protection test case - ieee power & energy society · protection test case t. e. mcdermott...
TRANSCRIPT
A DG protection test feeder has been defined for utility-fed, DG-fed and both-fed fault calculations.
F1B
C
F2
1
4
2
3A
D
Bx B0
B1 B2Bm
Bp
Bt Bg
Lat1 Lat2
T. E. McDermott, "A test feeder for DG protection analysis," PSCE 2011.• 34.5/12.47 kV Substation Transformer, 5 MVA, 7.19% Impedance• 29 kft to 1.65-MW Wind Turbine, Induction Generator,
6x Locked Rotor Current• Lat1 is 21.2 kft, Lat2 is 105.6 kft• Based on UVIG’s Illinois Rural Electric Case Study
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Interconnection transformer with ground source; limits temporary overvoltage on the high side; simplifies ground fault detection on the low side.
MAIN FAULTCONTRIBUTION
FROM EPSCONTRIBUTION
FROM DRTRANSFORMER
(MULTI-GROUNDED NEUTRAL)
FAULT
DG
V=0
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Transformer without ground source allows high-side temporary overvoltage; complicates ground fault detection from the low side.
ARRESTERSSUBJECTED TO LINE-TO-LINE VOLTAGES
PERMANENT LINE-TO-GROUND FAULT
UTILITYINTERRUPTINGDEVICE OPEN
UNGROUNDEDTRANSFORMERCONNECTION
G
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Protection with ∆-Y Transformer can be achieved with high-side voltage transformers (VT or “PT”).
DELTA / WYETRANSFORMER
PTs (3-phase) for59N relay
59N (or 59G)
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Test Case Setup
• Solved in OpenDSS– http://sourceforge.net/projects/electricdss– Program and input files publicly available
• Input Variations– 4 Fault Locations– 5 Fault Types (25-Ω SLGF; 0-Ω SLGF, 3-phase,
phase-phase, phase-phase-ground)– Utility Source present or not– DG (Off; On with Y-∆, Y(Rn=4Ω)-∆, ∆-Y
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Test Case Outputs
• All Device and Fuse Currents; Phase & Ground– Fault detection– Phase and ground coordination
• Phase and Sequence Voltages at POI– IEEE Std. 1547 voltage trip, 59N trip, etc.– Temporary Overvoltage (TOV)
• Sequence Currents at POI– Unbalance trip
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0-Ω SLGF at Bm, ∆-Y Transformer
• A sees 920 Amps Phase and Ground < 2 s• C sees 125 Amps no trip• 0.6 per-unit voltage at C > 2 s• 0.34 per-unit V0 or V2 at B and C• 4.8% I2 at C
F1B
C
F2
1
4
2
3A
D
Bx B0
B1 B2Bm
Bp
Bt Bg
Lat1 Lat2
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… After Recloser A Trips
• All Device Currents Approach Zero• 1.7 per-unit voltage on two phases at B• Normal phase voltages at C; IEEE 1547 won’t trip• 1.0 per-unit V0 at B Can Trip C on This• Transfer Trip from A is another option (expensive)
F1B
C
F2
1
4
2
3A
D
Bx B0
B1 B2Bm
Bp
Bt Bg
Lat1 Lat2
9
Time-Current Curves apply to overcurrent protection; not directly related to the feeder model.
0.01
0.1
1
10
100 1000 10000
Tim
e [s
]
Primary Current [Amps]
Example Time-Current Curves
40K Fuse B:Phase A:Phase B:Grnd A:Grnd
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Functional definitions can be used for most relay and recloser time-current curves. What about fuses?
3/17/2014 ECE 2774: System Protection; Part 2
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Description Curve p α β
Moderately Inverse U1 0.02 0.0104 0.0226
Inverse U2 2 5.95 0.18
Very Inverse U3 2 3.88 0.0963
Extremely Inverse U4 2 5.67 0.0352
Short-time Inverse U5 0.02 0.00342 0.00262
( 1)trip p
TDt TDM
α β×= + ×
−
( 1)trip p
TDtM
α×=
−
Description Curve p α
Inverse C1 0.02 0.14
Very Inverse C2 1 13.5
Extremely Inverse C3 2 80
Long-time Inverse C4 1 120
Short-time Inverse C5 0.04 0.05
IEEE (U.S.) Form
IEC (International) Form
Should implement the IEEE Std. 1547 Voltage Trip Curve (this is now more adjustable per 1547a-2013).
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 0.5 1 1.5 2 2.5
Volta
ge T
hres
hold
[p.u
.]
Trip Time [s]
IEEE 1547 Voltage Trip Curves
• Trip on any RMS phase-to-phase voltage, except• Y-Y grounded or single-phase
trip on any phase-neutral voltage
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Sequence networks applied to fault analysis with DG; may need to use Norton equivalent with superposition.
12 0LZ −
12 0LZ −0SZ −
02 YZ − 02 YZ −
1 0TZ −
12 1LZ −
12 1LZ −1SZ −
12 YZ − 12 YZ −
1 1TZ −
12 1LZ −
12 1LZ −1SZ − 1 1TZ −
+
1.05puSV =
0 1 2F F FI I I− − −⇐ = =
XI
YI
Fault at the midpoint.
12 YZ − 12 YZ −
Zero seq.
Positive seq.
Negative seq.
UTILITY DG-THEV
0THZ −
+1THZ −
DGV
2THZ −
DG-NORT
1.1puDGI =
+
NORTZ
DG-XFMR
2 0TZ −
3 NZ
2 1TZ −
2 1TZ −
1mB −
2mB −
0mB −
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With PV inverters back-feeding a fault, the temporary overvoltage depends on grounding, load and controls.
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Conclusions
• Test Feeder Uses– Technical paper examples– Software vendor examples– P1729; Recommended Practice for DSA
• DG Protection Studies– Sequence & Phase; Voltages and Currents– With or without Utility Source– Representation of time-dependent curves (TCC)
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