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Uniper moves ahead in National Grid ESO inertia contract with Siemens deal

Image: Uniper.

Image: Uniper.

Uniper has appointed Siemens Energy to deliver grid stabilisation as part of its inertia contract with National Grid ESO.

Siemens will deliver the rotating grid stabilisation technology at Killingholme in Lincolnshire and Grain in Kent to allow Uniper to fulfil the four six-year contracts awarded in January.

Other successful bidders for the contracts include Drax, Statkraft, Triton and Rassau Grid Services (Welsh Power), with all of these either modifying existing assets or building new assets to provide stability services from inertia without having to provide electricity.

Two steam turbine generators will be repurposed and flywheels installed at Killingholme and two new synchronous condenser units will be built at Grain, both of which will be connected to the existing grid connections at each site. Work is due to start later this year, with contracted services to begin from 2021.

“The services provided by Uniper will make an important contribution in supporting the energy transition by maintaining grid stability and security of supplies whilst enabling more renewables to be integrated into the energy system,” Mike Lockett, Uniper UK country chairman and Group chief commercial officer power, said.

Traditionally, inertia is provided using the kinetic energy in the moving parts of large generators while they are providing electricity to the grid. This kinetic energy is released during frequency events on the grid, slowing the drop in frequency to allow other generators time to bring the frequency back up to normal levels.

As more renewables come onto the grid, the need to find new ways of providing inertia increases. This new approach to inertia comes alongside a range of other technologies and services being utilised by National Grid ESO to provide frequency response services, in particular battery storage and demand side response (DSR), which are able to provide fast responses in the event of a frequency drop.

Battery storage’s ability to provide inertial response was the focus of research from Northern Ireland’s Queens University Belfast in 2018 that found it could do so at a lower cost and with reduced emissions in comparison to traditional thermal generation, with 360MW of battery-based energy storage able to provide the equivalent stabilisation to Ireland’s all-island electricity system as would normally be provided by 3,000MW of thermal generation.

The speed at which battery storage responds has been a key feature of National Grid ESO’s new frequency response service Dynamic Containment (DC), with battery storage expected to make up the majority of accepted bids.

Launched in October, DC was created to bring frequency response closer to real-time, with National Grid ESO pointing to how rapid and real-time management of frequency is becoming increasingly important as more renewables come onto the system, replacing generation with inbuilt inertia.

Two other Dynamic services – Moderation and Regulation – are also set to be introduced, with Moderation designed to manage sudden frequency imbalance in intermittent generation and Regulation to manage small deviations when the frequency is close to 50Hz.


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