Case Study
Fiddler's Ferry 275kV Substation
Detailed electrical design for a 150MW transmission-connected BESS
HMF Consultants delivered detailed electrical design for OCU on SSE Utility Solutions' grid-facing Battery Energy Storage System at the former Fiddler's Ferry estate in Warrington, connecting at 275kV.
Project Overview
150MW BESS on a former coal-fired generation site
SSE US (Scottish and Southern Energy – Utility Solutions) is actively pursuing internally developed Battery Energy Storage System (BESS) projects to support low-carbon electricity generation targets.
The Fiddler's Ferry estate in Warrington has a long history of power generation. The coal-fired power station was decommissioned after SSE bought it in the early 2000s. SSE US is developing a 150MW, grid-facing, transmission-connected BESS project on this land.
Project Facts
Key project metrics
150MW grid-facing BESS
Transmission-connected storage on the Fiddler's Ferry estate
275kV connection
Bay connected to the FF-NG Substation
Principal Design Engineering
HMF leading design coordination for OCU with SSE
Expected energisation 2025
Key milestone aligned to programme delivery
Project Highlights
Detailed electrical design for OCU
HMF has conducted the detailed electrical design for OCU and progressed the following packages:
- Cable System Studies
- Power System Studies
- Electrical Secondary Design
- Electrical Primary Design
- MEP Design
Apart from the above electrical design, HMF also:
- Conducts regular design reviews with SSE / OCU
- Performs the Principal Design Engineering role
Key Deliverables
Connection package scope
- Design and develop the 275kV SLD, KLD and LVAC schemes for the bay connected to the FF-NG Substation
- Perform 275kV and 33kV cable study and calculations
- Complete and submit the 275kV cable route and bonding schematic
- Develop the earthing design and report for the FF BESS site
- Design and develop the AIS layout of FF-TX Compound and NG Compound
- Design and develop the control and protection block diagram of FF-TX Compound and NF Compound
Engineering Challenges
Key engineering challenges
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Transmission bay interface
275kV SLD, KLD and LVAC schemes had to integrate with the bay connected to the FF-NG Substation.
-
Multi-voltage cable systems
275kV and 33kV cable studies, calculations, routing and bonding required concurrent analysis.
-
Compound coordination
AIS layouts and control/protection diagrams spanned FF-TX, NG and NF compounds.
-
Parallel design packages
Cable, power system, primary, secondary and MEP design progressed together under regular SSE/OCU reviews.
HMF Solution
Full electrical design leadership for the BESS connection
HMF delivered detailed electrical design for OCU across cable system studies, power system studies, primary and secondary design, and MEP — while performing the Principal Design Engineering role.
Regular design reviews with SSE and OCU kept the 275kV connection package, earthing design, AIS layouts and protection architecture aligned to programme.
Outcome & Impact
Programme-ready design toward 2025 energisation
The completed deliverables support construction progress on a critical transmission-connected BESS asset, with expected energisation in 2025.
Fiddler's Ferry contributes to UK low-carbon generation by enabling flexible, grid-facing storage on a redeveloped former coal site.
