Monitoring the national electricity grid Engineers at National Grid’s National Control Centre in Wokingham are responsible for balancing national supply with demand on a minute-by-minute basis.

This requires not only constant monitoring of each circuit but live calculation of the capacity of the grid, ensuring it stays within operating limits.

OCC has been supplying National Grid with modelling software to calculate the capacity of critical components in the network since 2000. Now it has implemented the Circuit Thermal Monitor, which is used by the National Control Centre to constantly monitor critical circuits, calculating capacity and raising alarms if a circuit approaches its thermal constraints. National Grid maintain a public record of the constraints on the national electricity system and what they cost.

National Electricity grid

From design to go-live

Work on the Circuit Thermal Monitor started in 2006. OCC consultants worked with National Grid IT and engineering staff to capture requirements and resolve the high-level design. The software needed to be compatible with the National Control Centre infrastructure. An additional challenge was that the project team had to develop and deliver the new software as part of a larger Control Centre upgrade by General Electric. This necessitated close working with GE staff in Shanghai and Florida to ensure compatibility both in implementation and project milestones – this was a project that could not slip.

From 2007 to 2009, the OCC team designed, developed and tested the software that models the changing temperatures and electrical capacity of critical components, most importantly transformers and cables. In autumn 2009, the integrated system went live and the Circuit Thermal Monitor was operational.

The Circuit Thermal Monitor is implemented in C++ and Fortran and runs on a Unix platform.

The Circuit Thermal Monitor in use

Today, the engineers responsible for managing the national electricity supply can see up-to-the minute calculations of the capacity of circuits on the grid, identification of hotspots and an indication of the time available to resolve potential overloading. The Circuit Thermal Monitor performs continuous calculations; should an unexpected failure occur, the system automatically updates the control room with new capacity and time estimates.

The Circuit Thermal Monitor is also used by National Grid’s Network Planning department, where it models how the network will respond in different situations, from emergency management through maintenance planning to future network design. With better tools for modelling, National Grid can undertake more comprehensive planning of the capacity and resilience of the network.