Question

•The 3-phase system consists of a generator, circuit breaker, power transformer and extra high voltage transmission line.

•The generator is rated at 60Hz, 1559Mva and 24kV. The sub-transient reactance is 2*%. The winding connection is wye with the neutral grounded.

•The transformer is a 1550Mva, 3-phase, shell type, 2-winding transformer with a 24kV delta winding and a 525kV grounded wye winding. Neglect saturation and core losses. The exciting current is 1.0% of the rated current. The capacitance of each low voltage winding to ground is 5000pF. The through impedance is 5% with an X/R ratio of 5+.

•The transmission line is rated at 525kV and is 10+ miles in length. Following are the positive and zero sequence characteristics of the line:

• Zero sequence R = 0.578 ohms per mile

• X = 1.68 ohms per mile

• Y = 5.0 micromhos per mile

• Pos. sequence R = 0.0254 ohms per mile

• X = 0.595 ohms per mile

• Y = 7.034 micromhos per mile

Draw a one line diagram of the system with any needed calculations for PSCAD input

Answer #1

A three-phase wye-connected (Y) synchronous generator is
operating at Ea = 8.OLO° kV (lineneutral) and has synchronous
reactance of X~ = 1.0 fl . The generator is connected to a
threephase delta-wye connected step-down transformer that is
constructed from three individual single-phase transformers. Each
the single-phase transformers has rated power of 200 kVA has a
turns ratio of 4:1 where the rated primary voltage of 8.0 kV and a
rated secondary of 2.0 kV and a per-unit series reactance of...

A 300MVA, 20KV three-phase generator has a sub-transient
reactance of 20%. The generator supplies two parallel synchronous
motors (M1 and M2) over a 100km transmission
line. The line has two transformers T1 and T2 at the beginning and
at the end of the line respectively. Both motors are rated at
13.0KV with X"=20%. Motor M1 has a rated input of 100MVA and M2 has
a rated input of 50MVA. The transformer T1 is rated 350MVA,
20/230KV and T2 is rated...

A 100 MVA, 13.2 kV three phase generator (G) having a
synchronous reactance of 10% is connected to a three phase Y-Y
transformer T1 which feeds a 132 kV 10 miles transmission line
having an impedance per phase of 2 + j5 ?/mile. At the receiving
end of the transmission line is a Y-Y step down transformer T2.
Three loads are connected to the secondary side of the transformer
T2. Loads are as follows:
Load#1 40 MVA at 0.8 pf...

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