本文關(guān)鍵詞： MATLAB仿真 三相電壓不平衡度 消弧線圖　出處：《大連理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：電力系統(tǒng)在正常運(yùn)行及事故狀態(tài)下均會(huì)發(fā)生三相電壓不平衡,本文主要分析的是系統(tǒng)在正常運(yùn)行時(shí)發(fā)生的三相電壓不平衡現(xiàn)象。闡述了系統(tǒng)三相電壓不平衡對(duì)發(fā)電、供電、輸電及配電環(huán)節(jié)中各種用電設(shè)備造成的損害,并通過(guò)公式,計(jì)算了三相電壓不平衡時(shí)變壓器的容量損耗以及輸電線路的不平衡附加線損值。本文針對(duì)以下幾種引起三相電壓不平衡的不同起因,進(jìn)行了研究分析：1、當(dāng)電力系統(tǒng)的配出線路基本為架空線,且沒(méi)有進(jìn)行換位,導(dǎo)致三相對(duì)地電容不平衡時(shí),將出現(xiàn)中性點(diǎn)位移電壓,引發(fā)三相電壓不平衡現(xiàn)象。2、中性點(diǎn)經(jīng)消弧線圈接地的系統(tǒng)中,消弧線圈將放大三相電壓的不平衡度。還容易與系統(tǒng)中的線路、母線等容性元件產(chǎn)生諧振,引起三相電壓的劇烈波動(dòng),對(duì)電力系統(tǒng)危害極大。3、電力系統(tǒng)處于欠補(bǔ)償運(yùn)行時(shí),出現(xiàn)開關(guān)合閘、單相接地等擾動(dòng)激發(fā)導(dǎo)致電磁式電壓互感器鐵心磁飽和,從而產(chǎn)生鐵磁諧振,引起三相電壓不平衡。4、在大連地區(qū),普遍存在三相負(fù)荷不平衡現(xiàn)象,特別電氣化鐵路的牽引機(jī)車及煉鋼、電解鋁等沖擊性負(fù)荷大量分布各地。雖然在入網(wǎng)時(shí)考慮到盡量平均分配三相負(fù)荷,但其常伴有隨機(jī)性與非同時(shí)性,表現(xiàn)為三相不平衡負(fù)荷,導(dǎo)致三相電壓不平衡。5、電力系統(tǒng)在發(fā)生單相接地、線路斷線以及諧振等異常時(shí),也會(huì)發(fā)生三相電壓不平衡現(xiàn)象。本課題以大連某個(gè)三相電壓不平衡度超出國(guó)家標(biāo)準(zhǔn)的66kV系統(tǒng)為例,利用MATLAB軟件中的simulink工具箱,根據(jù)實(shí)際的運(yùn)行參數(shù),建立仿真模型。并提出在相電壓最低的線路末端加裝電容器的方法來(lái)降低三相電壓不平衡度。通過(guò)仿真分析,驗(yàn)證該方法的可能性。本文的研究方法和結(jié)果為降低大連地區(qū)三相電壓不平衡度提供一種簡(jiǎn)單的方法。
[Abstract]:Three-phase voltage imbalance will occur in power system under normal operation and accident. This paper mainly analyzes the phenomenon of three-phase voltage imbalance in normal operation. Damage caused by various electrical equipment in transmission and distribution links, and through formulas, The capacity loss of transformer and the additional line loss of unbalanced transmission line are calculated when the three-phase voltage is unbalanced. When the distribution line of the power system is basically an overhead line and no transposition is carried out, the neutral displacement voltage will appear when the capacitance of the power system is unbalanced and the relative capacitance is unbalanced. In a system where the neutral point is grounded by an arc-suppression coil, the arc-suppression coil will amplify the unbalance of the three-phase voltage. It is also easy to resonate with the lines and bus lines of the system. It causes severe fluctuation of three-phase voltage, which is harmful to the power system. When the power system is in undercompensated operation, the switching and closing, single-phase earthing and other disturbance excitation lead to magnetic saturation of the core of the electromagnetic voltage transformer, which results in ferroresonance. Causes three-phase voltage imbalance. 4. In Dalian area, three-phase load imbalance is common, especially traction locomotive and steel-making of electrified railway, The impact load of electrolytic aluminum is widely distributed all over the world. Although the three-phase load is considered as evenly as possible when entering the network, it is often accompanied by randomness and non-synchronization, which is manifested as three-phase unbalanced load. Leading to unbalance of three-phase voltage. 5, when the single-phase grounding, line breakage, resonance and other anomalies occur in the power system, Three-phase voltage imbalance will also occur. Taking a 66 kV system with a three-phase voltage unbalance degree exceeding the national standard as an example, using the simulink toolbox in MATLAB software, according to the actual operation parameters, The simulation model is established, and the method of adding capacitors at the end of the line with the lowest phase voltage is put forward to reduce the imbalance of three-phase voltage. The research methods and results in this paper provide a simple method to reduce the unbalance of three-phase voltage in Dalian area.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TM711

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本文編號(hào)：1539662