active method to mitigate induced voltages on pipelinesapic/uploads/forum/pst1f2018.pdf · 2018. 5....
TRANSCRIPT
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Department of Electrical and Computer Engineering
University of Alberta
Difei Tang, Jing Yong and Wilsun Xu
Active Method to Mitigate Induced Voltages
on Pipelines
Background
Field Measurement
Reference
Active Mitigation
Conclusion
Experiment Results
Harmonic Voltage Induction on Pipeline
The severest induced voltage occurs at the two
terminals;
The change of terminal impedance changes the
induced voltage at both terminals;
Induced voltage varies according to load currents
of overhead AC power lines and soil resistivity.
R L
RgRg
Active
Mitigation
System
Rs Cs CsRs
R L
CsRs
Rc
Lc
1km 1km
Ip
IcIg
Vind
Vsa
VgCsRs
Rc
Lc
EMF
[1] CIGRE Working Group 36.02 Guide, “Guide on the influence of high voltage
AC power systems on metallic pipelines,” 1995.
[2] EPRI Document EL-904, “Mutual design considerations for overhead AC
transmission lines and gas transmission pipelines,” 1978.
Active mitigation method for induced voltage on
buried pipelines;
Two neutralizing voltage sources;
Field measurement and Experiment validation.
Before Mitigation After Mitigation
Pipeline Equivalent
Circuit
Active
Mitigation
System
Parallel length 2 km
Separate distance 20 m
Soil resistivity 100Ωm
+
+ _
_
Vinduced
Pipeline
Powerline
EMF (Electromotive Force)
Insulating
coating
Metallic pipeHoliday
Current
Power line current EMF in a pipeline;
EMF A potential difference Vinduced
Vinduced drives a current to ground;
This current causes pipeline corrosion and personnel
safety issue
Powerline
Pipeline (1km)Test Post
Grounding rod
Voltage
recorder
(no AC mitigation measures & parallel pipelines)
(no branches in parallel zone)
Grounding rod
Voltage
recorder
Test Post
VA VB
EMF=VA-VB
Measurement Setting (Collaborate with ATCO gas)
GPS-synchronized voltage recorder
±50V differential, 3 channel
12 bit ADC
Sampling rate: 3840S/s (64S per cycle)
Site of Field Measurement
Induced Voltage at Pipeline Terminals
Cycles
Indu
ced
Vo
ltag
e (V
)
Cycles
Indu
ced
Vo
ltag
e (V
)
Left Terminal (M1) Right Terminal (M2)
Harmonic Order
Perc
enta
ge
of
the R
MS
of
Induced
Harm
onic
Vo
ltag
e (%
)
Derivation of Induced EMF
Obtain the Induced voltage at pipeline turning points A and B,
then EMF=VA-VB
cycles
Induced
EM
F (
V)
Harmonic Order
Perc
enta
ge
of
the R
MS
of
Induced
Harm
onic
Vo
ltag
e (%
)
Equivalent Circuit
Two active sources that are applied to the left
and right terminals
Superposition Principle
Practical Application
1) A power supply;
2) A controllable voltage source;
3) A voltage detector.