Meeting the remote minigrid energy management challenge

Demand management is being used to optimize energy use in the hydro-power network of a west Scotland community
Published: Thu 20 Oct 2016

Energy management may be more critical on a large-scale network but it’s not only there that it is necessary to optimize energy use and it is no less important in smaller community settings.

Consider the case of the community of Knoydart, a remote location accessible only by boat or on foot on the west coast of Scotland. The 120-strong resident community with its local businesses and other facilities and a healthy tourism industry aren’t connected to the UK national grid and have relied on power from a 180kW capacity hydro plant along with a back-up diesel generator. However, increasing demand leading to outages in winter – and what has become something of a tradition, especially during the Christmas and New Year holidays – indicated the system was close to its capacity.

To address this the Knoydart Foundation, which owns the power generation, in 2014 initiated a two prong programme to increase the power capacity through dam improvement work and to improve grid performance through demand side management. With these improvements, which have seen the hydro capacity increased to over 220kW, Knoydart’s energy supply is expected to be secured for the next 40 years.

Demand management solution

“It was clear that the demand for power within the community was beginning to reach the limitations of the power grid and therefore the board of community directors decided to take pre-emptive action before it started impacting on the quality of life for residents,” says Kyle Smith, Knoydart Renewables operations manager.

The solution was found in Energy Assets’ Z-Lynk PLC-based demand management system. In addition, working with the local community energy developers Local Energy Scotland and Community Energy Scotland and the University of Edinburgh, a programme was launched to influence energy behaviour. A smart lightbulb was installed in a community office to provide a visual indicator (from green to red) of the power status, and a website was created showing real-time power usage.

The Knoydart Foundation and Energy Assets’ engineers created a priority stack of loads that could be switched should the power threshold be reached. Receivers were installed across the network and control software written to ensure that when the hydro system came close to its maximum threshold, progressive and automatic load switching would take place. The load switching system is linked to a data tracker sampling power levels every 10 seconds.

The Energy Assets system also monitors the cumulative amount of time each load is shed, thereby ensuring that switching is evened-out across several loads of equal priority. For Knoydart, this works in conjunction with storage heaters in homes, ensuring that no particular home is overly burdened. The network can also shed loads based on mains frequency, not just on power demand. [Engerati-Digital Transformation in the Energy Sector]

Energy efficiency to the fore

In addition to demand side technology, Knoydart is also investing in more energy efficient storage heating and encouraging residents to charge heaters overnight through off-peak tariffing. In time, the Foundation hopes that the enhanced reliability of the grid will enable the introduction of in-line electric boilers that can be operated automatically through Z-Lynk when there is spare network capacity, thus offsetting oil consumption from existing oil-fired boilers.

Alan Jones, director of Technology and Product Development at Energy Assets, suggests there are lessons to be learned for the whole country from the project at Knoydart.

“We are all aware that the gap between power generation and demand is narrowing, so we need technological solutions, such as the Z-Lynk control system, to switch loads when needed to avoid major power outages,” he says. “To this extent, the situation in Knoydart is no different to the national picture – and nor is the solution, it’s just a matter of scale. Indeed, what this project proves is just how valuable load switching can be in balancing capacity, not just for remote communities but for the country as a whole.”

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