National Grid to reduce inertia requirement for frequency response services

[dan_b]

Actually there's loads of interesting geek stuff in this report, but one thing that stood out for me was this section.
Reducing the minimum inertia requirement which will reduce the cost of stability rservices.
What actually does 120 GVAs equate to in laymans terms?

Frequency and stability
The Security and Quality of Supply Standard (SQSS) requires us to produce a Frequency Risk and Control Report (FRCR) and submit to Ofgem every year.
FRCR aims to set out the right balance between risk and cost to the consumer when managing frequency on the GB electricity system. FRCR 2023 recommends we reduce our existing minimum inertia requirement from 140 GVAs to 120 GVAs. This will reduce operational costs by approximately £65m per year whilst maintaining our risk profile in frequency control. This is mainly driven by the continuous growth in Dynamic Containment (DC) and the reduction in loss of mains risk volumes delivered through the Accelerated Loss of Mains Change Programme (ALoMCP). The final report can be found from ESO website1
.
Once approved by Ofgem, we will implement the policy change in two stages.Initially we will r educe to 130 GVAs and operate at this level for 1 – 2 months and then we will reduce further to 120 GVAs. This phased implementation gives us and industry time to adapt to the lower inertia and puts us on a glide path to meet our 2025 zero carbon ambition. We will provide advanced notice to industry prior to the change once the timing has been clarified.

https://www.nationalgrideso.com/documen ... 6/download

[marshman]

In real terms that will "supply" about 2.4GW for 1second. 120GVA is the total energy stored in inertial terms, but as soon as you start to draw on it it will start to slow so the "useable" stored energy is only around 2%, so for 120GVA that is "only" 2.4GVA useable before the frequency will drop below the lower limit.

Good explanation here: (though a little out of date)

https://watt-logic.com/2017/10/12/inertia/