【摘要】：絕緣子污閃是造成電力系統(tǒng)安全運(yùn)行故障的主要原因之一。通過(guò)對(duì)絕緣子的動(dòng)態(tài)積污特性的研究,可以了解絕緣子表面動(dòng)態(tài)積污機(jī)理及絕緣子在復(fù)雜環(huán)境條件下的積污狀況;從而可以采取有效措施來(lái)減小絕緣子表面積污,以及降低污閃發(fā)生的概率。絕緣子積污過(guò)程是大氣環(huán)境中的污穢顆粒與絕緣子表面相互作用并耦合的過(guò)程,國(guó)內(nèi)外學(xué)者使用過(guò)多種方法進(jìn)行絕緣子積污特性的分析研究,但都沒(méi)有采用離散元方法(DEM)和計(jì)算流體動(dòng)力學(xué)方法(CFD)耦合的技術(shù)對(duì)絕緣子的積污特性進(jìn)行數(shù)值分析。文章引入離散元技術(shù),通過(guò)建立動(dòng)態(tài)積污模型,分析絕緣子動(dòng)態(tài)積污特性,然后采用DEM-CFD耦合技術(shù)對(duì)標(biāo)準(zhǔn)型和防污型兩種棒狀絕緣子表面動(dòng)態(tài)積污過(guò)程進(jìn)行數(shù)值模擬,并分析污穢顆粒在絕緣子表面沉降的特性,從而根據(jù)地勢(shì)環(huán)境、氣候條件以及污穢類型等各種影響因素對(duì)絕緣子進(jìn)行選型和安裝。文章首先分析絕緣子的動(dòng)態(tài)積污過(guò)程,建立了顆粒在外流場(chǎng)運(yùn)動(dòng)、顆粒與絕緣子表面接觸粘附的動(dòng)態(tài)積污模型。通過(guò)對(duì)積污模型的計(jì)算和分析,得到灰塵顆粒從絕緣子表面脫附所需的最小水平風(fēng)速。然后根據(jù)離散元方法和計(jì)算流體力學(xué)方法耦合技術(shù),利用仿真軟件EDEM和FLUENT,選擇合適的數(shù)值耦合模擬方法,采用RNG k-ε湍流模型對(duì)空氣流場(chǎng)進(jìn)行數(shù)值計(jì)算,采用JKR模型進(jìn)行顆粒和絕緣子表面的接觸分析,并分析耦合域內(nèi)污穢顆粒的動(dòng)力學(xué)特性;采用歐拉耦合的方法模擬污穢顆粒在絕緣子表面的沉積過(guò)程,并考慮湍流脈動(dòng)及表面能對(duì)顆粒擴(kuò)散的影響,從而得到絕緣子表面的積污特性,在得到了絕緣子外部流場(chǎng)以及絕緣子表面污穢顆粒累積特性的基礎(chǔ)上,分析了氣流速度、來(lái)流角度、粒徑和絕緣子安裝傾角等對(duì)絕緣子動(dòng)態(tài)積污特性的影響。論文研究結(jié)果表明:重力沉降的臨界水平風(fēng)速與粒徑呈二次函數(shù)關(guān)系;顆粒脫附所需的最小水平風(fēng)速隨粒徑呈負(fù)一次冪函數(shù)分布,粒徑越小,顆粒吸附性越好,越易粘附在絕緣子表面,粒徑增加,顆粒碰撞反彈概率增加,顆粒脫附性能提高;顆粒與上表面碰撞的入射角度小于與下表面碰撞的入射角度,傘裙下表面積污比上表面嚴(yán)重;絕緣子親水性對(duì)顆粒粘附性能影響最大,顆粒潤(rùn)濕性對(duì)粘附性能影響最小;對(duì)于已粘附顆粒,需要風(fēng)力剪切流速大于30.8m/s時(shí),顆粒才會(huì)被清除。一定時(shí)間內(nèi),絕緣子表面粘附的污穢顆粒數(shù)隨時(shí)間呈線性增長(zhǎng)趨勢(shì);隨著風(fēng)速的增加,顆粒粘附速率先增加,然后逐漸下降,粘附速率最大時(shí)對(duì)應(yīng)的風(fēng)速為最適合積污風(fēng)速,最適積污風(fēng)速隨粒徑的增加逐漸降低,降低幅度越來(lái)越小;當(dāng)來(lái)流角度為135°左右時(shí),顆粒粘附速率最大;來(lái)流角度的變化使顆粒與絕緣子下表面二次碰撞大于上表面,增大了上表面積污。當(dāng)絕緣子軸線、風(fēng)向和重力方向不在同一平面內(nèi)且互相垂直時(shí),積污速率最快,但此時(shí)絕緣子安裝傾角對(duì)積污速率的變化影響不大;絕緣子安裝角度主要對(duì)絕緣子軸線、風(fēng)向和重力方向在同一平面內(nèi)時(shí)的絕緣子積污速率變化影響較大;因此,可以根據(jù)不同工況下絕緣子表面積污特性,指導(dǎo)不同地區(qū)絕緣子的安裝,以便減小絕緣子表面積污;同時(shí),可以觀察絕緣子表面積污狀態(tài),對(duì)絕緣子表面可視化清洗提供指導(dǎo)。
[Abstract]:The flashover of the insulator is one of the main causes of the safe operation of the electric power system. Through the study of the characteristics of the dynamic accumulation of the insulator, it is possible to know the mechanism of the surface dynamic accumulation of the insulator and the pollution condition of the insulator under the complicated environmental conditions, so that the surface area of the insulator can be reduced by taking effective measures, and the probability of the occurrence of the pollution flashover can be reduced. The pollution process of the insulator is the process of the interaction and coupling between the pollution particles in the atmospheric environment and the surface of the insulator, and the domestic and foreign scholars have used a variety of methods to analyze the characteristics of the pollution of the insulator. However, no discrete element method (DEM) and computational fluid dynamics (CFD) coupling technique are used to analyze the pollution characteristics of the insulator. In this paper, the discrete-element technique is introduced, and the dynamic accumulation and pollution characteristics of the insulator are analyzed by establishing a dynamic soil-accumulation model, and then a DEM-CFD coupling technique is adopted to perform numerical simulation on the surface dynamic accumulation process of the two rod-shaped insulator surfaces of the standard type and the anti-fouling type, And the characteristics of the settlement of the pollution particles on the surface of the insulator are analyzed, and the type selection and the installation of the insulators are carried out according to various influencing factors such as the terrain environment, the climatic conditions and the pollution type. In this paper, the dynamic deposition process of the insulator is analyzed, and the dynamic deposition model of the particle contact and adhesion between the particles and the surface of the insulator is established. The minimum horizontal wind speed required for desorption of the dust particles from the surface of the insulator is obtained by the calculation and analysis of the pollution model. and then using the simulation software EDEM and FLUENT to select a suitable numerical coupling simulation method according to the discrete element method and the computational fluid dynamics method, and the dynamic characteristics of the dirty particles in the coupling domain are analyzed, the deposition process of the dirty particles on the surface of the insulator is simulated by the method of the Euler coupling, the influence of the turbulent fluctuation and the surface energy on the particle diffusion is taken into account, the pollution characteristics of the surface of the insulator are obtained, On the basis of obtaining the external flow field of the insulator and the accumulation characteristics of the dirty particles on the surface of the insulator, the effect of the gas flow velocity, the flow angle, the particle size and the installation angle of the insulator on the dynamic fouling characteristics of the insulator is analyzed. The results of the research show that the critical horizontal wind speed of the gravity settlement is the quadratic function relation with the particle size, the minimum horizontal wind speed required by the particle desorption is distributed with a negative power function with the particle size, the smaller the particle size, the better the particle absorption, the more easily adhered to the surface of the insulator, the particle size is increased, the particle collision rebound probability is increased, the particle desorption performance is improved, the incident angle of the collision between the particles and the upper surface is smaller than the incident angle of the collision with the lower surface, the surface area of the umbrella skirt is more serious than the upper surface, and the hydrophilicity of the insulator is the biggest influence on the adhesion performance of the particles, The particle wettability has a minimum effect on the adhesion performance; for the adhered particles, the particles will be removed only when the wind shear flow rate is greater than 30.8 m/ s. During a certain period of time, the number of dirty particles adhered to the surface of the insulator increases linearly with time, The optimum pollution-free wind speed decreases with the increase of the particle size, and the decreasing range is smaller and smaller; when the flow angle is about 135 擄, the particle adhesion rate is the most; the change of the flow angle causes the secondary collision of the particles and the lower surface of the insulator to be larger than the upper surface, and the upper surface area is increased. when the axis of the insulator, the wind direction and the gravity direction are not in the same plane and are perpendicular to each other, the pollution rate is the fastest, when the wind direction and the gravity direction are in the same plane, the change of the pollution rate of the insulator is relatively large; therefore, the installation of the insulator in different regions can be guided according to the characteristics of the surface area pollution of the insulator under different working conditions, so that the surface area of the insulator is reduced; and meanwhile, The surface area of the insulator can be observed, and the visual cleaning of the surface of the insulator can be provided.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM216

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本文編號(hào)：2510892