Kev sib ntaus sib tua ntawm cov khoom siv hluav taws xobkev nyiag tooj liab hauv cov kab ke hauv avtab tom hloov lawv cov lus qhia maj mam: es tsis txhob hloov cov hlau tooj liab khov kho uas raug nyiag los nrog cov hlau tooj liab zoo ib yam, tam sim no muaj ntau tus neeg tswj cov khoom siv uas tau teev cov hlau tooj liab clad steel (CCS) rau cov hlau hauv av, kev sib txuas laj kab thiab kev sib txuas.Peb pom tias qhov kev xav yooj yim - CCS strand nqa ib txheej tooj liab ntshiab 0.25 hli hla lub plawv hlau, yog li nws ua lub luag haujlwm hluav taws xob tab sis tuav ib feem ntawm cov tooj liab khov kho tus nqi seem, thiab hauv peb qhov kev paub txog kev xa khoom tawm qhov kev hloov pauv ib zaug ntawd tshem tawm cov tub sab tub nyiag cov ntaub ntawv lag luam.Kuv tau siv 12 xyoo los muab cov khoom siv hluav taws xob rau cov tuam txhab hluav taws xob thiab lawv cov neeg cog lus hauv ntau dua 60 lub tebchaws, thiab tsab xov xwm no taug kev los ntawm cov ntaub ntawv tub sab nyiag uas yog tus tsav tsheb hloov pauv, cov lej engineering uas tus kws sau ntawv spec yuav tsum xyuas, thiab daim ntawv teev npe tseeb uas kuv xa mus rau cov neeg yuav khoom uas tab tom rov sau lawv cov qauv tom qab muaj tub sab nyiag.
- Peb vam khom rau qhov kev ntsuam xyuas ntawm US Department of Energy uas suav 18,400 qhov xwm txheej tub sab nyiag tooj liab uas tau tshaj tawm los ntawm 618 lub chaw muab hluav taws xob hauv ib xyoos, thiab cov xov hlau hauv av ntawm cov ncej thiab hauv cov chaw hloov hluav taws xob tau raug xaiv ua lub hom phiaj tseem ceeb.
- Peb hais Eskom cov lus hais tias kev nyiag tooj liab ua rau South Africa lub teb chaws poob nqi ntawm R5 billion thiab R7 billion ib xyoos, nrog rau lub tuam txhab hluav taws xob nws tus kheej siv nyiaj txog R2 billion txhua xyoo los hloov cov xov hlau raug nyiag.
- CCS strand xa 15% txog 40% IACS conductivity nrog lub zog tensile ntawm 560 txog 1040 MPa - kwv yees li ob mus rau tsib zaug muaj zog dua li tooj liab annealed - thaum nws cov hlau core ua rau nws yuav luag tsis muaj nqis ntawm qhov chaw pov tseg.
- Hauv peb cov lus hais txog kev xa tawm, CCS strand feem ntau khiav 25% txog 40% qis dua tib lub taub hau tooj liab ib 'meter', feem ntau vim tias lub plawv hlau hloov feem ntau ntawm cov tooj liab.
- Peb ib txwm ntsuas qhov sib pauv raws li qhov ua txhaum cai es tsis yog los ntawm txoj kab uas hla: phim qhov sib npaug ntawm qhov seem tooj liab ua ntej, tom qab ntawd xaiv cov lej ntawm cov xov, chav kawm conductivity thiab clamps.
2 teev sawv ntxov ntawm qhov chaw hloov hluav taws xob: cov ntawv ceeb toom txog qhov xwm txheej hais li cas tiag?
Hauv kaum ob xyoos uas peb nyeem cov ntawv ceeb toom txog qhov xwm txheej, muaj ib qho xwm txheej rov ua dua. Hauv qhov xwm txheej ntawd, ib tug tub sab txiav lub laj kab ntawm lub chaw nres tsheb tsis muaj neeg tsav, tsis quav ntsej txog cov khoom siv hluav taws xob uas muaj zog kiag li, thiab mus ncaj qha rau cov tooj liab uas yooj yim tshaj plaws thiab zoo li muaj kev nyab xeeb tshaj plaws hauv lub vaj: cov hlua khi av ntawm cov qauv hlau, cov hlua khi lub laj kab thiab cov hlua khi rau ntawm cov ncej sab nraud.LubKev ntsuam xyuas ntawm US Department of Energy txog kev nyiag hlau tooj liab los ntawm cov chaw muab hluav taws xobcov ntaub ntawv qhia meej txog tus qauv no - cov tub sab tau tsom mus rau cov xov hlau tooj liab uas nyob rau ntawm cov ncej hluav taws xob, sab hauv cov transformers thiab hauv cov chaw hloov hluav taws xob, thiab ib qho xwm txheej tau sau tseg tau yuam kom lub chaw hluav taws xob tshem tawm lub zog hluav taws xob tsuas yog kho cov xov hlau uas tub sab tau txiav kom zoo.Xyoo 2008 xwb, muaj 618 lub tuam txhab hluav taws xob uas tau tshawb fawb tau tshaj tawm tias muaj 18,400 qhov xwm txheej tub sab nyiag tooj liab nrog rau tus nqi kho ntawm USD 22 lab, thiab 13 tus neeg tau tuag thoob plaws hauv kev sim ua raws li tau tshaj tawm.
Peb pom tib yam qauv deb tshaj qhov Asmeskas.Raws li ib qhocov lus tshaj tawm Eskom, kev nyiag tooj liab ua rau South Africa kev lag luam raug nqi ntawm R5 billion thiab R7 billion ib xyoos, thiab cov chaw siv hluav taws xob siv li R2 billion ib xyoos los hloov cov xov hlau raug nyiag. A Cov xov xwm tshaj tawm ntawm tsoomfwv South Africarov ua dua tib yam R2 billion tus lej thiab sau tseg tias kev nyiag cable ua rau muaj kev tsis ua haujlwm ntev uas cuam tshuam rau cov lag luam thiab cov kev pabcuam tseem ceeb. Kuv hnov zaj dab neeg tib yam ntawm txhua lub teb chaws thaum kuv tham nrog cov thawj coj khoom siv hluav taws xob: qhov kev txiav txim hloov pauv tsis tshua muaj qhov mob - qhov tsis ua haujlwm, kev nyab xeeb thiab kev nyiag rov ua dua yog.
Daim ntawv them nqi zais cia: tus neeg tsav tsheb grounding raug nqi dab tsi tiag tiag?
Thaum cov hlau txuas hauv av ploj mus, kuv ib txwm ceeb toom cov neeg yuav khoom tias cov hlau yog qhov pheej yig tshaj plaws ntawm qhov teeb meem.Raws li peb qhov kev paub dhau los, cov nqi tiag tiag suav nrog cov neeg kho, lub sijhawm tsis ua haujlwm lossis tsis muaj hluav taws xob, kev pheej hmoo kev nyab xeeb thaum lub grid khiav tsis muaj nws txoj kev ua txhaum uas tau tsim, thiab qhov yuav luag paub tseeb tias tus tub sab yuav rov qab los thaum tooj liab tshiab tau teeb tsa.Qhov kev ntsuam xyuas ntawm DOE ua rau pom tseeb tias qhov kev nyab xeeb yog dab tsi: cov chaw muab hluav taws xob tau kaw hluav taws xob rau ntau txhiab tus neeg siv khoom tsuas yog kom cov khoom siv av uas raug tub sab nyiag puas tsuaj kom muaj kev nyab xeeb kho. Thiab lub chaw hloov hluav taws xob uas poob cov khoom siv av tsis yog teeb meem nyiaj txiag xwb - yog tsis muaj nws txoj kev tsim los ntawm av, qhov hluav taws xob txhaum nrhiav lwm txoj kev, thiab cov hluav taws xob kauj ruam thiab kov ib puag ncig lub vaj tuaj yeem ua rau tus neeg tom ntej uas taug kev nkag mus tuag taus.
Kuv qhia cov neeg yuav khoom kom tsis txhob siv nyiaj rau kev nyiag tooj liab ua ib txoj kab kho, thiab tus qauv rov mus xyuas dua yog qhov laj thawj.Peb hu txhua qhov kev txiav txim hloov pauv ua ib qho kev caw qhib rau kev mus ntsib dua, vim tias koj nyuam qhuav rov qab muab cov khoom seem rov qab rau hauv lub khw muag khoom pov tseg hauv zos.Peb pom tias cov khoom siv uas khiav tawm ntawm lub voj voog hloov cov khoom siv, tsis yog lub xauv xwb.
Nyeem cov kev hloov pauv tshwj xeeb: vim li cas ho hloov ntawm kev hloov pauv mus rau kev hloov pauv hauv kev tsim qauv?
Kuv pom ib qho qauv meej meej thoob plaws cov ntawv cog lus hloov pauv uas peb tau hais hauv ob peb xyoos dhau los hauv qhov kev hloov pauv ntawm cov lus qhia tom qab raug nyiag ntau zaus. Hauv peb qhov kev paub, thawj qhov kev txiav txim yuav khoom hloov pauv zoo li nrog zoo li. Qhov thib ob ntxiv cov koob yees duab lossis kev saib xyuas. Los ntawm qhov thib peb, tus kws ua haujlwm rov sau dua tus qauv nws tus kheej - thiab qhov ntawd feem ntau yog thaum kuv lub inbox tau txais daim duab kos nrog "tooj liab clad steel" sau hla tus neeg tsav tsheb hu. Peb tsis yog tib leeg hauv qhov kev nyeem no - kev taw qhia kev lag luam taw qhia tib qho kev taw qhia: lubDaim ntawv qhia txog CEATI txog kev coj ua zoo tshaj plaws hauv kev txo kev nyiag tooj liabqhia meej meej txog lwm txoj hauv kev rau tooj liab, kev luam ntawv tus neeg xyuas hluav taws xob thiab kev hloov pauv tsim rau kev ua av saum toj thiab hauv qab qib ua cov tswv yim tseem ceeb, nrog rau kev ua laj kab, teeb pom kev zoo thiab kev ua raws li txoj cai.
Peb hais meej meej: cov koob yees duab thiab cov laj kab kho cov tsos mob; cov khoom siv conductor kho qhov ua rau.Vim tias kev tub sab yog kev ua txhaum cai nyiaj txiag, qhov kev txo qis uas ruaj khov tshaj plaws yog qhov uas rho tawm cov nyiaj tau los - thiab CCS strand ua qhov ntawd thaum tseem ua kom lub zog hluav taws xob zoo. Peb pab neeg tau pom cov chaw muab kev pabcuam hauv nroog hauv thaj chaw muaj kev tub sab ntau ua tus qauv CCS rau txhua qhov kev sib txuas siab dua, thiab lawv cov ntawv ceeb toom tub sab tsuas yog ploj ntawm lub rooj sib tham kev ntseeg siab txhua hli.
Cov lej engineering: tus kws sau ntawv spec yuav tsum kuaj xyuas dab tsi tiag?
Peb yeej tsis cia zaj dab neeg tiv thaiv kev tub sab nyiag ua kev zam txim rau qhov tsim hluav taws xob tsis zoo, yog li cia kuv muab cov lej tso rau ntawm lub rooj. PebCCS strand hlauthiabtooj liab clad steel stranded hlauCov kab no yog tsim los ntawm 7 txog 37 txoj hlua nrog tag nrho cov txoj kab uas hla los ntawm 4.2 hli txog 22.5 hli, ib txheej tooj liab ntshiab ntawm 0.25 hli, thiab cov chav kawm conductivity los ntawm 15% txog 40% IACS. Lub zog tensile khiav ntawm 560 txog 1040 MPa, thiab lub neej ua haujlwm ntsuas tshaj 50 xyoo. Rau kev siv, peb99.97% ntshiab tooj liab stranded conductorzaum ntawm 90% + conductivity rau cov qauv tsim uas xav tau tooj liab khov kho.
| Vaj tse | CCS strand (peb cov khoom) | Cov xov tooj liab khov kho (ib txwm muaj) | Nws txhais li cas hauv lub vaj uas muaj neeg nyiag khoom ntau |
|---|---|---|---|
| Kev coj ua | 15%–40% IACS | ~100% IACS | Loj CCS nce ib lossis ob txoj kab uas hla kom phim qhov ua haujlwm txhaum |
| Lub zog tensile | 560–1040 MPa | ~220 MPa annealed | CCS tiv taus kev txiav thiab ncab zoo dua |
| Feem pua ntawm cov tooj liab | Tsawg tus neeg tsav tsheb | 100% | Tus nqi seem ntawm CCS yog ib feem ntawm cov tooj liab khov kho |
| Lub neej ua haujlwm | >50 xyoo | >50 xyoo | Tsis muaj kev nplua rau lub neej voj voog rau qhov kev sib pauv |
| Tus nqi khoom siv (peb cov lus hais xa tawm) | 25% -40% qis dua ib 'meter' | Lub hauv paus | CCS feem ntau pheej yig dua rau kev yuav, tsis yog tsuas yog khaws cia xwb |
| Kev siv zog txiav | Cov hniav blunts siab - hlau core | Qis | Cov tub sab tso tseg txoj kev txiav ib nrab ntawm txoj kev |
Cov xov CCS pheej yig dua 25% txog 40% dua li cov hlau tooj liab uas muaj tib lub cheeb hauv peb cov lus hais xa tawm, feem ntau vim tias lub plawv hlau hloov feem ntau ntawm cov tooj liab uas tsav tus nqi.Peb nyiam taw qhia tias qhov sib txawv no nthuav dav thaum twg tooj liab nce siab, uas yog thaum lub siab ntawm kev tub sab nyiag nce siab - tus neeg tiv thaiv kev tub sab nyiag pheej yig dua piv rau tooj liab thaum koj xav tau nws tshaj plaws.
Qhov loj ntawm qhov sib pauv los ntawm qhov ua txhaum: vim li cas kev theej daim duab thiaj ua rau yuam kev?
Kuv pom ib qho yuam kev ntau zaus hauv thawj zaug CCS cov lus qhia: theej cov tooj liab txoj kab uas hla ncaj qha. Peb tau pom tias txoj hauv kev ntawd ua rau tus neeg hlau me dua.Ib txoj hlua IACS CCS 30% xav tau kwv yees li 1.7 npaug ntawm thaj tsam ntawm tus neeg hlau tooj liab uas nws hloov pauv kom nqa tib lub luag haujlwm txhaum, yog li txoj haujlwm raug yog: xam qhov seem tooj liab sib npaug uas xav tau, tom qab ntawd xaiv CCS txoj kab uas hla thiab chav kawm conductivity uas ua tau raws li nws.Peb cov xov hlau npog 7 txog 37 txoj hlau nrog cov kab uas hla ntawm 1.4 hli txog 3.2 hli, yog li yuav luag txhua qhov hu xov tooj liab qub muaj ib kauj ruam loj dua CCS uas tseem haum rau cov clamps txheem thiab cov pwm exothermic.
Kuv tshuav koj ib qho lus ceeb toom ncaj ncees los ntawm thaj teb no.Peb ntseeg tias CCS yog cov lus teb zoo rau kev sib txuas hauv av, kev sib txuas thiab kev sib piv, tab sis nws tsis yog qhov hloov pauv rau txhua qhov kev khiav tooj liab.— cov khoom siv hluav taws xob uas muaj zog tas mus li thiab qee cov kev siv hauv kev sib txuas lus tseem siv tau tooj liab khov kho, thiab peb cov kab tooj liab 99.97% muaj rau cov xwm txheej ntawd. Peb xav tias tus neeg muag khoom ntseeg tau qhia koj tias ciam teb nyob qhov twg es tsis yog muag CCS rau txhua yam.
Tus neeg ntsuas kev npaj hloov chaw ntawm CCS
Kos cim rau cov khoom uas koj twb tau them lawm. Tus qhab nia qhia tias koj cov lus qhia hloov pauv tiav npaum li cas.
1/8 — theem thaum ntxov. Xa koj cov dej num txhaum thiab txoj kab uas twb muaj lawm rau peb, thiab peb yuav sau cov seem nrog koj.
Cov khoom siv yog lub ntsiab lus tseem ceeb - tab sis cov chaw pabcuam zoo tshaj plaws ua li cas lawv thiaj li tiv thaiv tau lawv?
Hauv peb cov khoom xa tuaj, CCS strand ua qhov hnyav, thiab cov chaw muab kev pabcuam uas muaj cov ntaub ntawv tub sab nyiag huv tshaj plaws muab nws ua ke nrog ob qho kev coj ua pheej yig. Ua ntej, peb pom zoo kom muaj kev cim tus neeg xyuas hluav taws xob: cov lus qhia ntawm CEATI teev cov kev ntsuas tiv thaiv kev luam ntawv ntawm tus neeg xyuas hluav taws xob, thiab peb tuaj yeem muab cov strand nrog kev txheeb xyuas uas ua rau kev muag rov qab pom tseeb.Qhov thib ob, peb yaum kom yuav khoom kom huv si - ib qho lus qhia uas teev cov chav kawm conductivity, tooj liab txheej tuab, tensile ntau thiab strand suav tsis tseg chaw rau kev hloov pauv ntawm cov khoom mos, tooj liab siab thaum lub sijhawm teeb tsa.
Los ntawm peb sab ntawm lub rooj: daim ntawv xaj hloov khoom uas raug tub sab nyiag zoo li cas?
Peb saib qhov ceev ceev tseem ceeb npaum li tus nqi thaum lub tuam txhab hluav taws xob lossis nws tus neeg faib khoom sau ntawv rau peb tom qab muaj xwm txheej. Peb lub Hoobkas hauv Xinchang khiav lub Hoobkas 3,000 m² nrog ntau dua 40 tus neeg ua haujlwm tsim khoom thiab pab pawg R&D 5 tus neeg, xa tawm mus rau ntau dua 60 lub tebchaws, thiab tuaj yeem tsim tau txog li 100,000 meters ntawm CCS strand ib hlis. Kev ua haujlwm zoo khiav raws li ISO 9001 system - koj tuaj yeem txheeb xyuas qhov kev lees paub ntawd txhais li cas ntawmnplooj ntawv ISO 9001 tus qauv raug cai— thiab rau cov neeg yuav khoom uas xav tau kev kuaj hluav taws xob ntawm cov ntaub ntawv grounding los ntawm lwm tus,CEPRI (Lub Koom Haum Tshawb Fawb Txog Fais Fab Hluav Taws Xob Tuam Tshoj)yog lub koom haum lees paub uas cov ntawv tshaj tawm ntawm pawg thawj coj lees txais. Peb cov khoom xa tawm tau txog USD 15 lab hauv xyoo 2022, thiab feem ntau ntawm cov khoom ntawd tam sim no xa mus rau cov chaw muab kev pabcuam rov tsim kho cov tes hauj lwm hauv av uas raug tub sab nyiag.
Kuv khaws peb yam tseem ceeb uas siv tau rau hauv txhua daim ntawv hais nqe hloov pauv:Peb ntim cov xov los ntawm dov rau koj qhov ntev teev tseg, xa khoom los ntawm Shanghai lossis Ningbo, thiab npaj cov ntaub ntawv xa tawm tag nrho - daim ntawv them nqi, daim ntawv teev khoom, daim ntawv pov thawj keeb kwm thiab daim ntawv pov thawj xeem - ua ntej lub thawv kaw.Yog tias koj tab tom ua kom muaj tus qauv thoob plaws ntau lub chaw hloov pauv, peb kuj tuaj yeem tuav qhov chaw tsim khoom kom xa cov xaj rov qab yam tsis muaj kev sib tham txog lub sijhawm ua khoom tshiab. Koj tuaj yeem saib tag nrho cov khoom hauv pebtooj liab clad hlau hlau pawg.
Cov lus nug nquag nug
Puas yog CCS strand grounding zoo ib yam li cov tooj liab khov kho?
Peb teb tias yog, yog tias nws raug ntsuas los ntawm qhov ua haujlwm txhaum tsis yog los ntawm txoj kab uas hla. Tus neeg hlau CCS ntawm 30% lossis 40% IACS, nce ib lossis ob qhov loj me, nqa tib lub sijhawm txhaum li tooj liab uas nws hloov, thiab kuv ib txwm pom zoo kom tus kws tsim qauv paub meej qhov seem tooj liab sib npaug ua ntej peb hais nqe.
Vim li cas cov tub sab thiaj tsis quav ntsej txog CCS strand tom qab thawj qhov xwm txheej?
Vim tias kev lag luam ploj mus, raws li peb tau pom thoob plaws peb cov nyiaj siv hluav taws xob. Lub plawv hlau txhais tau tias ib 'meter' ntawm CCS tsuas muaj ib feem ntawm cov tooj liab hauv cov khoom siv hluav taws xob khov kho, cov chaw pov tseg tsis them nyiaj ntau rau nws, thiab lub plawv hlau ua rau cov cuab yeej txiav uas cov tub sab nqa tsis muaj zog. Cov lus mus sai sai hauv cov tes hauj lwm tub sab txog cov chaw uas tsis tsim nyog pheej hmoo lawm.
Puas yog CCS strand raug lees txais hauv cov qauv kev siv hluav taws xob?
Peb taw qhia cov neeg yuav khoom mus rau cov lus qhia txo qis kev siv hluav taws xob xws li daim ntawv qhia txog kev nyiag tooj liab CEATI, uas qhia meej txog lwm txoj hauv kev rau cov neeg hlau tooj liab, thiab peb lub Hoobkas muab cov xov CCS rau hauv cov khoom siv hluav taws xob thiab EPC cov lus qhia thoob plaws ntau dua 60 lub tebchaws. Peb paub tias kev lees txais yeej ib txwm nyob nrog tus qauv hauv zos, yog li kuv xav kom xa cov chav kawm conductivity thiab daim ntawv pov thawj xeem rau koj tus kws ua haujlwm tshwj xeeb ua ntej kev sib tw.
Kuv yuav tsum xaiv chav kawm conductivity twg rau kev grounding substation?
Kuv hais txog 30% IACS feem ntau rau kev sib txuas ntawm laj kab thiab cov pigtails siab dua; kev sib piv thiab kev khiav ntev dua feem ntau yog qhov ua pov thawj 40%. Kev suav qhov txhaum tam sim no txiav txim siab, thiab peb tsim cov chav kawm 15%, 21%, 30% thiab 40% thoob plaws tib qho 7-rau-37-strand.
Puas yog CCS strand tuaj yeem raug welded exothermically zoo li tooj liab?
Yog — peb vuam CCS strand nrog cov pwm exothermic txheem phim rau txoj kab uas hla ntawm strand, thiab lub plawv hlau tsis cuam tshuam rau qhov vuam. Peb muab cov pwm sib phim thiab cov hlau vuam, yog li qhov sib koom ua ke thiab tus neeg xyuas hluav taws xob tuaj yeem los ntawm ib qho kev xa khoom.
Tom qab raug tub sab nyiag, daim ntawv xaj hloov pauv tuaj yeem xa tau sai npaum li cas?
Peb lub peev xwm txhua hli rau CCS strand yog txog li 100,000 meters, thiab cov kab uas hla tus qauv txav mus sai sai los ntawm peb cov kab. Kuv npaj daim ntawv them nqi, daim ntawv teev cov khoom ntim khoom, daim ntawv pov thawj keeb kwm thiab daim ntawv pov thawj kuaj ua ke nrog kev tsim khoom kom cov ntaub ntawv teeb tsa yeej tsis dhau los ua qhov tsis zoo.
Puas yog lub chaw pov tseg yuav tsis kam txais CCS tiag?
Peb pom tias feem ntau cov chaw ua haujlwm raug cai kawm paub txheeb xyuas cov hlau nplaum tooj liab sai sai - kev sim hlau nplaum qhia txog lub hauv paus hauv vib nas this. Qee tus tseem lees txais nws ntawm tus nqi sib ze ntawm cov hlau, uas yog qhov tseeb: qhov sib txawv uas pab nyiaj rau kev nyiag tooj liab tsis nyob ntawd.
Rov sau koj tus qauv grounding tom qab muaj tub sab nyiag?
Xa peb daim ntawv teev sijhawm ntawm tus neeg coj hluav taws xob los ntawm cov lus qhia raug nyiag - lossis tsuas yog lub luag haujlwm ua txhaum thiab txoj kab uas koj siv ua ntej - thiab peb yuav xa rov qab CCS strand sib npaug nrog chav kawm conductivity, suav cov strand, clamp thiab pwm haum, thiab daim ntawv hais nqe los ntawm lub Hoobkas.
Jane Yang— Tus Thawj Saib Xyuas Kev Muag Khoom, Xinchang Shibang New Material Co., Ltd.
Jane tau siv 12 xyoo ua haujlwm rau lub rooj xa khoom ntawm peb lub Hoobkas tiv thaiv xob laim thiab av, pab cov tuam txhab hluav taws xob, cov neeg ua haujlwm hauv grid thiab cov neeg faib khoom nrhiav cov khoom siv tiv thaiv kev tub sab, CCS strand thiab cov khoom siv hlau tooj liab nrog kev kuaj thiab kev txhawb nqa cov ntaub ntawv tag nrho.
Lub sijhawm tshaj tawm: Cuaj hlis-14-2026