3.2 North of England Boundaries

The North of England transmission region includes the transmission network between the Scottish border and the north Midlands.

This includes the upper north boundaries B7, B7a and B8. The figure below shows likely power flow directions at system winter peak

 

The arrows in the diagram illustrate power flow directions and are approximately scaled relative to the winter peak flows.

Regional Drivers

The connection of large amounts of new generation, most of which is intermittent renewables, in Scotland and the north will cause overloading in the northern transmission network unless appropriate reinforcements are in place. Future power transfer requirements could be more than double compared to what they are today in some scenarios.

Regional drivers

The future energy scenarios suggest the northern transmission region could see a range of changes as shown in the graph. 

All four scenarios suggest growth in low-carbon and renewable generation, in addition to new storage and interconnector developments. The connected fossil fuel generation could see sustained decline in all but the Steady Progression scenario. 

Large connections could cause network issues if connected to the north region.

Presently, most of the northern transmission network is oriented for north-south power flows with connections for demand and generation along the way.

At times of high wind generation, the power flow will mostly be from north to south, with power coming from both internal boundary generation and generation further north in Scotland. 

When most of this area and Scotland is generating power, the transmission network can be highly overloaded. The loss of one of the north to south routes can have a highly undesirable impact on the remaining circuits. 

The highly variable nature of power flows in the north presents challenges to voltage management, and therefore automatic reactive power control switching is utilised. This helps to manage the significant voltage drop due to reactive power demands which arise at times of high levels of power flow on long circuits. 

Operational reactive switching solutions are also used to manage light loading conditions when the voltage can rise to unacceptable levels. The high concentration of large conventional generators around Humber and South Yorkshire means that system configuration can be limited by high fault levels. Therefore, some potential network capability restrictions in the north can be due to the inability to configure the network as desired due to fault level concerns. 

As the potential future requirement to transfer more power from Scotland to England increases, B7 and B7a are likely to reach their capability limits and may need network reinforcement. The potential future restrictions to be overcome across B7 and B7a are summarised: 

  • Limitation on power transfer out of north east England (boundary B7) is caused by thermal limitation for a fault on the double circuit between Harker–Hutton. 
  • At high power transfer, thermal limitations occur on a number of circuits within the north east 275kV ring. 
  • Limitation on power transfer from Cumbria to Lancashire (boundary B7a) occurs due to thermal limitation at Padiham–Penwortham circuit. 

The need for network reinforcement to address the above-mentioned potential capability issues will be evaluated in the NOA 2020/21 CBA. 

Boundary Regions

Click on the regions below to expand the boundary and understand its capability and challenges.

If you would like to learn how to interpret the graphs, click the button below.

 

Interpreting boundary graphs

The graphs show a distribution of power flow for each scenario, in addition to the boundary power transfer capability and NETS SQSS requirements for the next twenty years. 

Each scenario has different generation and demand so produces different boundary power flow expectations. 

From applying the methodology in the NETS SQSS for wider boundary planning requirements (as discussed in section 2), we determine: 

  • the economy criteria - solid coloured line
  • security criteria - dashed coloured line
  • current boundary capability – solid black line

The current boundary capability is expected boundary capability for the coming 2020/21 year’s winter peak study. This will change over time as the network, generation, and demand change, all of which are uncertain and so a straight back line shows the present capability.

The calculations of the annual boundary flow are based on unconstrained market operation, meaning network restrictions are not applied. This way, the minimum cost generation output profile can be found. 
We can see where the expected future growing needs could be by looking at the free market power flows in comparison with boundary capability.

Using the B6 boundary charts as an example below, there are four charts – one for each of the scenarios in the FES.

On each graph, the two shaded areas provide confidence as to what the power flows would be across each boundary:

  • the darker region shows – 50% of the annual power flow or the 75th percentile in the range of power flows
  • the lighter region shows – 90% of the annual power flows or the 95th percentile in the range of power flows

From the regions, we can show how often the power flows expected in the region split by the boundary are within its capability (black line). 

If the capability of the boundary is lower than the two regions over the next 20 years, there might be a need for reinforcements to increase the capability. 

However, if the line is above the shaded regions, it shows that there should be sufficient capability here and that potentially no reinforcements are needed from a free market power flow perspective until the shaded regions exceed the capability (black line).

Close panel
Boundary B7 – Upper North of England

 

Boundary B7 bisects England south of Teesside. The area between B6 and B7 has been traditionally an exporting area, and constrained by the power flowing through the region from Scotland towards the south with the generation surplus from this area added. 

Boundary flows and base capability

 

The boundary capability is 6.3GW, and is limited thermally by the post-fault load rating of transformers at Harker under the Harker–Hutton double-circuit fault.

For all scenarios in the FES, the SQSS economy required transfer and expected power flows quickly grow to beyond the present boundary capability. This suggests a strong need for network development to manage the increasing power flows.

The FES show a lot of intermittent renewable generation in the north, meaning the spread of boundary power flows is very wide. With low generation output in the north it is credible to have power flowing from south to north feeding northern demand. The magnitude of the south to north power flows is low compared to those in the opposite direction so network capability should be sufficient to support those conditions.

Boundary B7a – Upper North of England

 

Boundary B7a bisects England south of Teesside and into the Mersey Ring area. It is used to capture network restrictions on the circuits feeding down through Liverpool, Manchester and Leeds. 

Boundary flows and base capability

 

The boundary capacity has remained 8.7GW limited thermally by the post-fault load rating of the 400kV circuits from Penwortham.

For all except the Steady Progression scenario, the SQSS economy required transfer and expected power flows grow to well beyond the present boundary capability in the next ten years. This suggests a need for network development to manage the increasing power flows.

The FES also shows a lot of intermittent renewable generation in the north, meaning the spread of boundary power flows is very wide. With low northern generation output, it is credible to have power flowing from south to north feeding northern demand.

The magnitude of the south to north power flows is low compared to those in the opposite direction so network capability should be sufficient to support those conditions.

Boundary B8 – North of England to Midlands

 

Boundary B8 is one of the wider boundaries that intersects the centre of GB, separating the northern generation zones including Scotland, Northern England and North Wales from the Midlands and southern demand centres.  

Boundary flows and base capability

 

The boundary capacity is 10.3GW limited thermally by the post-fault load rating of the Cellarhead-Drakelow 400kV circuit.

Across all four FES, the SQSS economy required transfer and expected power flows grow to beyond the present boundary capability. This suggests a need for network development to manage the increasing power flows.

The FES shows a lot of intermittent renewable generation in the north - the spread of boundary power flows is very wide.

With low northern generation output, it is credible to have power flowing from south to north feeding northern demand, although this is not significant until beyond ten years in the future. The magnitude of the south to north power flows is low compared to those in the opposite direction so network capability should be sufficient to support those conditions