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A wind farm transformer - step-up substation for wind turbines collects the output of one or more turbines and raises it to the 35 kV array voltage that the wind farm uses. It stands beside the tower, coordinated with the tower foundation, and takes the turbine cable from below. The transformer is mounted outside the enclosure with external radiators so heat leaves the compartment, while the high voltage, transformer and low voltage compartments remain separated for maintenance.
Core and windings of the wind farm transformer - step-up substation for wind turbines follow the duty of the turbine: CRGO Hi-B silicon steel with electrolytic copper, foil on the low voltage side, in an oil-paper system with low-temperature oil for cold regions. The tank is Q235 steel with external radiators and carries a pressure relief valve, a Buchholz relay and oil and winding temperature devices. C4 or C5 coating protects onshore units and a C5-M system covers offshore sites.
| Electrical & Standards | Rated capacity | 1600-5750 kVA for 2-6 MW turbines (tendered ratings 2150-5750 kVA); higher ratings engineered to order |
Voltage combination (HV-LV) | HV 35 kV mainstream (66 kV offshore option); LV turbine side 0.69 kV mainstream / 1.14 kV for large turbines | |
Vector group | Dyn11 / DYn11 common; Ynd11 per grid & earthing requirements | |
Tapping | Off-circuit +/-2x2.5% standard - HV-side taps | |
Rated frequency | 50 Hz standard; 60 Hz for export, engineered to order | |
Cooling | ONAN mainstream; ONAF optional | |
Noise | Transformer sound level approx. <=55-70 dB(A), typical per rating | |
Protection / IP & environment | IP54 mainstream (IP65 sandstorm option); wide temperature swings; wind-turbine duty - impact loads & harmonics | |
Standards & certification | GB、CE、IECEE CB、KEMA、ISO; IEC 60076 / IEC 62271-202; applicable wind farm grid codes | |
| Structure & Materials | Enclosure & shell | Prefabricated steel enclosure; double-layer panels with fireproof thermal insulation; rain-shed roof |
Compartment layout | Separated HV / transformer / LV compartments; transformer externally mounted with external radiators for heat rejection | |
Core | CRGO Hi-B silicon steel | |
Windings | Electrolytic copper - LV foil, HV wire | |
Insulation system | Oil-paper composite; low-temperature mineral oil for cold regions | |
Insulating oil | Mineral oil mainstream; natural ester option for environmental projects | |
Transformer tank | Q235 steel tank with external radiators; pressure relief valve, Buchholz relay, oil / winding temperature devices | |
Bushings & terminations | Composite silicone-rubber bushings; weather-resistant rubber sealing strips | |
Corrosion / coating | Epoxy zinc-rich primer + top coat; C4/C5 onshore or C5-M offshore grades | |
Mounting & base | One-piece lifting lugs; bottom cable entry; placed beside the turbine, coordinated with tower foundation |
The core is built from CRGO Hi-B silicon steel with fully mitered joints, which keeps no-load loss and sound level down over the long operating hours of a generation asset. An amorphous metal core is available on request where no-load loss is the deciding factor.
On the inverter side the winding carries a high current at a low voltage, so the low voltage winding is produced as electrolytic copper foil. Foil construction gives a uniform current distribution, a low stray loss and a good withstand against the harmonic currents that inverter duty imposes.
The high voltage winding is wound from electrolytic copper wire and insulated for a system voltage of 10 kV or 35 kV, with an aluminium winding offered as an option where the project specifies it.
Oil-immersed units use an oil-paper composite insulation system with PCB-free mineral oil, and ester oil where the project is environmentally sensitive. Where oil is not acceptable, the transformer is supplied as a dry-type unit with epoxy cast-resin insulation.
The tank is fabricated from Q235 corrugated or plain plate and is fully sealed, with no conservator. Cooling is by oil circulation to the tank walls and radiators for oil-immersed units, or by air for dry-type units, with forced cooling applied where the rating requires it.
The enclosure is a double-layer sandwich construction in steel or composite board with a fireproof thermal-insulation filling and a rain-shed roof. Natural ventilation is combined with forced ventilation so that heat is rejected from the transformer room under full load.
The high voltage and low voltage rooms are fully separated, and the transformer is mounted externally or semi-externally so that its heat does not load the switchgear rooms. Door interlocks prevent access to a live compartment in service.
Porcelain or composite bushings are fitted for the high voltage connections, and the cables enter from below through a bottom entry with cable seals, which suits the buried cable practice used on most PV and wind sites.
Vector group Dyn11 is the common connection, with Ynd11 applied where the grid and earthing arrangement calls for it; the delta low voltage winding suppresses third harmonic currents. Off-circuit taps of plus or minus 2 x 2.5 percent are standard, and an on-load tap changer can be specified where the grid voltage moves during the day.
Base lifting lugs allow the complete unit to be lifted in one piece onto its foundation, and the footprint follows the factory datasheet. For coastal or offshore sites a C4 or C5 anti-corrosion coating system, silicone seals, anti-condensation heating and rodent-proof mesh are applied.
Every renewable energy transformer is routine tested as a transformer and, where the scope includes the enclosure and switchgear, function tested as a complete assembly before shipment.
Core steel, foil and wire conductor, tank plate and insulating oil are inspected against the approved specification on receipt, and traceability records are kept for every batch used in the active part.
Winding, core stacking, tanking and oil filling are checked stage by stage, so that every Wind Farm Transformer - Step-Up Substation for Wind Turbines is verified against its design before it moves to final testing.
Routine testing follows IEC 60076 and covers winding resistance, ratio and vector group, no-load and load loss, impedance, insulation resistance, applied and induced voltage withstand, and oil tightness on sealed units. Where the supply includes the enclosure, the assembly is checked to IEC 62271-202 practice and against the applicable PV or wind grid-code requirements.
The unit is shipped with a routine test report and a certificate of conformity, recording the measured values against the nameplate data.
Wind Farm Transformer - Step-Up Substation for Wind Turbines is configured around the generation asset it serves: the inverter or turbine output voltage, the collection network voltage and the grid connection requirements come first, and the transformer, enclosure and protection follow from them.
Capacity is built from 1000 kVA to 3150 kVA and above, with higher ratings engineered for larger blocks. The high voltage side is normally 10 kV or 35 kV, and the low voltage side follows the inverter, typically 0.27 kV, 0.315 kV, 0.4 kV or 0.8 kV, with 0.8 kV used for large central inverters.
Cooling is oil-immersed ONAN or ONAF, or dry-type AN or AF where no oil is permitted. Insulation is oil-paper composite with mineral oil, or ester oil for environmentally sensitive projects; vector group Dyn11 or Ynd11, off-circuit taps or an on-load tap changer, CRGO Hi-B or amorphous core, and aluminium windings are all selectable.
For the enclosure and site conditions, the double-layer shell, compartment layout and C4 or C5 anti-corrosion coating are matched to the location, with silicone seals, anti-condensation heating and rodent-proof mesh for humid, coastal or desert sites.
Renewable energy transformers are packed for long-distance transport to generation sites, which are often remote and have limited handling equipment on arrival.
Secure Packaging: Bushings, accessories and control cabinets are protected and braced against vibration and impact, and openings are sealed against moisture and dust.
One-piece Lifting: Base lifting lugs allow the complete assembly to be lifted in one piece, so no reassembly is needed at the site.
Reliable Transport: Road, rail or sea freight is arranged to the project schedule, with the route and handling method agreed for oversized units.
Complete Documentation: Routine test report, certificate of conformity, drawings, manuals and shipping documents travel with the unit.
Installation Support: Guidance on foundation, cable entry, earthing, protection settings and energisation is available through commissioning.
Inverter-fed and turbine-fed plants impose harmonic currents and load swings on the transformer, and the design accounts for that duty rather than treating the unit as a plain distribution transformer.
The degree of protection, the tank or enclosure construction and the coating system are matched to the site conditions.
Yes. Where oil is not acceptable at the site, the transformer can be built as a dry-type unit with cast-resin insulation, which removes the oil and the fire load from the installation.
