study of electromagnetic interference on distribution ... of electromagnetic interference on...
TRANSCRIPT
Study of Electromagnetic Interference on Distribution Conductors
from Parallel Transmission Line and Practical Mitigation Solutions
Mike Shen, PEng, MASc, SMIEEE
2014 IEEE PES T&D Conference
Chicago, IL, USA
1
Acknowledgement
• Appreciate the opportunity of working on NextEra Wind Farm project.
• Appreciate my co-authors, Shilpa Shah and Ramin Eftekhari, for their contributions.
2
Outline
• Introduction
• Basics of Electric and Magnetic Fields
• Joint-use Transmission Line and Distribution Line
• Induced Voltage on Distribution Neutral from Overbuilt Transmission Line
• Different Mitigation Solutions
• Summary
3
Introduction
• Renewable energy resources are increasingly built at remote rural areas.
• Developers prefer to share the ROW of existing transmission or Distribution lines and route their HV tap line along the existing ROW.
• Excessive induced voltage and current on distribution neutral and phase conductors may occur during normal operation, fault, and transient conditions of the transmission system.
4
Cont.
• Electromagnetic Interference from transmission line includes magnetic induction effect and electrostatic effect.
5
Magnetic induction
Electrostaticinduction
HV line MV or LV line
Line current
Couplingcapacitor
Basics of Electric Fields
• Point charge 𝑄 and Electric field 𝐸
• Line charges and Electric field 𝐸
• A long single phase ac transmission line and Electric field 𝐸
6
Cont.
• Vector addition of electric fields under a three-phase transmission line
7
θ1
A B C
r1 r2 r3
θ2 θ3
EA(t)EB(t)
EC(t)
P
Cont.
• Electric potential 𝑉 and the electric field 𝐸
8
Basics of Magnetic Field
• A short section current carrying wire
• A long current carrying wire
• A long single phase ac transmission line
9
Cont.
• Vector addition of magnetic fields under a three-phase transmission line
10
θ1
A B C
r1 r2 r3
θ2 θ3
HA(t)
HB(t)
HC(t)P
I (out) I I
Cont.
• Changing magnetic field and the induction voltage
11
Loop
BV
E
Joint-use Transmission
Line and Distribution Line
12
Induced Voltage from Electric Field
• Electric field under TL Phase A to ground
13
0
5
10
15
20
25
0 2 4 6 8 10 12 14 16
Tran
sve
rse
vo
ltag
e (
kV)
Seperation distance (m)
• Voltage induced on the ungrounded neutral conductor
Cont.
• Neutral conductor is 12 m from the lowest TL phase conductor.
– Ungrounded -> 486 V
– Single point grounded -> 0.3 V
– Multi point grounded -> 0.06 V
14
Induced Voltage from Magnetic Field
• Magnetic field under TL Phase A to ground
15
• Voltage induced on the ungrounded neutral conductor
0
50
100
150
200
250
300
350
400
450
500
0 2 4 6 8 10 12 14 16
Lon
git
ud
ina
l v
olt
ag
e (
V)
Seperation distance (m)
Cont.
• Neutral conductor is 12 m from the lowest TL phase conductor.
– Ungrounded -> 60.0 V
– Single point grounded -> 60.0 V
– Multi point grounded -> 14.8 V
16
Different Mitigation Solutions
• 25 ohm ground resistance
• 10 ohm ground resistance
17
0
2
4
6
8
10
12
14
16
-3000 -2500 -2000 -1500 -1000 -500 0 500 1000 1500 2000 2500 3000
Ind
uce
d v
olt
ag
e (
V)
Distribution length (m)
0
1
2
3
4
5
6
7
8
9
10
-3000 -2500 -2000 -1500 -1000 -500 0 500 1000 1500 2000 2500 3000
Ind
uce
d v
olt
age
(V
)
Distribution distance (m)
Cont.
• Bury 1 km 4/0 bare copper conductor on each end of DL
• Balancing of TL phase conductor geometry
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0
1
2
3
4
5
6
7
-3000 -2500 -2000 -1500 -1000 -500 0 500 1000 1500 2000 2500 3000
Ind
uce
d v
olt
ag
e (
V)
Distribution length (m)
0
0.01
0.02
0.03
0.04
0.05
0.06
-3000 -2500 -2000 -1500 -1000 -500 0 500 1000 1500 2000 2500 3000
Ind
uce
d v
olt
age
(V)
Distribution length (m)
Cont.
• T/L Transposition
– Every 1000m
– Every 100m
19
0
1
2
3
4
5
6
7
8
-3000 -2000 -1000 0 1000 2000 3000
Ind
uce
d v
olt
age
alo
ng
neu
tral
(V
)
Distribution line length (m)
0.4
0.41
0.42
0.43
0.44
0.45
0.46
0.47
0.48
0.49
0.5
-3000 -2000 -1000 0 1000 2000 3000
Ind
uce
d v
olt
ag
e (
V)
Distribution line length (m)
Cont.
• Increase the separation distance between distribution neutral and transmission line.
• Convert overhead distribution system to shielded power cable.
20
Thank you for your attention
Questions?
21