National Grid ESO suggests urgent Grid Code modification amidst demand drop due to lockdown


NATIONAL Grid Electricity System Operator (ESO) has raised an urgent Grid Code modification that would allow it to disconnect embedded generation due to lower demand.

The modification – raised on 30 April – will clarify the ESO’s legal powers to instruct DNOs to disconnect embedded generation.

This is classified as generation that is connected to the distribution network, for example domestic solar and battery storage.

This applies to embedded generation that is not part of the Balancing Mechanism, with the ESO already having the ability to turn down and disconnect Balancing Mechanism participants.

A National Grid ESO spokesperson told ICON: “The tools and processes our control room currently has in place to balance supply and demand mean Great Britain’s electricity System is one of the most reliable in the world.

“As a prudent System Operator we are working with industry to explore additional options to help us to manage the unprecedented situation caused by COVID-19 and reduced demand for electricity.

“No one should be concerned about their electricity supply, we have comprehensive plans in place to ensure we safely and securely manage the system at all times – including through this unprecedented period.”

The spokesperson underlined that grid code modification is clarifying an existing process, rather than implementing something new.

Also, this process would only be deployed in the ‘unlikely event of an emergency’, helping to ensure that, supply of electricity is maintained even in those situations.

The modification has been raised as the ESO is balancing the grid while the COVID-19 lockdown has led to a dramatic drop in demand.

According to ESO, demand has dropped 20% lower than predicted levels, a situation it said in its Summer Outlook report that would cause it to use its existing balancing services more often as well as create new sources of flexibility and curtail wind output in particular.

As a result, it is requesting the ability to disconnect embedded generation as ‘a last resort’ to maintain system stability during periods of exceptionally low demand.

While the ESO said it is establishing a new service for downward flexibility management to mitigate the operational risks caused by COVID-19, it ‘may be necessary to seek to control embedded generators’ if all commercially available options through the new service and the BM have been taken.

Embedded generators that are not part of the BM but are disconnected will not be compensated for the emergency action, it said.

Outlining an implementation date of 7 May, the ESO stressed the importance of having this in place prior to the 8 May bank holiday, when it expects particularly low demand and “significant operational risk”.

Currently, it said, the Grid Code shows its ability to make these instructions is ‘ambiguous’ and leaves DNOs in a position that may expose them to legal risk, resulting in the need for clarity through the modification.

If the modification goes ahead, there are a number of instructions National Grid ESO may give, including:

  • Specific instructions requiring the network operator to disconnect specified embedded power stations.
  • Asking the network operator to disconnect embedded power stations supplied via one or more specified Grid Supply Points with an aggregate Registered Capacity of a specified value.
  • Asking the network operator to disconnect embedded power stations supplied via one or more specified Grid Supply Points so that a specified proportion of the aggregate Registered Capacity is disconnected.
  • However, the ESO is looking to establish a more considered solution, suggesting a potential option of the development of a roughly symmetrical arrangement to the existing demand conditions in section OC6 of the Grid Code.
  • To support this, it has included a sunset clause that will time out the additions to the Grid Code in October 2020 if not further amended.

Ofgem must approve the modification for it to be implemented, with a decision due 7 May.

The full modification proposal form is available here