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Phn I:

1/V s o dng,p,cos ,tn s,nng lng tc dng,nng lng phnkhng cho trm pha cao p

A B C

RRA

A

A

TI 3 PHAV V V V V V HZ

H

Z

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*C/m cch mc l ng:

UAB

+ Cng t tc dng:

UA

Ta c: p = pA + pB + pC = uA iA + uB iB + uCiC

IA

m iA + iB + iC = 0 => iC = - iA - iB

IC

UBC

=> P = uA iA + uB iB - uC iB - uC iA = uACiA + uBCiB

Chuyn v tr hiu dng ta c:

P = UACIA cos(UAC ,IA) + UBCIB cos(UBC ,IB)IBUB

+Cng t phn khng 3 pha 2 phn t:

Ta c:

Mq = K[ IAUBC cos(IA ,UBC) + IBUCA cos(IB ,UCA) + ICUAB cos(IC ,UAB)]

=K[IAUBC cos(900) + IBUCA cos(900) + ICUAB cos(900)]

=K[IAUBC C + IBUCAsin + ICUABsin ]

= K3[IAUA sin +I BUB sin +I CUC sin ]

=K3Q3pha.

IC

IB

IA

UCA

UAB

U

UC UB

UA

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2/Chn thang o cho thit b trn s :

*Khi trm bin p lm vic ch nh mc:-Dng in nh mc pha cao p:

15000

247,4358( )3. 3.35

dm

dm

dm

SI A

U= = =

- Cng sut tc dng :

3. . .cos 15000.0,92 13800( )dm dm dm dm

P U I kW= = =

-Cng sut phn khng:

2 2 2 215000 13800 5878,7754( Ar)dm dm dmQ S P KV = = =

*Khi trm bin p lm vic ch non ti:

Int = 0,6Idm = 0,6.247,4358 = 148.4148 (A)

3. . .cos 3 35 148,4148 0,6 5398,3014( )nt nt nt nt P U I kW= = =- sai s khi o dng l nh nht ta dng bin dng:

247,4358( )

5( )scdm

tcdm

I A

I A

=

Vy KI =300

5= 60

- Do pha cao p c Um=35(kV) nn ta chn UB l :

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U1m= 35 (kV)

U2m= 0,1(kV)

Vy

35

3500,1UK = =Nh vy ta s chn thang o cho:

+Ampe k:

V dng in pha th cp ca BI nh mc l 5A nn ta chn Ampe k c thang ol DA = 5A

+Vol k:

V dng in pha th cp ca BU nh mc l 100V nn ta chn Vol k c thang ol DV = 100V

+Cos v tn s:

Tn s v gc lch pha gia in p v dng in khng ph thuc vo tn s bini ca BU v BI nn ta chn thang o cos vi cos[-1;1] v 0 f 60Hz

+Cng t tc dng v phn khng:

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Nu 1 thng lm vic t = 720h .

2 23( . .cos . )

td dm dmW U I t =

U2m = 0,1(kV)=100(V) l in p th cp ca BU

I2n l dng in pha th cp ca BI l 5(A)

Vy Wtmax cos 1max =

3.0,1.5.1.720 623,538( )tdmaxW kWh = =

Tng t :

Wpkmaxsin 1max =

3.0,1.5.1.720 623,5383( )pkmaxW kVArh = =

Nh vy:

- Chn cng t c thang o l 650 (kWh) vi cng t o cng sut tc dng

- Chn cng t c thang o l 650(kVArh) vi cng t o cng sut phn khng

3/Tnh ch s ca mi cng t trong thi giang 1 thng bit c 80% thi gian

ca MBA lm vic ch nh mc,20% thi gian my bin p lm vic ch non ti .Xc nh costb ca ph ti

Gii:

Ta c: d80

.720 576( )100m

t h= =

20

.720 144( )100nt

t h= =

*Ch s cng t tc dng:

a/Ch nh mc:

Cos = 0,92 => =23 0IA

UA

UAC

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( ) ( )AC A AC A BC B BC Btd1

U I cos U , I U I cos U , IW .t

350.60

+

= =

0 0

AC A BC BU I cos(30) U I cos(30 )

.t350.60

+ +=

( ) ( )0 0 0 0U I cos 30 23 U I cos 30 23.350.60

AC A BC B

t

+ +

= =

( )0 0dm dmU I cos 7 cos 53.t

350.60

+= =

( )( )

0 035.247,4358 cos 7 cos 53

.576 378,72 kWh350.60

+= =

b/Ch non ti:

Cos =0,6 053 =

IB

UA

IA

IBUB

UC

U

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( ) ( )AC A AC A BC B BC Btd2 nt

U I cos U , I U I cos U , IW .t

350.60

+= =

( ) ( )0 0 0 0

AC A BC B

nt

U I cos 53 30 U I cos 53 30.t

350.60

+ += =

0 0

nt ntnt

U I (cos 23 cos 83 ).t

350.60

+= =

( )

( )0 035.0,6.247,4358 cos 23 cos 83

.144 37,1376 kWh350.60

+= =

Vy s ch ca cng t tc dng trong 1 thng l :

1 2 378,72 37,1376 415.8576( )td td td W W W kWh= + = + =

*Ch s cng t phn khng:

a) Ch nh mc :

( )A A A B B B C B C dm dm dmpk1 dm dm

U I U I

3 I U sin I U sin I U sin 3 3I U sinW .t .t

K .K K .K

+ + = = =

2 23.35.247,4358. (1 0,92 )3. . .sin. .576 279,287( )

. 350.60dm dm dm

dm

U I

U It kVAr

K K

= = =

b) Ch non ti :

2 2

2

3.35.148,4148. (1 0,6 ).1443. . .sin .85, 4869( )

. 350.60nt nt nt nt

pk

U I

U I tW kVAr

K K

= = =

Vy s ch ca cng t phn khng trong 1 thng l :

1 2 279,287 85,4869 364,7739( )pk pk pkW W W kVArh= + = + =

*Xc nh cos tb ca ph ti:2 2 2 2

415,85760,752

(415,8576) (364,7739)td

tb

td PK

Wcos

W W = = =

+ +

4/Tnh sai s tng i v tuyt i ca php o:

a.Phng php tnh sai s:

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S dng phng php tnh sai s gin tip.

Gi s c 1 php o gin tip i lng y thng qua php o trc tip x1,x2,...,xn: y=f(x1,x2,..., xn).

Ta c: 1 2 ... ny y ydy dx dx dxx x x = + + +

Sai s tuyt i l:

2 22 2

1 211 2

...n

n kkn k

y y y yy x x x x

x x x x=

= + + + =

Trong : 1x , 2x , nx : l sai s tuyt i ca php o cc i lng trc

tip 1x , 2x ,, nx

- Sai s tng i:

1 2

22 22 2 2

2 2 21 2

1 2

... ...n

ny x x x

n

y x y x y x y

y y x y x y x

= = + + + = + + +

Trong :1x

,2x

,nx

l sai s tuyt i ca php o cc i lng trc tip

1x , 2x , nx

b/Tnh ton:

* Sai s php o dng in :

- Dng thc t : I = IA . KI

IA : S ch ca Ampemet .

KI : S ch ca my bin dng

-Sai s tuyt i ca Ampemet .

.IA A D =

A : Cp chnh xc ca Ampemet .

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2

100A =

D: Gi hn o ca Ampemet .

D= 5 (A)

2

. .5 0,1( )100IA A

D A = = =

- Sai s tuyt i ca my bin dng :

.KI KI IK =

KI : Cp chnh xc ca my bin dng .

2

100=KI

KI : L h s my bin dng

300

5=IK

KI 2 300. 1,2100 5 = =

a) ch nh mc :

I = IA . KI

Vi247,4358

4,12( )300

5

= = =dmAdmI

II A

K

Sai s tuyt i ca php o khi lm vic nh mc l :

( )2

22 2 2 2 300. . .0,1 4,12.1,2 7,775

= + = + =

Idm I IA Adm KIK I

Vy : 247, 4358 7, 77( )= I A

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.KU KU KUD =

1

100=KU : Cp chnh xc ca TU .

DKU =350 : thang o ca bin in p .

1 35. 3,5( )

100 0,1 = =KU V

-Sai s tuyt i ca php o in p:

( ) ( ) ( ) ( )2

2 2 235. . .2 100.3,5 782,62( ) 0,782

0,1 = + = + = =

U U UV KU V K U V kV

35 0,782( ) = U kV

-Sai s tng i :782,62

.100% .100% 2,24%35000

= = =UU U

*Sai s php o nng lng tc dng :

a/Ch nh mc :

Ta c:

1. . 350.60.378,72 7953120( )= = =tddm U I td W K K W kWh

- Sai s tuyt i : ' .Wtddm Cto CtodmD =

Trong :

1,5

100=Cto : cp chnh xc ca cng t tc dng .

CtodmD : Gii hn o ca cng t tc dng.

( )3. . . 3.0,1.5.576 498,83= = =Ctodm ct ct dmD U I t kWh

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( )'1,5

.498,83 7,48100

= =Wtddm kWh

Vy sai s tuyt i ca php o nng lng tc dng l :

( ) ( ) ( )2 2 2'

1 1. . . . . .Wtddm U I Wtddm U KI td KU I td K K K W K W = + +

60

1,2

= =

I

KI

K

350

3,5

= =

U

KU

K

1

'

378,72( )

7,48( )

=

=

td

Wtddm

W kWh

kWh

Thay s ta c:

( ) ( ) ( )2 2 2

350.60.7,48 350.1,2.378,72 3,5.60.378,72

237276,6( )

= + +

=

Wtddm

kWhm

Vy 7953120 237276,6( )= tddmW kWh

- Sai s tng i ca php o cng t tc dng ch nh mc l :

237276,6.100% .100% 2,98%

7953120

= = =WtddmWtddm

tddmW

b) Ch non ti :Tng t ta c :

2. . 350.60.37,1376 799889,6( )= = =tdnt U I Wtd W K K W kWh

- Sai s tuyt i ca cng t :

' .Wtdnt Cto Ctont D =

Trong :

1,5

100=Cto : cp chnh xc ca cng t tc dng .

( )3. . . 3.0,1.5.144 124,708= = =Ctont ct ct nt D U I t kWh

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' 1,5 .124,708 1,871( )100

= =Wtdnt kWh

Vy sai s tuyt i ca cng t tc dng ch non ti l :

( ) ( ) ( )2 2 2'

2 2. . . . . .Wtdnt U I Wtdnt U KI td KU I td K K K W K W = + +

60

1,2

= =

I

KI

K

350

3,5

= =

U

KU

K

2

'

37,1376( )

1,871( )

=

=

td

Wtdnt

W kWh

kWh

Thay s ta c :

( ) ( ) ( )2 2 2

350.60.1,871 350.1,2.37,1376 3,5.60.37,1376

42987,2( )

= + +

=

Wtdnt

kWhm

Vy 799889,6 42987,2( )= tdntW kWh

- Sai s tng i ca php o nng lng tc dng ch non ti l :42987,2

.100% .100% 5,4%799889,6

= = =WtdntWtdnt

tdntW

*Sai s php o cng sut phn khng :

a/Ch nh mc :

1. . 350.60.279,287 5865027( )= = =PKdm U I PKW K K W kVAr

- Sai s tuyt i :

1 .Wpk Cto CtoD =

1

100=

Cto

: cp chnh xc ca cng t phn khng .

CtpkdmD : di o ca cng t phn khng .

( )498,83Ctpkdm CttddmD D kVArh= =

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' 1 .498,83 4,98( )100

= =Wpkdm kVArh

- Sai s tuyt i :

( ) ( ) ( )

( ) ( ) ( )

2 2 2'

1 1

2 2 2

. . . . . .

350.60.4,98 350.1,2.279,287 3,5.60.279,287

167738,63( )

= + +

= + +

=

Wpkdm U I Wpkdm U KI pk KU I pk K K K W K W

kVArh

Vy 5865027 167738,63( )= pkdmW kVArh

- Sai s tng i :

167738,63.100% .100% 2,86%

5865027

= = =

Wpkdm

Wpkdm

PKdmW

b) Ch non ti :

2. . 350.60.85,4869 1795225( )= = =pknt U I PKW K K W kVArh

- Sai s tuyt i ca cng t :

'

. =Wpknt Cto Ctpknt D

Trong :

1

100=Cto : l cp chnh xc .

( )124,708Ctpknt Cttdnt D D kVArh= =

' 1

.124,708 1,247( )100 = =Wpknt kVArh

- Sai s tuyt i ca php o :

2 2 2(350.60.1,247) (350.1,2.85,4869) (3,5.60.85,4869)

47928,86( )

= + +

=Wpknt

kVArh

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Vy 1795225 47928,86( )= pkntW kVArh

- Sai s tng i ca php o :

47928,86.100% .100% 2,67%

1795225

= = =WpkntWpknt

PKntW

*Sai s php o costb:

a) Ch nh mc :

- Cng thc :

2 2 2 2

td

tb

td pk

P Wcos

P Q W W = =

+ +

Sai s tuyt i ca cng t o cos TB

22

cos cos. .tbdm tbdmtbdm tddm pkdm

tddm pkdm

cos W W W W

= +

Trong :

+

2

2 2 2 2cos ( + ). +pkdmtbdm

tddm tddm pkdm tddm pkdm

WW W W W W =

2

2 2 2 2

cos. .

( + ). +

pkdmtbdmtddm tddm

tddm tddm pkdm tddm pkdm

WW W

W W W W W

=

( )

23

2 2 2 2

279,287.7,48 5,5.10

378,72 279, 287 . 378,72 279, 287

= =+ +

+/ 2 2 2 2.

cos ( + ). +tddm pkdmtbdm

pkdm tddm pkdm tddm pkdm

W W

W W W W W =

2 2 2 2

.cos. .

( + ). +

t ddm pkdmtbdmpkdm pkdm

pkdm tddm pkdm tddm pkdm

W WW W

W W W W W

=

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( )3

2 2 2 2

378,72.279,287.4,98 5,1.10

378,72 279, 287 . 378,72 279, 287

= = + +

Vy:

3 2 3 2 3(5,5.10 ) ( 5,1.10 ) 7,5.10 = + =tbdmcos

-Sai s :

37,5.10.100% .100% 0,82%

0,92

= = =

tbdm

tbdmcos

tbdm

cos

cos

b) Ch non ti :

2 2tbnt tbnttbnt tdnt pknt

tdnt pknt

Cos CosCos ( . W ) ( . W )W W

= +

Trong :

+

2

2 2 2 2

cos

( + ). +pknttbnt

tdnt tdnt pknt tdnt pknt

W

W W W W W

=

2

2 2 2 2

cos. .

( + ). +

pknttbnttdnt tdnt

tdnt tdnt pknt tdnt pknt

WW W

W W W W W

=

2

2 2 2 2

85,4869.1,871

(37,1376 +85,4869 ). 37,1376 +85,4869

0,0169

=

=

+ 2 2 2 2.cos

( + ). +tdnt pknt tbnt

pknt tdnt pknt tdnt pknt

W W

W W W W W

=

2 2 2 2

.cos. .

( + ). +

tdnt pknt tbntpknt pknt

pknt tdnt pknt tdnt pknt

W WW W

W W W W W

=

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2 2 2 2

3

- 37,1376.85,4869.1,247

(37,1376 +85,4869 ). 37,1376 +85,4869

4,89.10

=

=

Vy: 2 3 20,0169 ( 4,89.10 ) 0,0176 = + =tbntcos

- Sai s tng i :0,0176

.100% .100% 3%0,6

= = =

tbnt

tbntcos

tbnt

cos

cos

Phn II: o lng v bo v cho trm ngi ta cn thu thp cc tn hiuin v khng in.Hy tnh ton h thng truyn dn cho trm

1/M hnh:

Ta s dng m hnh truyn dn ni tip-song song

2/S lng knh: 12

c k hiu nh sau:

- Knh 1(S1) : tn hiu dng pha A

- Knh 2(S2) : Tn hiu dng pha B .

- Knh 3(S3) : Tn hiu dng pha C .

- Knh 4(S4) : Tn hiu in p pha A .

- Knh 5(S5) : Tn hiu in p pha B .

- Knh 6(S6) : Tn hiu in p pha C .

- Knh 7(S7) : Tn hiu in p UAB .

- Knh 8(S8) : Tn hiu in p UBC .

- Knh 9(S9) : Tn hiu in p UCA .

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- Knh 10(S10) : Tn hiu cos .

- Knh 11(S11) : Tn hiu tn s pha A .

- Knh 12(S12) : Tn hiu tn s pha B

3/Chn b dn knh (Mux):

-Trong thc t c nhng i lng khng in nh : nhit ,p sut.... v truyn dn cn c cc thit b chuyn i chun ha trong o lng.Cc sensor lla chn hng u cho cng vic ny.

-Tn hiu chun trong o lng v +dng: 4 20mA

+p :0 5V or0 10V

Hin nay cc b chuyn i chun ha o lng c tch hp lun trong ccsensor m bo tnh gn nh v tin dng.

-i vi 12 knh tn hiu,ta c th chn b Mux 16 bt u vo 4 bt u ra nhng m bo vic tin li cho vic chn tn hiu v sa cha khi c s c ta chncc b Mux theo nhm tn hiu.

Vy:

+Tn hiu dng : Chn Mux1 2 address

+Tn hiu p : Chn Mux2 3 address

+Tn hiu tn s: Chn Mux3 2 address

+Tn hiu cos : Chn Mux4 2 address

4/Lp bng trng thi:

+Mux1: Dng pha A: D0

Dng pha B: D1

Dng pha C: D2

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A0 A1 C1 Q1

0 0 1 D0

0 1 1 D1

1 0 1 D2

x x 0 0

+Mux2:

p pha A: D3

p pha B: D4

p pha C: D5

p dy AB: D6

p dy BC: D7

p dy CA: D8

A3 A4 A5 C2 Q2

0 0 0 1 D3

0 0 1 1 D4

0 1 0 1 D5

0 1 1 1 D6

1 0 0 1 D7

1 0 1 1 D8

x x x 0 0

x x x 0 0

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+Mux 3:

Tn hiu cos : D9A6 A7 C3 Q3

0 0 1 D9

x x 0 0

x x 0 0

x x 0 0

+Mux 4:A8 A9 C4 Q4

0 0 1 D10

0 1 1 D11

x x 0 0

x x 0 0

M+ ux :

A10 A11 C5 Q5

0 0 1 Q1

0 1 1 Q2

1 0 1 Q3

1 1 1 Q4

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