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Modification: P349

Facilitating Embedded Generation Triad Avoidance Standstill

Proposer: ScottishPower

Current Phase: Awaiting Implementation

Lead Analyst: Giulia Barranu

Implementation Date: 22 February 2018 (to be confirmed)


This Modification will introduce a requirement under the BSC for Suppliers that are the registrants of New Embedded Generators to tell their Half Hourly Data Aggregators (HHDAs) which Metering System IDs (MSIDs) relate to New Embedded Generation. They will also be requited to tell their HHDAs to provide Period Metered Data from these MSIDs to the Transmission Company (TC) in the most efficient and cost-effective manner.

New Embedded Generators will be defined for the purpose of this Modification by Connection Use of System Code (CUSC) Modification Proposal (CMP) 264 ‘Embedded Generation Triad Avoidance Standstill’.CMP264 currently defines a New Embedded Generator as any Half Hourly (HH) metered embedded generation unit commissioned after 30 June 2017, where commissioned is defined as the point at which an MSID is first registered in the Supplier Meter Registration Service (SMRS) and first commences generation.

The implementation of CMP264 requires both SVA and CVA meter data flows for new embedded generation. It is believed that the Transmission Company already receives the necessary CVA metered data to allow for the benefits of CMP264 to be realised. If this is assumption is proved invalid, this Modification will require including CVA as well as SVA registered generators.


P349 was raised by ScottishPower on 4 July 2016. The Proposer has requested that this Modification be treated as an Urgent Modification Proposal.

An Urgent meeting of the BSC Panel will be held on 4 July 2016. The Panel will consider the Proposer’s request for Urgency and will agree a recommendation to the Authority on whether or not P349 should be treated as an Urgent Modification Proposal. The Authority then considered the Panel’s recommendation and determined on 11 July that P349 should not be treated as an Urgent Modification Proposal.

The P349 Assessment Procedure Consultation was issued on Monday 8 August 2016, with responses due back by 26 August 2016. The Workgroup considered the responses to the Assessment Consultation and the extension to the related CUSC Modification timetable. The Workgroup agreed that an extension would be required to ensure that P349 can take into account the solution(s) agreed under CMP264. ELEXON requested a two month extension to the P349 Assessment Procedure Timetable. The Panel approved this at its meeting on 8 September 2016.

The second Assessment Procedure Consultation was issued on Monday 20 February 2017 with responses due by Monday 13 March 2017.

The Assessment Report was presented to the Panel at its meeting on 13 of April. The Report Phase Consultation was issued on 19 April 2017 with responses due by 8 May 2017. The Draft Modification Report was presented to the Panel at its meetingo n 11 May 2017. The Panel recommended conditional approvalof Options 1, 2 and 3 depending on Ofgem’s decision on the CUSC modifications. The Final Modification Report was issued to the Authority on Monday 22 May. The Authority approved Option 2 on 22 June 2017 for implementation on 22 February 2018.


P349 Final Modification Report  [1.8 Mb]
Document Date: 22 May 2017

P349 Draft Modification Report  [1.8 Mb]
Document Date: 12 May 2017

P349 Report Phase Consultation  [1.6 Mb]
Document Date: 19 April 2017

P349 Assessment Report  [1.5 Mb]
Document Date: 13 April 2017