C2C P2/6 security of supply

A key element of the Capacity to Customers (C₂C) project was to explore the interaction between demand side response (DSR) services and existing industry policy, more specifically the network planning requirements in ER P2/6. This stipulates the security of supply to customers based on the aggregation of their demand as it appears on the network. In its simplest form, the recommendation sets out the amount of capacity that must be available on the network for specified demand thresholds, so that demand can always be supplied when capacity becomes unavailable due to a fault or a planned outage.

As C₂C uses the inherent latent capacity specified as a requirement of ER P2/6 for the connection of new demand, there will be instances, following an outage and prior to network switching, when customers’ unconstrained demand cannot be supported. This will lead to potential non-compliance under the current framework. For the purposes of the C₂C trial a derogation from the requirements of P2/6 was granted for all demand groups supplying the trial circuits.

The remit of this work was to present a recommendation for how DSR could be accommodated within ER P2/6, and provide a consistent and practical approach for the industry to follow when assessing the contribution of DSR to security of supply assessments.

It was proposed that:

• In the short term an appropriate allowance for DSR should be taken into account when calculating group demand or by adjusting network capability. It is up to each distribution network operator (DNO) to justify and formally record its approach for each DSR connection.
• It is up to each individual DNO to decide on the percentage of DSR that it will take into account when calculating group demand and this value should be recorded.
• At the time of project closedown it is the view of the industry that for extra high voltage networks the gross level of demand (group demand plus the responsive demand) should be curtailed to ensure that the system is able to maintain supplies to customers while responsive demand is disconnected.