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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
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
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)
§ 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 (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
Power TransformersLife Cycle Optimization and Performance Equalization
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.
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 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
Power TransformersLife Cycle Optimization and Performance Equalization