Phan II: DjA TU'- DIEN LY 153
TAC DONG CUA BAG TU"
DOT vol M O T SO H E T H O N G CONG NGHE 6 VIET NAM
Ha Duyen Chau, Le Trirong Thanh, Nguyin Thanh Dung Vien Vat ly Dia cdu
18 Hodng QuSc Viet, Cdu gidy, Hd Npi Email: hdchaiiipfiiuvahoo.com
Tom tdt: He thdng truyin tai dien 500 - 220kV ciia Viet Nam, vai dp ddi gdn 5000km tic Bdc vdo Nam, cimg nhu he thdng Sng ddn ddu khi vai dp ddi han 400km a phdn phia Nam lanh thd Viet Nam Id ddi tuang tdc dpng mgnh me ciia bdo tic. Bdt ddu tu nhicng ndm 2000, Vien Vdt ly Dig cdu duac nhdn nhiem vu nghiin cicu tdc dpng ciia bdo tic doi vai cdc he thong cong nghi^
ndy de cd the tim ra nhicng bien phdp cdn thiet phdng trdnh vd hgn che nhicng tdc hgi cd the ciia bdo tic xay ra ddi vai he thong. Sau nhiiu ndm nghiin ciru, cdc cdn bp Vien Vdt ly Dia cdu dd thu duac nhieu ket qud trong viec thuc hien nhiem vu. Trong bdi viet ndy se duoc trinh bdy mpt cdch tdng quan nhicng kit qud do. Cu the Idn ddu tien a Viet Nam da hodn chinh duac quy trinh cdng nghe ghi chinh xdc ghi ddng dien cdm icng GIC (Geomagnetically Induced Currents) chgy qua mdy bien dp ciig hi thong truyen tdi dien 500-220kV vd dien thi dng - ddt PtoS-V (Pipe-to-Sol
Voltages) cua dng ddn ddu khi ddi vai ddt xung quanh. Tic viec ghi lien tuc ndy da thu duac cdc tdp hap die lieu GIC vd PtoS-V, khdng nhicng phuc vu thuc tiin cho viec du bdo khd ndng tdc dpng ciig bdo tic doi vai he thdng , truyen tdi dien hoac dng ddn ddu khi, md cdn Id ngudn tu lieu qui gid trong viec nghien cim dp ddn. cdu triic vd Trdi ddt, phuc vu cho nhieu muc dich khoa hoc khdc nhau. Dd khdng dinh duoc rdng GIC vd PtoS-V cd lien quan chat che vai tic truang Trdi ddt, vai hi sd tuang quan rdt cao, nhdt Id khi cd bdo tic xdy ra. Qua cdc bieu do tdn sudt. cd the thdy rdng ddi vai he thdng truyen tdi diin, sd licang cdc gid tri GIC cao la khd lan. GIC nhiiu khi dgt din gid tri 8, 9 Ampe. gid tri cd thi gdy ra sic roi loan cua hi thdng rale^
trong cdc mdy bien dp. Ddi vai he thdng dng ddn ddu khi, cd the thdy sd luong gid tri PtoS-V cao (>1,3V vi gid tri tuyet ddi, nghia Id vicat qud gid tri an todn cho phep vi mat an mon, cd tdc dpng gdy an mon dng mgnh) len din hdng trdm nghin, Id khd lan. Nhicng gid tri ndy chi xdy rg khi cd bdo tic hoac cd nhieu logn tic lan. Cdc md hinh GIC vd PtoS-Vxdy dung theo ly thuyit phii hop khd tdt vai gid iri ghi duac trin he thdng.
Tir khoa: Bdo tic. Ddng dien cam icng dia tic GIC. Hi thdng truyen tdi dien.
Ong ddn ddu khi. Dien the dng - ddt PtoS-V.
15 ! Tuyfen tap cac cong trinh nghien CLFU Vat ly Dja c l u 2008
l . M o d a u I Xung quanh chiing ta luon luon ton tai m(3t tir truong Trai dat tac dgng thuong xuyen len
mgi mat hoat dong cua con nguoi, Tir tnroTig na\- co lien quan chat che voi su hoat dgng ciia Mat Trai, Khi xa\- ra hien hxang bimg no sac cau tren Mat Troi, mot lugng khong 16 cac hat tich dien dugc phong ra ti-ong kliong gian. Phan dong hat nay chuyen dgng ve phia Trai Dat se nen ep cac dirong sue tix tmong. lam cuong do tir truong quan sat dugc tren be mat Trai Dat thay doi doi nggt. Tirong tac giua cac hat tich dien ciia plasma Mat Troi va tarong tir ciia Trai Dat se lam cho cac hat tich dien na\' chuNcn dong cuon xoay Uong tir quyen thanh he dong dien xung quanh Trai dat. Ngoai ra, do birc xa Mat troi va su ion hoa trong tang dien ly da tao ra cac he dong dien Sq. Sd, Chinh cac dong chay trong tang dien Iy nay ciing se gay nen cac nhieu loan tii' a viuig xich dao voi bien do rat Ion. Theo nguyen Iy cam img dien tir ciia Faraday, khi c6 m(Dt truong tir ben ngoai bien doi theo thai gian, se xuat Iiien dong dien cam ling chay trong tat ca cac vat dan, rCIii dong dien nay chay trong cac he thong thiet bi ky thuat do con nguoi tao ra, cam img do tmong dia tir thi dugc ggi la GIC (Geomagnetically Induced Cuirents), Trong nhung nam Mat 'Yvbi hoat d(5ng manh, bao tir xuat hien thuong xuyen va bien do bao c6 the dat {a\ gia tri rat Ion toi nam, sau tram hoac hang ngan nT, nhat la ti-ong vung cue va \iing xich dao. Dong dien cam img di kem voi nhung hien tugng nay se rat Ion CO the gay n(2n nhung tac hai khong the lirong truac dugc. Vi du lich sir da chimg kien nlrting thi(;t hai khong 16 do bao tir ga\- ra. dien hinh la tran bao tir ngay 13 thang 3 nam 1989 vao liic 07^5'^^ UT da lam cho he thong tru)en tai dien cao the 735kV o Quebec (Canada) ngimg hoat dgng trong \'6ng 9 gio dong ho. gay thiet hai hang ty d61a My [9].
Tac dong ciia dong dien cam irng do trirong tir ciia Trai Dat tod he thong dien cao die, cac •*
he th6ng cap ngam truyen tin qua bien, cac 6ng dan dau khi vu'gt dai duong... da dugc nghien ciai 6 nhieu nuoc tren the gioi, dac biet la o cac nuoc phat trien o nliu Thiiy Dien [10], Phan Lan [13. 14]. Anh [8], Nga [15]. My [12]. Canada [I, 16], hoac a mot sl nuoc o thi giod thu ba nlur Sec [11 ]. .\n dci). In d6 ne xi a,,, 0 Viet Nam, tir tliang 6 nam 1994 he thing dirong day 500kV o nuoc ta \'OT tong chieu (.lai gan I500kin, cimg \6i 3400kni dirong day 220kV va nhieu tram bien ap bat dau tir tram Hoa Binh toi tram cii6i cimg la tram Phii Lam - Thanh pho H6 Clii Minh da di vao hoat d(3ng. Vao dau nhung nam 2000, do sir phat triln nganlr diu Idii cua Viet Nam. mot he diong ong dan dau khi dai hon 400km da dugc xay dung tren vimg bien phia Nam niroc ta. Niroc ta nam trong vimg \'T d(3 thap, bien d(3 bien thien ciia tarong tir trong cac bao tir thuong kha Ion do anh hirong manh ciia dong dien xich dao. Hon nira, nhu da biet. hoat d(3ng Vlat trod tlray d6i iheo chu trinh 11 nam. Trong chu trinh thir 23 ciia hoat dgng Mat trod. Mat Uod dat den hoat d(3ng cue dai vao nhung nam 2000-2001. Do vay viec ngliien cim tac d(5ng ciia bao tir doi \oi duong day 500kV-220kV cimg nhu Ing dan diu khi la can thiet do co Llic de ra nhung bien phiip phong ch6ng kip thoi, ngan ngii-a tac hai c6 the
xay ra, ; Voi muc dich nhir vav, \an de duac de ra triroc hit la khao sat xem klii tii' tarons biln
tliien, trong he tliong tmyen tai dien 500-220k\' cung nhu he thing Ing dan diu khi ciia chimg fa c6 xuat hien dong dien cam ung hay khong? Khi da khing dinli dugc su tin tai khach quan cua dong dien nhir \ a_\. xa) dung mot he thong cong nghe ghi dong dien cam img chay trong duong day trung tinh cua cac tram biln ap 500 kV-220kV hoac cac bich cua Ing
Ph^nii: OIATU- DIEN LY 155
^ dau khi; tim hi(:u sir tuong quan giira dong dien cam img ghi dugc vod tmong biln thien t^ ghi dugc tai cac Uam dia tir; tinh toan dong dien cam img Iy thuyet hi so lieu bien thien tir dl nghien cim cau true do dan ciia v6 Trai Dit trong \amg dat cac tram bien ap; thong ke va nghien ciai cac bao hr va cac qui luat xuit hien ciia chung de tien toi du bao chimg vod do chinh xac can thiet, tien tod du bao dugc do Ion ciia dong dien cam img xuat hien khi bao tir xay ra. Tir do de xuat cac phuang an thich hgp phong chong tac hai co the c6 ciia dong dien cam img doi voi hoat dgng ciia duong day cao thi 500 kV-220kV va ong dan dau khi o nuoc ta.
2. Vai net ve lich su nghien cuu
Van de ve tac dgng ciia nhieu loan tir va bao hr len cac he thong cong nghe da dugc nghien cim tir giira the ky thir 19, bat dau la doi vod cac he thong dien tin luc do dang phat trien manh me. Ngay tix khi cac duong day dan dai dugc sir dung vao thuc tien nhu cac day dien bao, tac dgng ciia nhieu loan tir noi chung va bao tir noi rieng bat dau dugc nhan thay.
Trong thod gian hi 1825 - 1991, nhung sir co Ion ciia cac he thong cong nghe xay ra do bao tir thuong trimg dimg vao cac nam Mat trod boat dgng cue dai: 1847, su co xay ra doi voi duong day dien bao a Anh, Florence-Pisa; 1858, 1859 ngimg tre lien lac dien bao chau Au, chau My, tir 1860 - 1907, 1918, 1929: nhieu loan Ion doi vod cac day cap dien bao 6f nhieu nuoc; 1940:
sir CO he thong dien lire gay ra do bao tir; 1957: te liet he thong dien lire Toronto; 1972: gian doan vien thong lien luc dia, ngimg hoat dong he thong vien thong L-4; 1989: te liet hoan toan he thong dien luc Quebec...
Trong nhiing nam gan day, 6 nhieu quoc gia tren the giai, nhieu cong trinh nghiem tiic ve ly thuyet ciing nhu thuc tien da dugc thuc hien de nghien cim cac he thong dien, dac biet la tinh de nhay cam ci'.a chimg doi vod cac dong dien cam img sinh ra trong cac nhieu loan tir va bao hi, vi du nhu cac cong trinh ximg quanh dirong day 400kV ciia Phan Lan, duong day 500kV o Columhia (thuge Anh), duong day 735kV a Quebec, roi o My, Nhat Ban v.v.., nhu da noi a tren. Dong thod, tir cuoi nhung nam chin muoi, dau nhirng nam 2000, viec nghien cmi dong dien cam img Uong cac ong dan dau khi da dugc phat trien manli me, nhu 6 Canada [1], Phin Lan [13, 14], Thuy Diln [10], My [2], Sec [11], Nga [15]... Dac biet, cong ding quoc te dang thuc hien chuang trinh qu6c te STEP (International Solar Terrestrial Energy Program), nghien cim tac dgng ciia cac dong nang lugng trong moi tmong Mat troi - Trai dat len thod tilt, klii hau cung nhu cac c6ng Uinh xay dimg,
5. Cu so- Iy thuyet ciia phuong phap nghien ciru
Tir truong biln thien theo thoi gian se lam xuat hien cac dong dien cam img, cung
^ikn thien theo thai gian, chay trong cac vat dan. Su bien thien ciia tir tmong Trai dat
!am cam img ra cac hieu dien the trong cac lop be mat Trai dit. Khi co dilu kien thu|n '9d la cac he thing cong nghe dai, vi du dirong day tmyen tai dien cao thi hoac ong dan lau khi, hieu dien thi cam img nay se gay ra cac dong dien cam img chay trong cac he hong dan dien diii do {Hinh 1). Doi voi mot jie thong truyin tai dien cao ap, bao tir tap
•a cac dong dien cam img dia tir GIC manh den nhieu am-pe chay giira cac diem tiep dat 'ua he thing dien lire, cac tram bien ap cung nhu cac dilm trung gian, trong khi chi can
156 Tuydn tap cac c o n g trinh nghien CLPU Vat ly Dja c l u 200g
vai am-pe la c6 the lam roi loan hoat dgng ciia tram bien ap. Cac dong dien cam img nay lam cho loi cua cac may bien ap bi bao hoa, dien the hi meo di, tao ra cac hai dieu hoa khac nhau, trong do gia tri ciia cac hai chan ciia the hieu ciing nhu cuong do dong dien la rat Ion. co kha nang lam ngat cac bg bii, lam no cac cau chi, lam n6ng chay cac v6 bgc ciia dav dan. va lam hone ca mav bien ao.
TruoTig dien
GIC 1 pha
GIC I
3 pha ^ Mat dat
y yy y y y y ^ y y y y y y y y y y y y y- y y y y y
Hinh 1. GIC chay vao he t h i n g truydn tai dien
O Viet nam, duong day dien cao the {Hinh 2) bao gom gan 1500km duong cap 500kV va 3400km duong cap 220kV va nhieu tram bien ap (Hoa Binh, Da Ning, Pleiku, Phil Lam), He th6ng dirong day dugc tiep dat tren nhtrng viing dit co do dan dien chenh lech nhau rat Ion. Khi di qua nhirng vimg dat co dien tro cao, co thi gay nen cac dong dien cam img dja tir rat manh chay qua cac tram biln ap tren mat dit.
Duong ong dan dau khi ciia Viet Nam viing Nam Con Son {Kinh 3) dai gin 400km chay tir viing Lan Tay Lan Bo vao viing Viing Tau - Ba Ria. Ong dugc lam tir thep due.
Doi voi 6ng dan khi kh6, duong kinh ciia 6ng la 406,4mm, v6 Ing day tir 10-15mm, con doi vai 6ng dan khi long, duo-ng .kinh ciia ong la 168,3mm, v6 Ing day 7,1mm.
Cong viec nghien cim phai thuc hien cac buac sau day:
• Nghien cim bao tir va cac qui luat xuit hien ciia chung, mot mat de du bao, mat khac de nghien cim m6i tirong quan \ai cac thong sl ciia he thing dien lire va Ing dan dau khi (dong dien, dien the):
• Dat may ghi dong dien cam irng trong dirong day trung tinh ciia biln ap duong day 500kV-220kV ho^c bich noi cua Ing dan diu khi. Nghien cim thing ke de tim qui luat xuat hien. khang dinh mli tirong quan. tir do tiln hanh viec du bao;
• Nghien cim do dan viing co diro-ng day di qua de tim kha nang xuit hien dong dien cam img tai \iing do.
4. He thong thiet hi ghi dong dien cam ung trong he thing truven tai dien SOOKV-^
220KV va ong dan khi
De tien hanh ghi dong dien cam irng chay trong day trung tinh tai cac tram biln ap 500kV-220kV. chiing toi dimg mot he may gom cac thilt bi sau:
Phin II: O j A T U - DIEN LY
157
• Tram ghi GIC
• fiai dia tu
. Duong day 500kV Duong day 220kV
Hinh 2. He t h i n g truydn tai dien cao th§ 500 - 220kV Viet Nam va he t h i n g dai tram dja tip
Viet Nam
Hinh 3. Duang ong dan khi Viet Nam
• Ampe kim va dien kl HIOKI - 3109 DC CLAMP ON HITESTER do hang HIOKl i« E. E. C0RP0Ry\T10N - Nhat Ban san xuit;
I - Bg chuvin dii ADC - 16 de chuyen d6i tin hieu tir tirong tir sang sl;
May vi tinh de ghi so lieu;
' Day nli tir ampe kim kep vao day trung tinh, day noi (chong nhieu) tir dien kc den bo biln dii ADC. Diing mot nan dong 220V - 6V de nuoi dien kl.
58 Tuy§n tap cac cong trinh nghien ciyu Vat ly Dja cau 2008
Cac thiet bi ghi dugc lap theo so do a Hinh 4.
Be ghi dien thi Ing - dit tai Ing din khi chay trong khu vuc Ba Rja - VQng Tau, da dugc dat mot he may gom cac thiet bi sau: Dien cue noi dat, day dan hoc kim chong nhieu de truyen tin hieu tir duong ong vao may ghi, bg chuyen doi ADC - 16 va phan mem kem theo, may vi tinh de ghi so lieu va cac phu tiing kem theo.
Cac thiet bi ghi dugc lip theo so do a Hinh 5. Vi tri diem dat thiet bi la tren mot phan doan ong dan khi kh6 va 3 ong dan khi long di tir nha may xir Iy khi Long Hai tren bo bien Vung Tau den Phuoc Floa. Cap dan tin hieu gom 6 day dan noi tir:
duong ong dan khi kh6 tir Long Hai (I), duo'ng ong dan khi kho di Phu My (2), 3 duong 6ng dan khi kho di Phii My ((3), (4). (5)), va day dan dien cue (6). Cac day dan nay se dua tin hieu vao bg chuyen doi ADC va ghi vao may tinh. Cac dau noi dugc xiet chat theo day da dugc thiet ke tir truoc o cac test point va mat bich.
May bien a p T 2
Du'O'na vao tram
Tij bang
Ban dieu
khien
J=Z]
may tinh, Ban datdien ke
HU
Thiet k l : Ha Duyen Chau P.Tram tru-ang: V u O u ' c C h u Phong KTKH : Nguyen Van Thanh
Duyet: P.Giam doc NMTD Hoa Binh • Pham Van Tu'u
Hinh 4. Sc do dat cac thilt bi ghi dong dien cam u'ng GIC tai tam b i l n ap 5C0kV Hoa Binh
Phan II: O I A T U ' - DIEN LY
159
Phong dieu khien
Ban dat may linh
24
May no
Tram bom
Nha may XLT Iy khi Long Hai 15km
^ Dirong ong dan khi kho
^Cap day dan tin hieu
\
Bich Ham cap
NMD
BaRia H j Bich
"®-
Bich
i
•®3 ong dan khi hoa long den Phuoc Hoa
Hinh 5. S c d l dat cac t h i l t bi ghi dien th§ ong d i t tai Tram phan phoi khi Ba Rja
5. Ket qua thu thap va sir ly so lieu 5. 1. So lieu bien thiin tir vd bdo tu-
Bk thuc hien viec nghien cim tac dgng ciia bien thien tir, bao tir 6 Viet Nam, chimg toi sir dung sl lieu ghi lien tuc trirong dia tir trong he thong dai tram dia tir quoc gia:
Sapa (tinh Lao Cai, each Ha Ngi 400km ve phia Tay bac), Phii Thuy (Gia Lam - Ha Noi), tai vimg bien thanh ph6 Da Lat (tinh Lam Dong), va tai thi xa Bac Lieu (tinh Bac Lieu) (Hinh 2) [7]. Trong so 4 tram nay. tram Phu Thuy da dugc lap may ghi tir hien s6 GEOMAG ciia Phap vien trg tir nam 1993, c6 do chinh xac cao (Do phan giai 0,InT cho tir kl Fluxgate va 0,0InT cho tir ke proton) dat trinh do quIc tl. Tram nay da dugc chinh thirc cong nhan la dai OMP (Observatoire Magnetique Planetaire - Dai dia tir hanh tinh), mot thanh vien ciia chuong trinh INTERMAGNET quIc tl tir nam 1995.
Dai thu hai sir dung may ghi tir hien so la dai xich dao tir Bac Lieu, tir nam 1998 da dugc phia Nhat Ban trang bi may ghi tir FRG-601 do Nhat Ban san xuit, voi do phan giai 0,lnT trong chuang trinh hgp tac truang Dai hgc Kyushu va Vien Vat ly Dia cau Ha Ngi. Dai Vat ly Dia ciu Da Lat tir truoc den nam 2003 sir dung may ghi tir quang ca do Lien bang Nga san xuit, ghi tir tren giay anh voi do nhay 2-3nT/mm. Tir nam 2003, trong chuang trinh hien dai h6a dai tram, Vien Vat ly Dia ciu dugc trang bi may ghi tir hien sl GEOMAG gilng nhu a Phu Thuy. Con tai dai Vat ly Dia cau Sapa, liien nay van sir dung may ghi tir quang co tren giay anh ciia Lien bang Nga san xuat. So lieu tir cac dai dugc giri ve Ha Ngi hang ngay (d6i voi may ghi tir hien so) va hang thang doi vai may ghi tir quang co (Sapa). Tir nhirng so lieu nay, chung toi nghien cim, thong ke
160 TuySn tap cac c o n g trinh nghien CLfu Vat ly Dja c l u 2008
dugc tat ca cac bao tir xay ra tren lanh tho Viet Nam, nghien cim dugc bien thien Sq, Sd gay ra do nhung he dong dien tren tang dien Iy, ciing nhu he vong dong xich dao chay tren vimg phia Nam ciia lanh th6 nuac ta. Tren Hinh 6 la mgt vi du ve mot gian do tir cho tran bao tir thu dugc tai dai OiMP Phii Thuy trong ngay 31/3/2001. Tren gian do la duong ghi ciia ba ylu to tir truong Trai dat la do tir thien (D), tinh bang phut g6c, thanh phan nam ngang (H) va thanh phan thang dung (Z), tinh bang nT. True ngang la thai gian, tinh theo gio UT.
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Hinh 6. Vi du mot ngay bao tu- ghi tai Phu Thuy (ngay 31/3/2001)
5. 2. So lieu GIC thu duac tai cdc tram bien dp
Do de tai dugc thuc hien trong nhieu giai doan khac nhau, viec dat cac thilt bi ghi GIC dugc thuc hien trong cac thc-i-dilm khac nhau: Cac tram 500kV Hoa Binh tir thang 6/1999 din 2003, tram Phii Lam tir thang 1/2000 - 12/2002, tram Pleiku tir thang l/20oI - 12/2002 va tr^m biln ap 220kV Hai Phong tir thang 1/2003 - 12/2003. Tren Hinh 7(a) la mot vi du ve mot ngay ghi GIC tai tram biln ap 500kV Hoa Binh, ngay 28/6/1999 (true ngang chi thai gian theo UT, true dimg la GIC tinh bing A).
^ Trong cac tram bien ap 500kV diu dugc dat cac tu bii dgc va dien khang. Chinh cac thilt bi nay da ngan can dugc cac dong dien GIC mot chilu xam nhap vao he thong duong day 500kV. Doi voi he thong truyin tai dien 220kV thi khac: do khon^ co cac thilt = bi hi bii dgc va dien khang nen cac dong dien mot chilu xam nhap dl dang. Do vay cac dong dien nay co the chay trong he thing 220kV, qua cac day tmng tinh vao cac may biln {
ap 500 - 220kV, gay roi loan cho hoat dgng ciia cac may nay khi c6 bao hi xay ra. \
Phin II D j A T U - DIEN LY 161
Nhu tren Hmh 7 (a), c6 the thiy ring duong ghi GIC chua dung nhieu thong tin:
truac het do la "phong dien truong" trong khu vuc tram bien ap, gay ra do nguyen nhan nhan tao: do cau tnic dac biet ciia tit ca cac thiet bi trong khu vuc nhu cac may biln ap, he thing day dan.,., thir hai la dong dien GIC ma chung ta dang nghien cim, gay ra do cam ung dien tir trong cac vat dan khi tir truong Trai dat bien thien. Do vay de nghien cim GIC, truac het can loai bo phong dien truong. Tren Hinh 7(c) la do thi eiia GIC sau khi da loai bo phong bang each xay dung mot duong cong tir sir lam tron tix chinh duong ghi tir (a), sau d6 lay gia tri thuc ciia GIC trir di cac gia tri lam tron nay. De so sanh, tren Hinh 7(b) dugc bieu dien do thi dao ham ciia thanh phan tir truong X theo thod gian (true ngang la thod gian tinh theo UT, true dung la dX/dt tinh bang nT/phut). C6 the thay rang giiia duong GIC gay ra do cam ung co sir tuong quan rat tot voi duong dao ham dX/dt ciia thanh phan X ciia tir truong Trai dat.
(a)
4
1 0
40
W
/U/V—^,-12 15 18 21 24
20
15 16 21 24
(b)
(c)
Hinh 7. GIC ghi duac tai Hoa Binh ngay 28/6/1999 (a), dao ham thanh phin X cua truang dia t u theo thai gian tai dai dja tiJ' Phu Thuy (b) va GIC da loai bo phong (c)
5. i. So liiu diin the dng ddt thu thap duffc tai ong ddn khi Bd Ria
Trong nam 2004, viec thu thap so lieu so lieu dien thi Ing - dat dugc thuc hien tai Tram phan phii khi Ba Ria thuoc tinh Ba Ria - VOng Tau, nim each Long Hai 15km va Phu My 28km. Tren Hinh 8 la vi du ve dien thi Ing dit thu dugc cho ngay bao tix7- 8/11/2004. Tren hinh nay, true ngang la thod gian tinh bing gia UT, Uuc dung the hien dien
162 T u y l n tap cac c o n g trinh nghien c i r u Vat ly Dja c l u 2008
the ong-dat tinh bing v6n cho 5 duong ong khac nhau, trong d6 (a), (b) va (c) la cac duong ong dan khi long ((3), (4), (5)), con (d), (e) chi cac duong Ing dan khi kho ((1), (2)), theo cac ky hieu da trinh bay trong Hinh 5. Tren hinh nay, co the thay rang 4 do thi (2), (3), (4), (5) c6 dang dap gan nhu nhau: cac xung dien the deu vao nhiing thod diem nhu nhau, co bien do gan nhu nhau. Dilu nay la do cac do thi nay bieu thi dien the ong - dat phan tir Ba Ria di Phuoc Hoa, gay ra do he dong dien cam img trong long dat chay trong khu \arc nay, trong khi do do thi (1) bieu dien dien the ong - dat gay ra do he dong dien cam ung chay trong khu virc tir Ba Ria di den Long Hai, theo chieu ngugc lai. De tien so sanh Uen Hinh 8(f) dugc ve lai bao tir thanh phan H va Hinh 8(g) la dao ham thanh phan H theo thod gian.
Hinh 9 la gian do bao tir ciia ngay 7-8/11/2004 tai Phu Thuy. Co the thay rang giira do thi dien the ong dat va bien thien ciia truong tir {Hinh 8(f)) c6 mot moi tuong quan rat khang kbit vod nhau: Cac xung ciia chiing deu trimg kbit len nhau.
Viec ghi so lieu da dugc tien hanh tir thang 4/2004, den het 2004.
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6. Ket qua nghien cuu thong ke GIC I
1
6. 1. Tdn sudt xudt hien GIC trong hi thong truyen tdi diin ? I
I
Tren Hinh 10\k do thi bieu dien tin suit xuit hien dong dien cam img GIC tai fram biln ap 220 kV Hai Phong cho nam 2003, 500kV Hoa Binh tir 1999-2003, con Hinh II la cho 2 tram Pleiku j cho 2 nam 2001 va 2002) va Phu Lam (cho 3 nam 2000, 2001, 2002).
True dimg bieu dien so lan xuat hien GIC (thang lo ga rit), true ngang chi cac khoan'acuang do GIC 0.0 - 0.2A. ,,,, 1.8 - 2.0A, >2A, Co the nhan thay gia tri cuong do GIC nho 0.2 - 0.4
Phan II. DjA T i r - DIEN LY ^ j g ^
A chiem uu the, Nhung gia tri Ion ciia GIC chi xuat hien khi co bao tir. Bien do Ian nhit ciia GIC Uen cac tram bien ap ghi dugc cho den nay la 8.2 Ampe.
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Hinh 10. T i n s u i t xuat hien GIC tai tram bi§n ap 220kV Hai Phong va 550kV HoaBinh
Qua cac do thi, ta co nhan xet chung nhat la mac dii bao tir la hien tugng chung toan cau, nhung dong dien cam img xuat hien tai moi vimg, moi noi, theo thai gian khac nhau la khac nhau, ca ve cuong do, bien do ciing nhu dang bien doi.
Dii voi tram Hoa Binh, tram co thai gian ghi GIC dai nhat, ta thay rang trong khi trong nam 2000 co hang chuc Ian gia tri GIC vugt qua 2A, trong 2001 c6 den hang tram lin GIC dat gia tri > 2 A, trong do co nhieu gia ui GIC dat din 6, 7 A, thi dii vai 1999, 2003 chi c6 vai ba gia Ui. Dac biet trong nam 2002, khong co gia tri GIC nao dat den lA. Dii voi tram Pleiku, gi6ng nliu d6i voi tram Hoa Binh, trong nam 2001, co den hang tram lin GIC dat din 2A va hon,_ con nam 2002 so lin xuit hien GIC lai it han di (khong CO gia tri nao vugt qua 2A). D6i vai tram Phu Lam, sl gia tri GIC Ion it hon so vai 2 tram Hoa Binh va Pleiku: nam 2000 kh6ng co gia tri nao >1 A, nam 2001 chi co mot vai gia tri >2A. Dac biet trong 2002 lai co mot so gia tri GIC >2A.
Nhu vay, ta thay rang tai Pleiku gia tri GIC thuong dat gia tri Ion nhit, con tai Phii Lam, GIC dat gia tri nho nhat trong cac so lieu GIC ghi dugc tai 4 tram. Dilu nay co the giai thich dugc do dien tro dat khu virc Pleicu kha Ion, con a Phu Lam la nho nhat, va mot mat khac nira do cau triic ciia mang luai duong day 500-220 kV.
Dii voi tram biln ap 220kV Hai Phong, tan suat xuit hien GIC cung tap trung vao cac gia tri 0,2 - 0,4 A, chi co mot vai gia tri >2A, Nhin chung so voi cac tram 500kV,
164 Tuyln tap cac cong trinh nghien ciru Vat ly Dja c i u 2008
gia tri GIC thu dugc tai tram 220kV la nho hon, boi vi tai tram nay chi co mot duong day cap 220kV dua vao may bien ap, trong khi do tai cac tram 550kV, he thong duong cap 220kV din la kha nhilu.
Ve cuong do GIC, ta nhan thay cac gia tri GIC Ion nhat thuong xuat hien vao nam 2000, nhit la nam 2001. Bien do GIC Ion nhit ghi dugc vao ngay bao tir 31/3/2001 tai Pleiku, voi gia tri 8.2A. Trong ngay nay, bien do GIC thu dugc or Hoa Binh la 6.1 A.
Ngay CO gia tri GIC lan nhit thu dugc 6 Hoa Binh la 6.5A vao ngay bao tir 15/7/2000.
Trong cac nam khac cung c6 mot sl gia tri Ion nhu bao tir ngay 28/6/1999, GIC co bien do 3.4A, bao tii- ngay 16/5/2000 gay ra GIC co bien do 3.4A, bao tir ngay 24/11/2001 gay ra GIC voi bien do 5.2A. Ngay ca nam 2003 cung co mot sl lin GIC dat din 4A.
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Hinh 11. Tan s u i t x u i t hien GIC tai tram b i l n ap 550kV Phu Lam va Pleiku
Ta nhan thay rang tan suat xuit hien GIC lan thuong tap trung vao nam 2001. Dilu nay la do nam 2001 la nam hoat dgng manh nhit ciia chu trinh Mat troi lin thir 23. Dilu nay cung thay ro tren cac so do tin suit bien do bao tir xuit hien tai Phu Thuy cho cac nam tir 2000 - 2004, trinh bay trong Hinh 12. Tren cac so d l nay,'true dimg bilu dien tan suat xuat hien bao tir voi cac bien do khac nhau, true ngang bilu dien bien do cua bao tir. Tren cac so do nay co the thiy ring dai da sl bao tir co bien do 50 - I50nT.
Trong cac nam 2000 - 2001, 5, 7 tran dat bien do tir 150 - 250nT, con trong cac nam 2002-2004, s6 tran vai bien do nay it hon nhilu, chi mot vai tran. Trong nam 2000 co 2 tran rat Ion. dat toi 426nT vao ngay 6/4/2000 va 532nT vao ngay 15/7/2000 Dac biet trong nam 2001, co mot tran bao tir dat din bien do 638nT, Ion ^ l i t trong chu trinh hoat
Phan II; DjA T i r - DIEN LY 165
dgng Mat tro-i Ian thir 23 (chi nho hon tran lan nhit 650nT dat dugc vao 13/3/1989 tai Sapa). Ngoai ra. trong nam 2001 cung con c6 tran 407nT vao 1 thang sau do, vao ngay 11/4/2001, Trong nam 2002, tran Ian nhit chi dat den bien dp 320nT vao ngay 1/10/2002, Bao tir trong nhirng nam tilp theo van con boat dgng rat manh, Dien hinh trong nam 2003, co 2 tran dat bien do din 564nT vao ngay 31/10/2003. va 618nT vao ngay 22/11/2003. va trong nam 2004, co mot tran dat bien do 5 0 " n r vao ngay 7/11/2004, Nhu vay co thi thiy bao tir lan khong chi tap trung vao nam hoat dong manh nhit (2001) ma Uong cac nam khac hoat dong Mat troi vin co the lam xuit hien nhiing tran bao tir Ion, co the gay ra GIC lan tac dong den boat dong ciia cac he thong cong nghe.
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Hinh 12. T i n s u i t x u i t hien bao ti> tai Phu Thuy tiy 2000-2004
6. 2. Tan xudt xudt hien diin the dug - ddt PtoS-V trong hi thong ong ddn ddu khi
Tren Hmh 75 la so d l bilu dien tan suat xuat hien dien thi Ing - dit cho duong ong dan khi (I) chay tir bo biln Long Hai vao Ba Ria, va duong Ing dan khi (2) chay tir Ba Ria din Phuoc Hoa. Co thi nhan thiy gia tri dien thi Ing - dit V nho (<1,3V) chiem phin lan. Tuy vay nhung gia tri V>1.3V ciing kh6ng phai la it (din hang tram ngan). Co nhilu gia tn dat din 1.7, 1.8V (tinh gia tri tuyet dii). Nhii-ng gia tri Ion nhu vay thuong chi xuit hien khi co bao tir. Gia trj tuyet d6i lan nhat dien the Ing-dat ghi dugc tai cac Ing la 1.8V.
166 Tuyln tap cac cong trinh nghien cu'u Vat ly Dja c l u 2008
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Hinh 13. Tan suat xuat hien dien t h i I n g - d i t V tai tram Ba Rja nam 2004
7. Ket qua tinh mo hinh dong dien cam ung ly tuyet tii' so lieu bien thien tir 7. /. Tinh mo hinh GIC chay trong hi trong truyin tdi diin
Phan tich 6 tren da cho chimg ta thay sir tirong quan ro ret giira biln thien cua trirong dia tir va dong dien cam irng. Van de dat ra la hay tinh toan ly thuylt dong dien cam img nay tii'bien thien ciia trirong tir dira tren cac nguyen ly vl cam img dien tir va mot so gia thuyet nhat dinh ve ngu6n cung nhu ve ciu triic do dan ciia Trai Dit. Day la mot nhiem vu quan trong trong viec du bao cho viec phong chIng GIC Ion co thi gay nii ro cho he thong truyen tai dien,
Viec tinli toan Iy thuyet dong dien cam irng do biln thien tir GIC trong mot he thong truyen tai dien co the dugc chia thanh 2 buoc:
« Triroc het tinh toan dien truong theo phuong nim ngang tao ra tren bl mat Trai Dit khi CO bien thien tir khi chua co mat he thing vat dan;
• Buoc tiep theo, dien truang nay dugc xem nhu la dien truong ben ngoai dat len he thong vat dan, va tir day se tinh toan dong dien cam img dua theo cac thong sl va cau true cua he thong mang luoi truyin tai dien.
Trong buoc thir nhat, de don gian co thi gia thilt sir biln thien truong dien tir so cap la song phang truyen theo phuong thang dirng xuIng duoi, Trai Dit la nira khong gian dong nhat voi do dan kh6ng doi.
Chii y rang trirong dia tir la bien dii cham theo thai gian, bo qua dong dich, tir he phuong trinh Maxwell c6 the vieV.
J/r^Ur^a _i^t -u
i
Ph§nll. DIATU"- DIEN LY 167
trOng do: g.,- la dao ham theo thai gian ciia thanh phan truong Bx (dBx/dt); t, u la biln thai gian; po la do tir thim trong chan khong; a la do dan dien ciia Trai Dit
Mot bilu dien tuong tu dii vai thanh phin di?n truong theo phuong X dugc tinh theo dao ham truo'ng tir theo phuong Y nhirng dii diu truac tich phan:
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Viec tinh dao ham theo thoi gian cua cac thanh phin truong tir tir chuoi so lieu rai rac CO the thuc bien bang bieu thirc sau:
git) = ^^^^^ (3) A
Bn la gia tri trirong tii' tai thoi diem tn va /„_, <t <t^
Voi viec tinh dao ham theo cac gia tri rai rac ciia truong nhu vay, cong thirc tich phan tinh truang dien tai thai diem t„ dugc viet duoi dang:
E{t,) = -yi=(^,v-, - R, - VMg,.^) (4)
trong d6 T la chu ky lay mau va
R^,= Y^gjN-n + l (5)
= , V - A / i
vai N la thoi dilm tinh, M vl mat ly thuyet thi phai bing-co. Nhung thuc tl cho thiy khi liy M = 100 (nghia la liy gia tri truong bien thien tir bit dau tir 100 phut truoc thai dilm tinh dong dien cam irng), dong dien cam img tinh dugc c6 the dat den do chinh xac tuong dii. Khi da tinh dugc dien truang, c6 the tinh dugc dong dien cam irng tao ra do tir truong Trai Dat.
0 buoc thu hai dong dien cam irng do truong tir gay ra c6 the dugc xem nhu dong dien dit chay duoi tram biln ap hoac dong cam irng chay qua day trung hoa ciia tram biln ap xuIng dit va co thi tinh dugc theo cong thirc:
l = a.Ex-^ b. Ey + c ^ (6) trong do:
Ey. Ex: Dien truang (tinh bing V/km), tinh theo cac cong thirc (1), (2) 1 : Cuong do GIC (tinh bing A)
a,b : He sl phu thuoc vao ciu triic mang luoi duong day va dien tro suat ciia duang day (tinh bing A km/V) ^ ^ , . j^ , c • He sl dugc cong them de lam phii hgp ket qua tinh ly thuyet voi ket qua do thuc nghiem (tinh bang A). , . , ,;
Diing phuong phap binh phuang t6i thieu se xac dinh dugc cac tham so a, b va c de lam phii hgp dong dien cam img ly thuylt voi dong dien cam irng quan sat dugc vai do dan dien cho truoc.
168 Tuy4n tap cac cong trinh nghien cCru Vat ly Dja c^u 2008J
GIC, A
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— : GIC tinh Iy thuylt; : GIC ghi dugc
Hinh 14. Dong dien GIC tinh ly t h u y l t va ghi duo-c ngay 15/7/2000 tai Hoa Binh
Tir CO so phuong phap da neu 6 tren chung toi da tien hanh tinh dong dien cam ung tren co so s6 lieu ghi bien thien tir ciia tram dia tir Phu Thuy (moi phiit mot gia tri) cho nhiing ngay bao tir. Tren Hmh 14 trinh bay mot vi du ve dong dien cam img tinh dugc cho khoang thoi gian 14-23hUT ngay 15/7/2000, vo-i gia tri do dan hieu dimg la a = 1,3x10" Q'
'm"'. Tren hinh ve ciing trinh bay dong dien cam img chay qua day trung hoa ghi dugc tai tram bien ap 500 kV Hoa Binh tai khoang thod gian tuong img. Co the thay rang giiia hai duong CO sir phii hgp kha tot, Cac phep do dac triroc day cho thay rang truong bien thien tit tai Phil Thuy va Hoa Binh la hoan toan tuong dirong nhau, do dan thu dugc a tren ciing co the xap xi do dan tuong dirong ciia v6 Trai Dat vimg duoi tram bien ap 500 kV Hoa Binh.
7. 2. Mo hinh diin thi dng ddt trong hi thong ong ddn khi Bd Ria i Sir dung cong nghe nhu tren chiing t6i da tinh mo hinh dien the ong dat cho ong dan khi a Ba Ria tir so lieu bien thien tir. Cac tinh toan cho thay dien the ong - dat cam img tinh toan dugc voi mo hinh song phang va Trai Dat dong nhat voi do dan khong doi kha phii hgp voi dien the ong - dat cam img do dugc trong khoang thai gian da neu, nhat la doi voi cac truong hgp bao tir, Tren Hmh 15 la mot vi du mo hinh dien thi ong dat tinh cho ngay 7/11/2004, voi a = 2.9x1 C'^O'V"'. Co thi thiy giira hai duong, ly thuyet (duong ngat quang) va ghi dugc i diro'ng lien) c6 mot sir phii hgp rit tit.
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Hinh 15. Dien t h i I n g - d i t tinh toan va ghi d u y c tai tram Ba Ria ngay 07/11/2004
(net lien): dien the dng-ddt ghi duac (net did): diin the dng-ddt tinh todn
Phan II O I A T U - DIEN LY
169
Su phu thuoc cua do dan bieu kien vao miic do hoat dong dia tir
Chimg toi da khao sat sir phu thuoc cua a vao Kp bang each tinh gia tri do dan a cho cac boat dgng tir co chi sl Kp khac nliau cho timg khoang thoi gian khac nhau, sau do liy trung binh cac do dan cho moi gia trj ciia chi sl Kp. Kit qua dugc trinh bay trong Bdng I.
Co the thay rang do dan a co xu huong tang theo boat dgng dia hi. Tuy nhien tir gia hi Kp = 3 den 8, a thay d6i chiit it xung quanh gia tri 1,4 x 10'^ Q"'m" . Sai so ciia viec tinh cac gia trinaylaO.Olx ]0"Q"'nT'.
Bang 1: S u phu thuoc do d i n a (x 10-3 Q-1m-1) vao chi s6 Kp
Kp a
0 0,409
1 0,761
2 1,666
3 1,343
4 1,504
5 1,259
6 1,411
7 1,456
8 1,366
9 4,326
8. Van de du bao bao tir va GIC Ion
Nhu tren da trinh bav, cac gia tri GIC Ion chi xuat hien khi co cac tran bao tir Ion. Nhung
^ ' C> • • • CD
gia tri nay co the gay tac hai cho he th6ng truyen tai dien neu kh6ng co cac bien phap xu ly kip thoi. Mot van de dat ra la phai biet truoc khi nao co bao tix xay ra, voi cuong do se ga\' ra cuong do GIC CO bao nhieu de c6 bien phap hiai hieu nhat. Nhu tren da thay, khi co bao tir Ion, GIC CO khi dat den 7A, 8 A. Nhung gia tri nay rat co the gay ra nhirng boat dgng roi loan ciia he thong ro le bao ve may bien ap cung nhu cac thiet bi Uong he thong truyen tai dien cao ap, nhat la d6i voi cac tram bien ap 220kV, trong khi chi can 4A ciing dii tac dong vao hoat dong ciia he thong ro le. Nhu vay phai du bao dugc Idii nao xuat hien GIC manh. Mu6n vay, tmoc het phai dii bao dugc klii nao bao tir xuat hien. Nhin chung viec du bao bao tir la mot van de klia phirc tap va doi hoi phai c6 so lieu tir nliieu nguon. Cho toi hien nay c6ng viec du bao bao tir dai ban dugc chiing t6i tien haiili tren co so so lieu ciia dai dia tir dien ly Phii Thiiy, ket hgp voi so lieu ciia cac dai dia tix khac tren the gioi, dat dugc do chinh xac khac nhau phu thuoc vao timg loai bao. Doi vol viec du bao ngan ban, chiing toi sir dung so lieu lay tir cac Trung tam so lieu dia tir the gioi, dac biet tir cac so lieu ve tinh, cung nhu tix sir trao doi thuong xuyen voi cac nlia khoa hgc dia tix tren the gioi, boi vi hien tugng bao tix xay ra c6 tinh chat toan cau, do c6 lien quan chat che voi hoat dong Mat troi, tat nhien co bien do va dien bien bao tir bi anh hir6ng ciia nhieu yeu to dia phuong (vi du phu thuoc ciu triic tang dien ly khu virc nghien ciai v.v,..),
Trong nhung nam Mat troi boat dong manli, Vien Vat Iy Dia ciu da cung cip thuong xuyen du bao bao tir cho T6ng cong ty dien lire Viet Nam, nhat la dii voi nhimg tran bao tix m ^ . Mot trong nhung bien phap hg da sir dung la giam bat cong suit tmyen tai ciia he thong, nhim giam thilu toi mirc toi da tac hai ciia bao tir, cu the la ciia cac dong dien cam img do no gay ra.
9. Ket lusin chung
I Sau nhilu nam nghien ciru, chiing toi da thu dugc nhiing kit qua chinh sau day:
170 Tuy4n tap cac cong trinh nghien cicu Vat ly Dja c l u 2008
• Lin diu tien a Viet Nam da thilt lap qui trinh cong nghe dat he may ghi chinh xac dong dien cam img qua duong day trung tinh cua tram bien ap 500-220kV ciing nhu dien thi Ing dit trong be th6ng 6ng dan dau khi o Viet Nam. Da chung minh dugc ring khi bien thien tir va bao tir xuat hien, se lam phat sinh mot dong dien cam img rit Ion di vao he thing duong day cao the 500-220kV qua duong day trung tinh ciia cac may bien ap ciing nhu 6ng dan dau khi. Cu the da ghi dugc tap hgp dong dien nay tai cac tram bien ap 500kV Hoa Binh, Phu Lam, Pleiku va 220kV Hai Phong va dien thi ong dat tai 6ng dan khi Ba Ria;
• Da xac dinh dugc do dan bieu kien ciia viing dat noi co duong day 500-220kV hoac ong dan diu khi chay qua, cung nhu da xay dirng dugc mo hinh dong dien cam img Iy thuyet tir s6 lieu bien thien tir gan viing nghien cim;
• Da xac dinh dugc moi tuang quan giira GIC va bao tir qua viec nghien cuu thong ke tan suat xuat hien GIC ciing nhu bao tir;
» Xay dung dugc mot ca sa dir liiu ve dong dien cdm irng cho duong day 500kV- 220kV va ve dien thi ong ddt cho 6ng dan khi, ciing nhu mot chuong trinh hgp tac quoc te ve van de nay;
• Ket qua da dugc dua vdo dp dung vdo thirc tien de du bao sir xuat hien nguy hiem ciia dong dien cam irng co the gay tac hai cho cac may bien ap trong he thong truyen tai dien cao ap 500kV cung nhu ong dan dau khi ciia Viet Nam;
• Gop phan canh bao cac sir c6 tren he th6ng dirong day dan dai (ke ca duong truyen tai dien va 6ng dan dau khi) khi co bao tir.
Mot phan ket qua ciia nghien ciru da dugc trinh bay o cac Hgi nghi khoa hgc trong nuoc va quoc te [3,4,5,6].
Loi cdm an: Viec nghien cicu tdc dpng cua bdo tic ddi vai cdc hi thdng cdng nghe da thu duac nhicng kit qud rdt quan trong nhd su quan tdm chi dao vd tao diiu kien thuan lai cua Ban Gidm doc Trung tdm Khoa hoc Tu nhien vd Cdng nghi Qiidc gia, nay la Vien khoa hoc vd Cdng nghe Viet Nam, ciia ban lanh dao Vien Vdt ly dia cdu, nhd su tham gia nhiet tinh cua tdt cd cdc thdnh vien trong Phdng nghiin cicu Dia tic, cdc cdn bp trong cdc ddi trgm dia tic Viet Nam, ciing nhu su cdng tdc chdt che ciia cdc cdn bp thuoc Ban ky thudt luai dien, Tnmg tdm dieu dp quoc gia, cdc trgm biin dp Hod Binh, Pleiku. Phil Lcim . Hai Phong thuoc Tdng Cdng ty dien luc Viet Nam, trgm phdn phdi khi Bd Ria. Cdng ty chi biin vd kinh doanh cdc san phdm khi thupc Tdng cong ty ddu
khi Viet Nam. Chimg tdi xin chdn thdnh cdm an. , Cong trinh nay dugc hoan thanh nho sir ho trg cua chuong trinh nghien ciru co ban
7.111.06
10. Tai lieu tham khao
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in Geophysics 8 (1986), D. Reidel Publishing Company, 239-259.
3. CHAU H. D., N.^ T. K. THOA, L. T. THANH, T. T. K. HOA, N. V. QUAN, T. Q.
HAO, 2005a. Kit qud nghien cicu tdc dpng cua bdo tic ddi vai hi thdng truyin tdi diin cao thi a Viet Nam. Tuyln tap cac bao cao khoa hgc tai Hgi nghi khoa hgc quoc gia ky niem 30 nam ngay thanh lap Vien Khoa hgc va Cong nghe Viet Nam,
1975-2005.HaNoi, 231-304,
4. CHAU H. D., L. T. THANH, N. T. DUNG, 2005b. Kit qua buac ddu nghien cicu tdc dpng ciia bdo tic ddi vdi hi thdng dng ddn ddu khi Viet Nam. Tuyen tap cac bao cao Khoa hgc tai Hgi nghi Vat ly toan quIc lin thir VI, 11/2005, Ha Ngi, 1-8.
5. CHAU H. D., N. T. K. THOA, T. Q. HAO, L. H. MINH, L. T. THANH, T. T, K.
HOA, N. V. QUAN, 2001. Preliminary results of the studies on GlCs in Vietnamese 500kVpower system. lAGA-IASPEI joint Scientific Assembly, 19-31 August 2001 Hanoi, Vietnam.
6. CHAU H. D., 1998. Anh huong cua bdo tic len he thdng truyin tdi diin, Tuyen tap
"He thing truyin tai dien 500kV qua 4 nam van hanh", Tong cong ty dien lire Viet r Nam, 127-161.
7. Chau H. D., 1997. Mgng luai ddi trgm vd cdc kit qud khdo sdt dig tir a Viet Ngm. Thanh - tim nghien cim Vat Iy Dia ciu 1987 - 1997, NXB Khoa hgc va Ky thuat, 159 - 201.
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[0. HARDE C , C. Johansson, 1996. Space weather effects on natural gas pipelines, M.
Sc. Thesis, Physics Department, Lund University, Sweden, 80 pgs.
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SUMMARY
IMPACTS OF MAGNETIC STORMS ON THE TECHNOLOGIC SYSTEMS
500-220kV electric transmission system, with the length of nearly 5000km from the North to the South, as well as the petrol and gas pipelines network of Vietnam, with the length of more than 400km in the South of Vietnam, are the objects to the strong impacts by the magnetic storms. Beginning from the 2000 years, the Hanoi Institute of Geophysics was charged the task to study the impact of magnetic storms on these technological systems for finding out the necessary measures to avoid and reduce the possible harmful effects of magnetic storms on them. In this article, one presents the overall results from this study. Concretely, for the first time, in Vietnam one has built a technology of recording the GIC (Geomagnetically Induced Currents) flowing through the transformer of the electric transmission system and the Pipe-to-Soil voltages (PtoS- V) on the petrol and gas pipelines network. From these recordings, one has obtained a data collection of GIC and PtoS-V, These data are precious, not only they cater for the practical predictions of the impacts of the magnetic storms on the electric transmission system and the petrol and gas pipelines network, but also they're documents in the studies of the Earth's crust conductivity, crust structure... for various purposes. One found that GIC and PtoS-V are closely correlated to the variation of magnetic fields, with very high value of correlation coefficient, especially when there are magnetic storms. Through the frequency diagrams, one can see that for the electric transmission system, the quantity of the high values of GIC are rather big. GIC can reach the values of 8, 9 Ampere, which can cause the trouble in the activity of the relay system in the transformers. For the gas pipelines, one can see that the quantity of the high values of the PtoS-V (>I,3V in the absolute values, that is exceeds the corrosively permissible safe values) reaches hundred thousands, which can cause the strong corrosions for the pipelines. These values appear only when there are magnetic disturbances or storms.
The models GIC and PtoS-V, theoretically built are concordant very well with those
recorded. ^ Key words: Magnetic storms, Geomagnetically Induced Currents GIC. Electric
transmission system. Petrol and gas pipelines. Pipe to Sol Voltages PtoS-V. i
