750kV Transformer On-Site PD and Induced Withstand Test: Case Study and Recommendations 750kV Tansfurmawa na PD da Take da Zafi a Gida: Misalai da Takardunawa

I. Bincike

A cikin kasar Najeriya, tushen gurbin kungiyar Guanting–Lanzhou East na 750kV ta fi sani a ranar 26 ga watan Satumba, 2005. Wannan tushen ya haɗa biyu na makarantar—Lanzhou East da Guanting (da yake da shi masu kyaututtuka uku na 750kV, uku daga baka suna cikin gurbin kyaututtuka na uku, daya ta da shi a ciki). A cikin wannan tushen, ana samun kyaututtukan 750kV a Najeriya. A lokacin tushen bayanen bayanen, ana samun fitaccen ciyawa a cikin kyaututtukan Phase A na Lanzhou East Substation. An yi ciyawon PD zuwa 12 a kan bayanen bayanen. Wannan takarda ta baƙe tsari, addinin samun bayanen, bayanan, da kuma abubuwan da suka faru a cikin ciyawan PD na kyaututtukan, kuma ya ba muhimmancin adabin ingantaccen a labarai don in taimakawa waɗannan masu yi ciyawon PD a cikin kyaututtukan 750kV da 1000kV.

II. Paramaitoijin Kyaututtukan

Kyaututtukan mai kyau a Lanzhou East Substation an yi shi a Xi’an XD Transformer Co., Ltd. Abubuwan da suka fi dace sun hada:

• Model: ODFPS-500000/750

• Gargajiya na Votaji: HV 750kV, MV (da tap changer ±2.5%) kV, LV 63kV

• Ingantaccen Kashi: 500/500/150 MVA

• Gargajiya na Votaji da Yake Da Sani: 800/363/72.5 kV

• Hanyoyin Tashidance: Cikin ruwa da zafi (OFAF)

• Zara na Ruwa: 84 tons; Zara na Duk: 298 tons

• Darajar da Kyaututtukan na Votaji na Gargajiya: Full-wave impulse 1950kV, chopped-wave impulse 2100kV, short-time induced withstand voltage 1550kV, power frequency withstand voltage 860kV

III. Addinin Samun Bayanen da Tsari

(A) Addinin Samun Bayanen

Idan an yi bayanen a cikin GB1094.3-2003, addinin samun bayanen na ciyawa na kyaututtukan ta haɗa wasu lokaci—A, B, C, D, da E—da votajin da ke amfani da su a cikin bako. Votajin da ke amfani a lokacin C ya haɗa 1.7 per unit (pu), inda 1 pu = Um/√3 (Um wanda yake da gargajiya mafi yawa). Wannan daraja ya ɗauke da Um da ake bayyana a cikin GB1094.3-1985. Idan kyaututtukan Lanzhou East, Um = 800kV, saboda haka votajin da ke amfani a lokacin C ya zama 785kV.

(B) Tsari na Gargajiya na Votaji

• Gargajiya na votaji na ciyawa na Lanzhou East transformer ita ce 860kV. Idan an yi bayanen a cikin "Commissioning Test Standards for 750kV UHV Electrical Equipment" na State Grid Corporation of China, votajin da ke amfani a cikin samun bayanen bayanen ya zama 85% na ma'aikata na factory test, ya'ni 731kV, wanda yake da daraja da ke da shi a lokacin C (785kV).

• Don in taimakawa al'amuran da ke faru a cikin votajin da ke amfani a lokacin C da votajin da ke amfani a cikin samun bayanen bayanen, tsarin da suka bayyana sun ce idan votajin da ke amfani a lokacin C ya ɗauke da 85% na ma'aikata na factory withstand voltage, zan iya gudanar da shi a kan mai amfani da mai samun bayanen. "Technical Specification for 750kV Main Transformers" ta bayyana cewa votajin da ke amfani a lokacin C na samun bayanen bayanen ita ce 85% na ma'aikata na factory withstand voltage. Saboda haka, votajin da ke amfani a lokacin C na samun bayanen bayanen na Lanzhou East transformer ya zama 731kV. An yi ciyawa na PD da kuma samun bayanen bayanen a cikin yanayin kasa, inda samun bayanen bayanen ta yi aikin ciyawa na PD.

(C) Tsari na Ciyanwa na Ciyawa na PD

Idan an yi bayanen a cikin votajin na 1.5 pu, ciyawa na PD na kyaututtukan ya kamata zama ɗaya da 500 pC.

IV. Yanayin Samun Bayanen

Daga ranar 9 ga watan Agusta, 2005, zuwa ranar 26 ga watan Afrilu, 2006, an yi ciyawon PD zuwa 12 a cikin kyaututtukan Phase A na Lanzhou East Substation. Bayanan da suka fi dace sun hada:

Kwamitin da, PD na wakar MV na A na mutanen tashin kima ta shiga ranar haske ya zama daga 600 zuwa 910 pC, wanda ya fi girma da kaɗan 500 pC. Amma, bayan da aka yi karatu ƙarin a ranar 26 ga Afrilu, 2006, ba da shiga, PD ya zama 280 pC, wanda yake da ma'ana.

V. Tafiya na Karatu

(A) Tashin Haske na Karkashin PD (PDIV) da Tashin Haɗa (PDEV)

• Masana'antar Ta'birin: GB7354-2003 da DL417-1991 sun bayyana PDIV da PDEV da sauyi. Misali, "kwantita mai tsabta" a cikin bayanan suna da laifi—amman 500pC ana amfani da ita, wanda yake iya haɓaka gaba-gaban a fannin yadda ake amfani da shi. Duk da haka, gajimata na lokaci a kan karatu yana iya kasance da filayen zuwa miliyan pC, wanda yake iya haɓaka a neman yanayin karkashin PD.

• Bayanan Masu Karatu: A kan 12 karatu na PD da aka yi a Lanzhou East Phase A transformer, PD ya zama kadan-kadan da haske, bane da kawo karamin (karamin da ke fiye ~200pC), wanda yake iya haɓaka a neman PDIV mai zurfi. A wasu karatu, an samu PD mai kyau a hasken da ke kadan, wanda yake iya haɓaka a neman cewa PDIV ya haɗa. Duk da haka, ƙarin na ƙasa na gwamnati GB1094.3-2003 bai tabbatar PDIV ko PDEV, wanda yake iya haɓaka a neman cewa masu karatu suka gudanar da aikinsu.

(B) Neman Yanayin Karkashin PD

• Abubuwan Da Su Ka Samu Wani Tsari: Yadda ake amfani da sabon hanyar na PD na ultrasonic don neman yanayin karkasha, tana neman farkon lokaci na rayuwarsa da PD ta faru a kan sensors na ginin tank. Amma, wannan hanyar tana da abubuwan da su ka samu wani tsari, kamar yadda ake buƙata energy mai karkashi (da ake iya samun shi a kan sensitivity na sensor), da kuma neman yanayin da ba daidai ba saboda reflections da refractions na ultrasonic waves daga inner windings.

• Bayanan Masu Karatu: A lokacin da aka yi karatu na shiga, tushen neman yanayin PD ta ba da bayanin yanayin karkasha. Tushen monitoring na control room bai samu inganci na PD a hasken da haske, wanda yake iya haɓaka a neman ma'anar bayanin. Sabon tushen online monitoring da aka shirya suna iya samun ƙarin bayanin a lokacin da aka yi karatu a ranar 26 ga Afrilu, 2006. Saboda haka, bayanin neman yanayin PD na ultrasonic ya kamata a nuna ilimi a lokacin da PD ya kadan.

(C) Matsalolin Karkashin PD

Hakanan standard ta bayyana limiti 500pC a 1.5 pu, amma a fannin yadda ake amfani da shi, ba da muhimmanci a matsaloli daga 500pC zuwa 700pC—sun sama da matsaloli. Duk da haka, idan PD yana kadan da 1000pC, ba za a samun ƙarin bayanin karkashin PD a kan transformer, kuma tushen neman gajimatarka ba za a samun ƙarin bayanin. Rukunawa 750kV transformer (mai kadan da mai karamin) zuwa factory don repair ya kamata damar ƙarfin.

VI. Takaitaccen

(A) Zama Level na Insulation

Tushen induced withstand voltage na Lanzhou East transformer yana kadan. Idan an neman tarihin da experience na domestic 750kV transformer manufacturing, da kuma abubuwan da suka buƙata a yi karatu na PD a lokaci, an kiran da transformers na 750kV na ƙarin da induced withstand voltage da yake kadan da 900kV.

(B) Jera Criteria na Karatu na PD a Lokaci

A duniya, karatu na PD suna yi kawai a factory, ba a lokaci ba. A China, karatu na PD a lokaci yana da muhimmanci a commissioning. An kiran da a jera criteria na acceptance na karatu na PD a lokaci na 750kV transformers zuwa kadan da 1000pC, saboda:

• Transformers na PD da take kadan da 500–1000pC suna samu PD mai kadan bayan a yi karatu ƙarin bayan a yi storage ko operation (misali, Lanzhou East Phase A transformer).

• Idan PD yana kadan da 1000pC, ba za a samun ƙarin bayanin karkashin PD, tushen neman gajimatarka ba za a samun ƙarin bayanin, kuma rukunawa zuwa factory ya kamata damar ƙarfin.

• Karatu na PD a lokaci na 750kV da 1000kV transformers suna zama "quasi-withstand tests":

• Voltage margin mai kadan: A Lanzhou East transformer, PD test voltage a 1.5 pu (693kV, ±3% measurement uncertainty: 672–714kV) yana kadan da commissioning withstand voltage na 731kV, wanda yake da margin mai kadan da 2.4%. Idan transformers na ƙarin da 750kV yana da induced withstand voltage da yake kadan da 900kV, commissioning test a 765kV yana da margin mai kadan. Haka na ƙarin, a 1000kV transformers, PD test voltage (1.4 pu = 889kV) yana kadan da 935kV withstand level.

• Duration mai tsawo: Hakanan standard withstand duration yana kadan da 56 seconds (a 108Hz test frequency), karatu na PD mai tsawo yana yi 1.5 pu zuwa 65 minutes. Karatu ƙarin yana iya haɓaka cumulative insulation damage, wanda yake iya haɓaka transformer lifespan.

• Akwai wasu misalai da karatu ƙarin a lokaci yana iya haɓaka PD mai kadan zuwa acceptable levels; amma, PD levels yana iya zama (misali, Lanzhou East Phase A transformer: 700pC a ranar 10 ga Agusta, 2005, zama 910pC a ranar 23 ga Satumba).

(C) Redefine PD Inception and Extinction Voltages

Standards na yanzu suna da sauyi na bayanai game da PDIV da PDEV, wanda yake iya haɓaka tafiya na karatu (misali, Lanzhou East case). An kiran da a redefine waɗannan terms da numerical criteria mai tsabta, da kuma guidance don cases inda PDIV da PDEV ba su da yanayin mai zurfi ba.

(D) Zama Research on Practical On-Site Techniques

• Harzama Dangantaka PD na Turbin Da Sabon Yadda: Dangantaka PD masu yawa a littattafai suna nuna shaida daga tushen labarai, wanda ba'a ci gaba da yadda turbin ta aiki a cikin yawan rayuwa. Dukunuka da suka nuna babu zai iya taimakawa waɗannan mafi girma a cikin yawan rayuwa. Yana da kyau a harza da kula da dangantaka PD daga yawan rayuwa, sannan bayyana su a cikin littattafai masu taimaka don bincike mai sauƙi da kayayyakin.

• Tsara Binciken Tsari Masu Kayayyaki: Tsari masu kayayyaki shine muhimman matsalolin a cikin binciken PD a cikin yawan rayuwa. Ingantattun da ke tsari ya fi yake ba zan iya maye ƙaramin inganta da tsari masu kayayyaki. Ana bukata karin bincike game da masabtaccen tsari da hanyoyin tsara.

(E) Rarrabe Ilimimin Mafi Girma Don Masu Bincike

Binciken PD shine mafi girma da abin daɗi a cikin binciken kisa ga rarrabe a cikin yawan rayuwa. Amma amfani da ƙarfin kuɗi suna daɗi. Masu bincike yana da kyau a yi ilimi mai zurfi a cikin sadarwa da kullum, kula da kaya, samun kayayyaki, da kuma kayayyakin PD, sannan yana da kyau a samun rarrabe a gaba da ƙarin bincike.

(F) Kula Da Kiyaye A Cikin Zabubuwa Na Farko

GB7354-2003 ya nuna cewa adadin zabubuwa PD yana da kyau a zuba zuwa farko kadan a shekarar biyu ko bayan inganta mai yawa. A cikin yawan rayuwa, wannan ba'a ci gaba da yadda ake amfani da shi. Ana bukata a yi zabubuwa a cikin batuwar gwamnati don inganta mai ma'ana a cikin bincike.

(G) Yi Noma Online Idan Ya Yi Kyau

Takardun noman online ya ci gaba da takarda. Idan PD na turbin da take da 750kV ya fi yawa, amma ba a gaba da tsari mai yawa, yana da kyau a yi noma online mai kyau. Wannan yana da kyau a noma PD, amma kuma paramatar da kamar dogon jiki, fadada da kuma kasuwanci, don inganta mai haɗin kwallonsa.

VII. Tabbacin Da Neman Gwamnati

• Tabbaci: Standardun da ke cikin yawan rayuwa ba su iya bayyana sadarwa masu yin da kawo PD, wanda ya ƙareta tsari masu taimaka a cikin binciken kisa. Tsarin insulasyon na turbin da ke Lanzhou East 750kV shine da yawa, wanda ya ƙareta cewa binciken PD na za'a ci gaba da "quasi-withstand" test. Ƙarin binciken PD na 12 a cikin turbin Phase A ya fi yawa waɗannan insulasyon da yawa. Turbin 750kV na gaba yana da kyau a kan tsarin insulasyon da yawa da 900kV.

• Neman Gwamnati: Binciken da kuma tashin ƙarfin AC ultra-high-voltage na 1000kV na China an kammala, amma aikace-wata suna daidai. Idan tsarin insulasyon na 1000kV na turbin shine da yawa, yana da kyau a fara binciken kisa don taimakawa a cikin amfani da shi a cikin yawan rayuwa.