Fault Analysis in HVDC Systems
Using Signal Processing Techniques
Benish Paily
School of Electrical and Electronic Engineering
You Supervisors’ Names Here
Dr. Malabika Basu
Dr. Michael Conlon
29th November, 2013
Presentation Overview
1
2
3
•HVDC - Next Dimension
•HVDC Projects
•Fault Analysis of HVDC System
2
HVDC-Next Dimension
1. Current Link HVDC System
2. Voltage Link HVDC System
• LCC HVDC
1980
• VSC HVDC
• MULTITERMINAL
HVDC
1954
FUTURE
Total 200,000MW HVDC Transmission
Capacity in operation or under construction
170 Projects around the world
ABB: 90 Projects, 120,000MW
HVDC Light Technology
Siemens: HVDC Plus Technology
3
HVDC Projects
HVDC Projects in Europe (ABB)
East West Interconnector (HVDC
Light)2013, connecting Ireland and
Wales
1.
2.
3.
4.
5.
6.
4
Link between Ireland and Wales
Power rating: 500MW
AC Voltage: 400 kV
DC Voltage:± 200kV
DC Underground cable: 2*75 km
DC Submarine cable: 2*186 km
Fault Analysis of HVDC Systems
HVDC system subjected to
DC Line Fault
HVDC system subjected to
AC line fault at Rectifier & Inverter side
1. Single line to ground fault (SLG)
1. Line to ground fault
2. Line to line fault (LL)
2. Line to line fault
3. Double line to ground fault (DLG)
4. Triple line to fault (3L)
5
Faults in HVDC System
DC Faults
AC Faults
DC Current increases to 2.2 p.u.
DC Current
DC Voltage
DC Voltage falls to zero at the rectifier
6
Fault Identification in HVDC System
abc to dq0 transformation
1. Computes the direct axis, quadratic axis and
zero sequence quantities in a two-axis
rotating reference frame for a three-phase
sinusoidal signal
2. Known as Park transformation
7
abc to dq0 transform in DC and AC
fault of HVDC
PEAK MAGNITUDE OF DQ UNDER DC FAULTS
Parameter
Normal Operation
Distance (km)
DQ magnitude
0
12.38
50
26.58
100
27.48
150
28.09
200
28.18
250
28.40
DC Fault
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abc to dq0 transform (conti.)
PEAK MAGNITUDE OF DQ VALUES UNDER AC FAULTS AT
RECTIFIER SIDE
AC Faults at Rectifier side
Peak Magnitude of dq in unit
No Fault
12.38
Single line to ground fault
99.23
Line to line fault
150.60
Double line to ground fault
144.96
Triple line to ground fault
223.18
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Wavelet Transform
1. Mathematical Technique
2.Analysing signals simultaneously in time and frequency
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Wavelet transform in DC and AC fault
of HVDC
DC faults at
150 km, 250 km
Absolute maximum value of five levels wavelet coefficients of dc line current
for dc fault at various fault distances
DC Fault
Normal
Operation
50 km
100
km
150
km
200
km
250
Km
Max. value
of
wavelet
coefficient
s in five
level
0.09
0.18
0.28
0.67
0.78
0.83
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Wavelet transform (cont.)
SLG and LL
Fault
Absolute maximum value of five levels wavelet coefficients of dc current for
various ac fault at rectifier side
AC Fault at
Rectifier
side
Normal
Operation
Maximum
coefficients
0.09
SLG
LL
0.35
0.43
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DLG
0.25
LLL
0.41
Conclusions
• 1. Fault Identification in HVDC system is a challenging process because
it should be accurate and fast
• 2. abc to dq0 and wavelet transform can be applied to fault
identification
• 3. In fault identification abc to dq0 transform performed very well but
the accuracy of fault distance estimation was poor.
• 4. Wavelet transform is considered as a powerful signal processing tool
for transient analysis of signal
• 5. Wavelet transformation effectively proved that it can detect the
abrupt changes of the signal indicative of a fault.
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Thank you