Project Type: Grid-Scale Battery Energy Storage System (BESS) Auxiliary Power & Substation Integration
Completion Date: (Planned for Q3 2024)
Location: East Midlands, United Kingdom
Client: A leading renewable energy developer and asset operator
Challenge: To design a highly reliable, compact, and integrated auxiliary power supply for a new 33kV BESS substation. The auxiliary system must power all critical control, protection, and environmental support equipment within a space-optimized containerized enclosure, ensuring 24/7 operational readiness of the BESS.
Core Solution: TSTYNICE supplied and engineered a compact, indoor-rated auxiliary transformer as the heart of the substation’s low-voltage AC power system.
Equipment Supplied
Auxiliary Transformer: 100 kVA, ONAN, Dyn11, 33 kV / 0.415 kV
Quantity: 1 unit
Mounting: Indoor, floor-mounted within a dedicated compartment
Insulation: High-temperature, low-flammability liquid (e.g., silicone or ester fluid) or specifically designed dry-type (cast resin) transformer for superior indoor safety (see recommended variant below).
Cooling: ONAN (Oil Natural Air Natural)
Key Features
Dyn11 Vector Group: Provides a neutral point on the LV side, essential for supplying both single-phase (lighting, sockets) and three-phase (A/C) loads safely and balancing the auxiliary board.
Low Impedance & High Inrush Withstand: Designed to handle intrush currents from multiple motor starts (e.g., air conditioning units) without causing excessive voltage dips for sensitive SCADA electronics.
Compact Footprint & Low Noise: Optimized for installation within a confined container room, with noise levels minimized to prevent interference with control room operations.
Full Compliance: Manufactured and tested in accordance with UK National Annex of BS EN 60076, IEC 60076, and DNO requirements (e.g., ENA, EREC).
Integrated Protection: Furnished with standard protections (Buchholz relay, pressure relief device, temperature indicators) with provision for remote monitoring signals.
Recommended Compact & Suitable Variant for Containerized Setup
Given the indoor installation within a shared container enclosure housing the control room, the highest priority is safety, space-saving, and minimal maintenance.
Recommended Variant: Cast Resin (Dry-Type) Transformer, Vacuum Cast (VPI) or Encapsulated Design
Model Suggestion: TST-CR-100/33-0.415-Dyn11
Why this is the optimal choice:
Enhanced Fire Safety: Contains no liquid dielectric, eliminating the risk of oil leakage, fire, or explosion. This is a critical safety advantage in a confined container space shared with expensive switchgear and control systems. It meets the stringent F1 fire hazard class standards.
Compact Design: Dry-type transformers can be designed with a more compact profile compared to equivalent oil-filled units with necessary safety clearances and bunding requirements.
Reduced Civil Works: No need for fireproof walls, oil containment pits, or complex drainage systems within the container, simplifying installation and saving space.
Environmentally Friendly & Low Maintenance: No oil testing, filtration, or disposal concerns. It is ideal for indoor applications with minimal maintenance overhead.
Excellent Thermal Performance: The cast resin winding assembly provides excellent resistance to moisture and contaminants, suitable for the potential humidity variations inside a container (when combined with the dehumidifiers).
Project Execution
Close collaboration with the BESS EPC contractor and container manufacturer for early dimensional and interface alignment.
Transformer designed with sidewall or roof-mounted cable boxes to facilitate neat cable entry/exit through the container wall.
Pre-delivery testing included routine tests plus special acoustic noise measurement and partial discharge test to ensure reliability in the electromagnetic environment of a BESS.
Delivery coordinated to align with the container fit-out schedule for just-in-time installation.
Operational Results & Client Benefits
Guaranteed Auxiliary Power Reliability: Ensures continuous operation of HVAC, battery thermal management, and control systems, which are vital for BESS availability and revenue.
Space Optimization: The compact dry-type solution maximized usable space within the container for switchgear and control panels.
Safety & Compliance: The solution met all DNO (Distribution Network Operator) guidelines and internal safety standards for indoor electrical plant.
Reduced Lifetime Cost: Eliminated ongoing oil monitoring costs and simplified insurance requirements for the indoor electrical installation.
Seamless Integration: The auxiliary transformer provided a clean, stable 415V supply, forming the robust backbone for the entire substation's ancillary services.
