本文選題：短路電流 + 變壓器　； 參考：《華南理工大學(xué)》2014年碩士論文

【摘要】：近年來隨著廣東電網(wǎng)裝機(jī)容量和各級(jí)電壓網(wǎng)架建設(shè)的高速發(fā)展，500kV網(wǎng)架結(jié)構(gòu)大大增強(qiáng)，珠江三角洲地區(qū)基本形成了雙回路內(nèi)外環(huán)網(wǎng)的結(jié)構(gòu)。電網(wǎng)結(jié)構(gòu)的加強(qiáng)滿足了廣東電網(wǎng)負(fù)荷增長和可靠供電的需求，但同時(shí)也帶來了電網(wǎng)短路容量的問題。由于電網(wǎng)結(jié)構(gòu)加強(qiáng)，500kV變壓器采用自耦變壓器等原因，部分500kV變電站出現(xiàn)單相短路電流高于三相短路電流的現(xiàn)象，成為限制電網(wǎng)運(yùn)行和發(fā)展的主導(dǎo)因素之一，需控制單相短路電流水平的增長。目前，廣東電網(wǎng)主要通過500kV變電站分區(qū)供電的方式減小單相短路電流，但分區(qū)供電會(huì)減低整體電網(wǎng)的運(yùn)行穩(wěn)定性和可靠性，提高了電網(wǎng)運(yùn)行安全風(fēng)險(xiǎn)。 本文首先介紹了廣東電網(wǎng)的架構(gòu)特點(diǎn)，指出廣東電網(wǎng)負(fù)荷集中、網(wǎng)架結(jié)構(gòu)日益龐大，500kV變電站的220kV單相短路電流普遍高于三相短路電流水平，且逐年增大，嚴(yán)重制約電網(wǎng)穩(wěn)定運(yùn)行與發(fā)展。提出變壓器中性點(diǎn)經(jīng)小電抗器接地的方式能有效降低短路電流，能保障500kV變電站采用聯(lián)網(wǎng)供電的方式下提高電網(wǎng)運(yùn)行可靠性，并能促使變壓器中性點(diǎn)的工頻過電壓、操作過電壓也大幅下降，從而降低其絕緣水平，降低設(shè)備成本。介紹了國內(nèi)部分省級(jí)電網(wǎng)在500kV主變中性點(diǎn)加裝小電抗的成功應(yīng)用案例。 本文對(duì)變壓器加裝中性點(diǎn)小電抗的必要性進(jìn)行分析，計(jì)算了廣東電網(wǎng)在全接線方式和分區(qū)供電方式下的短路電流值，并根據(jù)單相和三相短路電流的對(duì)比，對(duì)廣東電網(wǎng)500kV變電站加裝小電抗接地的適宜性進(jìn)行評(píng)估和分類，并對(duì)各個(gè)類別的500kV變電站加裝小電抗后的短路電流進(jìn)行計(jì)算。根據(jù)對(duì)廣東現(xiàn)有500kV站的短路電流、送電能力、潮流及N-1分析的結(jié)果，并結(jié)合遠(yuǎn)景電網(wǎng)發(fā)展分析，廣東電網(wǎng)500kV變電站主變中性點(diǎn)需加裝小電抗有橫瀝站、莞城站、鵬城站、寶安站、香山站共5個(gè)變電站，且分析出橫瀝站和香山站主變加裝小電抗限制單相短路電流的效果最為明顯。 本文介紹了500kV站主變中性點(diǎn)加裝小電抗的裝設(shè)模式分為兩種，一是站內(nèi)全部主變均裝設(shè)，二是部分主變裝設(shè)。通過計(jì)算分析，同時(shí)在4臺(tái)主變裝設(shè)小電抗對(duì)單相短路電流的限制效果要優(yōu)于僅在部分主變裝設(shè)小電抗的限制作用。因此，從降低短路電流效果和經(jīng)濟(jì)效益方面綜合考慮，，建議鵬城站四臺(tái)主變中性點(diǎn)、寶安站四臺(tái)主變、莞城站四臺(tái)主變和香山站三臺(tái)主變中性點(diǎn)都裝設(shè)小電抗。 接著，論文對(duì)橫瀝站、莞城站、鵬城站、寶安站、香山站5個(gè)變電站的采用的小電抗容量進(jìn)行分析計(jì)算，計(jì)算不同大小的電抗值能降低的單相、兩相和三相短路電流，經(jīng)過經(jīng)濟(jì)和技術(shù)方面考慮，推薦橫瀝站主變裝設(shè)的小電抗均取15Ω、莞城站小電抗均取15Ω、香山站小電抗均取10Ω、鵬城站小電抗均取10Ω、寶安站小電抗均取10Ω。 論文還對(duì)500kV主變中性點(diǎn)加裝小電抗的方案進(jìn)行綜合分析，預(yù)測5個(gè)變電站加裝推薦值的小電抗后，廣東電網(wǎng)的運(yùn)行方式比安裝前得到優(yōu)化，短路電流明顯減小。另外，根據(jù)對(duì)小電抗裝設(shè)方案的綜合分析及適應(yīng)性分析結(jié)果，擬定了5個(gè)500kV變電站加裝小電抗的較為理想的時(shí)間，其中香山站建議在2010年夏季前安裝，橫瀝站、鵬城站和寶安站建議在2010年底前安裝，莞城站建議在2011年夏季前安裝。 基于對(duì)5座500kV變電站不同運(yùn)行方式的短路電流，分析和計(jì)算中性點(diǎn)入地電流和接觸電位差和跨步電位差，并選擇了變壓器中性點(diǎn)與接地串聯(lián)小電抗器之間不安裝隔離開關(guān)，只裝設(shè)接地開關(guān)的接線方式。根據(jù)設(shè)備的絕緣水平和當(dāng)?shù)氐木唧w條件，選定了66kV電抗器、66kV接地開關(guān)、66kV氧化鋅避雷器的型號(hào)和參數(shù)。 最后，制定了5座500kV變電站中性點(diǎn)加裝小電抗的一次、二次和土建實(shí)施方案，進(jìn)一步論證了加裝小電抗的可行性和適宜性。
[Abstract]:In recent years , with the high speed development of Guangdong power grid installed capacity and voltage network frame construction at all levels , 500kV grid structure has been greatly enhanced , the structure of double - loop inner and outer ring network is basically formed in the Pearl River Delta region .

In this paper , the structure characteristics of Guangdong power grid are introduced . It is pointed out that the load concentration of Guangdong power grid , the structure of grid frame is increasingly large , 220 kV single - phase short - circuit current of 500 kV substation is generally higher than that of three - phase short - circuit current , and it can effectively reduce the short - circuit current by year by year .

In this paper , the necessity of the small reactance of the neutral point of the transformer is analyzed , the short - circuit current value of the Guangdong power grid in the whole wiring mode and the divisional power supply mode is calculated . According to the comparison between the single - phase and three - phase short - circuit current , the short - circuit current in the 500 kV substation of Guangdong power grid is evaluated and classified . According to the development analysis of the far - view power grid , the main transformer neutral point of the 500 kV substation in Guangdong power grid needs to be equipped with a small reactance which has 5 substations , and the effect of the main transformer plus small reactance limiting single - phase short - circuit current in the Hengli station and the Xiangshan station is most obvious .

In this paper , the installation mode of small reactance for main transformer neutral point of 500kV substation is divided into two types , one is the installation of all main transformers in the station , two is partial main transformer installation , and the limitation effect of small reactance on single - phase short - circuit current is better than that of only partial main transformer installation . Therefore , it is suggested that four main transformer neutral points in Pengcheng station , four main transformers in Baoan Station , four main transformers in Dongguan City Station and three main transformer neutral points of Xiangshan Station are installed with small reactance .

Then , the paper analyzes the small reactance capacity adopted by Hengli Station , Dongguan City Station , Pengcheng Station , Bao ' an Station and Xiangshan Station , and calculates the single - phase , two - phase and three - phase short - circuit current which can be reduced by the reactance value of different sizes .

In addition , according to the comprehensive analysis of the small reactance installation scheme and the results of the adaptability analysis , five 500 kV substations are proposed to be installed before the end of 2010 , and the Dongguan City Station is recommended to be installed before the summer of 2011 .

Based on the short - circuit current of different operating modes of five 500kV substations , the neutral point - in - ground current and the contact potential difference and the step - step potential difference are analyzed and calculated , and the connection mode of the grounding switch is selected between the transformer neutral point and the grounded series small reactor . The model and parameters of the 66kV reactor , the 66kV grounding switch and the 66kV zinc oxide arrester are selected according to the insulation level of the equipment and the specific conditions on the ground .

In the end , a primary , secondary and civil engineering scheme of 5 500 kV substation neutral point plus small reactance is developed , which further demonstrates the feasibility and suitability of adding small reactance .

【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM41

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