28_Bergmann_HV testing of MV and HV Cables and GIS.pdf

8/12/2019 28_Bergmann_HV testing of MV and HV Cables and GIS.pdf

1/63

ON-SITE TESTING OF

HV CABLES AND GIS

CEPED 2013, Bali, Indonesia

Dr. Ralf BergmannHIGHVOLT Prftechnik Dresden GmbH


2/63

On-Site Testing of HV Cables and GIS

Content:

On-Site HV Cable testing Why spend money on HV tests?

Physical background: Cable characteristics and testmethods

Generation of continuous AC test voltages

Experience with continuous AC voltage testing

Test system examples

231/10/2013


3/63


Content:

On-Site GIS testing Test requirements

Test procedures

Test systems

331/10/2013


4/63

ON-SITE HV CABLE TESTING -

WHY SPEND MONEY ONON-SITE HV TESTS

On-Site Testing of HV Cables

On-Site Testing of HV Cables and GIS 431/10/2013


5/63


Jakarta at nightWithenergy transmission by cables

531/10/2013

Jakarta at nightWithoutenergy transmission by cables


6/63

31/10/2013 6On-Site Testing of HV Cables and GIS

Large cable installation in Indonesia in thefuture

PLN to lay $2b submarine cable from Sumatra to Java

Rangga D. Fadillah, The Jakarta Post, Jakarta | Business |Fri, February 17 2012, 9:19 AM

.The cable will span 700 kilometers connecting Bangko in South Sumatra andBogor in West Java. The cable will be used to transmit power supply from SouthSumatra, where a number of coal-fired power plants are currently underconstruction, to meet surging electricity demand in Java.

The cable will be able to transmit power with a total capacity of up to 3,000megawatts [MW] from Sumatra to Java, Nasri explained..


7/6331/10/2013 7On-Site Testing of HV Cables and GIS

Bali crossing with overhead cable or subseacable



Beautiful landscape should not bedestroyed by overhead lines


9/63On-Site Testing of HV Cables and GIS

Save energy transmission and distribution bycables is essential

Cable connections are and will be even more in the future abackbone of transmission and distribution systems especially due tothe special conditions of Indonesia

Interconnections of islands

Energy distribution in growing cities

Protected areas (national parks, recreation areas, tourism)

Because of power demand increase, the cables are stressed often toits maximum load capacity (and sometimes higher)

An unexpected break down of the cable may result in fatalconsequences for the customer (outage for hours) and the utility(penalty)

931/10/2013



Is on-site testing of HV cabls after installationnecessary?

Consequently, an evaluation of the cable condition based on on-site testing istechnically and economically necessary

HV cable seems to have a proven and quite simple design in respect to othercomponents like transformers

HV cable will be manufactured in a highly automated way, failures caused byhumans are minimized

HV cables have to pass an intensive test program in the factory

Significant works will be done at site, like jointing

Small mistakes can result in mayor failures


11/63

Withstand testscovered by IEC standards


Different testing during lifetime of a cable

Manufacturing

Damage

Mistake

Withstand

Testing

Testing

Diagnosis

Transportation Installation

Withstand

Testing

Powerfrequency50/60 Hz

OperationPower frequency

50/60 Hz

Cable li fe

Repair

Ageing

1131/10/2013

Withstand

Testing


12/63On-Site Testing of HV Cables and GIS

Requirements for dedicated on-site testmethods

After installation or repair

Load during on-site test should correspond to operational stress

Negligible ageing caused by on-site test

Easy adoption to different test requirements as voltage, cablecapacitance cable losses etc.

Designed for easy and frequent transportation, assembly andoperation

1231/10/2013

Diagnostic testing

Failures should be discovered easily

Negligible ageing of the remaining cable by the on site test


13/63

PHYSICAL BACKGROUND:

CABLE CHARACTERISTICSAND TEST METHODS



14/63


Possible Defects in Cables

Crack

Delaminating

Protrusion atsemicon surfaces

Void

Vented-tree (length 2.38 mm) atsemicon surface combined withelectrical treeSource: ABB Energiekabel GmbH

Water tree combinedwith electrical tree

1431/10/2013


15/63


General Characteristics of HV Cable

Operation: electrical field control bycapacitance (C) at 50 Hz

HV

Equivalent circuitat AC stress

XLPE Cable:

tan =

ic>> ir

C R

Ground

1531/10/2013


16/63


17/63


18/63






Easy adoption to different test requirements as voltage, cable

capacitance cable losses etc.


1831/10/2013

Diagnostic testing

Failures/Faults should be discovered easily



19/63

VLF


Field Reduction at Different Test Frequencies

Con-tinuous

AC0

20

40

60

80

100

0.01 0.1 1 10 100

%of

fieldstrength

in

defe

ctcompared

to

hea

lthyinsulatio

n

Test frequency in Hz

Defect 1

Defect 2

Defect 3

IEEE 400: Conductivity in defects can assume much different valuesthan in the bulk insulation material

1931/10/2013


20/63






Easy adoption to different test requirements as voltage, cable

capacitance cable losses etc.


2031/10/2013

Diagnostic testing

Failures/Faults should be discovered easily



21/63


Test of AC XLPE Cables with DC is not torecommended

Operation: electrical field control by C

Testing: DC changes electrical field distribution

DC creates space charges on failures(field emission, PD)

HV

Equivalent circuit

XLPE Cable:

tan =

ic>> ir

C R

Ground

2131/10/2013


22/63

VLF: Not suitable for HV / EHV Cables

Technical Consequences

Maximum field for healthy insulation: 30 kV/mm (IEC 62067)

3 or 4 U0simply not possible for HV and EHV cables(would damage healthy insulation)

VLF at 2 U0not able to find important defects

VLF not suitable for HV and EHV cable systems



23/63

What about DAC?

Description of test method: Charging the cable with DC voltage,

Discharging the cable through an inductance

Causes damped oscillation,

Usually repeated 50 times.


-100

-75

-50

-25

0

25

50

75

100

-15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1

Voltage/%oftest

volta

ge

time / s

2331/10/2013


24/63

Test procedure involves charging the cable with DC:

Duration up to approx. 1 minute per shot

Up to one hour of DC ramp voltage stress for total testduration

Cable risk due to space charges exists

Quick reversal of test voltage immediately after DC stress

DAC Danger for the test object?



25/63

Undefinedness of DAC test parameters

Damping:Influenced by Capacitance of

test object Resistances of

test system

Tan delta of cableFrequency:Depends on Capacitance of

test object

Inductance in testsystem

Duration of ACstress undefined,0.4 260 ms/shot



26/63

Undefinedness of DAC test parameters

Duration of AC stress:Undefined0.4 260 ms/shot

Varies by factor 600

30 minutes of continuous AC are equivalent to6,920 4.5 Mill ionshots of DAC

Total testing time: Days 8 YearsDC stress during most of the time(Charging takes 99.x % of total test time)



27/63

DAC Testing Time Insufficient

PD activity requiresstarting electrongenerated by radiation

Smaller defects have

less volume Lower starting electron

generation probabilityin a given time

Longer PD inceptiontime

Longer testing timenecessary to find

defects

Mark Fenger: Experiences with Commissioning Testing of HV &EHV Cable Systems: The Influence of Voltage Level and Durationfor Identifying Life Limiting Defects, Kinectrics Inc., Canada



28/63


What voltage wave shape can be used to testXLPE cable reliably and safely?

AC voltage in range of 20 to 300 Hz is the onlyrecommended wave shape to test XLPE cablereliably and safely

VLF 0.01 to 1 Hz is not an reliable test methodbecause the test frequency is to far away from theoperation frequency of 50 Hz (different behavior ofinsulation)

DC test can even damage an XPLE cable

Damped AC testing is more an DC test as an ACtest, only very few AC cycles

2831/10/2013


29/63

GENERATION OF

CONTINUOUSAC TEST VOLTAGES



30/63


Technical Solutions for HV AC Generators

TR LC THCH

CL

MD CC

AC

ACTCCompensatedtransformer

ACRLResonant test system with tunedinductance as series resonant circuit

TR

LH

TE

CH

CL

MD CC

AC

TR TE

LH CH

CL

MD CC

AC

ACRLResonant test system with tunedinductance as parallel resonant circuit

FC TELH

CH

CL

MD CC

AC

ACRFResonant test systemwith tuned frequency

ACf

3031/10/2013


31/63


Comparisons of different AC Test Systems

Mode of on-site test systemACTC

compensated transformerACRL

variable inductanceACRF

variable frequency

Frequency 50 / 60 Hz 50 / 60 Hz 20 to 300 Hz

Quality factor of resonance (5) 40 to 60 80 to 200

Power supply Single / two phase Single / two phase Three phases

Specific weight 15 to 20 kg/kVA 3 to 10 kg/kVA 0.5 to 2 kg/kVA

Maximum test powerper mobile system

0.5 MVA 4 MVA 35 MVA

3131/10/2013


32/63


Principle of Pulse Width Control ofACRF Circuit

Control and Feeding UnitExciterTransformer

VoltageDivider Test Object

Protection ImpedanceResonant Reactor

400 V3~

UE

UP

Frequency

Pulse widthUE UP

Frequency

Test voltagemagnitude

3231/10/2013


33/63


On-site Testing of Cables: Increasing Powerby Reactor Combinations

highervoltage

longer cables

3331/10/2013


34/63


On-site Testing of Cables: Arrangement ofan ACRF System, Type WRV T on a Trailer

Control and feeding unit

Excitingtransformer

HV reactor

HV filter andprotection unit

Canvas

Truck with trailer

3431/10/2013


35/63

EXPERIENCE WITH

CONTINUOUSAC VOLTAGE TESTING

Particular Tests



36/63


Survey among Users of Continuous AC TestEquipment Total Tests in each Cable Class

13

181

20781199

541

188

1

10

100

1000


37/63


38/63

TEST SYSTEM EXAMPLES

Particular Tests



39/63


On-site Testing of Cables: Truck with TestSystem 260 kV / 83 A

3931/10/2013


40/63


On-site Test of a 400 kV Cable System, 20 kmin London

4031/10/2013


41/63


Test of a 400 kV Cable System at theMadrid Airport

Courtesy of Pirelli Cables, Italy and UK

Installation of test system on-site

4131/10/2013


42/63


ACRF Configuration for Testing a 15 km long400 kV Cable System at Madrid Airport

Frequencyconverters

andcontrols

Excitertransformers

HV reactors16H II (9+9) H = 8.5 H

Voltagedivider

Blockingimpedances

Cable undertest:

15 km, 3.3 F

Test voltage: 260 kV (approx. 1.2 U0)Test frequency: 30 HzTest power: 42 MVA (50 Hz equivalent: 70 MVA)Feeding powerDemand: < 400 kVA, 400 V (3 phases)

1Master

Up to 8Slaves

4231/10/2013


43/63


Photos: Courtesy of CEPCO, K.S.A.

On-site Test ofa400kVCableSysteminJeddah,K.S.A.

4331/10/2013


44/63


45/63


Max. testable cable length: 100 km

Photos: Courtesy of ABB Power Tech Products, Sweden

AC Routine Test Facilities at a Supplier ofSubmarine Cables

4531/10/2013


46/63


ACRF System for MV Cable Testinginstalled in a Van

Control and feeding unit

Test voltage lead

Exciting transformer

HV resonant reactor

4631/10/2013


47/63


Voltage range: 3050100 kVCurrent range: 102550 AFrequency: 20300 Hz

On-site Test Systems for Medium VoltageEquipment

Application: MediumvoltagecablesRotating machinesCapacitor banks

4731/10/2013


48/63

ON-SITE GIS TESTING

TEST REQUIREMENTS




49/63

Same Testing Method used:

Test with AC voltages(necessary for same behaviour of particles in GIS)

Test voltages up to 800 kV

Test current in to order of less than up to a few A

Duty cycle of a few minutes only



50/63

ON-SITE GIS TESTING

TEST PROCEDURES




51/63

Common Duty Cycle of GIS Testing

testvoltagein

kV

time in min

PD Measurement(few minutes)

Test Voltage(few minutes)

Conditioning(some minutes)

Maximum some ten minutes



52/63

Standardisation: IEC 62271-203/2nd CD

Test Setup Requirements

Need of mobile HV AC test system

Preferably metal-enclosed design

Conventional or UHF PD measurement

Need of mobile HV impulse test systemLI up to 1700 kV andSI up to 1200 kV



53/63

ON-SITE GIS TESTING

TEST SYSTEMS




54/63


AC resonant test system with variable frequency; 1.5 A/ 325 kVCourtesy of Shenyang Kaidi High Voltage Electric, PR China

Mobile HV AC Resonant Test System

Metal-enclosed test systems with variablefrequency based on SF6-insulated

reactors up to 800 kV and 4.5 A

5431/10/2013


55/63


Advantages

Light-weight small HV AC testing device

Needs no safety clearance during operation

Allows sensitive conventional PD measurement

Very reliable test system also under harshconditions on site

Easy to operate



56/63

Connection by HV Lead WRV / G

Photo: courtesy of ABB Calor Emag Schaltanlagen AG, Mannheim / Germany

460 kV, 1.5 Ametal-enclosedHV reactor

HV divider /couplingcapacitor

HV lead



57/63

Connection by HV Lead WRV / T

260 kV, 83 Atank type resonantreactor

HV lead

HV lead

Photos: courtesy of China Light and Power Co.,Hong Kong



58/63


AC resonant test system with variablefrequency; 3 A/ 640 kVCourtesy of AREVA Aix-Les-Bains, France


Metal-enclosed test systems with variable frequency based onSF6-insulated reactors up to 800 kV and 4.5 A

5831/10/2013


59/63

O it T t S t ith SF I l t d


60/63


Voltage range:100680 kV

Current:

0.51.5 (3) A

Frequency:

40300 Hz

On-site Test Systems with SF6-InsulatedReactors

Application mainly for GIS also multipleapplication with SF6.

6031/10/2013


61/63

SUMMARY



62/63


63/63

YOUR COMMENTS AND

QUESTIONS

Thank you for your attention!

28_Bergmann_HV testing of MV and HV Cables and GIS.pdf

Documents

Transcript of 28_Bergmann_HV testing of MV and HV Cables and GIS.pdf