【正文】 繞組過電流。 d) 由于突然甩負荷引起的定子繞組過電壓；調(diào)速系統(tǒng)慣性較大的發(fā)電機，在突然甩負荷 時，可能出現(xiàn)過電壓，造成發(fā)電機繞組絕緣擊穿。 對于發(fā)電機 — 變壓器組，一般在發(fā)電機電壓側(cè)裝設(shè)作用于信號的接地保護；當發(fā)電機電壓側(cè)接地電容電流大于 5A時，應該裝設(shè)消弧線圈。 b、 負荷電壓（負序電壓及線電壓）啟動的過電流保護。 對于水輪發(fā)電機定子繞組過電壓，應裝設(shè)帶延時的過電壓保護。 對于轉(zhuǎn)子回路的過負荷，在 100MW及以上并采用半導體勵磁系統(tǒng)的發(fā)電機上應裝設(shè)轉(zhuǎn)子過負荷保護。 為了快速消除發(fā)電機內(nèi)部的故障，在保護動作于發(fā)電機斷路器跳閘的同時，還必須動作于自動滅磁開關(guān)，斷開發(fā)電機勵磁回路，以使轉(zhuǎn)子回路電流不會在定子繞組中再感應電動勢，繼續(xù)供給短路 電流。 反映轉(zhuǎn)子回路 2 次諧波電流的匝間短路保護 縱向零序電壓式匝間保護 發(fā)電機縱向零序電壓式匝間保護，是發(fā)電機同相分支匝間短路及同相不同分支之間匝間短路的主保護。 過去認為發(fā)電機為全絕緣的設(shè)備，在正常運行中中性點電壓低，不容易發(fā)生接地故障，即使發(fā)生，由于接地電流較小，不會對鐵心造成故障。為提高可靠性，兩部 分的保護區(qū)應相互重疊。 定子不對稱過負荷保護 勵磁回路接地保護同步發(fā)電機失磁保護 。80s. We sat on the back of pickup trucks for hours. The sky was blue, and we couldn39。s performers of the troupe still tour the region39。s Liaoning province, decades ago. The solider gave the old man a handmade saddle when they bid farewell. The story inspired Nasun to write Carved Saddle, a song that later became one of his most popular numbers. Now, every year, Nasun recruits young singers and dancers for the troupe. The troupe has also designed a new repertoire, which is mostly based on the daily lives of Mongolian people, especially the lives of nomadic families, and has bined contemporary musical elements with folk songs of the region. Haimu, a 25yearold khoomei (a local variant of overtone singing) singer, joined the troupe three years ago. Along with a sixmember band, he performs fast songs and soft ones that he writes－ all while playing the horsehead fiddle.Although I learned the piano since childhood and grew up listening to various kinds of music, to me, the folk music of Inner Mongolia is the root, he says. Performing in remote villages is pleasant. I feel at home on the boundless grasslands, and the warm people there make me feel fulfilled. The first round of spring auction season in Beijing ended last week, but it failed to create much spring in the art market. Although two pieces of Chinese painting fetched more than 100 million yuan, the decline in trading volume and sa le rate showed a downturn this year. In the ―Grand View: Chinese Painting Highlight‖ session at China Guardian 2021 spring auctions, Pan Tianshou’s representative work Eagle, Rock and Flora hit a record auction price of 279 million yuan, while Li Keran’s masterwork Jinggang Mountain fetched million yuan, an unexpected high in recent years. However, the trading volume fells to billion yuan from billion yuan in the same period the year before. The Huangchen 2021 Spring Auctions, which recorded million yuan in total sales, experienced the same. The section number went down to 5 from 12 pared to last year. According to expert Shao Jianwu, the art market did not attract much excitement this year due to the booming stock market and the persistent problems of fery and fake deals. The two pieces of Chinese painting notched up high price this spring due to their own value not due to a revival in the market. The successful transaction of two works with a hammer price of more than 100 million yuan once again confirms that valuable and rare works of high quality always earn the longlasting high price. Chinese painting and calligraphy is still the pillar of the market. However, the overall sales rate has dropped slightly, which reflects the demand for the ordinary auction goods has weakened,‖ said the president of China Guardian’s Hu Yanyan. Besides, the entry of new buyers also makes certain changes to the direction of purchasing. In a word, the overall market trend is very unpredictable. Although China Guardian 2021 Spring Auctions has achieved remarkable results, it does not mean that the market has walked out of the predicament. We still have to wait for the big economic boom to invigorate the art market.‖ Even so, the hot pursuit of some special items appeared this spring. A special session of China Guardian Spring Auctions titled ―Fine Gi。s Poly Theater. Their show, titled Ulan Muqir on the Grassland, depicted the history and development of the art troupe. Being from the region allowed me to embrace the culture of Inner Mongolia and being a member of the troupe showed me where I belonged, Nasun, the art troupe39。t have a formal stage. The audience just sat on the grass. Usually, the performances became a big party with local people joining in. For him, the rewarding part about touring isn39。s Shaanxi province pass through a stop on the ancient Silk Road, Gansu39。此電流在發(fā)電機空氣隙中建立的負序旋轉(zhuǎn)磁場相對于轉(zhuǎn)子為兩倍的同步轉(zhuǎn)速，因此將在轉(zhuǎn)子繞組、阻尼繞組以及轉(zhuǎn)子鐵心等部件上感應出 100Hz 的倍頻電流，該電流使得轉(zhuǎn)子上電流密度很大的某些部位（如轉(zhuǎn)子端部、護環(huán)內(nèi)表面等），可能出現(xiàn)局部的灼傷，甚至可能使護環(huán)受熱松脫，從而導致發(fā)電機的重大事故。但隨著單機容量的增大，特別是大型水內(nèi)冷機組，要求在保護區(qū)內(nèi)任何一點發(fā)生故障時均能反應。當接地電流比較大，能在故障點引起電弧時，將使繞組的絕緣和定子鐵心燒壞，并且也容易發(fā)展成相間短路，造成更大的危害。 同步發(fā)電機定子繞組匝間短路保護 發(fā)電機定子匝間短路保護可以有多種方案，應根據(jù)發(fā)電廠一次設(shè)備接線情況進行選擇。 1其他的異常工況保護。 b、 對 汽輪發(fā)電機勵磁回路的一點接地，一般采用定期檢測裝置；對大容量機組則可以裝設(shè)一點接地保護；對兩點接地故障，應裝設(shè)兩點接地保護，在勵磁回路發(fā)生一點接地后投入。 對于由不對稱負荷或外部不對稱短路而引起的負序過電流，一般在 50MW 及以上的發(fā)電機上裝設(shè)負序電流保護。 對于發(fā)電機定子繞組的匝間短路，當繞組接成星形且沒相中有引出的并聯(lián)支路時，應裝設(shè)單繼電器式的橫聯(lián)差動保護簡稱橫差保護。 5． 2 發(fā)電機保護類型 針對上述故障類型及不正常運行狀態(tài)，發(fā)電機應裝設(shè)以下繼電保護裝置： 對于 1MW以上發(fā)電機的定子繞組及其引出線的相間短路，應裝設(shè)縱聯(lián)差動保護簡稱電力工程系畢業(yè)設(shè)計（論文） 28 縱差保護。 c) 由于外部不對稱短路或不對稱負荷而引起的發(fā)電機負序過電流和過負荷；在轉(zhuǎn)子中感應出 100Hz 的倍頻電流，可使轉(zhuǎn)子局部灼傷或使護環(huán)受熱松脫，而導致發(fā)電機重大事故。 1） 故障類型及危害 發(fā)電機結(jié)構(gòu)主要由轉(zhuǎn)子與定子兩大部分組成，因而發(fā)電機故障包括定子與轉(zhuǎn)子故障。 第 5 章繼電保護的配置和考慮 5． 1 概述 發(fā)電機的安全運行對保證電力系統(tǒng)的正常工作和電能質(zhì)量起著決定性的作用，同時發(fā)電機本身也是一個貴重的電器元件，因此，應該針對各種不同的故障和不正常運行狀態(tài)，裝設(shè)性能完善的繼電保護裝置。 校驗動穩(wěn)定 電流互感器的內(nèi)部動穩(wěn)定能力用動穩(wěn)定倍數(shù) mK 表示，動穩(wěn)定倍數(shù) mK 等于互感器內(nèi)部允許通過的極限電流（峰值）與 2 倍一次額定電流（ 1NI ）之比。 動穩(wěn)定校驗： kAikAi imp 0 0 ??? 所以： 熱穩(wěn)定校驗滿足 6kV開關(guān)柜： 熱穩(wěn)定校驗： 3 9 6 22 ???tI t ])[( 2SkA 短路熱效應 kQ 為： tIIIQ zttzk ???? ?1210 2222 2 ??