Question

**Use MATLAB:**

A three-phase Y-A transformer is rated 225-kV:24-kV, 400 MVA and has a series reactance of 6.08 Ohms as referred to its high-voltage terminals. The transformer is supplying a load of 375 MVA, with 0.89 power factor lagging at a voltage of 24 kV (line-to-line) on its low-voltage side. It is supplied from a feeder whose impedance is 0.17 + j 2.2 Ohms connected to its high-voltage terminals. The total load in the system remains constant at 375 MVA.

**A)** Plot the line-to-line voltage which must be
applied to the sending end of the feeder to maintain the load
voltage at 24 kV line-to-line for load power factors in range from
0.3 lagging to unity to 0.3 leading.

**B)** Plot the sending-end voltage as a function
of power factor angle.

Answer #1

a) A three phase transformer rated at 30 MVA 10 kV(Δ)/1 kV(Y) is
supplying a load at the low voltage side. The load absorbs 5 MVA,
0.7 power factor lagging at line to line voltage 0.9 kV. The
transformer has an equivalent reactance 0.05 Ω/phase. Assuming 10
MVA and 1 kV as base value, draw the per unit diagram for the
system. Find the Line to Line voltage at the primary side of the
transformer.
b) A three-phase synchronous generator...

Problem 2. A three phase transformer rated at 5 MVA, 115/13.2 kV
has a per phase series impedance of 0.007 + j0.075 per unit (shunt
parameters are ignored). The low voltage side is connected to a
short distribution line which modeled by a series per phase
impedance of 0.02 +j0.1 per unit on the base of 10 MVA. The line
supplies a balanced three phase constant impedance load at 4 MVA,
13.2 kV with power factor of 0.85 lagging
•...

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...

A 125 MVA 11 kV three phase 50 Hz synchronous generator has a
synchronous reactance of 1.33 p.u. The generator achieves rated
open circuit voltage at a field current of 325 A. The generator is
connected to a network with an equivalent line-line voltage of 11
kV and an equivalent impedance of 0.17 pu on the generator base.
The generator is loaded to a real power of 110 MW.
a- Find the generated voltage Eaf in p.u. such that the...

1- 30-kV, three-phase transmission line has a per
phase series impedance of z = 0.05+j0.45 ohm per Km and a per phase
shunt admittance of y = j3.4x10-6
siemens per km. The line is 80 km long.
Using the nominal π
model, determine
a The transmission line ABCD constants.
b Find the sending end voltage and current,
voltage regulation, the sending end power
and the transmission efficiency when the line
delivers
1. 200 MVA, 0.8 lagging power factor at 220...

1- A 69-kV, three-phase short transmission
line is 16 km long. The line has a per
phase series impedance of 0.125 +
j0.4375 ohm per km. Determine the sending
end voltage, voltage regulation, the
sending end power, and the transmission
efficiency when the line delivers
a. 70 MVA, 0.8 lagging power factor at 64 kV
b. 120 MW, unity power factor at 64 kV
2-three-phase, completely transposed 345-kV, 200 km
line has two 795,000-
cmil 26/2 ACSR conductor per bundle...

A 3? power system consists of a Y-connected source (300 MVA, 23
kV) supplying a Y-connected load (240 MVA, 230 kV, PF = 0.90
lagging) through a step-up transformer (330 MVA, 23?/230Y kV, X =
0.11 per unit). Take into account the transformer’s phase shift and
choose the load terminal voltage VAN as the reference. Use base
values of 100 MVA and 230 kV at the load.
(a) Find the per-unit load currents (IA, IB, and IC).
(b) Find the...

A 3-phase, 5 MVA, kV, 60 Hz synchronous machine has a
synchronous reactance of 10 ohms per phase. The machine is
connected to kV, 60 Hz bus and is operated as synchronous condenser
(synchronous motor at no-load condition)
a. For normal excitation (excitation voltage terminal voltage),
find the line current. Draw the phasor diagram
b. If the excitation is increased to 150% of the normal excitation,
find the line current and reactive power delivered or absorbed by
the bus. Draw...

A 3-phase, 1.2 MVA, Y-connected, 6.6 KV, 6-poles, 60 HZ,
synchronous generator has a synchronous reactance of 30W and
negligible resistance. The generator is connected to an infinite
bus at 6.6 KV and 60 Hz.
a)Determine the excitation voltage (Ea) when the machine is
delivering rated power at o.8 PF lagging.
b)The field excitation current is increased by 10% without
changing the power input from the prime mover. Find the stator
current (Ia), the power factor and the reactive power...

A 60-Hz turbogenerator is rated 500 MVA, 22 kV. It is
Y-connected and solidly
grounded and is operating at rated voltage at no load. It is
disconnected from the
rest of the system. Its reactances are given below.
X'' = X1 = X2 =0.15pu, and X0 =
0.05pu
a ) Find the ratio of the subtransient line current for a single
line-to-neutral fault to
the subtransient line current for a symmetrical three-phase
fault.
b ) Determine the inductive reactance in...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 4 minutes ago

asked 5 minutes ago

asked 7 minutes ago

asked 8 minutes ago

asked 8 minutes ago

asked 8 minutes ago

asked 10 minutes ago

asked 10 minutes ago

asked 15 minutes ago

asked 18 minutes ago

asked 18 minutes ago

asked 18 minutes ago