Knocknagael Voltage Support Project

About the Project

SSEN Transmission is developing plans to strengthen the electricity transmission network in the Knocknagael area, south of Inverness, to support a secure and reliable electricity supply through 2030 and beyond. 

Why is the Project Required?

Significant investment is being made in the electricity transmission network across Scotland to help meet future energy needs and support the transition to cleaner sources of electricity.

Studies were undertaken to assess how these changes will affect the network in the future. The studies identified a need for additional equipment in the Knocknagael and Farigaig area to help maintain network stability and ensure the electricity system continues to operate safely, reliably and efficiently.

What the Project Involves?

To deliver the Project, the following elements are proposed: 

• A new voltage support facility, Static Synchronous Compensator (STATCOM), located on a separate site close to Knocknagael Substation. This equipment helps maintain stable voltage levels on the electricity network. The proposed site would cover an area of approximately 105 metres by 140 metres. 
• An extension to the existing Knocknagael 275kV Substation. This would involve extending part of the existing substation by approximately 130 metres by 50 metres to allow the new equipment to connect to the transmission network. Opportunities to coordinate these works with the adjacent Loch na Cathrach project are currently being considered. 
• A short section of 275kV underground cable connecting the new STATCOM facility to the substation extension. The final cable length will depend on the location of the selected site. 
• New Shunt Reactors installed within the Knocknagael and Farigaig area. This equipment helps manage voltage levels on the transmission network, improving network stability and supporting the efficient transmission of electricity. 

What is a STATCOM?

A STATCOM is a type of electrical equipment that helps keep voltage levels on the electricity network stable. 

As electricity demand and generation change throughout the day, voltage levels can rise or fall. A STATCOM responds very quickly to these changes, helping to keep the network operating safely, reliably and efficiently. 

You can think of it as a device that continuously balances voltage on the network, helping to maintain a secure and stable supply of electricity. 

(A 3D Visualisation of an indicative STATCOM layout) 

Project Timeline

The project is at an early stage of development, and our team is reviewing and assessing potential locations for the proposed STATCOM site and associated substation extension.  

Key steps include optioneering, stakeholder engagement, planning applications, procurement, and construction. 

We’re currently aiming to hold initial engagement events to present proposals in Early Autumn 2026.  

Subject to the necessary assessments, approvals and consents, construction of the STATCOM site is anticipated to begin in 2029, with completion expected in 2033. 

Other projects in the local area

The existing Knocknagael Substation is located close to the proposed Beauly–Peterhead 400kV overhead line and adjacent to the proposed Loch na Cathrach project, which will connect the Loch na Cathrach Pumped Storage Hydro Scheme to the transmission network. These projects and their associated works will be considered as part of the development of the proposed STATCOM project. 

To find out more about these projects, please visit the links below:  

Beauly - Peterhead 400kV OHL - SSEN Transmission 

Loch na Cathrach (formerly Red John Pump Storage Scheme 275kV Connection) - SSEN Transmission 

Community Engagement

Throughout the life of our projects, we aim to work positively with local communities and keep people informed about what we are doing. This is particularly important when we are developing a proposal and we want to understand what local people think about our plans.

We endeavour to take the time to discuss proposals with local community councils, encourage engagement from the wider community and listen to the feedback we receive.

We will do our best to answer any questions and address issues or concerns that are raised with us.

When our project progresses into construction, we will continue working closely with the local community to ensure that our work has as little impact on the lives of those living and working in the area and as many long term positive effects as possible.

How we’re embracing artificial intelligence (AI)
We intend to use AI to assist our experienced teams in the analysis of your feedback, so we can categorise key points raised more quickly. You can learn more about how we’re utilising AI on this dedicated web page.