High‑voltage engineering, infrastructure construction and energisation for one of Scotland’s largest onshore wind farms
Project Snapshot
| Project Detail | Information |
| Client | EDF Renewables |
| Original Developer | Infinergy Ltd |
| Location | Glendfiddich Estate, near Dufftown, Moray |
| Project Duration | 20 months |
| Installed Capacity | 177 MW |
| Services | Electrical Balance of Plant (EBoP), HV design, installation, testing & commissioning |
| Market Sector | Renewable Energy – Onshore Wind |
| DNO | Scottish & Southern Electricity (SSE / SHETL) |
| Turbines | 59 × Vestas V90 (3.0 MW) |
| Grid Connection Voltage | 132 kV |
| Powersystems Role | Full EBoP contractor for all electrical works from DNO point of connection to turbine terminals |
| Powersystems Fact | Powersystems Renewable Energy team has connected 24% of all UK land‑based wind turbines, delivering specialist HV design and grid connection expertise across the country. |
Dorenell 177 MW Wind Farm Case Study
Download the full Dorenell Wind Farm Case Study — designed for engineers, developers and technical stakeholders. This summary outlines the complete 132 kV grid connection, the Electrical Balance of Plant for 59 Vestas V90 turbines, and the full programme of HV design, installation, protection, SCADA and commissioning delivered by Powersystems for this 177 MW onshore wind project. It highlights how Powersystems engineered, constructed and energised one of Scotland’s largest and most complex upland wind farms, integrating 240 km of 33 kV cabling, two 120 MVA transformers and extensive civil, electrical and communications infrastructure across a 35 km² site. The document provides insight into grid compliance, earthing design, protection coordination required to deliver a resilient, high‑capacity renewable energy scheme on challenging terrain.
Client & Site Background
Infinergy Ltd submitted the original planning application for Dorenell Wind Farm in 2008. In November 2015, the fully consented project was acquired by EDF Renewables — one of the UK’s largest low‑carbon electricity generators, operating over 965 MW of onshore and offshore wind in operation, and a further 2.0 GW in planning and development.
The project forms part of EDF’s strategic commitment to drive large‑scale decarbonisation and support Scotland’s renewable energy targets.
The Challenge
EDF Renewables required a full Electrical Balance of Plant delivery for a large‑scale, complex wind farm covering 35 km² of upland terrain close to the Cairngorms National Park. Key challenges included:
- Designing and constructing electrical infrastructure for 59 turbines across seven arrays
- Building a 132 kV connection to the SHETL network
- Managing long cable routes, steep gradients and extensive trenching
- Delivering a high‑capacity substation with two 120 MVA transformers
- Coordinating energisation of a 22 km long DNO overhead line connection to Blackhillock Primary Substation
- Integrating full SCADA, fibre, protection and earthing systems across 240 km of cable routes
Powersystems were appointed as the EBoP contractor responsible for the complete design, build, installation, testing and commissioning of the entire HV system.
Our Engineering Solution
Powersystems delivered the full high‑voltage infrastructure from the 132 kV DNO interface through to the final termination at each Vestas V90 turbine. Works included:
- Two 120 MVA 33/132 kV transformers and associated HV plant
- Construction of a large 132 kV substation compound (150 m × 75 m) with two control buildings
- Installation of 240 km of 33 kV cabling across seven arrays
- Design and installation of 59 turbine transformer substations
- Construction of 40 km of cable trenches and associated civil works
- Delivery of a complete earthing system for turbines, metering building and outdoor compound
- HV, LV and fibre optic communication networks for SCADA and control
- Full suite of electrical studies including:
- Grid compliance analysis
- Earthing studies
- Lightning protection
- Insulation coordination
- Voltage and fault level studies
Powersystems worked closely with EDF Renewables engineers to translate concept designs into detailed, buildable technical solutions.
Project Process
- Early HV design, grid studies and DNO coordination
- Construction of turbine bases, crane pads and new access roads
- Substation civil works and building construction
- Installation of 132 kV plant and transformers
- Cable trenching and installation of 33 kV collector network
- Turbine connection, fibre optic routing and SCADA integration
- Commissioning of transformers, switchgear, protections and communications
- Energisation and phased turbine commissioning
- Final handover and documentation
Project Facts & Figures
- Installed Capacity: 177 MW
- Turbines: 59 × 3.0 MW Vestas V90
- Connection Voltage: 132 kV
- 133/33 kV Transformers: 2 × 120 MVA
- Site Area: ~35 km²
- Onsite Cabling: 240 km (33 kV)
- New Access Tracks: 42 km
- Export Capacity: Power for ~106,000 homes
- DNO: SSE / SHETL
Technical Specifications
High‑Voltage Infrastructure
- 132 kV open‑terminal switchyard
- 2 × 120 MVA transformers
- Protection & control panels
- 132 kV and 33 kV circuit breakers
- Automatic voltage regulation (AVR)
- SCADA and communication systems
33 kV Collection System
- 240 km of 33 kV underground cables
- 7 collector arrays feeding the main substation
- 59 turbine substations & 2.5 MVA turbine transformers
- Fibre optic comms for turbine monitoring & control
Civil & Structural
- Substation buildings
- 40 km of cable trenches
- 42 km of new access tracks
- Turbine crane hardstands
- Foundations for all HV equipment
Watch a short film on the Dorenell Wind Farm
Partnerships
The project was delivered in collaboration with:
- EDF Renewables – Client
- SHETL / SSE – DNO for 132 kV connection
- Vestas – Turbine supplier
- Civil and infrastructure partners for roads, foundations and trenching
Powersystems acted as the EBoP specialist responsible for delivering the HV engineering backbone of the wind farm.
Key Risks & Mitigations
- Transformer inrush & voltage dips – Mitigation: Controlled energisation procedures and protection settings ensured compliance with P28 limits.
- Challenging upland terrain – Mitigation: 42 km of engineered access tracks and phased logistics planning minimised weather‑related disruption.
- Long 33 kV cable routes (240 km) – Mitigation: Detailed cable rating, trenching design and QA inspections controlled voltage drop and installation risk.
- Environmental sensitivity near Cairngorms NP – Mitigation: Ecological supervision and carefully routed trenches protected habitats and met planning requirements.
- Complex DNO interface (132 kV / 22 km OHL) – Mitigation: Close coordination with SHETL and phased commissioning ensured safe, compliant energisation.
- Multiple contractors across 35 km² – Mitigation: Daily coordination, interface management and CDM governance-maintained project safety and continuity.
- Weather delays to lifts & HV works – Mitigation: Weather windows, flexible scheduling and protected work zones reduced programme impact.
- Large‑scale earthing challenges – Mitigation: Soil resistivity testing and additional electrodes ensured all step/touch voltages remained within statutory limits.
Environmental Considerations
- Generates enough energy to power 106,000 homes annually
- Significant contribution to Scottish Government renewable energy targets
- Reduces regional carbon emissions
- Supports Scotland’s ambition for 100% renewable electricity demand
Economic & Social Value
- EDF has committed over £8 million in community funding over the 25‑year lifetime
- Local regeneration plans supported in the Cabrach area
- Investment in local tourism and sustainability initiatives
- Job creation and local supplier engagement throughout construction
Future Prospects
Dorenell Wind Farm became fully operational on 20 December 2018, with all construction completed by 31 December 2018 — an exceptional delivery schedule for a project of this scale.
The wind farm stands as EDF Renewables’ largest onshore wind site to date and demonstrates a strong, ongoing partnership with Powersystems.
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- Sandy Knowe 86.4 MW
- South Kyle 240 MW
- LimeKiln 108 MW
- UK Onshore Wind EBoP (33–132 kV)
Powersystems deliver high voltage engineering and full EBoP services for the UK’s largest and most complex renewable energy projects.
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