UK Power Networks has an aging transformer population. 61% of all grid and primary transformers are over 50 years old, which is close to the average expected lifetime of a typical transformer. As per standard practice, the lifecycle of such assets would generally be extended via a combination of close monitoring of asset health and refurbishment. Currently, close monitoring is done through oil samples and periodic external inspections which provides an indication of transformer condition but not a definitive assessment of it’s condition and expected faults.
With the proposed further investment in online condition monitoring solutions through current and voltage variance monitoring faults can be predicted in advance and transformers can be maintained prior to fault occurrence. Several methods and products for condition monitoring are currently available in the market; however, most involve invasive probes. Traditional monitoring equipment requires invasive probes to be submerged in the oil to be able to work. This requires the oil in the transformer to be lowered/drained this therefore disturbs the core and requires a longer outage on the transformer. In addition to being relatively more intrusive, the traditional method implementation costs are significantly higher than our innovative solution.
Objectives
Deliverables:
- To establish if the new technology is a comparable alternative to existing technologies and can be used as a BAU application. If this solution can provide similar results of condition monitoring when compared with traditional monitoring the solution will be more viable as the cost of the solution and ease of installation is a lot cheaper.
- To establish if the technology can detect faults before existing condition-monitoring equipment can detect them.
Learnings
Outcomes
The system was live during a fault on the transformer. Neither the system being trialed or the Dissolved Gas Analysis (DGA) monitors on the transformer picked up this issue. The issue was with a termination on the transformer so not an internal fault which this equipment would be looking for. Although the equipment did not pick up the fault on the termination, it does show that one of the transformers was in worse condition than the other, which traditional oil results also confirmed. Therefore, we are confident this solution:
· Is a good alternative to online DGA monitoring where its installation is not financially viable; or
· Is a good solution as an additional system to compliment DGA monitoring.
However, if this was to be used as an ad-hoc solution, then it would not be financially viable due to the high level of effort required to prepare for implementation into business as usual. The necessary preparations are the same for ad-hoc and wide scale deployment, and as such are too great for ad-hoc implementation.
Lessons Learnt
Transformer Care successfully delivered all targets in the scope as the unit was installed on site and commissioned. However, the project took longer to complete the installation. This was down to a few factors the first being challenging contract negotiations. The second was getting internet connectivity for the device due to the trial site location (underground) and COVID-19 impact. As a result, there are a number of lessons which were learned during the project:
- The project confirmed that the novel monitoring system is cheaper and quicker to install and is a suitable alternative to gas monitoring alternatives. However, the new system is less suitable to identify issues with the oil or tank and more suited to identify issues with the core and windings;
- The project was led by the BAU business unit from start to end, which helped with the day-to-day delivery. This is a suitable way to manage innovation activities;
- Finalising the contract was challenging and led to a significant project delivery delay. The key lesson is to provide the technology provider with early visibility of the NIA requirements in advance of PEA registration;
- Enable more flexible insurance and warrantee values for innovation purposes. Many start-ups or SMEs cannot fulfil our standard insurance requirements;
- Communication clarity – this international collaboration between UK Power Networks and Enging (Portugal) had to overcome differences in ways of working and standards. To overcome these challenges we had to rely on engineering best practice and dedicate more time to the system integration aspects during the detailed design stages. Future international collaboration projects should consider difference in engineering design approaches;
- Data quality – issues with data quality affected the detailed system design, which had to be overcome by undertaking additional work during on-site installation and commissioning;
- Coordination with stakeholders – the selected site is in a busy part of our London Power Networks area. As such, we actively coordinated our site work with the local authority to ensure we avoid disruption to any planned events, such as the 2019 Christmas markets. Future projects should proactively coordinate with the local stakeholders to ensure minimal disruption is caused by any site activities; and
- On-site communication access – the selected site in underground which makes most means of establishing internet access challenging to implement. The selected method was impacted by COVID-19 and an alternative internet connection method was required to overcome the connection issues. This solution should be implemented in sites with good internet connectivity.
