Power System Analysis

1. TUTORIAL
SYMMETRICAL FAULTS
Course:Power system Analysis
Asha Anu Kurian
Dept of eee

3. fig2

4. Steps common for two methods

5. From fig2

6. Thevenin’s equivalent circuit
Find the prefault current as before

10. Change in generator current due to fault

12. • MVA sc-short circuitMVA=𝐴 = 𝑉0*𝐼 𝑓
Prefault voltage in p u Short circuit
current

13. • Three 6.6 kV generators A, B and C, each of I0% leakage reactance
and MVA ratings 40, 50 and 25, respectively are interconnected
electrically, as shown in fig, by a tie bar through curent limiting
reactors, each of I2% reactance based upon the rating of the machine
to which it is connected. A three-phase feeder is supplied from the
bus bar of generator A at a line voltage of 6.6 kV .The feeder has a
resistance of 0.06Ω/phase and an inductive reactance of 0.12
Ω/phase.Estimate the maximum MVA that can be fed into a
symmetrical short circuit at the far end of the feeder

14. Thevenin
equivalent

15. • Choose base MVA of the system:50MVA(highest rating),6.6kV
• MVA rating same throughout