NIA SSEN 0068 New Approach to Losses

Key Activities

The SHEPD licence area exports power to the transmission system in various locations and during differ times of the year. There was uncertainty as to whether the existing losses apportionment methodology was designed to manage reverse power flows. The ‘New Approach to Losses’ project was initiated to investigate the accuracy of the existing losses apportionment methodology and, if necessary, to create a new losses apportionment methodology, along with supporting engineering models and prepare them to a standard where they can be submitted to Elexon for approval.

Expected Benefits

Although no net benefits were expected, the project has ensured that there is a more equitable distribution of the value of losses across the customer base in SSEN networks. This was required to address the increasing generation/reverse power flows the networks are experiencing which were not adequately addressed by the previous method.

Progress

Early investigations found that the existing losses apportionment methodology was not designed to handle reverse power flow and therefore a new model was required to produce more accurate results. An investigation of the engineering models that were used to calculate losses showed that they were appropriate and so no changes were required. This project is now complete. A new losses apportionment methodology was created that took account for both downward and upward flows of power, onto or from, the distribution system from the transmission network. This underwent significant testing to demonstrate that the results it produced were robust. The methodology was submitted to Elexon and approved, and was then used to calculate the 2025/26 Loss Adjustment Factors that were subsequently published.