1
Pharos UniversityEE-272
Electrical Power Engineering 1“Electrical Engineering Dep”
Prepared By:Dr. Sahar Abd El Moneim Moussa
Dr. Sahar Abd El Moneim Moussa
Dr. Sahar Abd El Moneim Moussa 2
OVERHEAD TRANSMISSION LINEMEDIUM OHTL
Dr. Sahar Abd El Moneim Moussa 3
2- Medium OHTL: ( from 80 km to 240 km)
The medium OHTL can be represented either by:
i. - equivalent circuit ii. T- equivalent circuit
Dr. Sahar Abd El Moneim Moussa 4
i- - Circuit: Equivalent Circuit:
j X
VS VR
IS R
C/2C/2
Ics I ICR
Ir
Dr. Sahar Abd El Moneim Moussa 5
The General equation is:
In Matrix Form :
VS = 1+ Z VR
IS = 1+ IR
Dr. Sahar Abd El Moneim Moussa 6
The ABCD Parameters of a short T.L:
A=D= 1+, B=Z, C=
Efficiency:
x100%
Voltage Regulation:
= x100
Dr. Sahar Abd El Moneim Moussa 7
i- T- Circuit: Equivalent Circuit:
Dr. Sahar Abd El Moneim Moussa 8
The General equation is:
In Matrix Form :
VS = 1+ Z VR
IS = 1+ IR
Dr. Sahar Abd El Moneim Moussa 9
The ABCD Parameters of a short T.L:
A=D= 1+, B= Z, C=
Efficiency:
x100%
Voltage Regulation:
= x100
Dr. Sahar Abd El Moneim Moussa 10
Example 9A 50 Hz 200 km, transmission line has 132 kV between the lines at the receiving end and has per phase R=0.1 /km , L=0.828 mH/kmAnd C= 0.005 F/km. the line is supplying a load of 30MW at 0.85 lagging pf. Find using approximated -model:
a) A,B,C and D constants of the lineb) V and I at the sending end of the linec) and VR of the line
Dr. Sahar Abd El Moneim Moussa 11
Solution:Z= R+ j L= 0.1 x 200 + j 2 x x 50 x 0.828 x 10-3 x 200 = 20 + j 52 = 55 69 Y= j C= j 2 x x 50 x 0.005 x 10-6 x 200 = j 314 x 10-6 mho= 314x10-6 90 mhoYZ= -0.016 + j 0.00628 ( 1)
a) A= D= 1
B= Z= 20 + j 52 = 55 69
C= Y = j 314 x 10-6 mho= 314x10-6 90 mho
Dr. Sahar Abd El Moneim Moussa 12
b) Vs= A VR + B IR = VR + Z IR
VR (ph)= IR= =
Vs= 76210 0 + 55.7 69 x 154 -31.8= 83200 3.6 V
Is= C VR= + DIR= Y VR + I R
= 314 x 10-6 90 x 76210 0 + 154 -31.8= 143 -23.5 A
Dr. Sahar Abd El Moneim Moussa 13
c) PR= 30 MW
PS = 3 x VSph x Is x Cos S
S= VS - IS= 3.6 –(23.5) = 27.1
PS= 3 x 83200 x 143 x cos 27.1= 31.77 MW
%=
VR% =
Top Related