Power System Automation Lab
1
Overcurrent Protection for the
IEEE 34 Node Radial Test Feeder
Hamed B. Funmilayo, James A. Silva and
Dr. Karen L. Butler-Purry
Texas A&M University
Electrical and Computer Engineering Department
2
Introduction
• Major use of the benchmark radial test
feeders -- provide load-flow data for validating
load-flow results from existing/novel loadflow algorithms
• Extend Current IEEE 34 node test feeder
– Provide overcurrent protection, considering offthe-shelf protective devices
– Make available for studies under new scenarios
(such as DG impact)
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Work Reported in This Paper
• Model of Test feeder in DIgSILENT
PowerFactory 13.1 and conduct LF and
SC studies
• Coordination studies for temporary and
permanent faults for various fault
situations
• Select OCP devices for the test feeder
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IEEE 34 Node Radial Test Feeder
•
•
•
•
Developed by DSA Subcommittee
Majority at 24.9 kV (one 4.16kV lateral)
Total load: 2060 kVA at 0.86 pf
Long, unbalanced radial system
IEEE 34-Node Test Feeder system (modified from [1])
[1] Radial Test Feeders - IEEE Distribution System Analysis Subcommittee
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Over Current Protective Devices
• Modeled in DIgSILENT
• 1 recloser, 12 fuses
– Fuse saving for fuses 1, 2, 3, 4, 6, 7, 8, and 11
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Maximum and Minimum Fault Currents
Comparison of Maximum Fault
Current to IEEE TF Results
Comparison of Minimum Fault
Current to IEEE TF Results
Faulted
IEEE*
DIgSILENT
DIgSILENT
Faulted
IEEE*
DIgSILENT
DIgSILENT
Node
800
(A)
718.60
(A)
% Error
678.60
5.57
Node
800
(A)
479.30
(A)
459.00
% Error
4.24
808
526.50
510.20
3.10
808
309.40
322.26
4.16
816
335.40
329.94
1.63
816
213.50
205.49
3.75
824
313.00
310.50
0.80
824
195.10
194.06
0.53
854
272.90
276.40
1.28
854
175.90
173.68
1.26
832
223.10
217.70
2.42
832
146.20
140.55
3.86
858
217.70
213.30
2.02
858
143.00
138.06
3.45
834
211.30
208.40
1.37
834
139.30
135.19
2.95
836
206.90
204.40
1.21
836
136.50
132.71
2.78
840
206.10
203.61
1.21
840
136.00
132.27
2.74
890
406.50
440.10
8.27
890
94.10
87.94
6.55
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Recloser and Fuses Types
• Recloser
– Recloser's coordination range must provide adequate time to sense all
downstream faults.
– Fuse Saving mode used
– A triple single-phase electronic recloser was used
• Load side fuses
– Similar types of fuse links were selected for all branches within the
same nominal current range
– Voltage rating equal to or higher than the maximum bus voltage at the
fuse location
– Interrupting current rating larger than the maximum symmetrical fault
current at the fuse location
– Type K, T and X expulsion fuse links
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Step Down Transformer (XMF-1) Fusing
• A type T external expulsion cutout on the primary side
– The voltage rating equal to or greater than the voltage at transformer's
location
– The ampere rating equal to or greater than the anticipated normal
loading level
– The symmetrical short-circuit interrupting rating equal to or greater
than the maximum fault current
• Be able to withstand the inrush current generated when
transformer is energized
• Be able to protect against transformer faults and secondary
side faults (through faults)
• Serve as backup device by coordinating with the OCP device
downstream of the lateral
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Capacitor Bank Fusing
• Group fusing method is used. (One fuse
protects the capacitor bank)
• Promptly isolate the failed capacitor unit on
the line prior to any other protective device
on the system
• 1-phase grounded fault current without fault
impedance is assumed as the capacitor fault
value.
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Settings for Recloser and Load Side Fuses
Recloser Settings
No. of Instantaneous Trips
1
No. of Delay Trips
2
Nominal Voltage
14.4 kV, L-N
Minimum trip rating
100 A
Minimum Fault Current Observed at the Recloser
For The Minimum Fault At Each Lateral
Recloser
Faulted
Lateral
If recloser (A)
Node
800
800
Node
810
number
1
DIgSILENT
321.79
822
2
168.90
800
826
3
218.89
Instantaneous trip curve type
103
800
856
4
179.82
Delay trip curve type
134
800
888
5
61.08
800
864
6
126.36
800
848
7
165.82
800
838
8
166.88
800
Cap- 844
7
167.93
800
Cap- 848
840
7
165.82
11
165.88
Load Side Fuse Settings
Nominal Voltage Rating
Nominal Current Rating of Each
Fuse
24.9 kV, L-L or
4.16 kV, L-L
Based on each
branch’s current
800
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Coordination Studies
• Two terms for OCP operation
– Primary device
• Near to the fault and first to clear the fault
– Secondary (backup device)
• Backup of the primary device
• Coordination between recloser and fuse
– For temporary fault, K factor is used
– For permanent fault, fuse operates prior to recloser’s delay trip
• Coordination between fuse and fuse
– Max clearing time of primary fuse will not exceed 0.75 times the
minimum melting time of the secondary fuse
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Fault Case Studies
•
•
•
•
Fault on main feeder
Fault on ordinary laterals
Fault on laterals with reactive compensation
Faults on laterals with step-down transformer
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Fault on ordinary laterals
• Recloser operates on its
instantaneous trip for
temporary fault
• For permanent fault,
fuse operates to clear
the fault and isolates the
lateral
Delayed curve of recloser (backup)
Fuse melting time
Instantaneous trip of recloser
Recloser-Fuse coordination for min fault at 810
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Discussion of Results
– RECLOSER-FUSE COORDINATION TIME INTERVALS FROM DIGSILENT
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OPD List for the Test Feeder
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Summary/Conclusions
• A conventional overcurrent protection and
coordination scheme was implemented on IEEE 34
Node Test Feeder computer model in DIgSILENT
• The final list of selected OCP was provided
• Coordination was achieved for different cases
• This may be used for easy comparison and
assessment of future overcurrent protection studies
regarding radial distribution system with or without
additions such as DG
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Acknowledgement
• The authors would like to thank F. J. Verdeja
Perez, J. Mendoza, S. Duttagupta, M. Marotti,
K. Mansfield, T. Djokic, and H. E. Leon for their
contributions, along with the assistance of
Prof. W. H. Kersting.
• This work was supported in part by the U.S.
National Science Foundation under Grant ECS02-18309.
• Paper no. TPWRD-00792-2007.
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Contact information:
Dr. Karen L. Butler-Purry
Email: klbutler@tamu.edu