周夢(mèng)迪 彭彥卿 莊志堅(jiān)
摘 ?要: 基于Mayr電弧電路模型和Cassie電弧電路模型,考慮縱向氣流吹弧效應(yīng),對(duì)電弧電壓梯度[U]和電弧耗散功率[P0]進(jìn)行修正,建立降弓電弧電路分析模型。研究降弓速度、降弓時(shí)刻以及降弓電弧電流對(duì)降弓電弧電壓的影響。發(fā)現(xiàn)降弓電弧電壓呈現(xiàn)近似線性的增長(zhǎng)關(guān)系,降弓速度越高,降弓電弧電壓增長(zhǎng)得越快。降弓時(shí)刻對(duì)于電弧電壓的影響主要體現(xiàn)在電弧電壓出現(xiàn)的時(shí)刻差異,降弓電弧電壓的波形基本一致。不同電弧電流情況下,電弧電壓基本一致。文中的研究對(duì)于指導(dǎo)降弓操作、減輕弓網(wǎng)材料損失具有重要意義。
關(guān)鍵詞: 弓網(wǎng)電弧; 降弓電弧; 降弓速度; 降弓時(shí)刻; 電弧電流; 電弧電壓
中圖分類號(hào): TN710?34 ? ? ? ? ? ? ? ? ? ? ? ? ?文獻(xiàn)標(biāo)識(shí)碼: A ? ? ? ? ? ? ? ? ? ? ? ? 文章編號(hào): 1004?373X(2019)19?0159?05
Abstract: The dropping pantograph arc circuit model is established based on the Mayr arc circuit model and the Cassie arc circuit model. In the model, the arc voltage gradient [U] and the dissipation power [P0] are modified, and the longitudinal flow arc blowing effect is taken into consideration. The effects of the dropping speed, the dropping time and the arc current on the arc voltage are studied. It is found that the arc voltage increases linearly with time. The higher the dropping speed is, the faster the arc voltage increases. The effect of the dropping time on arc voltage is mainly reflected in the time difference of arc voltage, and the waveform of arc voltage is basically the same. The arc voltage is basically the same under different arc current conditions. The research in this paper is of great significance for guiding the operation of dropping pantograph and reducing the loss of pantograph?catenary material.
Keywords: pantograph?catenary arc; dropping pantograph arc; dropping pantograph speed; lowering time; arc current; arc voltage
隨著國(guó)民經(jīng)濟(jì)的迅速發(fā)展,鐵路運(yùn)輸向更高速度、更大運(yùn)載量、更加安全穩(wěn)定的方向發(fā)展,以滿足人們對(duì)于運(yùn)輸時(shí)效性以及運(yùn)輸量的迫切需求。弓網(wǎng)系統(tǒng)作為列車獲取電能的唯一途徑,對(duì)于保證列車高速、安全、穩(wěn)定運(yùn)行十分重要[1?2]。然而,由于列車運(yùn)行速度逐步提升導(dǎo)致振動(dòng)加劇、接觸線覆冰、升降弓操作等引起受電弓滑板與接觸線分離,造成弓網(wǎng)之間的空氣間隙被擊穿而形成弓網(wǎng)電弧。弓網(wǎng)電弧不僅使車載電氣設(shè)備承受高頻振蕩過(guò)電壓,還會(huì)燒蝕受電弓滑板、接觸網(wǎng)導(dǎo)線,輕者縮短弓網(wǎng)系統(tǒng)使用壽命,重者燒斷接觸導(dǎo)線,造成重大事故[3?5]。弓網(wǎng)離線電弧嚴(yán)重制約和影響了列車提速和運(yùn)行安全。
文獻(xiàn)[6]中根據(jù)瞬態(tài)熱傳導(dǎo)理論建立了弓網(wǎng)電弧燒蝕模型,分別對(duì)靜態(tài)電弧和運(yùn)動(dòng)電弧在兩種熱流輸入的情況下接觸線的熱過(guò)程進(jìn)行了仿真計(jì)算,結(jié)果表明靜態(tài)電弧比運(yùn)動(dòng)電弧對(duì)接觸線的電氣侵蝕程度更為嚴(yán)重。對(duì)于列車振動(dòng)、接觸線覆冰導(dǎo)致的弓網(wǎng)電弧,由于列車處于運(yùn)行狀態(tài),弓網(wǎng)之間具有相對(duì)運(yùn)動(dòng),電弧對(duì)于弓網(wǎng)材料的燒蝕較輕。而列車進(jìn)行降弓操作時(shí),列車處于靜態(tài),降弓導(dǎo)致的電弧對(duì)于弓網(wǎng)材料將會(huì)產(chǎn)生更為嚴(yán)重的損傷。因此,針對(duì)降弓電弧展開研究對(duì)于指導(dǎo)降弓操作、減輕弓網(wǎng)材料損失具有重要意義。
2.3 ?降弓電弧電流對(duì)降弓電弧電壓的影響
為了分析降弓過(guò)程降弓電弧電流對(duì)降弓電弧電壓的影響,研究不同降弓電弧電流對(duì)降弓電弧電壓的影響。
圖5顯示了降弓過(guò)程中降弓電弧電流的變化情況。由圖可知,隨著降弓過(guò)程的進(jìn)行,降弓電弧電流的幅值逐漸減小,主要原因可能是電弧逐漸增長(zhǎng)造成回路電阻值逐漸增大,使得回路的電流逐漸降低。
不同電弧電流時(shí)的降弓電弧電壓如圖6所示。由圖6可知,不同電弧電流情況下,電弧電壓基本一致。由電弧電壓與電流的關(guān)系可知,1~50 A范圍內(nèi)電弧電壓隨著電弧電流的增大而逐漸減小,主要是因?yàn)殡娀‰娏髟龃笫沟秒娀囟壬撸M(jìn)而使得電弧電阻減小。而在電流大于50 A以后,電弧電壓基本不變。
盡管電弧電流對(duì)于電弧電壓的影響不大,但是電流的增大使得電弧的燃弧強(qiáng)度增強(qiáng),對(duì)于弓網(wǎng)材料的威脅也會(huì)進(jìn)一步加大。因此,應(yīng)當(dāng)避免大電流情況下的降弓操作。
本文研究了降弓電弧的電氣特性,以及降弓速度、降弓時(shí)刻和降弓電弧電流對(duì)降弓電弧電壓的影響,得出如下結(jié)論:
1) 基于Mayr電弧模型和Cassie電弧模型,將Mayr電弧模型與Cassie電弧模型進(jìn)行串聯(lián),通過(guò)修正電弧電壓梯度[U]和電弧耗散功率[P0],建立降弓電弧電路模型。
2) 研究不同降弓速度對(duì)電弧電壓的影響,發(fā)現(xiàn)降弓電弧電壓呈現(xiàn)近似線性的增長(zhǎng)關(guān)系。降弓速度越高,降弓電弧電壓增長(zhǎng)得越快。通過(guò)增大降弓速度可以加快降弓電弧的熄滅速度,減輕電弧的損傷。
3) 降弓時(shí)刻對(duì)于電弧電壓的影響主要體現(xiàn)在電弧電壓出現(xiàn)的時(shí)刻差異,降弓電弧電壓的波形基本一致。降弓時(shí)刻為0°時(shí),電弧發(fā)生在0.042 s。降弓時(shí)刻從90°變化到360°時(shí),電弧發(fā)生時(shí)刻也從0.047 s增長(zhǎng)到了0.062 s。降弓時(shí)刻對(duì)應(yīng)的接觸網(wǎng)電壓卻有所不同,降弓產(chǎn)生的過(guò)電壓將會(huì)嚴(yán)重威脅列車設(shè)備。因此,可以考慮采用選相降弓裝置減輕降弓過(guò)電壓的影響。
4) 不同電弧電流情況下,電弧電壓基本一致。盡管電弧電流對(duì)于電弧電壓的影響不大,但是電流的增大使得電弧的燃弧強(qiáng)度增強(qiáng),對(duì)于弓網(wǎng)材料的威脅也會(huì)進(jìn)一步加大。因此,應(yīng)當(dāng)避免大電流情況下的降弓操作。
注:本文通訊作者為彭彥卿。
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