y DANH GI.A ANH HUONG CUA CONG HUONG DIEN AP
DO SONG HAI CUA TAI PHI T U \ EN DEN TU BU TRONG Ll/Cn DIEN 6 kV CONG TV THAN NAM MAU
KS. Nguyen Xuan Nhi, TS. Le Xuan Thanh Trur/ng Bgi hpc .Mo - Dja chdt
Bien tap: TS. Ddo Dac Tgo Tom tat:
(tie sir dung cdc thiit bj biin doi ttai phi tuyin) trong hi ihong diin mang lgi nhiiu lpi ich. Tuy nhien, viic sir dung chimg sinh ra song hdi Wong cdc mgng diin vd ldm mio dgng sdng dien dp vd dong diin. Diiu ndy ldm dnh hircnig l&n din sir ldm viic binh thucmg. dieu kiin an loan cdng nhu- ludi thp cua cdc thiet hj dien.
Tlidng qua viic md phong trin phdn mem ATP, hai bdo phdn lich. ddnh gid ldc dpng cua sdng hdi do tdi phi tuyin ddi v&i cdc hp tu bii cong sudt phan khdng. Tu dd. di xudt nhimg phucmg phdp phii hcrp di logi ho tdc dpng tiiu circ ciia song lidi ddi vcri cdc thiit bj trong mgng diin.
1. Mo" dau md h i m Id thugng la cae bg khdi ddng m i m , cac o l nang cao hieu qua san xuit, hien nay, cac bg b i i n t i n , cac thilt bj biin doi, d l l u khien...
thilt bj dien tir' cdng s u i t (tai phi tuyin) duge sir Cae thilt bi nay la nguyen nhan chinh sinh ra dung rgng rai trong mang dien cua eae md h i m
16, dac biet trong mang 6 kV.
Viee sir- dung cac thilt bi nay dem lai hieu qua Idn v l kinh t l . ky thuat nhung cung gay ra nhirng tae dgng tieu cyc den mang dien, ma dang ke n h i t la sinh ra sdng hai. Bai bao phan tieh k l cgng hudng dien ap do sdng hai ciia tai phi tuyin, anh hudng d i n tu bii trong ludi dien 6 KV. md Nam Mau.
2. Cong hu'dng dien ap do song hai ciia tai phi tuyen
2.7. Tai phi tuyin trong mang dien 6kV mo him Id
Tai phi tuyin duge sir dung trong mang dien
Q 24.6 % 2 25.5 x Q) 23.6 x 563
sdng hai trong mang dien 6kV eua md ham 16, ehung lam cho dang sdng ddng dien va dien ap bi meo dang, khong cdn hinh sin.
Hinh 1 va hinh 2 ghi lai dang sdng ddng dien va pho hai ciia mgt so tai phi t u y i n dugc do thyc t l trong mang dien 6 kV md h i m 16.
Qua cae k i t qua do thyc nghiem va ly thuylt trong hinh 1 va hinh 2 cho t h i y rang, tai phi tuyin trong ludi 6 kV ciia md gay meo dang ke sdng hai, THD d i u tren 23% (hinh 1), ea biet len d i n 115% (hinh 2). O i l u nay vi pham nghiem trgng cae Tieu chuan q u i e gia va quoe t l v l c h i t lugng dien nang [3].
2.2. Phirong trinh toan hoc khi co cong hwang
Ah 05 ®
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21.1 X 61.8 A
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THD
a) Dang sdng ddng dien bj Pho tiai ddng dien
Hinh 1. Dang sdng va phd hai d6ng dien do sau mot biin tin trong mang dien trung ap 6 kV mo him 16 [7]
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H/n/7 2. Dang sdng, p/id /la/ va he sd meo dang song cua mot sd tai phi tuyin thimng dung trong mang dien mo him 16
irng vdi t i n s l ca ban, V;
do nguon hai
Oien khang ciia mdt mang dien phu thugc vao tan s l . Trong mang dien, tan s l cgng hudng ca ban duoc xac djnh theo bieu thire (1) [2].
f^-1
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Trong dd:
L - Oien cam ciia mach dien, H;
C - Dien dung ciia mach dien, F.
Sy nguy hiem n h i t eiia sdng hai dd chinh la gay ra sy cgng hudng dien ap va cdng hudng ddng dien. O i l u nay lam cho bien do dien ap, ddng dien tang vugt qua gia trj danh djnh eiia cac thiet bj dien va gay nguy h i l m d i n cae thilt bj.
Gia trj hieu dung khi cd cgng hudng eiia dien ap va ddng dien do sdng hai cd the t h i y rd qua phuang trinh toan hgc (2) va (3):
jji~„dt=I^,^^]TTH!f;
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+ THD:(2)
(3)
Trong dd: U,,, - Gia trj hieu dung ciia dien ap
l(,j - Gia tri hieu dung eiia ddng dien irng vdi t i n sd ea ban, A;
THD^j, THD, - He s l meo dang sdng cua dien ap va ddng dien do sdng hai.
2.3. Anh htrang cua song hai do tai phi tuyin din thiit bj dien
Mgt so tac dgng tieu eye chinh eiia sdng hai ddi vdi cae thilt bj dien [1]:
- Lam sai leeh he thong thilt bj do d i m cac dai lugng dien, tir dd cd the lam cho he thong bao ve rale tae dgng n h i m I l n ;
- Lam giam tuoi thg cua MBA, cac dgng ea dien do hieu irng phat ndng phu tren b l mat (skin effect) va phat ndng dien mdi;
Tang phat ndng, giam hieu s u i t hay gay dao dgng ha tan s l eg hge;
- Cd the pha buy hoac ban ehe kha nang van hanh eua eae bg tu bii edng s u i t phan khang.
Trong cae tac dgng tren, tae dgng ciia sdng hai d i n MBA mang tinh dai ban, ehu y l u la lam giam thdi gian van hanh eua MBA. Cae k i t qua thyc nghiem ciia [4] da dua ra he so suy giam tuoi thg ciia MBA duge the hien nhu tren hinh 3.
Ooi vdi eae bg tu bii edng s u i t phan khang, anh hudng ciia sdng hai mang tinh c h i t tire thdi, cd the pha hiiy each dien hay gay dirt day KHCNM SO 2/2017 * CO DIEN - TII DONG HOA
e l u chi trong eae bd tu. Nguyen nhan chu y l u la do x u i t hien hien tugng cgng hudng song song vdi cac tu bii ngang va cgng hudng n i l t i l p vdi eactu bii dge[1].
Cae nghien ciru ciia [2] vdi cac bd tu bii tmh dat tren thanh cai 13 kV eiia TBA trung gian (ed sa dd nguyen ly nhu hinh 4) chi ra r i n g : Tiiy theo gia trj va bien do ddng dien hai, khi xay ra cgng hudng, dien ap dat len bd tu c6 the b i n g 1,8 Ug„ (hinh 5a) hoac d i n 2,5 U^,^ (hinh 5b).
Nhu vay, ed the thiy, nhirng tac ddng ciia sdng hai tdi eae bg tu bu edng s u i t phan khang la r i t nguy h i l m , cd the pha hiiy tire thi cac bg tu. Tieu chuan IEEE Standard 1036-1992 quy djnh nghiem ngat khi van hanh cac tu bii tTnh tren cac TBA trung gian, cu the:
- Ddi vdi cae dai lugng djnh mire eua bd tu bu:
+ Chi cho phep van hanh vdi dien ap eye dai 1.1 U, ;
' am'
+ Chi cho phep van hanh vdi dien ap eye dai 1.2U,.,;
+ Chi eho phep van hanh vdi ddng dien eye dai 180% L ;
am'
+ Cdng s u i t phan khang toi da duac phat la 135% Q,^.
- o i l vdi eae gidi han thdi gian:
+ Dien ap cyc dai chju dugc 2,2 i l n U^^ trong 0,1s;
+ Oien ap cyc dai chiu dugc 2,0 i l n U^^ trong 0,25s;
Hinh 3. He so suy giam tudi tho MBA tuong img vol do meo cua song hai [4]
+ Oien ap eye dai chiu duge 1,7 i l n U,„ trong I s ;
+ Oien ap eye dai chju duge 1,4 lan U^..^ trong 15s;
+ Oien ap eye dai chju duge 1.3 i l n U,._ trong 1 phut;
+ Oien ap eye dai ehju duge 1,25 i l n U,._ trong 30 phiit.
Tir eae k i t qua phan tieh tren, ed the t h i y r i n g anh hudng eiia sdng hai d i n cac bo tu bii cong s u i t phan khang la r i t nguy hiem. Cgng hudng ed t h i gay ra pha buy tire thdi ddi vgi cac bd tu. Do vay c i n loai trir tac hai ciia eong hudng do sdng hai ddi vdi cac bd tu bii 6 kV.
3. Phan tich danh gia cong hipang dien ap trong mang dien 6 kV mo h i m 16 cua Cong ty than Nam Mau
3.1. Dac diim lu-ai dien 6 kV mo him Id Cong ty than Nam Miu
Oe phuc vu eho cac hoat dgng san xuit, Cdng ty than Nam Mau sir dung mgt tram b i i n ap (TBA) trung gian 35/6 kV gom 2 may b i i n ap (MBA) cd dung lugng moi may 7.500 kVA. Cae phu tai 6 kV phia sau TBA 35/6 kV duge c l p dien theo sa do hinh tia, chu y l u la cae dgng ca bam nudc eao ap, cae dgng ca quat gid, dgng ca bang tai g i l n g ehinh va eae MBA 6 kV eung c l p dien eho cac phan xudng.
Trong ludi 6 kV cd eae tai phi t u y i n ehii y l u la cac bg khdi dgng m i m diing de khdi ddng
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Hinh 4. Sa dd thay thi mach cong huang song song khi dat tu bu tai thanh cai 6 kV cua TBA trung gian [2]
Bang 1. Thong so ky thuat chi tiet cac bo khoi dong mem 6 kV
Ma hieu HRVS-DN 140A-6000V
Dien ap dinh mirc, V 6000 (-15%++10%)
Dong dinh djnh mdc, A 140
Cap bao ve Chirc nang IP32 Han c h i dong dien khdi
dong ciia dong co
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Thong tin khoa hpc cong nghe mo
cho cac ddng ea cdng s u i t ldn. Thdng sd ky thuat chi t i l t ciia eae bg khdi dgng m i m cho d bang 1.
3.2. Mo hinh hoa va mo phong lu'di 6 kV Tit sa do nguyen ly cung cap dien thyc t l ciia Cong ty than Nam Mau, sir dung p h i n mem ATP cd dugc md hinh md phdng mang dien 6 kV cua Cdng ty than Nam M l u . Trong so d l nay, c6 ghi thdng s l ky thuat eiia mgt s l p h i n tir ca ban trong ludi dien.
3.2.7. Ngudn dien
Ngudn dien ciia Cong ty than Nam M l u dugc c l p tir Udng Bi qua 2 16 dudng day t r i n tren khong N0372 va N0373 loai AC-70 d i n TBA trung gian 35/6kV ciia Cdng ty. Thdng s l ky thuat ciia dudng day tren khdng va TBA trung gian ghi trong bang 2 va bang 3.
3.2.2. Tai chu yiu
Phu tai dien 6 kV ciia Cdng ty than Nam M l u ehii y l u la cac dong ca bam nude, quat gid, bang tai gilng chinh va cae MBA 6/0,69 kV hoae
6/0,4 kV cung e i p dien eho cac phan xuang hoae ehiiu sang van phdng. So lugng phu tai dien 6 kV ciia Cdng ty cho trong bang 4.
3.2.3. Ngudn hai
Nguon hai dugc md phdng b i n g maeh ehinh luu 6 xung, dugc bgm tryc t i l p vao mang dien qua thanh cai ehinh 6 kV eiia TBA trung gian 35/6 kV.
Sa d l nguyen ly eiia ngudn hai nhu md ta tren hinh 6.
3.2.4. NhCfng diim mo phong can quan sat Tac dgng nguy hiem n h i t cua sdng hai ehii y l u ddi vdi cac bg tu dien bii cong s u i t phan khang. Do vay, d l danh gia tac dgng cua sdng hai, e i n phai dat cac thiet bj do tai vj tri cac bd tu bii, cu t h i la tai thanh cai ehinh 6 kV TBA trung gian 35/6 kV va thanh eai 6 kV tram quat gid ehinh.
3.3. Kit qua
Sau khi md phong, thu dugc do thj dang sdng dien ap tai cac vj tri c i n quan sat, k i t qua the
a) b) Hinh 5. Dien ap (dan vj tirong doi) dat len tu khi c6 cong huang song song [2]
Bang 2. Thong sd ky thuat cac tuyin duong day tren kh6ng cip dien cho TBA 35/6kV, Cong ty than Nam Mau
Ma hieu day AC-70 AG-70
Chiiu dai, km 4,5 8,5
Nguon cap Lp 372-7 Uong Bi - Vang Danh Lp 373-7 Uong Bi - Vang Danh Bang 3. Thong sd ky thuat cua MBA trong Tram 35/6 kV Cong ty than Nam Miu
Ma hieu
BAD 7500-35±2x5% /6,3 kVA 7500
f^,,™. f^v So cip
35
Thu' cip 6,3
Ton that cong suit, kW
&P^, kW 11,4
AP„, kW 36
U„, %
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To noi day Y/A-11
KHCNM SO 2/2017 * CO DIEN - T l D 0 N ( , HOA
Sang 4. S6 luvng phij tai dien 6 kV cua Cong ty than Nam Miu nam 2016
w
May biin ap 6/0,69(0,4)kV Sd
luvng 50
Tdng cong suit djnh mirc, kVA
19.790
Dong CO bom cao ap Sd
luong 5
Tdng cong suit djnh mirc, kW
3.150
Dong CO quat gio Sd
luvng 4
Tdng cong suit djnh mirc, kW
2.840
Dgng co bang tai gieng Sd
luvng 2
Tong cong suit djnh mirc, kW
1.000
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Hinh 6. Sa do nguyen ly ngudn hai bing mach chinh luu 6 xung
Hinh 8. Cong huong dien ap tren bo tu bd duvc dat tai thanh cai 6 kV tram quat gio chinh
cua Cong ty than Nam Miu hien d hinh 7, 8 va tong hgp d bang 5.
Tir eae k i t qua thu dugc tren sa do t h i y r i n g edng hudng dien ap xay ra tren ludi 6 kV ed bien do cgng hudng vugt qua quy djnh eho phep theo tieu ehuan IEEE standard 1036-1992.
Bien do cgng hudng Idn se gay ra pha huy tire thi bg tu bii gay nguy hiem cho ca ngudi van hanh va ea thiet bj, lam anh hudng d i n qua trinh san x u i t eiia Cong ty.
4. Ket luan va kien nghj
Tir eae k i t qua nghien eiru, t h i y ro dugc sy nguy hiem khi xay ra cgng hudng dien ap do sdng hai eiia tai phi tuyen d i i vdi eae bo tu bii
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Hinh 7. Cong huvng dien ap tren bo tu bd duvc dat tai thanh cai 6 kV TBA trung gian 35/6 kV
cua Cong ty than Nam Miu
Bang 5. Kit gua mo phdng qua trinh cong hirong dien ap qua cac bd tu bu cua Cong ty than Nam Miu
Diem do
Thanh cai 6 kV TBA trung gian Thanh cai 6 kV tram quat gio
chinh Loal
tin hieu Dien ap
Dien ap
So pha cgng hwong
3
3
Do Ion tin hieu cgng
hirong 4 U „ .
4 U „ .
Thoi gian cgng hwong, s
0,36
0,36
cdng s u i t phan khang ciia Cdng ty than Nam Mau. Cgng hudng dien ap e6 t h i dien ra ngay ca khi tong do meo sdng hai ed gia trj t h i p , qua trlnh cgng hudng d i l n ra tren ca 3 pha. Do vay, c i n ed nhu-ng nghien eiru danh gia d l tim ra nhti'ng bien phap thich hgp n h i m giam thilu hoae loai trif cae nguy hiem d i i vdi cac bg tu bii ciia Cdng ty khi cd edng hudng xay ra.
Oe giam thieu tae hai eiia edng hudng dien ap do sdng hai ed the sir dung mgt s l bien phap nhu sau:
+ Loai bd hoae ban e h l sir dung tai phi t u y i n (ngudn hai) trong mang dien;
KHCNM s o 2/2017 * CO DIEN - T l DONG HOA
Thong tin khoa hoc cong nghe m o
• Sir dung thiet bi giam sat, danh gia mirc do anh hugng ciia sdng hai;
+ Sir dung cae bd Ige sdng hai tich eye;
+ Sir dung cuon khang mac ndi tiep vdi tu bii de Igc hai;
+ Sir dung MBA d i u Y/A,... ./.
Tai lieu tham khao:
1. Le Xuan Thanh (2014), Nghien cu-u mot si giai phap nang cao chat luvng dien nang trong Iwyl 6kV cac mo 16 thien Quang Ninh. Luan an t i l n sT ky thuat, Oai hge Md - Oja ehit. Ha Ngi, Viet Nam.
2. Vien Khoa hgc Cdng nghe Md - Vinaeomin (2016), Sao cao kit qua kiim toan nang Iwtyng Cong ty than Nam Miu - TKV.
3. Attachie, J.C, and Amuzuvi, C K . (2010), Investigating harmonic resonance and capacitor
bank switching at a power distribition substation using a fixed calacitor bank. Research Journal in Engineering and Applied Sciences, Vol 2:
1 9 0 0 - 1 9 0 9 .
4 Elmoudi, A.(2006), Evaluation power system harmonic effect Transformers loss of life. Doctoral Dissertation, Helsinki University of Tech. Findland.
5. Le Xuan Thanh (2015), Selection of a suitable schematic diagram for 35/6kV coal mine transformer substions to protect correction capacitor banks from seres resonance caused by power harmonics. P r o g r a m m e - MPES 2015:
557 - 563.
6. IEEE - STD-1036-1992. IEEE. Guide for Application of Shunt Power Capacitors.
7. IEEE STD 5 1 9 - 1 9 9 2 .
Evaluating the effects of the voltage resonant caused by harmonics of nonlinear loads to capacitor banks on the 6kV voltage network of Nam Mau Coal Company
Eng. Nguyen Xuan Nhi. Dr Le Xuan Thanh Hgnoi University oflWining gnd Geology Summary:
Using power electronics devices (nonlinear loads) on the electric power system brings many economical and technical benefits. However, using nonlinear loads is the main reason of ejecting power harmonics on electric network and lead to voltage and current waveforms distortion. It has great impact on normal operations, safety conditions as well as reducing the life of electrical equipments.
By using ATP simulation, the paper focuses on analyzing the negative effect caused by harmonics of nonlinear loads on capacitor banks. Basing on the analysis, the suitable methods will be recommended to eliminate negative effects of harmonics on electrical apparatus.
KHCNM s o 2/2017 * CO DIEN - TU DONG HOA
