As energy travels from the point of production to the end user, some of it is ‘lost’ on the system. Under the BSC arrangements there are two ways in which these losses are accounted for:

• Losses on the low voltage Distribution Networks are allocated through the use of Line Loss Factors (LLFs).
• Losses on the high voltage Transmission System are allocated across BSC Parties through the use of Transmission Loss Multipliers (TLMs).

Line Loss Factors

Line Loss Factors (LLFs) are multipliers which are used to scale energy consumed or generated in order to account for losses on the UK’s Distribution Networks. There are two types of Line Loss Factor: Central Volume Allocation (CVA) LLFs and Supplier Volume Allocation (SVA) LLFs.

• Supplier Volume Allocation (SVA) LLFs
  SVA LLFs are used in aggregation by the Half Hourly Data Aggregator (HHDA) for Half Hourly (HH) metering systems and Supplier Volume Allocation Agent (SVAA) for Non Half Hourly (NHH) metering systems.There are roughly 30 million metering systems registered in the Supplier Meter Registration Service (SMRS) – the SVA sector of the electricity industry. Many of these are banded together into Line Loss
  Factor Classes (LLFCs). LDSOs use these for assigning metering systems to a given tariff, for the purpose of Distribution Use of System (DUoS) charges. All metering systems in a LLFC will have the same LLF value.LDSOs need to submit SVA LLF values for all LLFCs on an annual basis, and also for a new LLFC when it is being registered
• Central Volume Allocation (CVA) LLFs
  CVA LLFs are multipliers used to scale meter readings taken at an Embedded site to an equivalent value at the Transmission System Boundary, to account for losses on the Distribution System.CVA LLFs are site-specific, and are applied at a Metering System ID (MSID) level via site Aggregation Rules. A full list of current site names, along with their MSID and GSP Group, can be found in MSID Site Names.LDSOs need to submit values for each site which requires CVA LLFs on an annual basis. They will also need to submit LLFs for any new sites registered within CVA that use LLFs in their Aggregation Rules

Processing of CVA and SVA LLFs

All LLFs submitted by Licensed Distribution System Operators (LDSOs) will be processed in accordance with BSCP128 ‘Production, Submission, Audit and Approval of Line Loss Factors’.

The LDSOs provide a LLF Methodology Statement that explains how they calculate both the Site Specific and Generic LLFs. We review the statements to see if they meet a number of principles in BSCP128. If the methodology meets the principles we present it to the ISG and SVG for approval. It is then used to calculate the LLFs. The latest approved methodology statements are available on the ELEXON Portal.

Where can I find Line Loss Factor Data?

All LLF data is published on the ELEXON Portal.

Transmission Losses

Under the BSC arrangements Transmission Loss Multipliers (TLMs) are applied to BM Unit Metered Volumes as a means of scaling to account for losses on the Transmission System. The formulas for calculating Transmission Loss Multipliers are set out in BSC Section T, Paragraph 2.3.1.

The Transmission Loss Multiplier (TLM) is applied to a BM Unit’s Metered Volume to adjust for Transmission Losses. Although TLMij is defined as a BM Unit-Settlement Period level variable, there are only two values for TLM per Settlement Period: one for BM Units belonging to Trading Units that are off-taking Trading Units in the Settlement Period, and one for BM Units belonging to Trading Units that are delivering Trading Units in the Settlement Period. This is because the Transmission Loss Factor (TLFij), used in the calculation of TLM, is zero for all BM Units.

Historic Transmission Loss Multipliers data can be downloaded from the ELEXON Portal, as well as historic Estimated Transmission Loss Adjustment (ETLMOs), which are parameters set for the purposes of BMRS reporting. These parameters are the estimated values of the ‘Delivering Transmission Losses Adjustment’ (TLMOj+), and the ‘Off taking Transmission Losses Adjustment’ (TLMOj-).

The Balancing Mechanism Reporting Service (BMRS) is used to display near real-time information relating to the operation of the Balancing Mechanism (BM).

The ISG reviews the ETLMO values from time to time on behalf of the BSC Panel.