Respuesta :
Answer:
(a) 0.00053
(b) 0.1 mΩ
Explanation:
- New per-unit reactance is given as:
New Per-unit reactance = [tex]2* \frac{100}{600} * (\frac{13.8}{345}) ^{2} = 0.00053[/tex]
- Ohmic reactance : [tex]\frac{13.8^2}{600} = 0.31 ohm[/tex]
- Ohmic per unit : 0.31 * 0.00053 = 0.1 mΩ
Given Information:
Zpu_old = 2 pu
Sbase_new = 100 MVA
Sbase_old = 600 MVA
kV_old = 13.8 kV
kV_new = 345 kV
Required Information:
Zpu_new = ?
ZΩ = ?
Answer:
Zpu_new = 0.000533 pu
ZΩ = 0.634 Ω
Explanation:
a) Find the per-unit value of the generator synchronous reactance on the specified bases.
When the base kVA and base kV are changed then we use following relation to update the per unit values.
Zpu_new = Zpu_old*(Sbase_new/Sbase_old)*(kV_old/kV_new)²
Zpu_new = 2*(100x10⁶/600x10⁶)*(13.8x10³/345x10³)²
Zpu_new = 0.000533 pu
b) Find the ohmic value of the synchronous reactance.
ZΩ = Zbase*Zpu_new
Where Zbase is calculated as
Zbase = (kVbase)²/Sbase
Zbase = (345x10³)²/100x10⁶
Zbase = 1190.25 Ω
ZΩ = Zbase*Zpu_new = 1190.25*0.000533 = 0.634 Ω
