Assignment -1: ECE 7440-T03 Advance Power System Protection
Generator Loss of Field and Out of Step Protection
Introduction:
In this assignment, you will study the operation of generator loss of field protection and generator
out of step protection through a power system simulated in PSCAD. In the assignment you need
to calculate the required settings for the respective relays and investigate the protection operation
with calculated settings. Submit a brief report that includes your calculations, essential simulation
results with short discussions, and conclusions.
Learning Objectives:
This assignment has the following learning objectives:
• To learn the method of calculating settings for a generator loss of filed protection.
• To learn the process of determining settings for a generator out of step protection.
• To familiarize with modeling the loss of filed and out of step protection in PSCAD
• To understand the operation of loss of field protection through simulations.
• To understand the operation of out of step protection through simulations.
Simulated Power System and Generator Data [1]
The model of the single-machine infinite bus (SMIB) power system used in the simulation
studies is shown in Fig. 1. For the simplicity, transmission lines are represented as lump
inductors. The data for the power system and the generator are given in Tables 1, 2 and 3.
Δ-Y
60 Hz, 230 MVA,
22 kV, generator
60 Hz, 300 MVA,
22/230 kV
transformer
230 kV parallel
transmission
lines
230 kV
infinity bus
Fig 1. The single machine infinity bus (SMIB) system model used for the assignment
Table 1 – Transmission line data
Transmission line series inductance per circuit per phase
Transmission line series resistance per circuit per phase
Transmission line shunt admittance
0.24 H
60 Hz
neglected
Table 2 – Transformer data
Rated frequency
Rated apparent power
Rated winding voltages
Winding connection
Series reactance
Copper loss
60 Hz
300 MVA
22 kV/230 kV
Δ -Yg
0.05 pu
0.001 pu
Table 4 – Instrument transformer data
CT ratings (ratio)
VT ratings (ratio)
Assignment 2: Generator LOF and OOS Protection
7500 A : 5 A (1500)
12.702 kV : 63.509 V (200)
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Table 3 –Generator data
Rotor type
Rated frequency
Rated power
Rated voltage
Inertia constant (H)
Direct axis synchronous reactance - unsaturated (Xd)
Quadrature axis synchronous reactance - unsaturated (Xq)
Direct axis transient reactance - unsaturated (X’d)
Quadrature axis transient reactance - unsaturated (X’q)
Direct axis sub-transient reactance - unsaturated (X”d)
Quadrature axis sub-transient reactance - unsaturated (X”q)
Armature resistance (Ra)
Negative sequence reactance - unsaturated (X2)
Zero sequence reactance - unsaturated (X0)
Direct axis transient time constant - open cct. (T’do)
Quadrature axis transient time constant - open cct. (T’qo)
Direct axis sub-transient time constant - open cct. (T”do)
Quadrature axis sub-transient time constant - open cct. (T”qo)
Neutral grounding resistance
Round rotor
60 Hz
230 MVA
22 kV
2s
2.2767 pu
2.2026 pu
0.2236 pu
0.4234 pu
0.1680 pu
0.1661 pu
0.0075 pu
0.1670 pu
0.0835 pu
9.0929 s
1.003 s
0.048 s
0.010 s
15 pu
LOF and OOS Relay Settings
A PSCAD simulation case of the above power system including the models of Loss of Field
(LOF) and Out of Step (OOS) relays is given in file “OMIB4Asg2ece7440.pscx”.
• Familiarize with the simulation case and verify whether all data are entered correctly. Follow
the instructions provided on the case to simulate various scenarios.
• Inspect the LOF and OOS relay page modules and understand the models. You can also refer
to pages 2.3, 2-76 and 2-83 of SEL generator protection relay manual for more details.
(https://www.eiseverywhere.com/file_uploads/18341fa37d63f8428fde669fa759eb78_1_SEL
_300G_IM_20100830.pdf).
• Following the procedure discussed in the class (based on IEEE generator protection tutorial),
determine the settings for the LOF relay. Remember that you need to set the relay impedance
values based on secondary ohms.
• Following the procedure discussed in the class (based on IEEE generator protection tutorial),
determine the settings for the OOS relay for both single blinder and double blinder schemes.
Use the simulation case for system studies if necessary. Refer to of SEL manual for
additional information.
• Present the steps of your calculation in the report with comments.
Verification of LOF and OOS Relay Operation and Settings
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•
•
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Enter the calculated settings to models. Make sure you enter the relevant values on the
models that plot Mho circles and blinders, if you want your settings correctly reflected on the
R-X plots.
Use the simulation case to verify the operation of LOF relay with the settings you
determined. Observe the protection under both full load and light load conditions. (You can
change the power flow by changing the initial voltage phase angle). Check the security of the
relay during external temporary faults.
Verify the operation of OOS relay under temporary faults, and during stable and unstable
power swings.
Present and discuss your results. Include only the essential graphs.
Assignment 2: Generator LOF and OOS Protection
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