For every boundary, the future capability required under each scenario and sensitivity is calculated by the application of the NETS SQSS Chapter 4 - Economy and Security planning methodologies.
We use the scenarios and the criteria stated in the NETS SQSS to produce the future transmission boundary requirements. The market simulation tools are used with the new scenarios and previous NOA recommendations to calculate projections of boundary power flow distributions and future network constraints. We then publicise these capability requirements and estimates so the TOs and Interested Persons can identify future transmission options.
More information regarding transmission requirements is published in the ETYS.
Potential transmission solutions to relieve thermal, voltage or stability constraints can be categorised into build options, operational options and reduced-build options.
Build options cover the breadth of asset improvement such as replacing circuit conductors (in overhead lines or underground cables), reconfiguring substation layouts to improve loadings through to new build such as new substations or circuits.
Operation options are based on buying services, typically from generation for instance to rapidly drop output which could be by intertrip, or by capping generation outputs. This would be for controlling thermal constraints.
Reduced-build options involve some capital outlay but less than an asset-hungry project based on primary plant. These might be based on control schemes or “light current” works, or re-tensioning overhead lines to reduce sag for higher thermal loadings.
We go into more detail in Table 2.2 Potential transmission solutions in section 2 of our NOA methodology.