Ukusuka kuhlulo ukuya kwimo yocingo, inkcazo epheleleyo kakhulu ye-grounding transformer

Iigridi zamandla ze-6kV, 10kV kunye ne-35kV kwinkqubo yamandla zihlala zisebenzisa imo yokusebenza engagungqiyo. Icala eliphantsi le-transformer ephambili kwigridi yamandla lihlala liqhagamshelwe ngendlela yenxantathu, kwaye akukho ndawo ingathathi cala enokuthi ibekwe phantsi. Xa kwenzeka impazamo yokumisa isiseko sesigaba esinye kwinkqubo engagungqiyo, unxantathu wevolthi yomgca uhlala ulingana. Inkqubo yamandla ingaqhubeka nokubonelela abasebenzisi ngombane kangangeyure e-1 ukuya kwezi-2, kwaye i-capacitive current incinci (ngaphantsi kwe-10A), nto leyo engayi kubangela i-arc engapheliyo. Ezinye iimpazamo zokumisa isiseko zesikhashana zinokunyamalala ngokuzenzekelayo, nto leyo esebenza kakhulu ekuphuculeni ukuthembeka kokunikezelwa kombane kunye nokunciphisa iingozi zokucinywa kombane. Nangona kunjalo, ngokwandiswa okuqhubekayo kwegridi yamandla asezidolophini kunye nokwanda okuqhubekayo kwemigca ephumayo yekhebula, i-capacitive current yenkqubo emhlabeni iyanda kakhulu, kwaye i-capacitive current ehamba kwindawo yempazamo emva kokumisa isiseko sesigaba esinye inkulu (ngaphezu kwe-10A).

I-arc ayilula ukuyicima, kulula ukuyivuselela i-ferromagnetic resonance overvoltage kwaye ivelise i-arc light grounding overvoltage engacwangciswanga, nto leyo enokubangela umonakalo kwi-insulation, iphazamise umgca kwaye yandise ingozi.

Ngokukodwa:

Ukuphela okukhawulezileyo kunye nokuqalisa kwakhona kwe-arc yokumisa isiseko yesigaba esinye kuya kuvelisa i-arc grounding over-voltage ene-amplitude ukuya kuthi ga kwi-4U (U lixabiso eliphezulu le-voltage yesigaba esiqhelekileyo) okanye ngaphezulu kwaye ixesha elide, oku kuya kubangela umonakalo omkhulu kwi-insulation yezixhobo zombane kwaye kubangele ukonakala kwi-insulation ebuthathaka; Kubangela ilahleko enkulu.

Ukuqhekeka komoya okubangelwa yi-arc eqhubekayo kutshabalalisa ubushushu bomoya ojikelezileyo kwaye kuthambekele kwi-phase to phase short circuit.

I-Ferromagnetic resonance over-voltage ingatshisa ngokulula i-voltage transformer ize yenze umonakalo kwi-arrester, nto leyo enokubangela ukuba i-arrester iqhume. Ezi ziphumo ziya kuyisongela kakhulu i-insulation yezixhobo ze-power grid kwaye zibeke emngciphekweni ukusebenza ngokukhuselekileyo kwe-power grid.

Ukuze kuncitshiswe amandla ombane angaphantsi komhlaba xa kukho impazamo yokumisa umhlaba yesigaba esinye, kuyimfuneko ukufaka i-arc suppression coil kunye nezinye izixhobo zokuhlawula kwindawo engathathi hlangothi ye-transformer. Ke ngoko, kuyimfuneko ukuseka indawo engathathi hlangothi ngesandla ukuze i-arc suppression coil iqhagamshelwe kwindawo engathathi hlangothi ukunciphisa i-grounding short-circuit breaking current kunye nokuphucula ukuthembeka kombane wenkqubo.

■ Ukusetyenziswa ngoku ekhaya nakwamanye amazwe

I-grounding transformer eTshayina idla ngokusebenzisa i-Z-type wiring (okanye i-zigzag wiring). Ukuze kongiwe indawo yotyalo-mali kunye ne-substation, i-winding yesithathu idla ngokongeza kwi-grounding transformer ukuze ithathe indawo ye-grounding esetyenziselwa ukubonelela ngombane kwizixhobo ezisetyenziswa kwi-substation. Ngokomgangatho wesizwe we-Reactor, indlela ye-grounding ye-grounding transformer inokwahlulwa ibe yi-grounding ethe ngqo; Isekelwe kwi-reactor, i-resistance kunye ne-arc compression coil. I-direct grounding ayikasetyenziswa eTshayina, kodwa amanye amasebe ophando lwamandla ombane aqalile ukuxoxa ngale nto. I-grounding transformer kumazwe angaphandle idla ngokusebenzisa okanye uqhagamshelo lwe-Z-type, olusetyenziselwa inkqubo ye-10kV engangcwatywanga kwaye lwenza ukhuseleko lwe-grounding network yokusasazwa. Xa inkqubo ine-grounding fault, i-grounding transformer inika i-impedance ephezulu kwi-positive sequence current kunye ne-negative sequence current kunye ne-low resistance to zero sequence current, okwenza ukhuseleko lwe-grounding lusebenze ngokuthembekileyo.

■ Isiguquli somhlaba esinezigaba ezintathu

I-transformer yokumisa iziseko ezintathu Olu hlobo lwe-transformer lusebenzisa i-wiring yohlobo lwe-Z (okanye i-zigzag wiring). Umahluko kwii-transformer eziqhelekileyo kukuba i-coil nganye yesigaba yahlulwe yangamaqela amabini kwaye ijikelezwe kwi-magnetic pole yale sigaba ngasemva. Inzuzo yolu qhagamshelo kukuba i-zero sequence magnetic flux inokuhamba ecaleni kwe-magnetic pole, ngelixa i-zero sequence magnetic flux yee-transformer eziqhelekileyo ihamba ecaleni kwesekethe yokuvuza kwe-magnetic. Ke ngoko, i-zero sequence impedance yee-Z-type grounding transformers incinci kakhulu (malunga ne-10 Ω), ngelixa eye-transformers eziqhelekileyo inkulu kakhulu. Ngokwemigaqo, umthamo we-transformer eqhelekileyo ene-arc suppression coil ayizukudlula i-20% yomthamo we-transformer. I-Z-type transformer inokuxhotyiswa nge-arc suppression coil enomthamo we-90% ~ 100%. Ukongeza kwi-arc suppression coil, i-grounding transformer inokuxhotyiswa nomthwalo wesibini, onokuthatha indawo ye-station transformer, ngaloo ndlela wonge iindleko zotyalo-mali.

■ Isiguquli somhlaba esinesigaba esinye

Isiguquli sokumisa umhlaba sesigaba esinye Isiguquli sokumisa umhlaba sesigaba esinye sisetyenziselwa kakhulu ukuvelisa ijenereyitha ene-neutral point kunye ne-neutral point grounding cabinet ye-Satons transformer ukunciphisa iindleko kunye nomthamo wekhabhinethi yokumisa umhlaba.

■ Iimpawu zokusebenza

(1) Impedance yokulandelelana kwe-zero ephantsi ukuqinisekisa ukuphuma kolandelelwano lwangoku lwe-zero;

(2) Uxinzelelo oluphezulu lokunciphisa umbane ongenamthwalo;

(3) Ukulahleka okuphantsi komthwalo ukuze kongiwe ukusetyenziswa kwamandla okusebenza kwemihla ngemihla.

■ Imo yocingo

Uqhagamshelo lwe-YNyn

I-transformer enale ndlela yoqhagamshelo idla ngokusebenzisa isiseko sentsimbi esineekholamu ezintathu, kwaye indawo engathathi cala kwicala le-high-voltage inokudityaniswa ne-arc compression coil ukuze kufezekiswe isiseko. Nangona kunjalo, xa i-single-phase grounded zero sequence current idlula kwicala le-high-voltage winding, i-zero sequence magnetic potential evelisiweyo ayinakulinganiswa yi-secondary magnetic potential, kwaye i-zero sequence magnetic flux kwicala elifanayo ayinakwenza iluphu kwisiseko sentsimbi esineekholamu ezintathu, ukuze inani elikhulu le-zero sequence magnetic flux linokudlula kuphela kwi-clamp, ioyile kunye ne-oyile tank body ukuze lenze iluphu evaliweyo, ngaloo ndlela kubangele ilahleko eyongezelelweyo kwi-oyile tank kunye ne-clamp, okubangela ubushushu obuphezulu bendawo. Ukusetyenziswa komthamo we-transformer kulinganiselwe. Imigaqo yokusebenza efanelekileyo yecandelo lamandla laseTshayina yenze la malungiselelo alandelayo kwimeko yokusebenza ye-neutral point connection arc compression coil ye-YNyn connection transformer:

(1) Umthamo wekhoyili yokunciphisa i-arc awuzukudlula i-20% yomthamo olinganisiweyo we-transformer;

(2) Ukuhla kwe-voltage ye-zero sequence eveliswa yi-zero sequence current ehamba nge-arc suppression coil kwi-transformer akumele kudlule i-10% ye-voltage yesigaba esilinganisiweyo;

Indlela yokudibanisa i-YNd connection transformer kunye ne-arc suppression coil XL ibonakaliswa kukuba unxibelelwano olunxantathu kwicala lesibini lunokubonelela ngendlela evaliweyo ye-zero sequence current, ngoko ke i-zero sequence reactance incinci. Ukongeza, ekubeni i-zero sequence magnetic potential ye-primary and secondary windings kwikholamu nganye engundoqo ilinganisiwe, ukuvuza kwe-zero sequence magnetic nako kuncinci. Nangona kunjalo, xa i-YN connection winding ingaphandle, ilahleko eyongezelelweyo ye-zero sequence ebangelwe kwi-oyile tanki nakwezinye izinto ayinakuphetshwa ngokupheleleyo. Xa iqhagamshelwe kwi-arc suppression coil, ukusetyenziswa kwamandla ayo kuya kuncitshiswa. Uphando lwangaphandle lubonisa ukuba indlela yokusebenza evumelekileyo ye-YNd grounding transformer eqhagamshelweyo yile:

(1) Xa umthwalo opheleleyo wesibini uqhelekile, umthamo wekhoyili yokunciphisa i-arc eqhagamshelwe kwicala le-YN awuzukudlula i-50% yomthamo olinganisiweyo we-transformer;

(2) Xa umthwalo wesibini ungama-50% kuphela omthamo we-transformer ngamaxesha aqhelekileyo, umthamo we-arc depression coil unokulingana nomthamo olinganisiweyo we-transformer.

Nangona icala lesibini lolu qhagamshelo linokubonelela ngombane kwimithwalo yengingqi okanye kwisitishi esingaphantsi ngokwaso, ukusetyenziswa kwaso kuya kunqongophala kakhulu kuba uqhagamshelo olunxantathu kunzima ukubonelela ngombane kubasebenzisi bamandla axutyiweyo kunye nokukhanyisa ngaxeshanye.

I-YN, uqhagamshelo lwe-d oluvulekileyo luqhagamshelwe kwi-arc-suppression coil XL, efana noqhagamshelo lwe-YNd. Indlela yoqhagamshelo lwe-d evulekileyo inokuqhagamshelwa nge-resistor okanye i-reactor ecaleni kwe-open triangle ukulungisa i-zero-sequence reactance ye-transformer, kwaye uqhagamshelo lwe-resistor lunokucinezela i-ferromagnetic resonance yenethiwekhi. Ukuba i-three-phase five column iron core iyamkelwa, ixabiso le-zero sequence impedance nalo linokwandiswa kakhulu, kwaye kunokwenzeka nokuba kukhutshwe i-arc suppression coil, kodwa isakhiwo siyinkimbinkimbi kwaye iindleko ziyanda. Ukongeza, ukusetyenziswa kwesibini koqhagamshelo lwe-open triangle akunakuhlangabezana neemfuno zobonelelo lwamandla kwimithwalo yengingqi kunye namandla okuzisebenzisa, ngoko ke le ndlela ayisetyenziswa kakhulu.

I-ZN, i-yn connection transformer iqhagamshelwe kwi-arc suppression coil XL, eyindlela eqhelekileyo yoqhagamshelo lwe-grounding transformer. Ngenxa yokuba i-zero sequence magnetic potential kwi-upper and lower half windings kwi-iron core column efanayo yendlela yoqhagamshelo lwe-zigzag ilingana ngobukhulu kunye necala elichaseneyo, elichaseneyo, i-zero sequence leakage flux incitshiswa ibe lixabiso elincinci kakhulu, ukuze ixabiso layo le-zero sequence reactance libe lincinci kakhulu, kwaye amandla ayo anokulingana namandla e-arc suppression coil eqhagamshelweyo.

I-grounding transformer esetyenziswa kakhulu ekhaya nakwamanye amazwe iqhagamshelwe ngolu hlobo. Ekubeni indlela ye-yn junction isetyenziswa kwicala le-low-voltage, inokubonelela ngombane wendawo okanye amandla okuzisebenzisa we-substation ngaxeshanye. Umthamo wecala le-low voltage uhlala uncinci kunowecala le-high voltage. Kwiimeko ezininzi, umthamo wecala le-low voltage ungaphakathi koluhlu lwe-80-200kVA.

Nangona umthamo olinganisiweyo wecala le-high-voltage unokulingana nomthamo wekhoyili yoxinzelelo lwe-arc edibeneyo, uqhagamshelo olunobume buka-Z luya kuba nokujika okuphindwe kayi-1.15 kunoqhagamshelo olunobume buka-Y, ngoko ke umthamo wokwenyani we-grounding transformer kufuneka ube ngamaxesha ayi-1.15 kumthamo wekhoyili yoxinzelelo lwe-arc.

■ Umgaqo wokusebenza

Umzobo womgaqo wokusebenza we-grounding transformer xa kukho impazamo yesigaba esinye kwinkqubo uboniswa yintambo eqhelekileyo ye-ZNyn. Xa i-grounding transformer idlula kubungakanani obuthile be-zero sequence current ngexesha lokusebenza, i-current ehamba kwii-single-phase windings ezimbini kwikholamu efanayo yentsimbi ikwicala elichaseneyo kwaye ubukhulu buyafana, ukuze amandla emagnethi aveliswe yi-zero sequence current ahluke nje kwi-offset, ukuze i-zero sequence impedance nayo ibe ncinci kakhulu.

Xa i-grounding transformer ingaphumeleli, i-neutral point ingadlula kwi-compensation current. Ngenxa ye-zero-sequence impedance encinci, xa i-zero-sequence current idlula, ukuhla kwe-impedance voltage eyenziweyo kufuneka kube kuncinci kangangoko ukuqinisekisa ukhuseleko lwenkqubo. Ngenxa yokuba i-grounding transformer ineempawu ze-low zero sequence impedance, xa kwenzeka i-single-phase grounding fault kwi-phase C, i-phase C ground current I ingena kwi-neutral point emhlabeni, kwaye yahlulwe yangamacandelo amathathu alinganayo ukuze idlule kwi-grounding transformer. Ekubeni i-three-phase currents engena kwi-grounding transformer ilingana, ukufuduka kwe-neutral point N akutshintshi, kwaye i-three-phase line voltage ihlala i-symmetrical.

Nangona kunjalo, kwinkqubo yokuvelisa, ukujika kunye nobukhulu bejometri yee-windings eziphezulu nezisezantsi ze-high-voltage winding azinakulingana ngokupheleleyo, nto leyo eyenza kube nzima ukuba amandla emagnethi aveliswa yi-zero sequence current acinywe ngqo kwicala elichaseneyo, kwaye asavelisa i-zero sequence impedance ethile, ngesiqhelo malunga ne-6-10 Ω. Xa kuthelekiswa ne-zero sequence impedance ye-star connected transformer ye-600 Ω, iingenelo zayo ziyabonakala. Ukongeza, i-zigzag grounding transformer inokwenza ilahleko ye-no-load current kunye ne-no-load incinci kangangoko. Xa kuthelekiswa ne-star connection transformer eqhelekileyo, i-phase iron core nganye ye-zigzag connection transformer yenziwe ngee-windings zeekholamu ezimbini ze-iron core. Ngokwe-vector diagram yayo, xa ithelekiswa ne-star connection transformer eqhelekileyo, kufuneka i-wounded amaxesha ayi-1.16 xa i-voltage ifana. I-amplitude ye-zero sequence impedance kunye ne-positive sequence impedance yenethiwekhi yokusasazwa kwedolophu ene-single-phase grounding phantsi kwe-neutral point resistance grounding mode yahlukile kakhulu. Xa imisinga ye-sequence yesigaba sesithathu kunye ne-negative idlula, amandla e-magnetic kwikholamu nganye ye-iron core ye-grounding transformer yimbumba yee-phasors ze-magnetic potential ze-windings ezimbini zezigaba ezahlukeneyo kwikholamu ye-iron core. Amandla e-magnetic kwiintsika ze-iron core ezintathu liqela le-three-phase equilibrium quantities kunye nomahluko wesigaba se-120 °. I-magnetic flux eveliswayo inokwenza i-loop kwiintsika ze-iron core ezintathu. Ukumelana kwe-magnetic kwisekethe ye-magnetic kuncinci, i-magnetic flux inkulu, kwaye amandla abangelwayo makhulu, ebonisa ulandelelwano olukhulu oluhle kunye ne-negative sequence impedance; Ke ngoko, i-grounding transformer ineempawu ze-large positive kunye ne-negative sequence impedance kunye ne-small zero sequence impedance.

■ Iiparameter eziphambili zobugcisa

Ukuze kuhlangatyezwane neemfuno zokulungiswa kwe-arc coil grounding coil kwinethiwekhi yokusasazwa, kunye nokuhlangabezana neemfuno zamandla e-substation kunye nomthwalo wokukhanya, i-transformer yoqhagamshelo yohlobo lwe-Z iyakhethwa, kwaye iiparameter eziphambili ze-grounding transformer kufuneka zibekwe ngokufanelekileyo.

(1) Umthamo ophambili wecala le-grounding transformer enomthamo olinganisiweyo kufuneka uhambelane nomthamo we-arc compression coil. Ngokweenkcukacha zomthamo we-arc compression coil ekhoyo, kucetyiswa ukuba kubekwe umthamo we-grounding transformer njenge-1.05-1.15 amaxesha omthamo we-arc compression coil. Umzekelo, umthamo we-grounding transformer exhotyiswe nge-arc compression coil enye ye-200kVA yi-215kVA.

(2) Umbane opheleleyo ohamba kwindawo engathathi hlangothi yetransformer xa kukho impazamo yesigaba esinye yombane ongathathi hlangothi:

Apho:

U yi-voltage yomgca wenethiwekhi yokusasazwa (V); i-Zx yi-impedance ye-arc suppression coil (Ω);

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

I-Zs yi-system impedance (Ω);

Ubude bomsinga we-neutral point compensation current buya kufana nobo be-arc suppression coil, obuya kuba ziiyure ezi-2 njengoko kuchaziwe.

(3) Impedance yokulandelelana kwe-Zero Impedance yokulandelelana kwe-Zero yiparameter ebalulekileyo ye-grounding transformer, enempembelelo ebalulekileyo kukhuseleko lwe-relay ukunciphisa i-single-phase grounding short-circuit current kunye nokunciphisa i-overvoltage. Kwii-zigzag (uhlobo lwe-Z) kunye nee-star/open delta grounding transformers ezixhunyiwe ngaphandle kwee-coils zesibini, kukho i-impedance enye kuphela, oko kukuthi i-zero sequence impedance, ukuze isebe lemveliso likwazi ukuhlangabezana neemfuno zesebe lamandla.

(4) Ilahleko yiparameter ebalulekileyo yokusebenza kwetransformer yokumisa umhlaba. Kwitransformer yokumisa umhlaba enekhoyili yesibini, ilahleko yayo engenamthwalo ingafana neyetransformer yokumisa kabini enomthamo ofanayo. Kwilahleko yomthwalo, xa icala lesibini lisebenza ngokupheleleyo, ilahleko yomthwalo wecala eliphambili ingaphantsi kweletransformer yokumisa kabini enomthamo ofanayo necala lesibini ngenxa yomthwalo olula wecala eliphambili.

(5) Ngokomgangatho wesizwe, ukunyuka kobushushu be-grounding transformer kulandelayo:

1) Ukunyuka kwamaqondo obushushu phantsi kombane oqhubekayo olinganisiweyo kuya kuhambelana nemimiselo yomgangatho wesizwe wee-transformers zohlobo olomileyo zee-transformers zamandla aqhelekileyo, kodwa oku kusebenza kakhulu kwii-transformers ezisezantsi ezinomthwalo oqhelekileyo kwicala lesibini;

2) Xa ubude bomthwalo wexesha elifutshane bungaphantsi kwe-10s (ngokukodwa xa indawo engathathi cala idibene nokumelana), ukunyuka kobushushu kufuneka kuhambelane nemimiselo ye-national standard power transformer kumda wokunyuka kobushushu phantsi kweemeko ze-short circuit;

3) Ukunyuka kobushushu be-grounding transformer kunye ne-arc compression coil xa zisebenza kunye kufuneka zihambelane nemigaqo yokunyuka kobushushu be-arc compression coil: ubushushu obujikelezayo obuhamba rhoqo kumbane olinganisiweyo yi-80K, osebenza kakhulu kwi-star/open delta connection grounding transformer; Kwi-winding enexesha eliphezulu lokuhamba kombane olinganisiweyo elichazwe njenge-2h, ubushushu obuchaziweyo yi-100K.