The challenge
The advent of new technologies, such as electric cars and heat pumps, is rapidly changing the UK's demand for electricity. Much of the current distribution infrastructure was created in the 20th century and was designed with a very different usage pattern in mind. Increases in demand can cause problems including the overheating of assets such as transformers in substations. This is in turn can lead to reduced lifetimes and, potentially, catastrophic fire damage.
As demands on the network increase and move from peaks and troughs to round-the-clock, electricity distributors need to ensure that their infrastructure is robust and reliable.
The solution
NPL embarked on a project to help Electricity North West (ENWL) and Ricardo Energy develop a sensor-based monitoring and analysis tool for use in substations.
The sensors were deployed in substations across ENWL’s area and the analysis tool was developed by Ricardo Energy. NPL used the captured data and substation information within a physics-based model to simulate various scenarios such as weather and load on the transformer. This data was used to create finite element models of the air flow and temperature distribution in six substations identified as either 'typical' or 'special' by ENWL. The models allowed NPL to provide guidance on the placement of vents and the deployment of other cooling technologies to ensure that substations could operate in all weather conditions and under a range of transformer loadings.
Initially NPL analysed a single snapshot in time at each substation, taking the measured data from some of the sensors and using it to predict the values expected from other sensors. This enabled us to make observations about the standard vent placements and how they could be improved.
The second stage of the project used a more complicated model to analyse how the temperatures in a substation varied over time. This helped to understand how the airflow, the load on the transformer and the air temperature could combine to affect the surface temperature of the transformer. This led to informed suggestions for changes in ventilation approach.
The impact
The work identified that reducing solar heating and increasing the amount of ventilation would improve the thermally-driven air flow within various types of substation buildings. ENWL has altered some of its substations in line with these recommendations, as part of a retrofitting campaign, and will continue to follow them for any new build projects. The project is currently gathering data to demonstrate the improved performance.