Hawthorn Pit BESS 60MVA Wilson Power Transformer

Projects
Hawthorn Pit BESS

49.9MW/99.8MWh Hawthorn Pit BESS

Located near Murton in County Durham, Hawthorn Pit is a 49.9MW/99.8MWh Battery Energy Storage System (BESS) developed by Harmony Energy and owned by Harmony Energy Income Trust.

The two-hour duration system uses Envision Energy battery technology and connects to the National Grid. It stores surplus electricity and releases it back to the network when demand is high.

We supplied, installed and tested the grid-connection transformer and the earthing transformer for the site.

Sector	Battery Energy Storage System
End User	Harmony Energy
Location	County Durham, UK
Scope of Work	60MVA 66/33kV Wilson Power Transformer 200kVA 33kV/425V Wilson Earthing Transformer

Image source: Harmony Energy

At the heart of the connection is a 60MVA 66/33kV Wilson Power Transformer. It connects the site's 33kV electrical system to the 66kV network.

Our engineers attended the site to supervise the offloading, site assembly and oil filling. This was followed by on-site acceptance testing, including Sweep Frequency Response Analysis (SFRA).

The transformer specification included an HV On-Load Tap Changer, allowing voltage regulation across the grid connection. It also includes oil and winding temperature monitoring, a pressure relief device, an oil-filled conservator and Buchholz relay, and other standard protection and monitoring equipment.

Alongside the grid transformer, we supplied a 200kVA 33kV/425V Wilson Earthing Transformer. This provides a neutral earth reference and supports the site's electrical protection system. Both transformers were built and tested to IEC 60076.