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An energy storage PCS & transformer skid for BESS projects integrates the power conversion system, the step-up transformer and the medium voltage switchgear on one base. Battery racks feed the converter at low DC voltage and the unit delivers to a 6 kV to 35 kV collector network, so the interface between the storage blocks and the grid is built, wired and tested in the factory. It suits utility-scale battery sites where the racks stand far from the point of connection.
Each energy storage PCS & transformer skid for BESS projects is built around a CRGO Hi-B core and electrolytic copper windings, with epoxy cast-resin insulation for the dry-type version or a fully sealed oil-paper system where oil is preferred. The containerized enclosure separates the converter room from the transformer room with a partition and keeps IP54 sealing. A heavy-duty C4 or C5 coating per ISO 12944 is applied for coastal battery parks, and the base is arranged for forklift or crane lifting.
| Electrical & Standards | Rated capacity / power | 2-3.45 MW per unit (2750/3150/3450 kW class); 5 MW string-type integrated units available |
Voltage combination (HV-LV) | Battery side 800-1500 Vdc -> step-up to 6-35 kV AC grid | |
Vector group | Dyn11 common; per neutral-earthing and grid-connection requirements | |
Tapping | Off-circuit +/-2x2.5% or +/-5%; OLTC optional per project | |
Rated frequency | 50/60 Hz | |
Cooling | Dry-type AN/AF or oil-immersed ONAN; cabin ventilation ducting | |
Protection / IP & environment | Enclosure IP54 and above; ~110% continuous overload capability; -40 to +55 degC ambient | |
Standards & certification | GB、CE、IECEE CB、KEMA、ISO; IEC 60076; international storage / grid codes | |
| Structure & Materials | Enclosure & shell | Containerized or skid-mounted prefabricated enclosure; steel body, rain-protective roof, double doors |
Compartment layout | Electrical room (PCS, local monitoring) and transformer room separated by a partition; MV switchgear panel integrated | |
Core | CRGO Hi-B silicon steel | |
Windings | Electrolytic copper, wire-wound or foil on high-current LV side | |
Insulation system | Dry-type epoxy cast-resin (flame-retardant, moisture-resistant) or fully sealed oil-paper | |
Insulating oil | Mineral oil standard; natural esteroptional | |
Transformer tank | Fully sealed type (oil version) | |
Ventilation & sealing | Louvered intakes / exhausts with filters; silicone sealing strips maintain IP54 | |
Corrosion / coating | C4/C5 heavy-duty coating per ISO 12944 for coastal projects | |
Mounting & base | Forklift- and crane-liftable; container / skid base |
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 Energy Storage PCS & Transformer Skid for BESS Projects 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.
Energy Storage PCS & Transformer Skid for BESS Projects 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.
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.
The vector group is chosen for the grid and earthing arrangement of the project, and for step-up duty it follows the low voltage winding configuration of the inverter, turbine or converter that feeds the unit. The connection applied to this unit is stated in the specification table.
The active part is selected against the loss and harmonic duty of the plant.
