Download Hw #4 (MSWord), due Session 25

ECE 526
Protection of Power Systems II
Session 21, Page 1/2
Spring 2013
ECE 526: HW 4
Out-of-Step Detection
Due session 25 (April 13)
S
Z1S
R
Z1L
Z1R
Relay 1
1
Relay
System Data:
VLL_Primary  230 kV
Primary nominal voltage
Nominal frequency
60 Hz
Voltage Transformer Ratio
PTR  2000
Current Transformer Ratio
CTR  160
Primary pos.-seq. line impedance
Z1LPRI  100 e
Sending source transient impedance
Z1S  0.25 Z1L
Receiving source transient impedance
Voltage behind the transient impedance Z1S
Z1R  0.25 Z1L
3 % above nominal
Voltage behind the transient impedance Z1R
3 % below nominal
Load angle between ES and ER
40 deg
j  87.6 deg

1) Calculate nominal secondary voltage.
2) Calculate ES secondary voltage.
3) Calculate ER secondary voltage.
4) Calculate the secondary line impedance.
5) Calculate the voltage and current at the relay location for the 40 deg load angle.
6) Calculate the apparent impedance at the relay location for the 40 deg load angle.
7) Calculate the 3-phase apparent power seen by the relay at S.
8) Set the Zone 2 reach at 120% of the line impedance and plot the line impedance and Mho
Distance element characteristic in the impedance plane.
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ECE 526
Protection of Power Systems II
Session 21, Page 2/2
Spring 2013
9) In the same impedance plane, plot the swing locus of the apparent impedance and identify the
apparent impedance calculated in 6).
10) Calculate the inner and outer right blinder and out-of-step timer settings to identify swings
slower than 4 Hz.
11) Plot the inner and outer right blinders in the same impedance plot.
12) Plot 2 seconds of the secondary voltages and currents at the relay location for slip frequency = 4
Hz.
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