Crossed wires: The challenge of reconnecting transmission and distribution

Getting a clearer view

In the past year the debate around connections reform has reached fever pitch, with a backlog of 420GW of generation projects seeking to join the grid.

By way of mitigation, National Grid Electricity System Operator (ESO) is implementing “first ready, first connected” connections reforms, with a “challenging” go-live date of 1 January 2025.

The reforms will introduce an early application window and two formal gates, to track project progression and “hold developers to account”.

Meanwhile, the ENA has produced its own reform plan, building on the ESO’s work around queue access as well as adapting the approach to connecting storage projects. The final area of focus – and the one that has probably received least focus so far – is the need to improve co-ordination between transmission and distribution.

For SSEN, which of course operates in both fields, the subject has long been debated internally.

Burchell, who heads up the distribution arm, insists there needs to be a “much clearer definition of the transmission and distribution interface”.

He explains that while transmission networks have “got a very clear view of generation growth” and the need to connect all the renewable generation up to 2050, they have a less defined view of what demand they’re likely to have coming from a distribution level.

He tells Utility Week: “Transmission operators are saying that if we have a really clear view of what distribution is needed, we could take a broader view of that. That’s why one of the things that we’ve been developing over the past year is a slightly different approach to the way we think about our system planning and the way we think about our investment in our system.

“We’re really positive about delivering greater flexibility on the network. We’re really positive and innovative in terms of delivering changes in the way we manage the system and the digitalisation of our system through DSO [the distribution system operator model].

“But the key thing for us is to have a really clear view of what’s needed on the distribution network so that we can help plan upwards, but we can also help locally with communities in terms of their spatial planning needs.”

Illustrating his point, Burchell recalls a conversation he had with a team during a site visit he made to a SSEN substation that had recently been upgraded. He was told that with more demand and connection applications coming into the substation, it would likely need upgrading again within the next few years.

“I thought to myself, how efficient is that for customers and communities? On the pathway between now and net zero, if we’re having to go back around substations that we’ve possibly already upgraded once or maybe even twice, and then have to do them again, how sensible is that? The thought struck me that what got us here won’t get us there [to 2050].”

The importance of the relationship between transmission and distribution is highlighted in the aforementioned ENA six-point action plan to release enough grid capacity over 2024 to decarbonise Great Britain’s power grid. Point six of the plan is to “further improve coordination between transmission and distribution operators”.

With an additional 112GW of capacity already installed, the trade body explained, the 139GW its plan delivers exceeds the 225GW needed to decarbonise the grid.

“This opens the door to enough customer projects to fully enable the decarbonisation of Britain’s electricity system by the committed date of 2035,” it added.

The ENA explains that given the increasing interdependence between connections at distribution and transmission levels, network operators are developing a new solution to improve coordination between the two.

This, it adds, includes reviewing the threshold at which impacts on the transmission network are assessed, improving transmission – distribution data exchanges, and reforming how distribution customers are charged for triggering transmission network reinforcements.

“These actions will create a more streamlined and equitable customer experience for distribution customers whose projects impact transmission,” the plan says.

The trade body’s director of electricity systems David Boyer tells Utility Week: “Distribution network operators and transmission operators are already working to make the measures detailed in ENA’s report Rising to Britain’s Net Zero Challenge, published at the end of last year, a reality and we have committed to providing regular quarterly updates over the course of 2024 on the progress being made. The first update will be provided at the end of Q1 2024.

“Network operators are also working closely with the regulator, government and the wider industry to implement the vision to reform the power grid articulated in the Winser Review and support the country in reaching our net-zero goals.”

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