panel session on new harmonic sources in modern...
TRANSCRIPT
Panel Session on
New Harmonic Sources in Modern Buildings: Characterization and Modeling
14PESGM1017, “Simulating Buildings to Predict
Harmonic Levels”
Prof. Mack Grady Baylor University
Waco, TX [email protected]
IEEE PES Annual Meeting
July 28, 2014 MG, page 1
Distribution System Modeling
A portion of the 500m grid pattern stacked wide enough
and deep enough to gradually encompass all buses
#1, Substation 12.47kV
#12, Apollo (1200 HP)
#11, Longs (200 HP + 0.5 MVA)
#14, Wipe Out (400 HP)
#16, Shop
#15, Big Boss (1250 HP)
#13, Jupiter (1200 HP + 0.5 MVA)
#2, Near Sub W.
#4, PBW (0.5 MVA)
#5, PBE (0.5 MVA)
#20, Substation 138kV, V = 1.02 pu
#9, Dorsey (250 HP)
#10, Taylor (400 HP + 1.0 MVA)
10/12.5/14 MVA Trans., Z = 6.54%, 10 MVA Base, X/R = 10, Load side tap = 1.025,
Delta 138/Grounded Wye 12.47kV
#8, Wilderness (250 HP)
#7, Star
#6, Base (3.0 MVA)
#3, Near Sub E.
600m, 1000MCM,
2 ckts
1300m, 1000MCM,
2 ckts
1300m, 1000MCM, 2 ckts
1000m. 350CU
2700m, 350CU
1300m, 350CU
1830m,1/0AL
1610m, 1/0AL
960m. 350CU
1700m, 350CU
1780m,1/0AL
860m, 350CU, 2 ckts
1150m,1/0AL
1370m, 1/0AL
Cable R+ X+ Impedances (ohms/km) (ohms/km)
1000MCM 0.0929 0.1138 350 CU 0.1582 0.1228 1/0 AL 0.6460 0.2030
Isc = 34.4 pu, 10 MVA base,
X/R =5.0
Load Summary
5.1 MW linear, pf 0.88
3.8 MW six-pulse DC motor drives, pf 0.85
1 km
10 m/sec.
What are the greatest uncertainties? Load levels of individual distorting loads, and likelihood of them simultaneously being at full power
Feeder Impedances Not much uncertainty
What do you want to know? Voltage distortion at substation LV bus and at feeder extremities. Current distortion at the substation. Is filtering needed? If so, how much, and where?
MG, page 2
What are the greatest uncertainties? Load levels of individual distorting loads, and likelihood of them simultaneously being at full power. Zero-sequence (i.e., triplens) harmonic propagation. Harmonic current phase cancellation. Wye-delta connections inside facility.
Wiring Impedances Not very important for harmonic calculations.
What do you want to know? Voltage and current distortion at LV bus of utility supply transformer. Is filtering needed?
A portion of the 500m grid pattern stacked wide enough
and deep enough to gradually encompass all buses
#1, Substation 12.47kV
#12, Apollo (1200 HP)
#11, Longs (200 HP + 0.5 MVA)
#14, Wipe Out (400 HP)
#16, Shop
#15, Big Boss (1250 HP)
#13, Jupiter (1200 HP + 0.5 MVA)
#2, Near Sub W.
#4, PBW (0.5 MVA)
#5, PBE (0.5 MVA)
#20, Substation 138kV, V = 1.02 pu
#9, Dorsey (250 HP)
#10, Taylor (400 HP + 1.0 MVA)
10/12.5/14 MVA Trans., Z = 6.54%, 10 MVA Base, X/R = 10, Load side tap = 1.025,
Delta 138/Grounded Wye 12.47kV
#8, Wilderness (250 HP)
#7, Star
#6, Base (3.0 MVA)
#3, Near Sub E.
600m, 1000MCM,
2 ckts
1300m, 1000MCM,
2 ckts
1300m, 1000MCM, 2 ckts
1000m. 350CU
2700m, 350CU
1300m, 350CU
1830m,1/0AL
1610m, 1/0AL
960m. 350CU
1700m, 350CU
1780m,1/0AL
860m, 350CU, 2 ckts
1150m,1/0AL
1370m, 1/0AL
Cable R+ X+ Impedances (ohms/km) (ohms/km)
1000MCM 0.0929 0.1138 350 CU 0.1582 0.1228 1/0 AL 0.6460 0.2030
Isc = 34.4 pu, 10 MVA base,
X/R =5.0
Load Summary
5.1 MW linear, pf 0.88
3.8 MW six-pulse DC motor drives, pf 0.85
1 km
10 m/sec.
Same loads, but distances shrink
A portion of the 500m grid pattern stacked wide enough
and deep enough to gradually encompass all buses
#1, Substation 12.47kV
#12, Apollo (1200 HP)
#11, Longs (200 HP + 0.5 MVA)
#14, Wipe Out (400 HP)
#16, Shop
#15, Big Boss (1250 HP)
#13, Jupiter (1200 HP + 0.5 MVA)
#2, Near Sub W.
#4, PBW (0.5 MVA)
#5, PBE (0.5 MVA)
#20, Substation 138kV, V = 1.02 pu
#9, Dorsey (250 HP)
#10, Taylor (400 HP + 1.0 MVA)
10/12.5/14 MVA Trans., Z = 6.54%, 10 MVA Base, X/R = 10, Load side tap = 1.025,
Delta 138/Grounded Wye 12.47kV
#8, Wilderness (250 HP)
#7, Star
#6, Base (3.0 MVA)
#3, Near Sub E.
600m, 1000MCM,
2 ckts
1300m, 1000MCM,
2 ckts
1300m, 1000MCM, 2 ckts
1000m. 350CU
2700m, 350CU
1300m, 350CU
1830m,1/0AL
1610m, 1/0AL
960m. 350CU
1700m, 350CU
1780m,1/0AL
860m, 350CU, 2 ckts
1150m,1/0AL
1370m, 1/0AL
Cable R+ X+ Impedances (ohms/km) (ohms/km)
1000MCM 0.0929 0.1138 350 CU 0.1582 0.1228 1/0 AL 0.6460 0.2030
Isc = 34.4 pu, 10 MVA base,
X/R =5.0
Load Summary
5.1 MW linear, pf 0.88
3.8 MW six-pulse DC motor drives, pf 0.85
1 km
10 m/sec.
Harmonics Modeling of Industrial Facilities and Commercial Buildings
MG, page 3
Measurement of TV current (typical of most single-phase electronic loads), and 60 Hz component of TV current
Sum of a-b-c currents above yields neutral return current, which consists mostly of 3rd harmonic, but with almost 3 times the 60 Hz rms
Shifting the above waveform in time, according to -120⁰ and +120⁰ of 60 Hz, represents having a TV on each a-b-c phase that share a common neutral wire
MG, page 4
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
0.0000 0.0167 0.0333 0.0500
Am
ps
Seconds
Television Current, Curve Fit to Find Fundamental Frequency Component
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
0.0000 0.0167 0.0333 0.0500
Am
ps
Seconds
A-B-C Phases
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
0.0000 0.0167 0.0333 0.0500
Am
ps
Seconds
Neutral Current = Sum of A-B-C Phases
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
0.0000 0.0167 0.0333 0.0500
Am
ps
Seconds
Television Current, Curve Fit to Find Fundamental Frequency Component
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
0.0000 0.0167 0.0333 0.0500
Am
ps
Seconds
Line Current Supplying Three PCs Connected in Delta, Having the Same Power Draw as the Previous Graph.
Line Current (Ia - Ib) shown here.
If the sum of (Ia – Ib) + (Ib-Ic) + (Ic – Ia) was plotted here, you would see that they add to zero. The THD of the line current feeding the delta is lower than the above case because the single-pulse is spread out into two smaller pulses.
MG, page 5
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
0.0000 0.0167 0.0333 0.0500
Am
ps
Seconds
CFL Current
-0.5
0.0
0.5
0.0000 0.0167 0.0333 0.0500
Am
ps
Seconds
LED Light Current
MG, page 6
• Simpler is better in this case. Assume balanced system. Treat nonlinear loads as current injectors with known harmonic spectra.
• Net30⁰ is the net delta-wye transformer phase shift of a nonlinear load (NonLin) relative to Customer Bus. Net30⁰ is 0⁰ for a Y-Y system, -30⁰ for one Δ-Y between a NonLin and Customer Bus, -60⁰ for two Δ-Y’s, and so on.
• Net30⁰ must be accompanied by logical variable ZPATH. If ZPATH is true, zero-sequence harmonics (triplens 3rd, 9th, etc.) from a NonLin can reach Customer Bus. Else, they are blocked.
• Transformer Z (the utility supply transformer) is the only Thevenin impedance used for calculations. Should Utility Z be significant, add it into Transformer Z, making sure to use the per unit method.
• Linear loads are mostly conventional induction motors (no drives). They are modeled as resistors. Specify ZPATH.
• Is the system really balanced? Probably not, but considering all the uncertainties, e.g., how loads are distributed on the phases, it works well enough in most cases.
• If a NonLin consists of many individual loads, such as 100’s of fluorescent lamp ballasts or PCs, a diversity factor must be applied to their total harmonic injection current levels to account for phase angle cancellation in higher-order harmonics. Otherwise, FAR TOO CONSERVATIVE.
A portion of the 500m grid pattern stacked wide enough
and deep enough to gradually encompass all buses
#1, Substation 12.47kV
#12, Apollo (1200 HP)
#11, Longs (200 HP + 0.5 MVA)
#14, Wipe Out (400 HP)
#16, Shop
#15, Big Boss (1250 HP)
#13, Jupiter (1200 HP + 0.5 MVA)
#2, Near Sub W.
#4, PBW (0.5 MVA)
#5, PBE (0.5 MVA)
#20, Substation 138kV, V = 1.02 pu
#9, Dorsey (250 HP)
#10, Taylor (400 HP + 1.0 MVA)
10/12.5/14 MVA Trans., Z = 6.54%, 10 MVA Base, X/R = 10, Load side tap = 1.025,
Delta 138/Grounded Wye 12.47kV
#8, Wilderness (250 HP)
#7, Star
#6, Base (3.0 MVA)
#3, Near Sub E.
600m, 1000MCM,
2 ckts
1300m, 1000MCM,
2 ckts
1300m, 1000MCM, 2 ckts
1000m. 350CU
2700m, 350CU
1300m, 350CU
1830m,1/0AL
1610m, 1/0AL
960m. 350CU
1700m, 350CU
1780m,1/0AL
860m, 350CU, 2 ckts
1150m,1/0AL
1370m, 1/0AL
Cable R+ X+ Impedances (ohms/km) (ohms/km)
1000MCM 0.0929 0.1138 350 CU 0.1582 0.1228 1/0 AL 0.6460 0.2030
Isc = 34.4 pu, 10 MVA base,
X/R =5.0
Load Summary
5.1 MW linear, pf 0.88
3.8 MW six-pulse DC motor drives, pf 0.85
1 km
10 m/sec.
● ● ●
VThevenin (sinusoidal)
Customer Bus (e.g., 480V)
Utility Z (small)
NonLin #1 NonLin #2
Linear#1
Linear#2
● ● ●
Distribution Side (12.47kV, etc.)
Utility Transformer Z
Net 30⁰
Net 30⁰
MG, page 7
Harmonic k HDFactork
1 - 3 1.0
4 - 7 0.9
8 - 13 0.6
14 - 15 0.5
> 15 0.1
Harmonic Diversity Factor – Apply This Factor to Estimate the Net Harmonic Current Injection of N Similar Nonlinear Loads
N Loads 1 Load
MG, page 8
MG, page 9
HAPS is free and downloadable from my Baylor web site. Google “Mack Grady”. HAPS is presently being revised to handle zero-sequence illustrated in this presentation.
Thank you for your attention!
MG, page 10