Over head transmission line fault detection system

Prashant Das Tauruspowertronics Pvt. Ltd

[email protected] www.tauruspowertronics.com

CIGRE INDIA

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mailto:[email protected]

http://www.tauruspowertronics.com/

Transmission lines


[email protected] www.tauruspowertronics.com 2

• Transmission lines constitute more than 60% of asset of power transmission.

• They traverse an incredible range of kilometer in harsh environments, climates and terrains.

• In India many of the Transmission lines currently in service were built in the 1960s and 70s and are subject to many problems including ageing.

• With growing demands, there is huge expectations from transmission companies to keep the transmission line uptime near to 100%.

• Hence accurate fault location, health check / monitoring the same is very much essential.



Type of common faults in overhead Transmission lines



All Types of Open & Short Category faults



Overhead Transmissionline fault locator & Analyzer



• Pre-Commissioning Check of EHV Lines –Continuity, Phase Sequence, line length verification.

• Ascertaining line healthiness before re-Charging.

• For Preventive & Predictive Maintenance of existing EHV Lines.

• Restore the EHV lines ASAP to maintain UP TIME.



Fault Locator and types of fault locator


[email protected] www.tauruspowertronics.com

OVER HEADTRANSMISSIONLINE FAULT LOCATOR (OHFL)

• Online• Offline

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OHFLBasic Principals of working



• ONLINE-Systems works on the principal of powersystem Parameters & Data is taken during stressedbreakdown condition and this data is in percentageaccuracy depending on the residual impedance ofthe line.

• OFFLINE-Systems works on the principal of Multiplepulse Eco Co-relation technique & doesn't requireany input parameters for accurate fault finding.



Online method some of it’s limitations



• Each Line require one dedicated equipment.

• It is not helpful for spur lines.• Open Circuit faults can’t locate through

online systems.• Fault locating accuracy may vary in

percentage. (+/_ 10% or more)• Pre-Commissioning tests are not possible.



Offline method



• Advanced high frequency multiple pulseco-relation technique

• How it works:- High frequency Coded pulse sent in to

the powerline- picks up different types of disturbance

and location- Information Decoded- Generates User Friendly Report and gives

complete vision of the line end to end



Offline methods and it’s advantages



• It’ is accurate up to +/- 100Mtr.• One equipment is enough for whole sub station.• It can be used for Spur line fault locating.• Pre –Commissioning tests are possible.• Offline system can identify the secondary faults

before re charging the line.• It can find out Open Circuit faults.• Does not require any complimentary system at other

end of the sub station.• It can Locate faults up to 2500KM.



Offline OHFL Diagnostic outputs



• Fault Locator(Breakdown): For finding the faults at accurate distance.

• Line Signature Analysis: for understanding the healthiness of the line.



Overhead transmission

line fault locator benefits



• Apart from finding dead faults , useful for predictive and preventive maintenance-

i) It can detect developing faults .ii) It can detect nature of the fault(Open/Short)iii) It can indicate severity of the fault (Level of the

Faults).

• Less time to find faults and its location. • Healthiness check up for the entire line .



Case Studies



• Short circuit Fault• De-capping• All jumpers not through in Quad line• Leaky Insulators• Clearance related problems• High frequency effects on transmission lines



CASE STUDIES

Short circuit FaultDe-cappingAll jumpers not through in Quad lineLeaky InsulatorsClearance related problemsHigh frequency effects on transmission lines



SHORT CIRCUIT FAULT at 112 KM



CASE STUDIES

Short circuit FaultDe-cappingAll jumpers not through in Quad lineLeaky InsulatorsClearance related problemsHigh frequency effects on transmission linesPrashant Das Tauruspowertronics Pvt. Ltd


Decapping Fault at 69 Km in B Phase

Decapping

Fault



CASE STUDIES



ALL JUMPERS NOT THROUGH AT 55 KM



CASE STUDIES



Corona due to loose jumper



CASE STUDIES



SIGNATURE AFTER THROUGH JUMPER



CASE STUDIES



Flashover insulator at 5.8 and 5.3 KM



CASE STUDIES





CASE STUDIES



Trees very close to Transmission Line in B-phase



CASE STUDIES



After Removal of trees



CASE STUDIES



• Line Signature Analyser could identify the stress of the linecaused by high frequency noise flowing on the surface ofinsulators and flashover.

• Line Signature Analyser printout with and without filtersreveal the presence of several kV’s of high frequency noiseand really a cause for flash over of insulators

• The noise was later found due to parallel HVDC lines andthyristor switching action



CASE STUDIES



Annexure –A without filterPadghe – BBLR – gain 1 without filter-Lots of noise



CASE STUDIES



Annexure – B with HVDC filterPadghe – BBLR– Gain1 No noise observed



CASE STUDIES

OFFLINE OVERHEAD LINE FAULT LOCATOR



Case Studies of 25 lines taken in a Transmission ZONE during 2011-2012 . Statistics are based on the OnM internal record maintained for 365 days

Line Lengths in

KMs

Without OHFL time

taken to rectify the fault in a line (Hrs)

With OHFL time

taken to rectify

fault in a line (Hrs)

No. Of Lines in

the Zone (Total

Sample 25 lines)

Average No. of

Tripping in a

Year/Line

Total Trippings in a Year

Ideally with OHFLtime

would have taken

OHFL used

at

Time taken to

find fault with

OHFL in ( Hrs)

OHFL not

used

Time taken to find fault in

HRS without

OHFL (Hrs)

Total

time take

n

EXTRA HOUR

S

0 to 150 KMs

15 3 19 3 57171 hrs

30 places

90 hrs

27 places

405 hrs

495 hrs

324 hrs

150 to 250 Kms

19 4 4 2 832 hrs

5 Places

20 hrs

3 Places

95 hrs

115 hrs

83 hrs

250 to 350 Kms

23 4 2 2 416 hrs

1 places

4 hrs

1 place

23 hrs

27 hrs

11 hrs



Case Studies

OFFLINE OHFL

Line Signature



Case Studies of 73 new lines in a Utility Transmission company in India

KV of the line No.of LinesNo of Tripping Without Line

Signature test

No.of Lines signature test was done

No. of lines successfully charged

after Signature Analyzer

132KV 5 3 3 3

220KV 20 11 9 9

400KV 40 16 14 14

765KV 8 3 3 3



Important parameters-while choosing an overheadtransmis

sion line fault locator



• Equipment should be Portable & Battery operated. • Induction Voltage Suppression capability.• Auto Impedance matching facility for the kit to be

used in any EHV Lines.• Instrument should be EMI/EMC Compliance.



PAPER

Presented by

POWERGRID IN CBIP – INTERNATIONAL CONFERENCE

Using Offline Fault Locator

TO DIAGNOSE THE TRANSMISSION LINE





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Thank you for

your attendan

ce



For more information Write to :

PRASHANT DAS

[email protected]

+91 9766355355




Documents

Over head transmission line fault detection system