Dynamic Containment: what is it, and why do we need it?

We’ve just rolled out our new Dynamic Containment frequency response service in our national control room, significantly boosting our ability to respond rapidly to disturbances in the flow of electricity around the grid.

At National Grid ESO it’s our job to keep that flow stable and get power to where it’s needed. One of the most important factors influencing the stability of the electricity system – and its resilience to disturbances – is frequency.

When we talk about frequency, we mean the measure of energy in and out of Britain’s transmission network – in other words, the supply of electricity (from generators like wind farms and gas plants) and demand for electricity (for example when we’re all using lots of power during the evening hours).

In an ideal world, supply and demand (the energy in and out of the electricity system) would be in perfect balance, and the power network would always be operating at a steady frequency of 50Hz – the frequency at which equipment in homes businesses and industries are designed to operate.

In reality, of course, supply and demand are in constant flux, with many other electricity system characteristics and variables also influencing the equilibrium on the grid at any one moment.

A deviation in system frequency can travel the full length of Britain’s network in the blink of an eye, so Dynamic Containment's response needs to be fast

Our control room engineers are managing these constant changes every second of every day to make sure supply and demand are in as near-perfect balance as possible to keep the frequency within one per cent of 50Hz – and keep the country’s lights on.

Dynamic Containment is the first in a suite of new services that will help us do this faster and more effectively than ever. It’s designed to act rapidly when triggered by a fault on the system – for example the loss of a generator – to catch and ‘contain’ the resulting deviation in frequency.

And its response capability needs to be fast. It can take no longer than the blink of an eye for a deviation in system frequency to travel the full length of Britain’s network, so Dynamic Containment will kick into action in under a second to manage the imbalance in the frequency.

This response is made possible through agreements we make with generators for them to be available and respond when needed. Batteries’ speed and flexibility make them particularly well-suited to the task, but any technology type can take part and we anticipate a wider range of providers participating in the future.

As more renewable generation contributes to the country’s electricity mix, and the grid more frequently operates with low inertia – which slows down deviations in frequency – this faster-acting frequency response is more important than ever.

Dynamic Containment is strengthening Britain’s electricity system, making it smarter and more flexible, and allowing us to accommodate more renewable power – meaning more progress towards our ambition of operating the system with zero carbon by 2025.