Fault Analysis in HVDC Systems Using Signal Processing Techniques

Benish PailySchool of Electrical and Electronic Engineering

You Supervisors’ Names Here

Dr. Malabika BasuDr. Michael Conlon

29th November, 2013

Presentation Overview

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1 • HVDC - Next Dimension

2• HVDC Projects

3• Fault Analysis of HVDC System

HVDC-Next Dimension

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• LCC HVDC

1954

• VSC HVDC1980 • MULTITERMINA

L HVDC

FUTURE

Total 200,000MW HVDC Transmission Capacity in operation or under construction170 Projects around the world

ABB: 90 Projects, 120,000MWHVDC Light Technology

Siemens: HVDC Plus Technology

1. Current Link HVDC System2. Voltage Link HVDC System

HVDC Projects

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HVDC Projects in Europe (ABB)

East West Interconnector (HVDC Light)2013, connecting Ireland and Wales

1. Link between Ireland and Wales2. Power rating: 500MW3. AC Voltage: 400 kV4. DC Voltage:± 200kV5. DC Underground cable: 2*75 km6. DC Submarine cable: 2*186 km

Fault Analysis of HVDC Systems

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HVDC system subjected to DC Line Fault

1. Line to ground fault

2. Line to line fault

HVDC system subjected toAC line fault at Rectifier & Inverter side

1. Single line to ground fault (SLG)

2. Line to line fault (LL)

3. Double line to ground fault (DLG)

4. Triple line to fault (3L)

Faults in HVDC System

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DC FaultsDC Current increases to 2.2 p.u.

DC Voltage falls to zero at the rectifier

AC FaultsDC Current

DC Voltage

Fault Identification in HVDC System

abc to dq0 transformation1. 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

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abc to dq0 transform in DC and AC fault of HVDC

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Parameter Distance (km) DQ magnitude

Normal Operation 0 12.38

DC Fault50 26.58

100 27.48

150 28.09

200 28.18

250 28.40

PEAK MAGNITUDE OF DQ UNDER DC FAULTS

abc to dq0 transform (conti.)

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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

PEAK MAGNITUDE OF DQ VALUES UNDER AC FAULTS AT RECTIFIER SIDE

Wavelet Transform

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1. Mathematical Technique2. Analysing signals simultaneously in time and frequency

Wavelet transform in DC and AC fault of HVDC

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Absolute maximum value of five levels wavelet coefficients of dc line current for dc fault at various fault distances

DC Fault NormalOperation

50 km 100km

150km

200km

250Km

Max. value of waveletcoefficients in five level

0.09 0.18 0.28 0.67 0.78 0.83

DC faults at 150 km, 250 km

Wavelet transform (cont.)

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Absolute maximum value of five levels wavelet coefficients of dc current for various ac fault at rectifier side

AC Fault atRectifier side

Normal Operation

SLG LL DLG LLL

Maximum coefficients

0.090.35 0.43 0.25 0.41

SLG and LL Fault

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