Liniyaning boshlanishida quvvat va kuchlanish berilgan holat. Yuqorida
ko„rib o„tilgan holatdagi singari liniya toki
I12
ni liniyaning bo„ylama qismi
boshlanishidagi quvvat
S
(1)
12
va kuchlanish
U1 orqali ifodalasak, u holda ma‟lum
shakl almashtirishlardan so„ng liniyada kuchlanish pasayishining bo„ylama va ko„ndalang tashkil etuvchilari uchun liniya boshlanishidagi ma‟lumotlar bo„yicha ifodalarni hosil qilamiz:
(1) P(1) r
Q(1) x
; (3.30)
U12
12 12 12 12
U1
(1) P(1) x
Q(1) r
. (3.31)
U12
12 12 12 12
U1
Liniya oxiridagi kuchlanish:
U U U ( 1 ) jU ( 1 ) . (3.32)
2 1 12 12
Yuqoridagilarga muvofiq liniya oxiridagi kuchlanish moduli va fazasi qo„yidagicha aniqlanadi:
U2 ; (3.33)
U (1)
2 arctg 12 . (3.34)
U
12
1
U (1)
,b- rasmda tasvirlangan kuchlanishlar vektor diagrammasidan ko„rinadiki, kuchlanish pasayishining ko„ndalang tashkil etuvchisi U12 kichiklashgan sari kuchlanish isrofi kuchlanish pasayishining bo„ylama tashkil etuvchisiga yaqinlashib boradi. Shu sababli 110 kV va undan past kuchlanishli tarmoqlarni hisoblashda ushbu tashkil etuvchi etarlicha kichik bo„lganligi sababli liniya oxiridagi ma‟lumotlar bo„yicha hisoblashlarda
(2) P(2) r
Q(2) x
, (3.35)
U12
U12
12 12 12 12
U 2
liniya boshlanishidagi ma‟lumotlar bo„yicha hisoblashlarda esa
(1) P(1) r
Q(1) x
U12
qabul qilinadi.
U12
12 12 12 12
U1
(3.36)
Transformatorlarning transformatsiyalash koeffisientlarini o’zgartirib rostlash
Yuqorida ko‟rib o‟tilgan podstansiyalarda kuchlanishni rostlash usulining samaradorligi bilan sхemasi 3.3- rasmda keltirlgan elektr tarmog‟ida podstansiyaning pastki tomonida kuchlanishni rostlash misolida tanishamiz.
3.3-rasm
Kuchlanishni pasaytiruvchi podstansiyaning pastki tomonida Un hoh=10.5 kV kuchlanishni transformatorning transformatsiyalash koeffiseintini tanlash hisobiga rostlash talab etiladi.
Transformator kuchlanishni yuklama ostida rostlovchi YuOR ±9x1,78 tipidagi qurilma bilan jihozlangan.
Elektr tarmoqni almashtirish sxemasi tuzamiz va uning parametrlarini topamiz.
Liniya o‟tkazgichining markasi AC-185.
Uning solishtirma parametrlari: r0=0.17 Om/km, x0=0.409 Om/km/, b0=2.82 *10-6 Sm/km. Liniyaning uzunligi: l=50 km.
Liniya almashtirish sхemasining parametrlarini topamiz: rl=r0 *l=0.17*50=8.5 Om
N l
xl=x0*l=0.409*50=20.45 Om bl=b0*l=2.82*10-6*50=0.141*10-3 Sm Qs=U 2*b =1102*0.141=1.706 MVAr
Transformator markasi ТРДНЦ-40000/110
UYuK=115 kV UPK=10.5 kV Uk=10.5% i=0.5 ∆PS.I=120 kVt ∆PQT=265 kVt
R QT
* U 2
265 *115 2
N
2.19 , Om
X UK
%* U 2
10.5 *115 2
34.72 Om
N
N
S
N
T 2 402
T 100S
100 * 40
ST
S.I
0.12 , MVt
QST
I S .I %* SN
100
0.5 * 40 0.2
100
MVar,
bu yerdagi P QT –qisqa tutashish isrofi, MVt
U k % - qisqa tutashuv kuchlanishi, % U N
P S.I -salt ishlash isrofi, MVt I S.I % - salt ishlash toki, % I N
Elektr tarmoqning almashtirish sхemasini chizamiz (3.4-rasm)
3.4-rasm
Elektr tarmog‟ining holatini hisoblaymiz.
РT
Р2 Q2
U
T T RT
N
352 152
1102
2.19 0.262 MVt
QT
Р2 Q2
U
T T XT
N
35 2 15 2
110 2
34.72 4.16
MVAr
∆S=0.262+j4.16 MVA
S1 SYu ST (35 j15) (0,262 j4.16) 35.262 j19.16 MVA
S2 S1 Spul (35.262 j19.16) (0.12 j0,2) 35.382 j19.36 MVA
Liniyaning oxirida hosil bo‟lgan zaryad quvvatini hisobga olamiz:
S3 S2
2
(35.382
j19.36) j 1.706 35.382
2
j18.507
MVA
Liniyadagi quvvat isrofi:
Р2 Q2
U
2
РL 3 3 RL
N
35.382 2 18.507 2
110 2
8.5 1.12
MVt
QL
Р2 Q2
U
2
L
3 3 X
N
35.382 2 18.507 2
110 2
20.45 2.69
MVAr
S4 S3 SL (35.382 j18.507) (1.12 j2.69) 36.502 j21.197
MVA
Liniyaning boshida generatsiya qilinayotgan quvvatni hisobga olamiz:
S5 S4
2
(36.502 j21.197) j 1.706 36.502 j20.344
2
MVA
Kuchlanish yo‟qotilishini aniqlash Liniyadagi kuchlanish yo‟qolishi:
U12
Р4 RL Q4 ХL
UN
36.502 8.5 21.197 20.45 6.76 kV
110
2- tugundagi keltirilgan kuchlanish:
U2 U1 U12 110 6.76 103.24 kV
Transformatordagi kuchlanish yo‟qolishi:
U 23
Р1 RT Q1 ХT
U 2
35.262 2.19 19.16 34.72 7.2 kV
103.24
Podstansiyaning PK tomonidagi kuchlanish:
U3 U2 U23 103.24 7.2 95.04 kV
Shohobcha kuchlanishi:
Ushoh
U3 U PK
10.5
95.04 10.5 95.04 kV
10.5
Ust 96.55 kV
Podstansiyaning PK tomonidagi hohlangan kuchlanish:
UN . hoh
U 3
KT
95.64 10.5 10.5
96.55
kV.
Shunday qilib ushbu holatda podstansiyaning paski tomonida kuchlanishning talab etilgan qiymati 10,5 kV transformator transformatsiyalash koeffitsienti K t=96,55/10,5 bo‟lganda ta‟minlanadi.
Kuchlanishni elektr tarmoqning reaktiv qarshiligi kompensatsiyalab rostlash usulining samaradorligi bilan sхemasi 3.5- rasmda keltirilgan elektr tarmog‟ining oхirgi punktida 110 kV kuchlanishni ta‟minlash masalasida tanishib o‟tamiz.
3.5- rasm
Elektr tarmoqni almashtirish sxemasi tuzamiz va uning parametrlarini topamiz.
Liniya markasi AC-240 r 0=0.13 Om/km x 0=0.401 Om/km b 0=2.85 *10 -6 Sm/km l=40 km
R L1=r 0 *l=0.13*40=5.2 Om X L1=x 0*l=0.401*40=16.04 Om b L1=b 0*l=2.85*10 -6*40=0.114*10 -3 Sm
Elektr tarmoqning almashtirish sхemasi 3.6- rasmda keltirilgan.
3.6- rasm.
Elektr tarmoqning holatini hisoblaymiz:
N L1
liniyaning zaryad quvvati: Qs1=U 2*b =1102*0.114=1.38 MVAr
N L2
liniyaning zaryad quvvati: Qs2=U 2*b =1102*0.0.0705=0.854 MVAr 2-Liniyaning oxirida hosil bo‟lgan zaryad quvvatini hisobga olamiz:
S4 S3
2
(15
j7) j 0.854 15 2
j6.573
MVA
Liniyadagi quvvat isrofi:
Р2 Q2
U
2
РL2 4 4 RL2
N
15 2 6.573 2
110 2
4.25 0.094
MVt
Р2 Q2
U
2
QL2 4 4 XL2
N
15 2 6.573 2
110 2
10.225 0.23
MVAr
S5 S4 SL2 (15 j6.573) (0.094 j0.23) 15.094 j6.803
MVA
Liniyaning boshida generatsiya qilinayotgan quvvatni hisobga olamiz:
S6 S5
2
(15.094 j6.803) j 0.854 15.094 j6.376
2
MVA
S7 S6 S2 (15.094 j6.376) (20 j8) 35.094 j14.376
MVA
1-Liniyaning oxirida hosil bo‟lgan zaryad quvvatini hisobga olamiz:
S8 S7
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