Learnings

Outcomes

The project has developed a retrofittable tap changer monitoring system and deployed it on 40 tap changers. The data from the system was collected and analysed.

Analysis has shown that issues with tap changers have been / could have been predicted. The analysis also provided trigger points for ENWL to consider embedding into policy, and provided confidence to the outcomes of existing policy.

The device techniques deployed include both electrical and mechanical (vibration) monitoring which when coupled together can identify several trends and incidents occurring within the tap changer.

The analytics developed for the project have been refined and adapted as the project learning has increased, and as specific tap changer events have occurred.

Towards the end of the project several of the monitored tap changer’s AVC schemes were adapted for inclusion in the CLASS service. The analysis of data collected on these tap changers showed no variance in condition between CLASS and non-CLASS units.

The project has also identified a road map towards a business as usual system. The project learning showed that the type, quality and number of data points and the associated monitoring devices can be modified without impacting system accuracy. This will allow a simpler roll out of the technology across the ENWL fleet of transformers.

ENWL are considering the next steps to full adoption of this methodology

Lessons Learnt

As a general lesson relating to projects collecting new data for analysis there needs to be a recognition that as you increase the volume of data collected and analysed the amount of learning increases. This is because the analysis techniques can be refined and improved resulting in further additional learning. The optimum point for this learning curve can only be estimated at project initiation and some flexibility is required based on the rate of progress being made.

On this project ENWL and our partners believe the additional analysis performed has been beneficial.

Whilst not project specific, the tracking of transformer tap position on certain unit types had occasional issues. This was due to the quality and compatibility of the mechanical contact arrangement within the historic tap changers with the electronic control equipment being fitted as part of modern tap change control systems.