A. Cc bo co chung

1

TNG CNG N NH, TIN CY CA LI IN 500 kV

SAU CC S C MT IN DIN RNG

V S CN THIT PHI TRANG B H THNG BO V

CHNG MT IN DIN RNG

Nguyn c Ninh

Trung tm iu h thng in Vit Nam

Tm tt: Cng vi s pht trin ca ngun in nhm p ng tc tng trng

ph ti cao, h thng in truyn ti xng sng 500 kV lin kt cc min ng vai

tr rt quan trng trong vic cung cp, trao i in nng an ton v kinh t. Vi

xu hng truyn ti ngy cng ln c v cng sut ln sn lng, vic vn hnh h

thng in 500 kV tr nn rt phc tp.

Trong bi cnh nhu cu truyn ti trn h thng in 500kV c xu hng ngy

cng tng, bo co trnh by nhng kh khn, nguy c mt n nh trong qu

trnh vn hnh v tng kt mt s s c nghim trng in hnh trn HT 500kV

trong nhng nm gn y.

Xut pht t nhu cu thc t, bo co cng nu r s cn thit phi trang b

h thng bo v chng s c din rng v nu nhng c im c bn ca h

thng ny.

1. QU TRNH PHT TRIN CA H THNG IN 500 kV BC - NAM

1.1. H thng in Vit Nam trc nm 1994

Cng ngh pht in xut hin ti Vit Nam vo cui th k XIX di hnh thc mt s nh

my pht in c lp cung cp trc tip cho li in khu vc. Khi min Bc Vit Nam c

gii phng nm 1954, tng cng sut in quc gia ch t 100 MW vi li in tha tht v

cp in p cao nht 30.5 kV. H thng in pht trin tt trong giai on 1975-1994 vi s

tham gia ca mt s cng ngh tin tin, cc nh my in ln nh nh my nhit in Ph Li

(4x110 MW), Nh my thy in Tr An (4x100 MW) v c bit l Nh my thy in Ha

Bnh (8x240 MW) ln lt c a vo vn hnh. Trong giai on ny, li in truyn ti

pht trin trn ton quc vi cp in p cao nht l 220 kV nhng vn cha lin kt h thng

in ba min thnh mt h thng hon chnh. H thng in ti ba min c iu hnh c lp

bi cc trung tm iu ca cc cng ty in lc min Bc, min Trung, min Nam. Do cha

c lin kt gia cc min nn cc thi im khc nhau mt s khu vc d tha in nng

trong khi nhng khu vc khc b thiu ht, cc vn v n nh ca cc h thng v cht

lng in nng cng thng xuyn gp phi.

HI NGH KHOA HC V CNG NGH IN LC TON QUC 2014

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1.2. Vn hnh ng dy 500 kV Bc - Nam mch 1

T nm 1994, ng y siu cao p 500 kV mch 1 c a vo vn hnh kt ni h thng

in min Bc, Trung, Nam thnh mt h thng duy nht. ng dy 500 kV vi chiu di

1488 km lin kt h thng in 3 min qua 5 trm bin p 500 kV (Ha Bnh, H Tnh,

Nng, Pleiku, v Ph Lm) ng vai tr quan trng to nn s cn bng nng lng ti u

gia ba min. Trong nhng nm u, in nng d tha ca thy in Ha Bnh v cc nh my

in min Bc c truyn ti p ng nhu cu cp in cho min Trung v Nam. Trong cc

nm t 1994 n 2000, tng in nng trao i gia cc min t 40 t kWh, t 13.8% tng

sn lng in quc gia.

1.3. Vn hnh ng dy 500 kV Bc - Nam mch 2

Cng vi s pht trin ca nn kinh t, h thng in 500 kV ang ngy mt m rng vi nhiu

ng dy lin kt gia cc vng min. T nm 2004, cc d n lin quan n ng dy 500

kV Bc - Nam mch 2 bt u c thc hin. ng dy 500 kV mch 2 c tc dng nng

cao kh nng truyn ti gia cc min v nng cao kh nng hot ng an ton ca h thng

trong cc ch s c N-1.

Bn cnh , cc ng dy quan trng khc cng c a vo vn hnh: ng dy Ph Lm

- Nh B - Ph M gii ta cng sut trung tm nhit in Ph M vi cng sut lp t

4000 MW (2004 - 2005); cc ng dy truyn ti v tng cng lin kt vi khu vc ng

Bc min Bc; cc ng dy lin kt vi cc ngun thy in khu vc Sn La - Lai Chu;

ng dy 500kV mch 3 Pleiku - M Phc Cu Bng (2014) Ngoi ra, cc d n thay

th thit b tng cng kh nng truyn ti trn li 500 kV/220 kV v ang tng bc

c thc hin p ng nhu cu cung ng in.

Nh vy, trong bi cnh nhu cu trao i in nng gia cc vng/min ngy cng tng, h

thng 500 kV pht trin tr thnh xng sng ca ton b h thng in quc gia, ng

vai tr quan trng trong vic kt ni cc khu vc ph ti/ngun in trn ton quc gp phn

m bo vn hnh h thng in an ton, kinh t.

n cui nm 2013, h thng 500 kV c tng chiu di 4887 km v 20 trm bin p (tng cng

sut 19350 MVA). Ph ti ln nht c ghi nhn trong nm 2013 l: quc gia - 20010 MW;

min Bc - 9081 MW; min Trung - 2383 MW; min Nam - 9687 MW. Sn lng tng ng

l: Quc gia - 129655 t kWh; min Bc - 51539 t kWh; min Trung - 12801 t kWh; min

Nam - 64207 t kWh [1].

2. MT S VN V TRUYN TI IN V VN HNH H THNG IN

500 kV N NH

c im a l ca t nc di v hp, nh hng n vic phn phi cc ngun pht ti

Vit Nam. Cc dng ngun in chnh bao gm thy in, nhit in than, nhit in turbin kh

(chu trnh n v chu trnh hn hp). Cc nh my thy in tp trung cc khu vc Ty Bc

min Bc, khu vc min Trung v khu vc Cao Nguyn min Nam. Cc nh my nhit in

than c xy dng gn ngun nng lng s cp trong khu vc ng Bc min Bc, khu vc

Bc Trung B. Cc nh my in turbin kh nm hai khu vc ng Nam B v Ty Nam B.

A. Cc bo co chung

3

Bn cnh , ph ti h thng in quc gia tp trung ch yu min Bc v min Nam c

bit l khu vc th H Ni v thnh ph H Ch Minh.

Do c im phn b khng ng u cng nh ch hot ng khc nhau ca cc dng

ngun in, li in 500 kV thng xuyn phi truyn ti mt lng cng sut rt ln, c bit

l cc ng dy Nho Quan H Tnh Nng trn giao din Bc Trung, cc cung on

ng dy t Pleiku n Ph Lm trn giao din Trung Nam. Xu hng trao i in nng

gia h thng in cc min ngy cng tng th hin trong bng 1 [1],[2].

Bng 1. in nng truyn ti gia cc min nm 2013 v c tnh cc nm 2014 - 2020

Giao din truyn

ti

Sn lng truyn ti nm (GWh)

2013 2014 2015 2016 2017 2018 2019 2020

Bc - Trung 3683 9535 12009 17460 18921 18513 17888 14967

-> 5379 9678 12009 17460 8921 18513 17932 15091

12471 15456 17493 22419 22523 20423 18231 21769

HI NGH KHOA HC V CNG NGH IN LC TON QUC 2014

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Hin tng sp in p gy st gim in p ti u nhn cng sut thng xut hin khi

truyn ti 500 kV cao. Sp in p cng c th xut hin u nhn cng sut do hu qu

ca s c cc ng dy 500kV quan trng hoc s c gy mt mt lng ngun ln u

nhn cng sut (s c t my, s c gim/ct kh) gy ra hin tng tng cng sut truyn ti

trn cc ng dy lin kt. Theo kt qu tnh ton hin tng vi cu hnh h thng in nm

2014, hin tng sp in p c th xut hin trong ch cao im trn ng dy H Tnh

- Nng khi truyn ti trn 2400/1980 MW ng vi ch vn hnh 2 mch/1 mch, trn cc

ng dy t Pleiku n Ph Lm l 3600/2600 ng vi ch vn hnh 3 mch/2 mch

ng dy [3].

Hin tng mt n nh ng trn h thng in c th xut hin khi c s c ln trn h thng

in. Tng kt cc s c ln cho thy mt n nh ng thng do s c cc ng dy 500 kV

khi ang truyn ti cao, in hnh l cc ng dy Nho Quan - H Tnh - Nng, cc ng

dy t Pleiku - Ph Lm. Theo tiu ch s c N-1 cc ng dy 500 kV, gii hn truyn ti

trn cc giao din Bc - Trung, Trung - Nam nm 2014 c tnh ton t xp x 1600 MW

v 2300 MW (ng vi cu hnh 3 mch ng dy 500 kV) [3]. Trong cc s c trn, vic

cc mch sa thi c bit, mch sa thi ph ti theo tn s, mch sa thi ph ti theo in p tc

ng ng vai tr ht sc quan trng trong vic lm gim nguy c s c lan rng. Nh , c

th xem xt cho php truyn ti cng sut trn cc giao din mc cao hn gii hn truyn ti

tnh ton trong mt s trng hp cn thit.

Mt s hin tng, s c in hnh trn h thng in trong mt vi nm tr li y:

(1) S c ngy 27/12/2006 lc 14h43 ti trm bin p 500 kV Pleiku. Mt my ct 500 kV

khng thc hin ct c khi c lnh ct do li h thng ngun nui DC. Chc nng chng h

hng my ct (50BF) tc ng thc hin ct thanh ci ti trm Pleiku. Trong thi im trc s

c, mt my ct kt ni vi thanh ci khc ca trm Pleiku c tch ra khi vn hnh, gy

ra hin tng tro lu cng sut chy vng t Ialy ti Ph Lm, tr li thanh ci Pleiku v ti

Nng. Hin tng dao ng in xy ra do lin kt 500 kV qu yu;

(2) Dao ng in trn ng dy 500 kV Pleiku - Nng lc 11h30 ngy 24/4/2008. Bo v

khong cch (F21) ti trm Nng nhn bit c dao ng cng cng sut trn ng

dy. Ti thi im ny, ng dy 500 kV Nng - H Tnh ang vn hnh mt mch duy

nht. Cng sut truyn ti trn cc ng dy Pleiku - Nng, Nng - H Tnh ln lt l

1040 MW v 690 MW;

Hin tng dao ng gy ct cc ng dy 500 kV Nng - H Tnh, Nng - Pleiku, h

thng in b tch i ti H Tnh, Nng. Tip theo bo v qu p tip tc ct ng dy 500

kV H Tnh - Nho Quan;

(3) S c ngy 04/10/2012: s c gy nhy ng dy Di Linh Tn nh khi ang truyn ti

cao cng sut vo min Nam, dn n dao ng v gy nhy c ng dy kNng Ph

Lm lm tch mng h thng in min Nam khi h thng in Quc gia. H thng sa thi ph

ti theo tn s thp tc ng ct 2147 MW;

A. Cc bo co chung

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(4) Ngy 02/4/2013, NM C Mau 2 (620MW), Ph M 1 GT3 (174 MW) ln lt ngng do

s c. Trong ngy c thi im in p ti cc thanh ci 500 kV Ph Lm, Tn nh xung ti

417 427 kV, k s vn hnh ra lnh sa thi 300 MW u ngun 110 kV m bo ch

in p min Nam;

(5) S c ngy 26/4/2013: Do iu kin vn hnh phi bypass 2 t b dc ti Nho Quan trn

ng dy Nho Quan - H Tnh v 4 t b dc ti H Tnh trn ng dy H Tnh - Nho Quan

v H Tnh - Nng dn n hin tng dao ng cng sut v gy nhy 2 mch ng dy

H Tnh - Nng lm tch mng h thng in min Bc vi h thng in min Trung v

min Nam;

(6) S c ngy 22/05/2013: s c gy nhy ng dy Di Linh - Tn nh khi ang truyn ti

cao cng sut vo min Nam, dn n dao ng v gy nhy mt s t my khu vc min Nam

v ng dy kNng - Ph Lm lm tch mng v gy mt in ton b h thng in

min Nam.

3. CC PHNG PHP HIN HU PHNG CHNG MT IN DIN RNG

Vi mc tiu m bo cung cp in an ton, n nh, tin cy v m bo cht lng in nng,

Trung tm iu h thng in Quc gia (A0) nghin cu v phi hp vi cc n v lin

quan trong vic ra cc gii php phng trnh mt in din rng. Cc gii php ny c

thit k da trn cc nhm nguyn nhn sau:

Mt n nh tn s do s c mt mt/ mt nhm cc t my hoc do s c gy mt lin

kt h thng in;

S c ng dy, my bin p 500, 220 kV quan trng;

Phng chng in p thp v sp in p.

Trn c s cc h thng bo v, mch lin ng c s dng:

(1) H thng sa thi theo tn s thp (F81);

(2) H thng sa thi ph ti c bit b sung;

(3) Cc mch sa thi ngun; hiu chnh sa thi t my min Bc;

(4) Cc mch sa thi c bit khi s c 1 phn t ng dy/ my bin p quan trng;

(5) Cc mch sa thi ph ti theo in p ti Ph Lm, Tn nh v mt s trm 220 kV min

Nam.

Cc mch sa thi trn ng vai tr quan trng trong cng tc vn hnh h thng in, phng

chng mt in din rng. Tuy nhin, do cu hnh h thng in thng xuyn thay i, nn cc

mch trn cn thng xuyn c cp nht, hiu chnh cho ph hp.

4. S CN THIT PHI TRANG B H THNG BO V CHNG MT IN

DIN RNG

HI NGH KHOA HC V CNG NGH IN LC TON QUC 2014

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Cng tc vn hnh cho thy rng, c th kp thi a ra cc lnh iu ph hp nhm ngn

chn cc s c mt in din rng, nhn vin vn hnh cn c trang b cc cng c mnh

phn tch, a ra c cc cnh bo nhanh chng, chnh xc v tnh trng vn hnh ca h

thng in trong h thi gian thc. Thm ch, h thng in cn c trang b cc bo v

thc hin mt lot cc hnh ng t ng trc khi h thng b tch ra hoc phn chia theo cch

thc c th kim sot c.

Cc s c din rng c th xy ra khi h thng vn hnh ch bin, xut pht t mt hoc

mt vi phn t b tch ra khi vn hnh v gy phn ng dy chuyn dn n vic mt lot cc

phn t b tch ra khi vn hnh. Trong khi , nhc im ln ca cc h thng iu khin v

gim st truyn thng l khng cung cp c cc hnh nh mang tnh ng ca h thng ngha

l cc nhn vin vn hnh khng c c bc tranh tng th xem ci g ang din ra trn h

thng. Hn na s c mt in din rng c th xut hin v din bin trong thi gian ngn, m

bn thn ngi vn hnh khng th kp a ra cc phn tch hay tnh ton nhm a ra c cc

quyt nh hp l. Cc mch sa thi & lin ng hin hu trong trng hp tc ng ng s c

tc dng phng trnh s c lan rng. Tuy nhin, cc mch ny c thit k cho nhng trng

hp c th v c th khng t hiu qu mong mun khi cu hnh h thng thay i.

H thng o lng, gim st v bo v din rng khai thc cc tin b mi nht trong cc k

thut v cm bin, truyn thng, my tnh, thut ton v c bit l cng ngh o lng c

ng b ha. S xut hin ca cc thit b o gc pha c ng b ha (Phasor Measurement

Unit) lm nn cuc cch mng ton din trong lnh vc gim st, iu khin v bo v h

thng in.

Theo nh ngha ca IEEE th thit b o gc pha Phasor Measurement Unit (PMU) l thit

b c kh nng ng b gc pha, tn s v tc thay i ca tn s thng qua vic o cc tn

hiu in p v/hoc dng in v tn hiu ng b thi gian. Thit b PMU c th thc hin cc

chc nng khc v c t tn theo cc chc nng ny (v d: nu thit b PMU c kh nng

ghi li dng sng ca cc tn hiu o s c gi l thit b ghi s c).

Thit b PMU rt ph hp theo di cc trng thi ca h thng in trong thi gian thc.

PMU c s tin b ng k so vi h thng SCADA/EMS, trong khi h thng SCADA/EMS l

h thng c tc cp nht t vi giy n vi pht, ch o cc gi tr RMS ch khng o cc

gi tr gc pha th PMU thng c tc cp nht cao (thng khong 10; 25; 50 gi tr o/s do

ngi dng ty chn), mi gi tr o c dn nhn thi gian c ng b ha vi chnh

xc cao thng qua h thng GPS v c th o c cc gi tr pha (bin v gc pha) ca

dng in v in p.

Gc pha ca in p v/hoc dng in t nhiu im o trn h thng in khi c ng b

thi gian thc c th gip nh gi tnh trng vn hnh ca h thng in mt cch tin cy v

chnh xc. Nhng thng tin v gc pha ny c th c s dng cho vic gim st h thng in

din rng (WAMs).

Ngy nay, vic o gc pha ng b c ng dng ch yu cho vic xc thc cc m hnh ho

h thng in, phn tch sau s c, hin th thi gian thc... v ha hn s ngy cng c vai tr

A. Cc bo co chung

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quan trng trong vic nng cao tin cy, n nh v tnh kinh t ca h thng in thng qua

vic iu khin v trang b phng thc bo v thi gian thc.

PMU: Phasor measurement unit; PDC: Phasor Data Concentrator

Hnh 2. Cu trc mt h thng gim st bo v v iu khin din rng

vi thit b o gc pha (PMU)

PMU c mt s ng dng c th nh sau:

o lng v gim st h thng in din rng phc v bo v chng mt in din rng;

Gim st v iu khin thi gian thc: gip cho cc nhn vin vn hnh nm bt mt cch

trc tuyn v ch vn hnh ca h thng;

nh gi v a ra cc cnh bo v tnh trng vn hnh ca h thng in;

Gim st n nh in p v n nh qu ;

H tr cng tc phc hi h thng...

Nh phn tch trn, h thng in 500 kV Vit Nam hin nay v nhng nm tip theo

thng truyn ti mt lng cng sut ln t h thng in min Bc, Trung vo min Nam.

HI NGH KHOA HC V CNG NGH IN LC TON QUC 2014

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Trong mt s ch vn hnh cc oan, nguy c xy ra mt n nh l rt cao (v d s c ngy

26/04/2013 gy nhy ng dy mch kp H Tnh - Nng sau khi 06 t b dc ti H Tnh

v Nho Quan b Bypass). Vic trang b cc b PMU (hoc cc b ghi s c c chc nng o

ng b gc pha) tng bc trin khai, khai thc cc tnh nng ca PMU nh tnh nng cnh

bo tnh trng vn hnh ca h thng in s gip cho ngi vn hnh c c nhng phn ng

kp thi v hiu qu

Hn na, theo l trnh trin khai xy dng h thng li in thng minh (Smart Grid) ti Vit

Nam c Chnh ph ph duyt (Quyt nh s 1670/Q-TTg ngy 08/11/2012 v vic Ph

duyt n pht trin Li in Thng minh ti Vit Nam) th trong giai on 2012 - 2016 s:

Trin khai cc ng dng nhm tng cng tin cy, ti u vn hnh li in truyn ti, li

in phn phi, gim tn tht in nng; tng cng h thng ghi s c, h thng pht hin v

chng s c mt in din rng nhm m bo truyn ti an ton trn h thng in 500kV. Do

, vic trang b cc b o gc pha cng l bc quan trng chun b c s h tng cho vic p

ng l trnh trin khai li in thng minh Vit Nam.

TI LIU THAM KHO

[1] Tng kt vn hnh h thng in quc gia nm 2013.

[2] Bo co nh gi trnh hnh cung cp in giai on 2014-2020.

[3] Bo co vn hnh li in quc gia nm 2014.

A. Cc bo co chung

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