14_Bergmann_HV TR.pdf

CEPE CEPED D 2013 2013,, Bali Bal i , Indon Ind onesi esia a

HIGH VOLTAGE TESTING ON TRANSFORMERS Dr.. Ralf Dr Ralf Bergm B ergmann ann HIGHVOLT Prüftechnik Dresden GmbH

Table bl e of con c ontent tents s 

Motivation and Standards

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Factory Factor y Testin Testing g – Latest Lates t Techno Technology logy

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On-Site Testing Testing – Same principle

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Summary

MOTIVA MOTIV ATI TION ON AN AND D STANDARDS

Motivation

Early recognit ion of: 

Design issues

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Production failures

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Insulation degradation

Motivation 

Transformer - Key compo nent in electric energy system

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Securin g Transformers‘ quality essential for reliability of electric network

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development and testing of transformers Extensive testing within development  

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Routine test Type test

Increase of old transformers in power grid Need to verify v erify old transformers‘ condition  Need

Standards STANDARDS FOR FACTORY TESTING Standards IEC

IEC 60076-1…3

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Standard s IE IEEE EE 

IEEE C57.12.00 - C57.12.90

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IEEE C57.152 (= old IEEE 62)

GOST 

GOST 1526, GOST 3484, GOST 52719-2007

On-Sit On-S it e Testi esting ng:: No separate st standards andards . use of same testing proc proce edures, poss ible test volt age reduct possible reduct ion f or service aged aged transformers

Possib oss ible le Te Test` st `s on pow p owe er transform transf orme ers Measurements  of winding resistance no-load loss and current Measurement of no-load

Dielectric tests Temperature-rise test Determination of sound levels Determination Determination of capacitances capacitances

Tests on on-lo ad tap-changers

Measure Measurement ment of tu rn r atio Measure Measurement ment of insu lation r esistance Measureme Measurement nt of the harmoni cs of th e no-load no-load current

FACTORY TESTING LATEST LA TEST TECHN TECHNOLOGY OLOGY

IMPULSE VOLTAGE TEST OF POWER TRANSFORMER  ACCORDING TO IEC 60076-3, POS. 13-15 IEC 60060-1 2010

Sample of light ning impulses impu lses Chopped lightning impulse

Full lightning impulse U

a – instant of chopping

1,0 0,9

B a

Tail time

C

0,7a

Front time 0,3

 A D

T1

0,1a

t TC

Requirements on impulse voltage vol tage test 

 Accuracy is important: important: Correctness of wave shape

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Space is expensive: Space saving solution

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Time is money: Quick test setup increasing output of factory

Conne onn ection ct ion Point oin t – The all in i n one sol ution uti on

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Test system consists of only two individual components: 1) Impulse generator 2) Connection Point  HV

divider

 Chopping

gap and

 Overshoot 

compensation

Benefits of Connection Point: 

Space saving solution

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Integrated overshoot compensation

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Only one connection to the test object

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Only one test setup is used

Space pace reduct reduction ion using usi ng Connecti Connection on Point MOST COMMON LAYOUT  Arrangement with divider, divider, overshoot compensation and chopping gap

Test object

Chopping gap

LAYOUT USING CONNECTION POINT  Arrangement with Connection Point

25% 25 % space reduc reducti tion on

Overshoot

Test object

Compensat ion

Connection point

Divider

Impulse generator

Impulse generator

Example: Test Test system s ystem ULI=1800 kV USI= 1150kV Space requ ir ed = 400 m²

Space Requi Required red = 300 m²

FACTORY TESTING  APPLIED VOLT VOLTAGE TESTING

 App  Ap p l i ed Vo l t age ag e Tes Testt IEC 60076-3, pos po s . 11 11  App  Ap p l i ed v o l t age ag e tes t estt o r s epar ep arat ate e so s o u r c e AC w i t h s t and an d vo v o l t age ag e test can be perfo performed rmed wit h 3 differe dif ferent nt type of test syst ems 

Transfo rmer base b ased d AC test sys tem - continuously duty cycle, high feeding power - high test system costs

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Resonant esonant test system w ith va v ariable inductance - perfect sine wave, proven/robust technology - less feeding power, less costs

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Resonant test syst em wit h variable frequency frequency - perfect sine wave, proven/robust technology - small components, lowest feeding power, best price

Example Exampl e of Appl ied Voltage ol tage Test Test for f or 1200 1200 kV

Test of transformer for 800 kV HVDC transmission at Siemens Nuremberg, Germany

 App  Ap p l i ed Vo l t age ag e Tes Testt – Variable ariabl e Frequ Frequency ency Test System Sys tem  ADVANT  ADV ANTAGES AGES 

Compact

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Easy extendable

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Low power consumption

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Operates according to IEC >80% of rated voltage

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Lowe Low er Investment Investment cost

Test system at Siemens Dresden, Germany

System Conce onc ept for f or Appl Applied ied Voltage Test Transformer to be tested 3

4

LV HV 5

400V 50 kVA 50/60Hz

1 2 3 4 5

Control and feeding unit Exciter transformer HV reactor Blocking impedance Voltage divider

FACTORY TESTING INDUCED INDU CED AC VOL VOLT TAGE TESTIN TESTING G

Soluti olu tions ons for Induced ndu ced Volt Volta age test test Generation of test frequency Since the test voltage Up for the induced voltage test is often higher than twice the rated voltage, the test frequency must be at least doubled to avoid over-excitation of the iron core.

Motor / Generator Set

Static Frequency Converter

Induce Induc ed AC Testi Testing ng based on Static Frequency Converter  ADVANT  ADV ANTAGES AGES 

Different frequencies frequencies for f or loss measurement m easurement and induced voltage testing provided by static frequency converter  – replacing replacing several different different motor-generator-sets motor-generator-sets

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Fulfill all demands dem ands of standards

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Efficient

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 Allows testing of transformers transformers >1000 >1000 MVA MVA

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Expandable

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Space-Saving

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Easy to operate, intrinsically safe

Induce Induc ed AC Testi Testing ng based on Static Frequency Converter

Block diagram of transformer test system

Induce Induc ed AC Testi Testing ng based on Static Frequency Converter Static frequency converter build in container

Cooling system

Step-up transformer transform er

Transformer test system for induced voltage tests, based on static f requency converter, type WV 2000-4000/170

High voltage filter

Induce Induc ed AC Testi Testing ng based on Static Frequency Converter

Static Frequency Converter built in Container

THD Value < 5%

Test voltage and current waveform – no-load loss measurement with THDu < 3.5% and THDi = 52% (150 MVA transformer)

Sens Sensit itive ive PD Measur Measurement ement

PD Level < 10 pC according to IEC 60270

ON-SITE TESTING – SAME PRINCIPLE

HV On-Site Testing

NO STANDARDS STANDARDS FOR ON-SITE TESTING 

HIGHVOL HIGHVO LT on-site test systems allow tests appropriate to standards of factory testing

On-Site Tests:   

 Applied  Applied Voltage Voltage Test Test Induced AC Voltage Tests Optional: Impulse Testing

ON-SITE TESTING –  APPLIED VOLT VOLTAGE TEST

Test System Syst em for f or Appli App lied ed Vol Voltage tage Test Test Resonant system with variable frequency  Wide load range of power transformers 5 to 40 nF 

Variable test frequency 40 to 200 Hz

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Voltage 360 kV – Expandable to 720 kV

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Electric current 5 A

Standard 40 foot trailer

 App  Ap p l i ed Vo l t age ag e – Procedur ro cedure e and Te Test sequence sequenc e 

Transportation to site

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Test arrangement and connection of test object (approx. 50 min)

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Start system system and enter test parameters (approx. 10 min) m in)

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Start automatic test sequence 

 Automatic search of test frequency frequency at 10% of U

test

(frequency shall be not less than 80% of rated frequency per IEC)

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Increase the voltage up to U

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W ithstand voltage voltage test

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Decrease the voltage up to 0 V

test

Finish test and print test report (HIGHVOLT Suite ®)

Summary Summ ary – Appli App lied ed Vol Voltage tage Test Test

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 Dielectric test of the main insulation (between winding and iron core/ tank; between the winding systems)

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Test voltage up to 360 kV with additional reactor up to 720 kV

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 Required power supply: 400 Volt (3~), 40 kVA

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Only one HV lead to connect the transformer under test

ON-SITE TESTING – INDUCED INDU CED AC VOL VOLT TAGE TEST T EST

Setup for Induced Voltage Test HV capacitive capacitive compensation uni t (Option)

4

5

1

2

Transformer to be tested

3

3 ~ 400V / 50~60 Hz PLC

1. 2. 3. 4. 5. 6.

Freq Freque uenc ncy y conv converte erterr Step Step-u -up p trans transfo form rmer er HV fifilter 1 HV com compe pens nsat atio ion n (Op (Opti tion) on) HV filt filter er 2 (Op (Opti tion on)) Loss Loss mea measu suri ring ng sy system stem

PD measuring system

1234

PD 6

1234

Design si gn of Mobile Mobi le Te Test Syst Syste em HV filter 1 Control room

HV test lead

Step-up transformer 

Static frequency converter

CT’s and VT’s

Space for accessories, HV electrodes, etc.

Power supply cable, HV connection cable

Space for accessoiries

Induce Induc ed vol v oltage tage – Proce Proc edure du re and Te Test Sequence (IE (IEC/ IE IEEE/cus EE/custo tomer mer spe sp ecifi ci ficati cation on)) 1. Trans ranspor porta tati tion on to sit site e 2. Test arrangeme arrangement nt and and connection connection of of test object object (approx (approx.. 50 min) 3. Start Start syste system m and enter enter test test para paramet meters ers U 



Typically:

test and

f

test (approx.

U test = 80% of U test at factory f test approx. 2 x f rated (between f

rated and

10 min)

200 Hz)

Choose frequency of test = f test : a) Factory test frequency i.e. 120 Hz,180 Hz, etc. b) Or to minimize the power demand choose frequency to take advantage of variable frequency to reach self compensation

4. Start automatic test sequence 5. Measure PD at test voltage levels specified 6. Finish test and print test report (HIGHVOLT (HIGHVOLT Suite®)

Capacitor pacito r Banks for Mobile Transfo Transform rme er Test Systems  APPLICATION  APPL ICATION Required for reactive power compensatio com pensation n during short-circuit tests, load-loss tests and on-load tap-changer tests SOLUTION 

Capacitor bank on one trailer or in one 40-foot container for single phase and small three phase types

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Capacitor bank on 2 trailers in four 20-foot containers for larger three phase types (3 containers for capacitors, 1 for measuring transducers)

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Standard types: - up to 250 MVA test objects: 36 kV / 24 MVA, HVCC 24000/36 - up to 500 MVA test objects: 36 kV / 54 MVA, HVCC 54000/36

Principl rin cipl e sketch of mobil m obile e capa capacit citor or bank bank HVCC 24000/36 Compensation units can be connected to form a 3-phase or a powerful single phase capacitor bank 40 ft trailer

cabledrums cable drums HV capacitive

CT1…CT3: phase current measurement

power measurement:

compensation units

CT4: protection against unsymmetrical currents

current transform transformer er / voltage transformer transformer

Mobil Mobi l e capacito capaci torr bank HVCC HVCC 2400 24000/ 0/36 36 insid ins ide e a 40ft container co ntainer  All transformers up to highest ratings can be tested on site

Higher power by mobile capacitive compensation banks is available

Summary Summ ary – Induced Indu ced Vol Voltage tage Test Test

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Output voltage: Up to 80 kV

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Output power: 1000 kVA / 620 kW

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Power supply: 400 V (3~) - 750 kV k VA mains supply sup ply or - 1200 kV kVA A diesel generator

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Only 3 HV cables to connect the transformer under test

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Easy set up: Within 1 hour ready to test

EXAMPLES OF TESTED TRANSFORMERS

Test of a 500 MVA Single Phase Transformer fo rmer in i n a Nuc Nuclea learr Powe ow er Stati Station on

Test of 1phase main transformer with WV 620-1000/80 Power supply by mobile diesel generator

Paralle rall el Operation Operatio n for f or Te Testin st ing g up to 1200 1200 MVA MVA Trans Transfo form rmers ers Parallel connection of up to 3 test systems (total: 1.9 MW/3 MVA)

 Sum  Summary mary  

Testing power transformers transfor mers up to 1200 MVA MVA  According to IEC IEC and IEEE standards standards

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Waveform distortion distortion THD < 5%

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Partial discharge (PD) noise level < 10 pC (with 2 nd HV filter)

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Free adjustable frequency 40 to 200 Hz (self compensation)

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Modular design allows for future expansion

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Easy and fast test set up

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