Transformer Life Cycle Power Transformers

ABB Brazil JCM A-1Power Products Division

Power Transformers© ABB Group14 de abril de 2015 | Slide 1

ABB BrasilPower Products Division

Dr. José Carlos MendesGte Tecnologia Transmissão e Produtos de PotênciaGte Desenvolvimento & EngenhariaEngenheiro Corporativo Executivo Global

ABB Asea Brown BoveriDivisão de Produtos de PotênciaTransformadores de PotênciaSão Paulo, SP - Brasil

email: [email protected]: + 55 11 2464 8410cel: + 55 11 9 8354 5358

+ 55 11 9 8112 7575

SANTIAGO CLJornadas Técnicas 2015

2015Abr14&15

Power Transformers:Life Cycle and Operational Cost Optimization –

Conventional, Wind and Solar Applications



Guarulhos, São Paulo - BR

ABB BrazilPower Products Division

Power Transformers

Blumenau, SC - BR

n PPTR Power Transformersl power transformers up to 765kVl shunt reactors up to 765kVl heavy current industrial transformersl service (Eng Solution, Factory and Site Repairs,

Monitoring Systems, TrServices)l insulation componentsl transformer components (Bushings, Tap

Changers, etc)n PPMV Medium Voltage, PPHV High Voltage

PPTR Distribution Transformers

ABB Brasil Power Products DivisionPower and Distribution Transformers



ContentContent

Content

q introductionq renewables energy

§ solar and wind power generation§ transformers applications and needs§ useful life and maintenance

q life cycle optimization§ from specification to end of life§ design optimization§ selection of alternatives§ loss evaluation to efficient transformers§ advanced technologies

q performance, reliability and failure modesq advanced minimum maintenance

§ optimized monitoring§ knowledge, condition and event based§ minimum periodic inspection

q advanced asset managementq conclusions

ContextRenewables Energy and Transformers Optimization



Renewables Energy and Transformers ApplicationsSolar and Wind Power Generation – Trends and Transformers Needs



ContextRenewables Energy – Solar Power

Vision by 2035 - SolarEnergy Supply from Chile

ChileRenewables Central Strategy§ 2018 - reduce electricity price§ 2014 - solar and wind up to 20% in tenders for regulated clients§ 400MW solar PV generation under contruction

Cerro Dominador 110MWCSP Concentrated Solar Power Plant

Atacama DesertPV Solar Power Plant



ContextRenewables Energy – Wind Power

El Arrayán 115MWWind Park 50x2.3MW, 0.69/35kV-220kV

ChileRenewables Central Strategy§ 2018 - reduce electricity price§ 2014 - solar and wind up to 20% in tenders for regulated clients§ 836MW wind installed capacity (~500MW in 2014)



Solar and Wind Power PlantsPower Transformers Applications

CollectorTransformer

InverterTransformer

InverterTransformer

ConnectionTransformer


InverterTransformer

InverterTransformer

PV DCGenerator

PV DCGenerator

PV DCGenerator

PV DCGenerator

Connection, GSUTransformer


WTGTransformer



WTGTransformer

WTGTransformer

WTGTransformer

Wind Farms

Solar CSP

Solar PV

WTG Technologies



Power TransformersSolar and Wind Power Applications

Wind Farm – Daily Variation of Load Current, Voltage, Power Factor

Wind Farm Collector Substation - Load Current, Voltage and Power Factor

Current, Arms Voltage, pu power factor, pu



Wind Farm – Steady State Voltage Load Flow

Us LF IL UHVc ULVc Ulim

pu % pu pu pu pu

1.00 54 0.28 1.035 1.044 1.091

1.05 54 0,28 1.086 1.095 1.091

1.00 100 0.52 1.038 1.052 1.070

1.05 100 0.52 1.089 1.100 1.070

TL69-1

Connection SSBUS 230 kV

G

Collector SSBUS 69 kV

WTGBUS 690 V

Wind Farm 2

Wind Farm 3

Wind Farm 4

Wind Farm 5

US

TL69-2

CapacitorBank

TL230 - 1

TL230 - 2

TL230 - 3

TL230 - 4

TL230 - 5

TL230 - 6

CapacitorBank

Connection SSBUS 69 kV

Collector SSBUS 34.5 kV

UChv

UClv

IL , LF = load factor

Wind Farm 1

Ulim



WTGTransformer

WTGBUS 690 V




Wind Farm - Voltage Control and Transformers Taps Adjustments

back-feedingno-load

SIN BR 230kV SIN – CEAS1 69kV COLLECTOR 34.5kV WTG DFIG 0.690kV

1 – 70.725 kV2 – 69.000 kV3 – 67.275 kV4 – 65.550 kV5 – 63.825 kV

1 – 36.225 kV2 – 35.363 kV3 – 34.500 kV4 – 33.638 kV5 – 32.775 kV

0.690kV34.500kV

Nhvc Nlvc Nhvg Nlvg

UgUgUcUcULUs Us UL

Uc =NhvgNlvg

× UgUL = NhvcNlvc

× Uc

UL =NhvcNlvc

×NhvgNlvg

× Ug

UL = NlvL

NhvL× Us

NhvL NlvL

operationinductive PF

US = NhvcNlvc

× NhvgNlvg

× UgNhvL

NlvL×

US = × ULNhvL

NlvL

P ± jQ

Power System WIND FARM 300MW – Electrical System

complete analysis requires Load Flow and Harmonic Load Flow for loading conditions

50.2GVA 1.5GVA9.8GVA




Renewables Energy and Transformers ApplicationsLife Cycle – From Specification to End of Life



Power TransformersLife Cycle Optimization

Transformer Life Cycle



Specification, Design, Manufacturing, Tests, Transportation, Receiving,Storage, Installation, Operation, Monitoring, Maintenance, End of Life


Power TransformersLife Cycle Optimization



Renewables Energy and Transformers ApplicationsLife Cycle – Design Optimization



Transformer§ core§ windings§ insulation§ connection§ tank§ expansion tank§ accessoriesØ bushingsØ tap-changersØ radiatorsØ motor-fansØ thermometers, level indicators, Buchholz

relay, pressure relief valve, pressure relay,air breathers, etc

Ø bushing current transformers BCTsØ surge arrestersØ command, control and protectionsØ sensors and monitoring system

Power Transformer

Power TransformersLife Cycle Optimization and Global Evaluation of Alternatives



§ core induction§ no load losses - core§ load losses – windings, connections, metal

structures§ short-circuit impedances§ leakage flux§ inrush-current§ short-circuit current§ short-circuit forces§ core over-excitation§ DC excitation component§ voltage and current harmonics§ overloading§ insulation (windings and main)§ cooling and temperature rise§ noise level§ new technologies (Nomex, Vegetable Oil,

Vacuum OLTC, CTCs, Bushings RIP & RIS, etc)§ on-line monitoring and diagnostic§ on-line asset management

Power Transformer – Design Optimization

Transformer Design

§ cost optimization§ no load losses optimization§ load losses optimization§ characteristics optimization§ performance (thermal, loading, short-

circuit, etc) optimization§ transportation limits§ interchanged ability

§ transformer optimization strategies:Ø Total Initial CostØ Losses CostØ Total Operational CostØ Life Cycle Total Cost

Transformer Design Optimization




Steps:

1. Technical Specification2. Procumeremt process3. Manufacturer and Factory qualification4. Quotations, Technical&Economic Analysis, Purchase, Contracts5. Electrical Design6. Design Review7. Mechanical Design8. Manufacturing9. Factory Final Acceptance Tests10. Final Tests Results and Analysis11. FRA at Factory before transport12. Monitored Transportation13. FRA at Site after transportation14. Erection at Site15. Commissioning at Site16. Energization17. Operation18. Monitoring19. Maintenance





Renewables Energy and Transformers ApplicationsLife Cycle – Optimized Selection of Alternatives



USD$kVA x Useful Life x Overloading Factor

Capital Cost:n purchasen transportn installation

Operation Cost:n losses (noLoad,

Load, Auxiliar)n maintenancen insurance premiumn repairsn performance

End of Life Cost:n replacementn transfern refurbishment

NPV, Total Cost / Life Cycle $ = $1+$2+$3

$1

$2

$3

Warranty of Useful Life Garantida, year

Life Cycle, years





Usual Method does not Evaluate:§ Quality§ Design and Manufacturing§ Withstand (electrical mechanical, thermal)

§ Risk of Failure§ Useful Life Expectancy§ Overloading Capability

Usual Evaluation Method:

n initial total cost:q equipment initial costq spare components costq transport costq installation cost (erection, supervision, etc)q comissioning costq extended guarantee cost

n losses cost (capitalisation)q no-load, load, auxiliar losses

n technical data tableq technical performance dataq technical guaranteed data

Global Value Index:§ total initial price, USD$§ rated power, kVA§ guaranteed useful life, years§ guaranteed overload, pu§ return on investment, % year





Technical Performance Evaluation

§ quantitative evaluation method§ powerful technical performance comparison of

different suppliers§ technical & economical equalization of several

technical quotations§ main performance data:Ø thermal performance (core, windings, connections)Ø useful life (as per IEEE)Ø total lossesØ short-circuit (IEC)Ø certified/qualified seismic performanceØ transient voltages and internal insulation withstand

(switching of reactors!)Ø reliability analysisØ global economic evaluation

Guaranteed Technical Data

To meet declared guaranteedtechnical data it is not a guarantee:

q for a specified minimum performanceq for a specified useful lifeq for a short-circuit withstand with

reliabilityq for a economic optimized solutionq for a minimum LC total costq for a reliable operation life with no

failure

USD$kVA x UsefulLife x OverLoadingFactor

Increasing Asset Quality: Minimum Maintenance

Power Equipment Performance Equalization




USD$kVA x UsefulLife x OverLoadingFactor


Alternatives A B

Characteristic Unit Cellulose ThUpgradedPaper, 65Cdeg

Hybrid, Nomex Paper,95Cdeg

Initial Cost USD 1 000 000 1 200 000Rated Power kVA 50 000 60 000Useful Life years 42 80Overloading Factor pu 1.15 1.40Overloadind Time h 4 4Global Value Index USD/kVA . year 0.46 0.23Ratio % 100 50.4




Renewables Energy and Transformers ApplicationsLife Cycle – Losses Evaluations to Efficient Transformers



q core induction, diameter, massq winding current densityq distance between windingsq winding diameters, width, height, massq tank mass

lossescost

manufac-turing cost

transformer mass, kg

valu

e,$

manufac-turing cost

transformer mass, kg

valu

e,$

manufacturingcost + losses cost

$$ Total Cost = Manufacturing Cost + Losses Cost = f (design variables)

Loss Capitalisation Cost, $/kWmaximum cost to pay to reducetransformer losse by 1 kW


lossescost

optimization

Manufacturing Cost:§ material§ labor§ over-heads

Power TransformersLife Cycle Optimization and Performance Equalization



No LoadLosses

EvaluationsValues

Interest rate 0.02 $/kWh 0.03 $/kWh 0.04 $/kWh

4% 3100 4650 6200

8% 2100 3150 4200

12% 1550 2300 3100

1 kW losses in 30 years 8600 hours/year

Load Loss evaluations depend on load profile per day, months etc and aretherefore a varying % of the full year value





Specificationsfor low loss

powertransformers

Net present value of future losses§ assumed value of energy losses during lifetime

§ interest rate to calculate present value

Values translated into§ value of NoLoad loss $/kW

§ value of Load losses $/kW

Loss evaluations are key part of specifications§ actual values reflect future energy price expectations

§ interest value chosen determines time horizon


Lossevaluations inspecifcations

have beenrelatively stablein recent years




Renewables Energy and Transformers ApplicationsLife Cycle – Specification for High Performance and Reliability



Harmonic Voltage and CurrentEffect on Transformer and Design Consideration

Harmonics: Voltage & Current§ core & windings losses§ faster degradation of insulation system

§ possible partial discharge

§ arcing

Required data from user§ K factor

§ harmonic spectrum

Design Considerations§ alteration of induction

§ additional cooling capacity

DC CurrentEffect on Transformer and Design Consideration

Presence of DC current§ small % of DC current leading to

saturation§ harmonics significantly higher for

unbalanced DC

Required data from user§ % of DC present

Design Consideration§ core appropriate induction




Continuous OverVoltage - OverExcitationEffect on Transformer and Design Consideration

StepUp and StepDown Operation and OverLoadingEffect on Transformer and Design Consideration

Exceeding V/F (Volts/Hz) ratio &component’s rating§ additional losses- core and coil§ insulation system weakening under full load

with overvoltage§ partial discharge PDs generation§ failure of component

Required data from user§ possible voltage limits§ frequency & duration of voltages going over

the continuous overvoltageDesign consideration§ core appropriate induction§ possible increase in BIL§ strengthen insulation system & processing§ possible use of power transformer components

Back feeding a step up transformer§ transformer designed as step up§ inrush current, voltage compensation

Required data from user§ step up /down operation possibility

§ short time overload duration & frequency

Design considerations§ core appropriate induction§ cooling§ additional kVA




Dissolved gas analysis(DGA) use as guidingprinciples

§ Standard refers to powertransformers

§ IEEE reviewing large databut pertaining to powertransformers

§ it is still an art not ascience

§ volume of paperinsulation/absorption ofgases

Reference to IEEE Standard C57.104, Table 1

Guideline for TDCG - Total Dissolved CombustibleGases

Two key points:

§ Table 1 assumes that no previous tests on thetransformer for DGA have been made and that norecent history exists.

§ the numbers shown in Table 1 are in parts of gas permillion parts of oil (ppm) volumetrically and are basedon a large power transformer with several thousandgallons of oil.


Renewables Energy Transformers: DGA Dissolved Gas Analysis



DGA can be used as a guide to detect:

§ partial discharge PD

§ high energy electrical arcing

§ thermal faults

§ cellulose insulation breakdown

§ overload(s)

§ overexcitations










The principal or key gasses associated with each typeof issue:§ Hydrogen (H2): generated by partial discharge/arcing

§ Methane (CH4): generated by relatively low elevatedtemperatures (150° C).§ Acetylene (C2H2): generated by arcing.

§ Ethane (C2H6): generated by high temperatures(<300° C).§ Ethylene (C2H4): generated by high temperatures

(>300° C).

§ Carbon Monoxide (CO): generated by oxidation ofcellulose insulation.

§ Carbon Dioxide (CO2): generated by oxidation ofcellulose insulation.










Points to be considered in data analysis

§ generation of gases in normal operation of transformer

§ rate of change of gases over a period of time

§ necessity of more than one sample over a period oftime

§ significance of change with reference to any event

§ normal operation of components

§ manufacturing process

§ comparison with a baseline DGA











Recommendation

§ IEEE C57.104 Table-1: use as a guide

§ analyze the data based on more than one sample

§ compare the analysis with the baseline

§ further testing based on significant rate of change

§ consult manufacturer for furthertesting/recommendations

Dissolved gas analysis (DGA)use as guiding principles



§ it is still an art not a science





Wind Farm Collector Transformers: DGA and Gasssing

120 ppm


TRc01 TRc02 TRc03 TRc04 TRc05 TRc06 TRc07 TRc08 TRc09 TRc10



2500 ppm


TRc01 TRc02 TRc03 TRc04 TRc05 TRc06 TRc07 TRc08 TRc09 TRc10

Wind Farm Collector Transformers: DGA and Gasssing



Renewables Energy and Transformers ApplicationsLife Cycle – Performance, Reliability and Failure Modes



voltageover-excitation

oil gassaturation

oil and insulationmoisture

actions drying insulation degassing oil WTG voltage controlTransf TAPS adjustments

oil, core, windingtemperature reduction

Replace Motor Fans D800Temperature Controlled

oil & insulation condition monitoringby a Hydran M2

daily load variation

WFarm Coll Tr01WFarm Coll Tr02WFarm Coll Tr03

load, MVA

Power Factor, puLoad Factor, ONAF2, pu

l

CollectorTransf TR03

Power TransformersLife Cycle and Failure Mode



Dielectric Inter-Turn Insulation Failure of LV Winding

reduced inter-turn insulation strength (withstand)

• free water• bubbles• water droplets

low-energy PD

reduced breakdown voltage

Dielectric Inter-TurnInsulation Failure

oil gas saturation

oil and insulation moisture

daily load variation

voltage over-excitation

• free-water formation at reduced temperatures• free water vapor bubbles at load changes• oil and insulation oxidation• increased oil conductivity• water droplets in the oil• reduced PD inception voltage• reduced Insulation Breakdown Voltage

• dissolved gas in oil• free gas bubbles at load changes• reduced PD inception voltage• reduced Insulation Breakdown Voltage

• winding temperature fast reduction• oil temperature slow reduction• water exchange from oil to insulation• free-water and bubbles at oil-insulation interfaces• bubbles formation at reduced temperatures• free water vapor bubbles at load changes• reduced PD inception voltage• reduced Insulation Breakdown Voltage

• magnetic core saturation• high harmonics saturated flux outside the core• overheating and metal hot-spots• oil gassing• water formation• oxidation oil/insulation• moisture increasing




water in oil

oil gas saturation

• insulation residual moisture at factory• entry during factory preparation for shipment• entry during transportation• moisture condensation over long time storage• moisture condensation in accessories

(conservator – shipped/storage not pressurized)• entry during site assembly• short-vacuum time at site after long time storage• core/winding/insulation heating in operation

water in insulation

• insulation residual moisture at factory• entry during factory preparation for shipment• entry during transportation• moisture condensation over long time storage• entry during site assembly• short-vacuum time at site after long time storage• core/winding/insulation heating in operation

• long time storage• high N2 content trapped in insulation• oil gassing from heated core/winding/metal parts• water and/or moisture vapor• oil/insulation oxidation (ñCO2)• short-vacuum time at site after long time storage

environment

• long time storage under N2 Nitrogen:Ø long time under N2 with in-tank gas variable

pressure (not automatic gas injection system)

• site assembly:Ø standard final processingØ standard vacuum time even after a long time

storage

• long time storage:Ø oil filled

• insulation conditioning:Ø oil samples and tests only 2 months beforeØ oil/insulation not conditioned to energization

• energization:Ø voltage control during a Wind Farm start-upØ connection to a strong HV power systemØ WTG GSU and collector transf tap settingsØ over-excitation

transformer• designed according to the specification• no-load excitation very low margin• full-load excitation very low margin• motor-fans OFF due to control with high

temperature settings keeping• long time storage under N2 with in-tank gas

variable pressure (no-automatic injection system)

oil and core high temperatures

• fans may be OFF due controls high settings• high core and windings hot-spots temperatures


Environment and Conditions



Renewables Energy and Transformers ApplicationsLife Cycle - Operation Monitoring Optimization



Monitoring

On-Line Monitoring and Sensors:

n load – current & voltagen ambient temperaturen top-oil temperaturen winding hotspot temperaturen moisture in oil/solid insulationn gas in oil H2, CO, C2H4, C2H2 (Hydran)n HV OIP cond bushings C1 & tand

ABB TECüs

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MinimumSensors

Power TransformersLife Cycle and Operation Optmization

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Renewables Energy and Transformers ApplicationsLife Cycle – Advanced Asset Managment



Advanced Asset Management

ActionAnalysisData1 2 3

EAM Mobile ERP

Sensors SCADA Historiador

§ Strategic Decisions§ Maintenance Plan§ Later Maintenance§ Replacement

§ Centralized Information§ Data Storage§ Data Management§ Data Protection

ALGORITHMS

§ ABB Methods§ Data Mining§ Condition Assessment ModelsØ failure riskØ asset condition




Advanced Operational BI

Data Processing andAnalytics

Subject Matter Workbench

Enterprise Asset and WorkManagement

Engineering Workbench

Complete InformationFleet to Equipment HealthActionable NotificationsBusiness Process WorkflowOptimization &Planning

Enterprise DataSources

Advanced Asset Management




Advanced Asset Management - Potential Benefits




Advanced Asset Management - Monitor




Advanced Asset Management - Monitor




Advanced Asset Management – Maintenance Planning




Renewables Energy and Transformers ApplicationsConclusions



Conclusions§ technology is now available for economic Wind and Solar power production§ renewables energy power generation are fast moving up in Chile and SAM§ up to 2018 will be 20% and in 2025-2030 will be 30% of power source in Chile§ Wind and Solar together Hydro and Natural gas forming Hybrid Power Plants§ renewables energy bring demand for power transformers§ specific requirements are established for such transformers applications§ transformers key aspects:

Ø environmental friendlyØ advanced technology applicationØ long useful life minimum 30 yearsØ high reliability and availability at minimum maintenanceØ intelligent monitoring and advanced asset managementØ optimum overall life cycle

§ demand for a partner with a solid and experienced technology


Renewables Energy Transformers

Documents

Transformer Life Cycle Power Transformers