consideration of air humidity second Townsend ionization coefficient calculation method, calculated by this method the results are consistent with experimental data. This method has important theoretical significance for the study of the conductor and the conductor surface discharge water molecular adsorption is considered.
(5) Peek formula due to its characteristics of simple and analytical, has long been used to estimate the conductor corona onset electric field. However, the formula is limited without considering the effect of air humidity. At present, there is not yet a better estimate of the analytical expression of the effect of air humidity on corona onset electric field considering the decomposition of conductor corona. The initial field based on considering corona inception field strength humidity are analyzed and deduced, combined with the numerical system of corona inception field strength and different humidity application conductor corona onset criterion under the calculation of the Peek formula was modified. The modified Peek formula to calculate the air humidity of the positive and negative polarity conductor corona onset considering the field are given. The calculation formula of Peek based on the different humidity corona inception field strength with the reported experimental results are in good agreement. Therefore, the proposed modified The Peek formula provides an effective and feasible theoretical estimate for the starting field intensity of conductors at different air humidity.
(6) based on the modified Peek formula given in this paper, the influence of air humidity on corona audible noise, corona loss and radio interference is systematically calculated and analyzed, and the following results are obtained.
Influence of humidity on corona audible noise for different radius positive conductor, large and small radii of A sound sound power level (PWL) respectively with humidity decrease and increase. For different radius negative conductor, PWL basically with the increase of humidity, but with a large radius conductor compared to effects on small radius the conductor of humidity on PWL is more significant. For different radius and conductors of different polarity, humidity on level Lso (SLA) effect is consistent, namely SLA increased along with the increase of humidity.
Effect of humidity on corona loss of positive conductor corona loss, large radius and small radius conductor respectively with the humidity decrease and increase. For the negative conductor corona loss, large radius of conductor along with the increase of humidity decreases first and then increases, the small radius of conductor corona loss with increasing humidity.
Influence of humidity on corona radio interference level: radio interference level positive conductor corona with humidity decreases. For large radius of conductor and the conductor surface field strength, the influence of humidity on the radio interference level significantly. For small radius of conductor, this change is very small, and almost not affected by the surface field strength of conductor.

【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM851

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