A boundary splits the system into two parts, crossing critical circuit paths that carry power between the areas where power flow limitations may be encountered.
When we assess future requirements, we bear in mind that we have many signed contracts for new generation to connect to the NETS.
In addition, the development of interconnectors connecting Great Britain to mainland Europe will have a big impact on future transmission requirements.
We do not know precisely how much new generation there will be, and where it will connect, or when existing generation will shut down.
Our FES helps identify credible ranges of future NETS requirements and present capability.
This is done using the ‘system boundary concept’, which calculates boundary capabilities and the future requirements for bulk power transfer.
The transmission network is designed to provide enough capacity to send power from areas of generation to areas of demand.
Limiting factors on transmission capacity include:
- Thermal circuit rating
- Voltage constraints
- Dynamic stability
From our network assessment, the lowest limit determines the network boundary capability.
The base capability of each boundary can be seen in the Electricity Transmission Network section.
This will be used in the NOA 2021/22 to assess reinforcement options to address potential future boundary needs.
Defining the NETS boundaries has evolved over many years of planning and operating the transmission system.
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When significant changes occur, new boundaries may be defined and some boundaries either removed or amended (we are transparent about any changes).
We do not study all boundaries, specifically those where no significant changes in the FES generation and demand data have been identified in previous years. We assume the same capability as the previous year for these boundaries.