RoCiT National Grid is the largest privately owned, independent transmission company in the world and one of the top 100 companies in the UK.

It owns and operates the high-voltage electricity transmission system that carries power from generators to local distributors across England and Wales. It also owns and operates transmission links to Scotland and France and plays a vital role in enabling the wholesale trade of electricity on behalf of the electricity market.

OCC has a long relationship with National Grid and was chosen for this project because of its competitive rates and prior experience in developing GLOIN, a predictive tool for thermal stress on buried cables, for National Grid’s engineers and planners.

Software modelling of cables in tunnels

With the rise in renewables and the decommissioning of several coal and nuclear power stations, electricity infrastructure in the UK is undergoing a rapid transformation. Several additional trunk routes are under development, including a number of new tunnels currently in the planning stage. To assist with this process, National Grid Asset Engineering commissioned the University of Southampton (UoS) to develop a model of the thermal properties of cables in tunnels and asked OCC to turn this research into a usable product. OCC had already developed the GLOIN tool for buried cables and an enhancement to the existing software to include this additional laying environment was the obvious choice.

The determination of thermal properties of cables in tunnels, and therefore of the load that can safely be carried (the cable ‘rating’), is a complex problem. Tunnel geometry, patterns of air flow and other heat sources have significant effects. RoCiT, the new module for GLOIN, allows National Grid to build a model of a tunnel that incorporates all these factors and calculates steady state and transient ratings for a variety of routine and emergency scenarios.

With this information, National Grid Asset Engineering can advise on tunnel construction and on the safe and efficient operation of the network.