National Gridâs cable tunnel network is a vital component of the power transmission grid within the London area, with the length of cable installed in tunnels scheduled to increase significantly in the coming decades. In order to achieve the required circuit ratings for tunnel cable installations, a degree of forced cooling is necessary. Typically this is achieved through the installation of large ventilation fans to force air through the tunnel network, removing heat generated by the operation of the cable system. Where high circuit ratings are required, very large fans may be specified to provide the appropriate flow rate of cooling air through the tunnel. The maximum emergency rating of the cable circuit can be achieved through operating the fans on a 100% duty cycle, however the costs of such operation (in terms of the electrical power utilised) represent a significant contribution to the OPEX costs associated with the tunnel.
Building on the modelling foundation of the RoCiT Project, this project will investigate the feasibility of advanced ventilation control schemes which will be designed to ensure the minimisation of ventilation running costs while maintaining a high emergency rating on the cable circuits installed in the tunnel. This will involve the further development of thermal models of the tunnel network, along with the analysis of data from operational 400kV transmission circuits.