NGHIEN CUTU - TRAO D O I
'NGHIEN CLFU GIAI PHAP NANG CAO Dp TIN CAY CUNG C A P D I E N C H O CAC PHU TAI TRONG MANG OlEN
PHAN P H 6 | CO MAY PHAT PHAN TAN
A STYDY SOLUTION FOR IMPROVING ELECTRICITY RELIABILITY FOR LOADS IN DISTRIBUTION NETWORK WITH DISTRIBUTED GENERATOR
TS. Bui Dinh Thanh', ThS. Nguydn Due Minh' 'Trudng Dai hgc Md - Dia chat
^Vien Khoa hpc Nang lugng Viet Nam
TOM TAT
Bdi bdo trinh bdy nghien cuu, de xudt gidi phdp nhdm ndng cao dd tin cay cho cdc phu tdi trong mang dien phdn phdi cd su dung mdy phdt dien phdn tdn khi xdy ra su cd mdt nguon dien chinh. Tinh todn cdc thong sd, che do ldm viec cua mang dien sau su cd bdng thuat todn Backward/
Forward khi cd ke den cdc rdng budc Ay thudt cua mang dien vd dp dung cdc ket qud nghien cuu ly thuyet vdo so do mang dien cu the.
Tir khoa: Luoi dien phdn phdi; Mdy phdt dien phdn tdn; Do tin cdy cung cdp dien; Thuat todn Backward/Forward...
ABSTRACT
This paper will introduce a solution to improve electricity reliability for loads in the distribution network with distributed generator in the fault of main power supply. Caculator parameters of electrical network after the incident by the algorithm Backward/Forward with technical constraints of power grid and application of this study results into electrical network diagram.
Keywords: Distribution Network; Distributed Generator; Electricity Reliability; Algorithm
Backward/Forward... ^
ISSN 0866-7056
TAP CHi CO KHi VIET NAM, Sd 1+2 nam 2016 www.cokhivietnam.vn
NGHIEN CUfU - TRAO 9(^1
1. LOI MO DAU
Dd nang cao dp tin cay cung cap didn cho cac phu tai thi mdt ttong sd cac chi tieu quan ttpng do la giam thdi gian gian doan cung cap dien cho chung. Day la muc tieu chimg cho tat ca cac qudc gia fren the gidi. Mdt ttong nhimg giai phap de nang cao dupe dp tin cay cho mang ludi dien phan phdi dd la ket ndi cac may phat dien phan tan (DG) vao mang ludi dien nay. Vide ket ndi cac DG se anh hudng ldm ddn cau hinh ciia mang dien va lam thay ddi cau tnic he thdng rale bao ve ciia mang dien. Khi thuc hien viec kdt ndi cac DG vao mang ludi dien phan phdi can phai dam bao nguyen tac la cac DG nay khdng dugc gay anh hudng den sir lam viec cua he thdng role bao ve va dieu khien san cd tten ludi dien phan phdi.
Mdt ttong nhiing yeu cau quan ttpng khi ket ndi cac DG vao ludi dien phan phdi do la cac DG can phai dugc each ly ngay ra khdi ludi dien phan phdi khi xay ra sir cd mat dien ngudn chinh. De thuc hien dupe yeu cau nay ddi hdi su lam viec chinh xac ciia he thdng rale bao ve, dugc cai dat ttong che dp lam vide song song ciia DG va ludi dien. Mat khac, nd ciing ddi hdi he thdng role nay phai nhanh chdng thich nghi sang che dp lam viec ddc lap ciia cac DG khi tach ra khdi ludi.
De tach DG ra khdi luoi dien hoat dong ddc lap thi can phai xem xet rat nhieu ylu ti khac nhau. Dau tien can phai xet den bai toan can bing cdng suat ttong mdi "Islanding" giija cdng suat cua DG va cac phu tai nham tan dung hdt kha nang phat cdng suat ciia DG; tuy nhien, ciing khdng dugc gay qua tai cho cac DG. Di6u nay, cd nghia la tdng cdng suat cua cac phu tai khdng dugc vugrt qua kha nang phat cdng suit cua DG. Ngoai ra, cac phu tai khac nhau se c6 nhiing ydu cau cung cap dien khac nhau (phu thupc vao loai phu tai), do do mdi DG cd ging ttong kha nang cd thd de cung cap cho mpt s6 lugng phu tai quan ttong tnrdc. Neu cdng suit cua DG khdng dii cung cap cho tit ca cac phu tai, thi mdt sd phu tai can phai dugc sa thai (bj gian doan cimg cap dien) ra khdi ludi nham dam bao can bang cdng suat giiia ngudn va tai.
2. DAT BAI TOAN
Bai toan dupe xem xet dua tten ham tdi uu dp lech cdng suat giira ngudn va tai khi xay ra su cd mat ngudn dien chinh va cac DG tach ra khdi ludi dien hinh thanh nen cac "dao"
boat ddng dpc lap vdi nhau. Ham muc tieu trong trudng hgp nay dugc xac dinh:
>iAP=2^.-S^.-
(1)Khi xay ra su cd cd the xudt hien hien tugng suy giam dien ap va tin sd ttong ludi dien, liic nay cac DG se tach ra lam vice ddc lap vdi nhau, mdi DG cd ttach nhiem cung cdp dien cho 1 sd phu tai vdi chat lugng dien nang va dp tin cay cung cap dien dam bao theo yeu cau [1]. Viec tach cac DG ra cip dien ddc lap cho 1 nhdm phu tai (hinh thanh cac dao cip dien
"Islanding") gdp phSn giam thidu thai gian gian doan cung cap dien cho nhdm cac phu tai nay khi xay ra su cd mit dien tir ngudn dien chinh ciia ludi, do dd gdp phin nang cao dp tin cay cung cap dien cho chiing.
didn;
Trong dd:
Pn - Cdng suat phu tai tai mit n ciia luoi Pn* - Cdng suat tai mit n* ttong cac "dao"
ciia ludi didn (cac dao nay dugc hinh thanh sau su cd va chiia so nut la N*);
N - Sd niit ttong ludi dien.
O che do lam vide sau su cd de dam bao cho cac thidt bi va phu tai lam viec bmh thucmg, ddi hdi ttong cac "dao" nay phai dam bao cac yeu cau ky thuat sau:
ISSN 0866 - 7056
TAP CHi CO KHi VIET NAM. Sd 1+2 nam 2016 www.cokhivietnam.vn
.-.^Jlll
NGHIEN CJU - TRAO OOl
+ Dam bao can bang cdng suat ngudn-tai ttong cac "dao": V / ^ ~y\P„, <E
Vdi: ^ ^ ^ - Tdng cdng suat tac dung cac DG ttong "dao";
^ P^,j - Tdng cdng suat tac dyng cac phu tai ttong "dao".
+ Dam bao dieu kien ddng nung ndng cho phep cua day dan: I^ <I^.
+ Dam bao didu kidn tdn hao didn ap cho phep: U^^^<U^<U^.
la phat cong su4t tac d\mg, cdn cdng suat phan khang se phat hoac tieu thu tiiy thugc vao che do lam viec ciia nd, vi vay ttong mdt sd trudng hgp chiing cd kha nang duy tri dn dinh dugc dien ap d i u cue may phat khi tai thay ddi. Trong tmh toan cd thd coi ring cdng suit phat phan khang cua DG cd kha nang thay ddi trong gidi han tir Q ^ ^ d d n Q ^ ^ .
3. TINH TOAN T H 6 N G SO L A M VIEC T R O N G CAC " D A O "
Didu kidn can bang cdng suat ttong cac
"dao" dugc th\rc hidn dua tten thuat toan tim kiem day du. Trong [2], md ta chi tidt viec hinh thanh cac "d mang" ngudn va tai (Hmh 1). Trong cac "d mang"; cdng suat cua cac ngudn dugc ky hidu mang d i u duang, cac phu tai mang dau am.
Vdi mdi "6 mgng" c i n phai kiem tta didu kien:
^yps + X - ^ y > 0 , vdi P;^ - Tdng cdng suat ciia cac phu tai ttong "d mang".
\ -20
'V-30.
:i2)i I
®-
-20
" • • , 2 , - '
•20 V -10 ( 5 ) , \ ( 6 )
( l l ) , , ' V+30 10),-j{4) (9)i
m
--.-.1
A P) .-';.,(*) -i':
•€>
,•''+30 (3)\
Hinh I. Cdc 6 mgng
Biiu kien \i dong nung nong cho phep va t6n that dien ap trong luoi di?n duoc tinh toan trong chS do xac lap. Trong tinh toan it che do xac lap cho cac "dao" c6 the su dung 2 mo hinh thay thS cho cdc nut DG dg tinh toan, do la mo hinh P-Q va P-U. Cac DG co chiic nang chinh
Bi tinh toan cac thong so lam viec trong cac 6c dao a ch8 dp xac lap co the su dung nhieu phuong phap khac nhau. Trong [3], de xuat su dung thuat toan backward/forward, trinh tu tinh toan se dupe thuc hien nhu sau:
1) Tai buoc lap iku tien p=0 (p la buoc lap), dat gia tri cdng sudt phan khang do DG phat ra tai niit k (la mit chua DG) la QG™ va dien ap tai tdt ca cac nut trong "dao" bSng dien ap dinh miic cua mang, luc nay cong suat t^i niit k se la:
Si.^Pn+jQn-iPG.+JQoi.''")
(3)2) (5 budc lap tidp theo p : ^ + l ; Tinh toan chd dp cua ludi theo thuat toan backward/
forward, ttinh tu tinh toan nhu sau:
+ Ddng dien phu tai tai mit k:
Ik -- (4)
+ Ddng dien chay tren doan day ndi giiia niit k va mit i:
. (p) 1 . (.Pi . (p)
/* = — ( / . + Z l i . ) (5) + Tdn hao dien ap tren doan day ndi giiia
mit k va mit i: '^
ISSN 0866 - 7056
TAP CHi CO KHi VIET NAM. Sd 1 +2 nam 2016 www.cokhivietnam.vn
NGHIEN CUfU-TRAOD6|
+ Dien ap tai nut k;
« , ' " = — ( ^ / ' ^ " - l - A C / - ' " )
(6)
(7)
"Y:
Kiem tra dieu kien dung ciia phep lap;
| ( 7 / " - £ / , < ' - ' > | < f (8) Hinh 3
Su dung thtmt toan backward/forwani, lap trinh tren ngon ngir Delphi tinh toan duoc gia tri dien ap tai cac mit trong "dao" co DG. Gia 3) N8u diSu kien (8) khong thoa man, hi ili?"! ap tai cac mit dugc th6 hien nhu tren hinh thay doi gia tri dat cua cong suit phan khang ^^ ^^
may phat thanh Q^,*' va tinh toan lai cho dfa khi dieu kien (8) dupe thoa man. Khi tmli toan co luu y, do cong suat phan khang ciia may phat Q^.
njm trong gioi han: Q^ SQoSQo , cho nen
Nguoc lai, neu Q,*' < Q.. . : dat O *> =
4) VI DU MINH HOA
0 hinh ve 2, gidi thieu ludi dien bao gdm ngudii dien chmh N cd cdng suit vd cung lan va DG cip dien cho cac phu tai. Gia thidt su cd xay ra fren dudng day 1-2, luc nay ludi dien se bi mat ngudn cung cip chinh, may phat DG se tach 1 bd phan phu tai ra de cung cip dien rieng cho nd nhu Hmh 3.
Hinh 4 5. NHAN XET VA K E T LUAN
Tu kdt qua tmh toan, nhan thiy tit ca dien ap tai cac mit deu n i m ttong gidi han cho phep (AU^=±5%). Cac phu tai dugc cung cip dien dam bao chat lucmg dien nang va cd do tin cay cao. •
Ngay nhan bai: 20/01/2016 Ngay phan bien: 22/02/2016 Tai lieu tham khao:
Hinh 2: Luoi diin
[1]. Barker Ph.R, De Mello R.W DeterminiDg the Impact of Distributed Generation on Power System: Part I - Radisl Distnbution Systems // IEEE PES Summer Meeting, Seattle, WA, USA, 2000,12p.
[2] Lu Y, Yi X., Wu J., Lin X. An InteUigent Islanding Technique Considering Load Balance for Distribution System with DGs // IEEE PES General Meeting, Montreal, Canada, June 18-22, 2006, 6p.
[3]. Electric power systems. VoL 1. Electnc networits // Y.E Song, N. Hatziaigynou, A. Bum e.a.;Edited by M. Eremia. B Editura Academiei Romane, 2006,605 p.
ISSN 0866 - 7056
TAPCHI CO KHi VIET NAM, Sd l + 2 n a m 2016 www.cokhivietnam.vn
