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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
§ 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
§ 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,
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
Transformer Life Cycle
Power TransformersLife Cycle Optimization and Global Evaluation of Alternatives
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
Power TransformersLife Cycle Optimization and Global Evaluation of Alternatives
Continuous OverVoltage - OverExcitationEffect on Transformer and Design Consideration
StepUp and StepDown Operation and OverLoadingEffect on Transformer and Design Consideration
Exceeding V/F 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 overvoltage
Design consideration§ core appropriate induction§ possible increase in BIL§ strengthen insulation system & processing§ possible use of power transformer components
Back feeding a step uptransformer§ 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
Power TransformersLife Cycle Optimization and Performance Equalization
Dissolved gas analysis(DGA) use as guidingprinciples§ Standard refers to power
transformers§ IEEE reviewing large
data but pertaining topower transformers§ it is still an art not a
science§ volume of paper
insulation/absorption ofgases
Reference to IEEE Standard C57.104,Table 1Guideline for TDCG - Total DissolvedCombustible GasesTwo key points:§ Table 1 assumes that no previous tests on
the transformer for DGA have been madeand that no recent history exists.§ the numbers shown in Table 1 are in parts of
gas per million parts of oil (ppm)volumetrically and are based on a largepower transformer with several thousandgallons of oil.
Power TransformersLife Cycle Optimization and Performance Equalization
Renewables Energy Transformers: DGA Dissolved Gas Analysis
The principal or key gasses associated with eachtype of issue:§ Hydrogen (H2): generated by partial discharge/arcing§ Methane (CH4): generated by relatively low elevated
temperatures (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 of
cellulose insulation.§ Carbon Dioxide (CO2): generated by oxidation of
cellulose insulation.
Dissolved gas analysis(DGA) use as guidingprinciples§ Standard refers to power
transformers§ IEEE reviewing large
data but pertaining topower transformers§ it is still an art not a
science§ volume of paper
insulation/absorption ofgases
Power TransformersLife Cycle Optimization and Performance Equalization
Renewables Energy Transformers: DGA Dissolved Gas Analysis
• 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
• 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
Conclusions§ technology is now available for economic Wind and Solar power production§ renewables energy power generation are fast moving up in Peru and SAM§ up to 2016 renewables energy to be 5% of power source in Peru§ 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
Power TransformersLife Cycle Optimization and Performance Equalization