Kusukela ekuhlukanisweni kuya kwimodi yokuxhuma, incazelo ephelele kakhulu ye-grounding transformer

Amagridi kagesi angu-6kV, 10kV kanye no-35kV ohlelweni lwamandla ngokuvamile asebenzisa imodi yokusebenza engaguquki. Uhlangothi olune-voltage ephansi lwe-transformer eyinhloko kugridi yamandla ngokuvamile luxhunywe ngendlela kanxantathu, futhi akukho phuzu elingaguquki elingaguquki. Lapho kwenzeka iphutha lokufaka isisekelo lesigaba esisodwa ohlelweni olungaguquki, unxantathu we-voltage yomugqa uhlala ulingana. Uhlelo lwamandla lungaqhubeka nokunikeza abasebenzisi amandla amahora angu-1 kuya kwangu-2, kanti i-capacitive current incane kakhulu (ngaphansi kuka-10A), okungeke kubangele i-arc ephindaphindayo. Amanye amaphutha okufaka isisekelo esisheshayo anganyamalala ngokuzenzakalelayo, okusebenza kahle kakhulu ekuthuthukiseni ukuthembeka kokunikezwa kwamandla nokunciphisa izingozi zokuphela kwamandla. Kodwa-ke, ngokwandiswa okuqhubekayo kwegridi yamandla yasemadolobheni kanye nokwanda okuqhubekayo kwemigqa ephumayo yekhebula, i-capacitive current yesistimu eya phansi iyanda kakhulu, futhi i-capacitive current egeleza endaweni yokwehluleka ngemva kokufaka isisekelo sesigaba esisodwa inkulu (ngaphezu kuka-10A).

I-arc akulula ukuyicisha, kulula ukuyivusa i-ferromagnetic resonance overvoltage futhi ikhiqize i-arc light grounding overvoltage ngezikhathi ezithile, okungase kubangele umonakalo wokushisa, kukhubeke umugqa futhi kwandise ingozi.

Ngokuqondile:

Ukuphela okungapheli kanye nokuqala kabusha kwe-arc grounding arc yesigaba esisodwa kuzokhiqiza i-over-voltage ye-arc grounding ene-amplitude efika ku-4U (U iyinani eliphakeme le-voltage yesigaba esijwayelekile) noma ngaphezulu futhi isikhathi eside, okuzobangela umonakalo omkhulu ekufakweni kwemishini kagesi futhi kubangele ukuwohloka ekufakweni kwe-insulation okubuthakathaka; Kubangele ukulahlekelwa okukhulu.

Ukuhlukana komoya okubangelwa yi-arc eqhubekayo kubhubhisa ukufudumala komoya ozungezile futhi kuthambekele ekujikelezeni kwesigaba kuya kwesigaba esifushane.

I-Ferromagnetic resonance over-voltage ingashisa kalula i-voltage transformer futhi ibangele umonakalo ku-arrester, okungase kubangele ngisho nokuthi i-arrester iqhume. Le miphumela izosongela kakhulu ukufudumala kwemishini yegridi yamandla futhi ibeke engozini ukusebenza okuphephile kwegridi yamandla.

Ukuze kuncishiswe amandla kagesi asebenza phansi uma kwenzeka iphutha lokufaka isisekelo lesigaba esisodwa, kuyadingeka ukufaka ikhoyili yokucindezela i-arc kanye namanye amadivayisi okubuyisela endaweni engathathi hlangothi ye-transformer. Ngakho-ke, kuyadingeka ukusungula indawo engathathi hlangothi ngesandla ukuze ikhoyili yokucindezela i-arc ixhunywe endaweni engathathi hlangothi ukuze kuncishiswe amandla okuphazamisa isisekelo futhi kuthuthukiswe ukuthembeka kokunikezwa kwamandla ohlelweni.

■ Ukusetshenziswa kwamanje ekhaya nakwamanye amazwe

I-grounding transformer eShayina ivame ukusebenzisa izintambo zohlobo lwe-Z (noma izintambo ezigobile). Ukuze kongiwe indawo yokutshalwa kwezimali kanye nesikhala sesiteshi esincane, ukugoqa kwesithathu kuvame ukungezwa ku-grounding transformer ukuze kuthathelwe indawo i-grounding esetshenziselwa ukuhlinzeka ngamandla emishini esetshenziswa esiteshini esincane. Ngokwezinga likazwelonke le-Reactor, indlela yokufaka isisekelo se-grounding transformer ingahlukaniswa ngokufakwa kwesisekelo ngqo; Isekelwe nge-reactor, ukumelana kanye ne-arc suppression coil. Ukufakwa kwesisekelo ngqo akuzange kusetshenziswe eShayina, kodwa eminye iminyango yocwaningo lwamandla kagesi isiqalile ukuxoxa ngalesi sici. I-grounding transformer emazweni angaphandle ivame ukusebenzisa noma uxhumano lwe-Z-type, olusetshenziselwa uhlelo lwe-10kV olungenasisekelo futhi lwakha ukuvikelwa kwesisekelo senethiwekhi yokusabalalisa. Lapho uhlelo lunephutha lokumisa phansi, i-grounding transformer iveza ukuphazamiseka okuphezulu ku-positive sequence current kanye ne-negative sequence current kanye nokumelana okuphansi ku-zero sequence current, okwenza ukuvikelwa kwesisekelo kusebenze ngokwethembeka.

■ I-transformer yokumisa phansi yesigaba ezintathu

I-transformer yokumisa isisekelo yesigaba ezintathu Lolu hlobo lwe-transformer lusebenzisa izintambo zohlobo lwe-Z (noma izintambo ezigobile). Umehluko kuma-transformer avamile ukuthi ikhoyili ngayinye yesigaba ihlukaniswe ngamaqembu amabili futhi iboshwe esigxotsheni sikamazibuthe salesi sigaba ngokuphambene. Inzuzo yalokhu kuxhumana ukuthi i-flux kamazibuthe yesigaba esingu-zero ingageleza esigxotsheni sikamazibuthe, kuyilapho i-flux kamazibuthe yesigaba esingu-zero yama-transformer avamile igeleza esijikelezweni sokuvuza kukamazibuthe. Ngakho-ke, i-impedance yesigaba esingu-zero yama-transformer okumisa isisekelo yohlobo lwe-Z incane kakhulu (cishe i-10 Ω), kanti eye-transformer evamile inkulu kakhulu. Ngokwemithetho, amandla e-transformer avamile anekhoyili yokumisa isisekelo ye-arc akumele idlule u-20% wamandla e-transformer. I-transformer yohlobo lwe-Z ingafakelwa ikhoyili yokumisa isisekelo ye-arc enamandla angu-90% ~ 100%. Ngaphezu kwekhoyili yokumisa isisekelo ye-arc, i-transformer yokumisa isisekelo nayo ingafakelwa umthwalo wesibili, ongathatha indawo ye-transformer yesiteshi, ngaleyo ndlela kongiwe izindleko zokutshalwa kwezimali.

■ I-transformer yokumisa isisekelo yesigaba esisodwa

Isiguquli sokumisa isisekelo sesigaba esisodwa Isiguquli sokumisa isisekelo sesigaba esisodwa sisetshenziswa kakhulu ekukhiqizeni ijeneretha enekhabhinethi yokumelana nesisekelo sendawo engathathi hlangothi kanye nekhabhinethi yokumelana nesisekelo sendawo engathathi hlangothi ye-Satons transformer ukunciphisa izindleko kanye nomthamo wekhabhinethi yokumelana.

■ Izici zokusebenza

(1) Ukuphazamiseka kokulandelana kwe-zero okuphansi ukuqinisekisa ukuphuma kochungechunge lwamanje lwe-zero;

(2) Ukuphazamiseka okuphezulu kokucindezela ukunciphisa amandla angenawo umthwalo;

(3) Ukulahlekelwa okuncane ngaphandle komthwalo ukuze kongiwe ukusetshenziswa kwamandla okusebenza kwansuku zonke.

■ Imodi yokuxhuma izintambo

Uxhumano lwe-YN

I-transformer enale ndlela yokuxhumanisa ivame ukusebenzisa umongo wensimbi onezikholamu ezintathu, kanti iphuzu elingathathi hlangothi ohlangothini olunezikholamu eziphezulu lingaxhunywa nekhoyili yokucindezela i-arc ukuze kufezwe ukumisa. Kodwa-ke, lapho umugqa we-single-phase grounded zero sequence ugeleza ohlangothini olunezikholamu eziphezulu, amandla kagesi akhiqizwayo e-zero sequence awakwazi ukulinganiswa yi-secondary magnetic potential, futhi i-zero sequence magnetic flux ohlangothini olufanayo ayikwazi ukwakha iluphu emongweni wensimbi onezikholamu ezintathu, ukuze inani elikhulu le-zero sequence magnetic flux lingadlula kuphela emzimbeni we-clamp, uwoyela kanye nowoyela ukuze kwakheke iluphu evaliwe, ngaleyo ndlela kubangele ukulahlekelwa okwengeziwe ethangini likawoyela kanye ne-clamp, okuholela ekushiseni ngokweqile kwendawo. Ukusetshenziswa kwamandla e-transformer kunqunyelwe. Imithethonqubo yokusebenza efanele yomkhakha wamandla waseShayina yenze amalungiselelo alandelayo ngesimo sokusebenza se-neutral point connection arc suppression coil ye-YNyn connection transformer:

(1) Umthamo wekhoyili yokucindezela i-arc akumele udlule u-20% wamandla alinganisiwe e-transformer;

(2) Ukwehla kwe-voltage yokulandelana kwe-zero okubangelwa ugesi we-zero ogeleza nge-coil yokucindezela i-arc ku-transformer akufanele kudlule u-10% we-voltage yesigaba esilinganiselwe;

Imodi yokuxhuma ye-transformer yokuxhuma ye-YNd kanye ne-coil yokucindezela i-arc XL ibonakala ngokuthi uxhumano oluyinxantathu ohlangothini lwesibili lunganikeza indlela evaliwe yamanje okulandelana okungu-zero, ngakho-ke ukusabela kokulandelana okungu-zero kuncane. Ngaphezu kwalokho, njengoba amandla kazibuthe okulandelana okungu-zero okulandelana kwama-windings ayinhloko nawesibili kukholamu ngayinye eyinhloko elinganisiwe, ukuvuza kwamandla kazibuthe okulandelana okungu-zero nakho kuncane. Kodwa-ke, lapho ukugoqa kokuxhumeka kwe-YN kungaphandle, ukulahlekelwa okwengeziwe kokulandelana okungu-zero okubangelwa ethangini likawoyela nakwezinye izingxenye akunakugwenywa ngokuphelele. Uma ixhunywe ne-coil yokucindezela i-arc, ukusetshenziswa kwamandla ayo kusazoncishiswa. Ucwaningo lokuhlola lwangaphandle lubonisa ukuthi imodi yokusebenza evumelekile ye-transformer yokusekela exhunywe yi-YN yile:

(1) Uma umthwalo wesibili ogcwele ujwayelekile, umthamo wekhoyili yokucindezela i-arc exhunywe ohlangothini lwe-YN akufanele udlule u-50% wamandla alinganisiwe we-transformer;

(2) Uma umthwalo wesibili ungama-50% kuphela womthamo we-transformer ngezikhathi ezivamile, umthamo we-arc suppression coil ungalingana nomthamo olinganiselwe we-transformer.

Nakuba uhlangothi lwesibili lwalokhu kuxhumana lunganikeza amandla emithwalweni yesifunda noma esiteshini esincane ngokwaso, ukusetshenziswa kwaso kuzoncishiswa kakhulu ngoba uxhumano oluyinxantathu kunzima ukuhlinzeka ngamandla kubasebenzisi bamandla ahlanganisiwe kanye nokukhanyisa ngesikhathi esisodwa.

I-YN, uxhumano lwe-open d luxhunywe nge-arc-suppression coil XL, efana noxhumano lwe-YNd. Imodi yokuxhuma ye-open d ingaxhunywa nge-resistor noma i-reactor ohlangothini lwe-open triangle ukuze kulungiswe i-zero-sequence reactance ye-transformer, futhi uxhumano lwe-resistor lungacindezela ne-ferromagnetic resonance yenethiwekhi. Uma i-three-phase five column iron core isetshenziswa, inani le-zero sequence impedance lingakhushulwa kakhulu, futhi kungenzeka ngisho nokukhipha i-arc suppression coil, kodwa isakhiwo siyinkimbinkimbi futhi izindleko ziyanda. Ngaphezu kwalokho, ukusetshenziswa kwesibili koxhumano lwe-open triangle akukwazi ukuhlangabezana nezidingo zokunikezwa kwamandla emithwalweni yesifunda kanye namandla okuzisebenzisa, ngakho-ke le ndlela ayisetshenziswa kabanzi.

I-ZN, i-yn connection transformer ixhunywe ne-arc suppression coil XL, okuyimodi yokuxhuma evamile ye-grounding transformer. Ngenxa yokuthi amandla kazibuthe e-zero sequence kuma-windings aphezulu nangaphansi kwengxenye ephezulu kukholamu efanayo yensimbi yendlela yokuxhuma ye-zigzag ilingana nosayizi ofanayo kanye nesiqondiso esiphambene, okuphikisanayo, i-zero sequence leakage flux yehliswa ibe yinani elincane kakhulu, ukuze inani layo le-zero sequence reactance lincane kakhulu, futhi amandla ayo angalingana namandla e-arc suppression coil exhunyiwe.

I-grounding transformer esetshenziswa kabanzi ekhaya nakwamanye amazwe ixhunywe kakhulu ngale ndlela. Njengoba indlela ye-yn junction isetshenziswa ohlangothini lwe-low-voltage, ingahlinzeka ngamandla endawo noma amandla okuzisebenzisa esiteshini esincane ngesikhathi esifanayo. Umthamo wohlangothi lwe-low voltage uvame ukuba mncane kunowohlangothi lwe-high voltage. Ezimweni eziningi, umthamo wohlangothi lwe-low voltage ungaphakathi kwebanga elingu-80-200kVA.

Nakuba umthamo olinganisiwe wohlangothi olune-voltage ephezulu ungalingana nomthamo wekhoyili yokucindezela i-arc exhunyiwe, uxhumano olunobunjwa buka-Z luzoba nokujika okuphindwe ka-1.15 kunoxhumano olunobunjwa buka-Y, ngakho-ke umthamo wangempela we-grounding transformer kufanele ube izikhathi ezingu-1.15 zomthamo wekhoyili yokucindezela i-arc.

■ Isimiso sokusebenza

Umdwebo womgomo wokusebenza we-grounding transformer uma kwenzeka iphutha lesigaba esisodwa ohlelweni uboniswa yizintambo ezivamile ze-ZNyn. Lapho i-grounding transformer idlula ngobukhulu obuthile bomugqa wamanje we-zero sequence ngesikhathi sokusebenza, umugqa wamanje ogeleza phakathi kwama-single-phase windings amabili kukholomu efanayo yensimbi usemaceleni ahlukene futhi usayizi uyalingana, ukuze amandla kazibuthe akhiqizwe umugqa wamanje we-zero sequence ahluke kakhulu ekulinganisweni, ukuze i-zero sequence impedance nayo ibe ncane kakhulu.

Uma i-grounding transformer yehluleka, iphuzu elingathathi hlangothi lingageleza ngokusebenzisa ugesi wokunxephezela. Ngenxa yokumelana okuncane kwe-zero-sequence, lapho ugesi we-zero-sequence udlula, ukwehla kwe-impedance voltage okukhiqizwayo kufanele kube kuncane ngangokunokwenzeka ukuqinisekisa ukuphepha kohlelo. Ngenxa yokuthi i-grounding transformer inezici ze-low zero sequence impedance, lapho kwenzeka iphutha le-grounding lesigaba esisodwa esigabeni C, ugesi wesigaba C ground I ugeleza ungene endaweni engathathi hlangothi emhlabeni, futhi uhlukaniswe izingxenye ezintathu ezilinganayo ukuze ugeleze ungene ku-grounding transformer. Njengoba ugesi wesigaba ezintathu ogeleza ungene ku-grounding transformer ulingana, ukufuduka kwephuzu elingathathi hlangothi N akushintshi, kanti ugesi wesigaba ezintathu uhlala ulingana.

Kodwa-ke, enkambisweni yokukhiqiza, ukujika kanye nobukhulu bejometri be-windings ephezulu nephansi ye-high-voltage winding akunakulingana ngokuphelele, okwenza kube nzima ukuthi amandla kazibuthe akhiqizwe yi-zero sequence current asuswe ngqo ohlangothini oluphambene, futhi asakhiqiza i-zero sequence impedance ethile, ngokuvamile cishe i-6-10 Ω. Uma kuqhathaniswa ne-zero sequence impedance ye-transformer exhunywe yinkanyezi engu-600 Ω, izinzuzo zayo ziyabonakala. Ngaphezu kwalokho, i-zigzag grounding transformer ingenza nokulahlekelwa kwamanje okungenamthwalo kanye nokulahlekelwa okungenamthwalo kube kuncane ngangokunokwenzeka. Uma kuqhathaniswa ne-transformer evamile yokuxhumeka kwenkanyezi, i-phase iron core ngayinye ye-zigzag connection transformer yakhiwe nge-windings yamakholomu amabili e-iron core. Ngokusho komdwebo wayo we-vector, uma kuqhathaniswa ne-normal star connection transformer, idinga ukugoqwa izikhathi ezingu-1.16 ngaphezulu uma i-voltage ifana. Ubukhulu be-zero sequence impedance kanye ne-positive sequence impedance yenethiwekhi yokusabalalisa yasemadolobheni ene-single-phase grounding ngaphansi kwemodi ye-neutral point resistance grounding ihluke kakhulu. Uma imisinga yokulandelana kwezigaba ezintathu emihle nembi igeleza, amandla kazibuthe kukholamu ngayinye yensimbi ye-grounding transformer iyisamba sama-phasor amandla kazibuthe emizila emibili yezigaba ezahlukene kukholamu yensimbi. Amandla kazibuthe ezinsikeni ezintathu zensimbi eyi-core yiqembu lamanani okulingana kwezigaba ezintathu anomehluko wesigaba ongu-120 °. I-magnetic flux ekhiqizwayo ingakha iluphu ezinsikeni ezintathu zensimbi eyi-core. Ukumelana kwamagnetic kwesekethe yamagnetic kuncane, i-magnetic flux inkulu, kanti amandla abangelwayo makhulu, okubonisa ukulandelana okukhulu okuhle kanye ne-negative sequence impedance; Ngakho-ke, i-grounding transformer inezici ze-large positive kanye ne-negative sequence impedance kanye ne-small zero sequence impedance.

■ Amapharamitha obuchwepheshe ayinhloko

Ukuze kuhlangatshezwane nezidingo zesinxephezelo sokumisa i-arc coil kunethiwekhi yokusabalalisa, futhi kuhlangatshezwane nezidingo zamandla esiteshi esincane kanye nomthwalo wokukhanyisa, kukhethwe i-transformer yoxhumano yohlobo lwe-Z, futhi amapharamitha ayinhloko e-transformer yokumisa adinga ukusethwa ngokufanele.

(1) Umthamo oyinhloko ohlangothini lwe-grounding transformer enomthamo olinganiselwe kufanele uhambisane nomthamo we-arc compression coil. Ngokusho kwencazelo yomthamo we-arc compression coil ekhona, kunconywa ukuthi kubekwe umthamo we-grounding transformer njengezikhathi eziyi-1.05-1.15 zomthamo we-arc compression coil. Isibonelo, umthamo we-grounding transformer ohlome nge-arc compression coil eyodwa engu-200kVA ngu-215kVA.

(2) Ingqikithi yamandla kagesi egeleza endaweni engathathi hlangothi ye-transformer uma kwenzeka iphutha lesigaba esisodwa lamandla kagesi okubuyisela amaphuzu angathathi hlangothi:

Kuphi:

U yi-voltage yomugqa wenethiwekhi yokusabalalisa (V); i-Zx iyi-impedance ye-arc suppression coil (Ω);

I-Zd iyi-primary zero sequence impedance ye-grounding transformer (Ω/phase);

I-Zs iyi-impedance yesistimu (Ω);

Ubude bomsinga wokunciphisa iphuzu elingathathi hlangothi kufanele bufane nobekhoyili yokucindezela i-arc, okuzoba amahora ama-2 njengoba kuchaziwe.

(3) Impedance yokulandelana kwe-zero Impedance yokulandelana kwe-zero iyipharamitha ebalulekile ye-grounding transformer, enethonya elibalulekile ekuvikelweni kwe-relay ukuze inciphise i-single-phase grounding short-circuit current kanye nokucindezela i-overvoltage. Kuma-zigzag (uhlobo lwe-Z) nama-grounding transformer axhunyiwe yi-zigzag (uhlobo lwe-Z) kanye nama-star/open delta angenawo ama-secondary coil, kukhona i-impedance eyodwa kuphela, okungukuthi i-zero sequence impedance, ukuze umnyango wokukhiqiza ukwazi ukuhlangabezana nezidingo zomnyango wamandla.

(4) Ukulahlekelwa kuyipharamitha yokusebenza ebalulekile ye-grounding transformer. Ku-grounding transformer ene-coil yesibili, ukulahlekelwa kwayo okungenamthwalo kungafana nokwe-double winding transformer enamandla afanayo. Ekulahlekelweni komthwalo, lapho uhlangothi lwesibili lusebenza ngokugcwele, ukulahlekelwa komthwalo ohlangothini oluyinhloko kungaphansi kokwe-double winding transformer enamandla afanayo nohlangothi lwesibili ngenxa yomthwalo olula ohlangothini oluyinhloko.

(5) Ngokwezinga likazwelonke, ukwenyuka kwezinga lokushisa kwe-grounding transformer kungokulandelayo:

1) Ukwenyuka kwezinga lokushisa ngaphansi komshini oqhubekayo olinganisiwe kufanele kuhambisane nezinhlinzeko zezinga likazwelonke lama-transformer ohlobo olomile ama-transformer anamandla ajwayelekile, kodwa kusebenza kakhulu kuma-transformer aphansi anomthwalo ovamile ohlangothini lwesibili;

2) Uma isikhathi somthwalo wesikhathi esifushane singaphansi kwamasekhondi angu-10 (ikakhulukazi uma iphuzu elingathathi hlangothi lixhunywe nokumelana), ukunyuka kwezinga lokushisa kufanele kuhambisane nezinhlinzeko ze-transformer yamandla ejwayelekile kazwelonke emkhawulweni wokunyuka kwezinga lokushisa ngaphansi kwezimo zesekethe esifushane;

3) Ukwenyuka kwezinga lokushisa kwe-grounding transformer kanye ne-arc compression coil uma kusebenza ndawonye kufanele kuhambisane nezinhlinzeko zokwenyuka kwezinga lokushisa kwe-arc compression coil: izinga lokushisa lokugoqa eliqhubeka ligeleza ku-current rated lingu-80K, elisebenza kakhulu ku-star/open delta connection grounding transformer; Ngokugoqa okunesikhathi esiphezulu sokugeleza kombane olinganisiwe ochazwe njengamahora ama-2, izinga lokushisa elicacisiwe lingu-100K.