Stability Pathfinder

Under steady state the mechanical and electrical energy must be balanced on the electricity network. When the electrical load exceeds the mechanical energy supplied, the system frequency will fall. The rate of change of frequency fall is dependent upon the initial power mismatch and system inertia.

A power network without inertia is one that is unstable, suffers from issues of power quality and is susceptible to blackouts. The primary mechanism for providing inertia is via the presence of heavy rotating equipment such as steam turbines and gas turbines driving rotating generators. This has traditionally been provided by conventional power plants (typically gas and coal) rotating at the same frequency as the grid (synchronous generation).

Stability is the ability of the system to withstand a network disturbance and continue operating normally.

With the threat posed by climate change, there is a requirement to decarbonise the UK energy system using renewable technologies. Doing this is resulting in large volumes of fossil-fuel power stations, the traditional providers of inertia, being replaced by renewable generation and other low-carbon technologies such as wind, solar and HVDC interconnectors. This is likely to result in a decline in system strength and increased risk for the network operation as the system becomes more volatile.

Stability Pathfinder is a National Grid ESO (NGESO) project to procure alternative methods of providing inertia. The intent is that, by 2025, NGESO will have transformed the operation of the electricity system such that it can be operated safely and securely at zero carbon.

The Stability Pathfinder project is split into two phases. Phase 1 resulted in five flexibility tenders worth £328 million awarded in January 2019 to Drax, Statkraft, Triton, Rassau Grid Services (Welsh Power) and Uniper. These participants will provide inertia but not electricity in what was hailed as a world-first approach at the time.

Phase 2 focusses on Scotland which is deemed a risk due to the high volume of renewables located there. The tender process is focussed on a broader range of technologies and unlike Phase 1 there will not be a zero MW condition as NGESO has identified that it can have an adverse impact on market distortion from bringing on active power alongside stability.

To participate in Stability Pathfinder requires EDL software which is fully supported by Genstar4. In addition, as there is an import MW (and a potential export MW in Phase 2), a participant needs to ability to import and reconcile the Elexon settlements files which is supported by the Genstar4 Settlements Module.

Enegen is providing its Genstar4 technology for Triton Power to participate in Stability Pathfinder at the Deeside Power site.

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