The energy network transition will require more agile, flexible and interconnected networks underpinned by reliable communications networks in particular where services for protection and control are concerned. Operational fibre optic networks are reaching an age where some of the equipment is starting to fail whilst other parts of the network are intact and may be able to provide significant further service life. This project will examine enhanced optical sensing methods to detect and track the ageing process of fibre optic cables and associated fittings with the aim of providing accurate health information and the capability to forecast failures. The research will include new optical sensing methods as well as new algorithms to interpret the data and correlate to other data sources.
Benefits
The fibre health monitoring project will deliver benefits to consumers via two value levers. The first lever concerns the avoidance of in-service failures. Based on recent events and asset data from the last 27 years, fibre optic cables tend to fail at a given rate which is likely to increase with age. On average an in-service failure will lead to service depletions and causes constraint costs to consumers as well as repair costs. On average such an event will cost £500k and the probability of such an event occurring will increase with asset age until the asset is replaced and the likelihood of failure is reset.
The second value lever concerns extended lifetime of fibre optic assets. By monitoring asset health the average useful lifetime of fibre optic cables can be raised from 40 years to 45 years. Delaying replacements and only replacing the assets that have got a high likelihood of failure will provide significant savings.
If successful, it is assumed that the new sensing technology could be available on the market within the next 2 to 3 years. The cost of a rollout on the NGET network is estimated at £2.4M.
Based on the modelling of likelihood of failure and extended asset life whilst considering the project cost and rollout cost the Net Present Value (NPV) of this project, shows a benefit of £2.9M. The benefits will reach consumers in terms of reduced constraint costs and reduced funding requirements for the ongoing provision of a secure and reliable operational telecommunications network.
Learnings
Outcomes
The trials are set to continue for the next few months, thereafter we can determine how the data from the sensors correlates to the environmental conditions.
Year 2023/2024
Supplier – EXFO
The main achievements were focusing on the behaviour of individual events on the network (and not just overall loss on the fibre route) and to model their behaviour over time. Instrument loss at the splice/macrobend event level and not only overall link level and have a system that can identify existing (and new arriving) connectors splices, macrobends in the system as they are detected. Early successes in the project were deployment automated correlation scores between loss events and all possible external metrics, determining which ones were affecting the loss signals, and to score this automatically. This allowed us to identify particularly sensitive macrobends in the system to temperature, and to triage these automatically using the automatic execution of the correlation model, and an automatic execution of the results report.
Later in the project the impact of weather events was detected such as storms on the behaviour of individual events on the OTDR traces from the network. This showed that the fibre system can undergo state changes from steady loss to degradation over time in quite short periods of time. With us automating the scoring of such changes in gradient of degradation, we were able to localise individual segments of fibre for repair.
Supplier - ADVA
Site testing and final report will be presented for the completion of the project. However, discussions have started for a possible follow-up project which would include a next round of testing in Q4 2024 / Q1 2025 and would address a range of new applications/use cases.
Recommendations for further work
Year 2023/2024
Supplier – EXFO
Recommendations will be discussed.
Supplier - ADVA
Recommendations are being made to implement asset management. This will enable predictive maintenance, bringing the sensing concept developed from a demo to a product state and tailoring the AI-based event detection to National Grid use cases. The goal will be to realisze autonomous detection of events and to provide accurate geographical localiszation of these events in a Geographical Information System
Lessons Learnt
Year 2022/2023
Results to date were inconclusive at this stage. Lessons learnt will be collated at the project completion stage.
Year 2023/2024
Supplier – EXFO
A combination of long term OTDR event analysis, not just at overall fibre loss level i.e., between transceiver and transceiver, but on individual points on the OTDR trace data is required. The loss data from every loss event on every route needs to be captured, and there can often be hundreds of these along each route. As these events change in amplitude loss over time, they can be modelled and correlated with other metrics.
Often the focus on fibre health projects to date have not been on the individual event loss data over time from every splice, connector, macrobend but only on overall loss. By looking at individual event behaviour it’s possible to localise where you need to fix, and when.
Other sensing techniques can be applied also looking for vibration sensing along the routes, or physical tampering with the fibre or connectors/splices.
Additional advanced localisation of polarisation mode dispersion events (i.e., where circular fibres are crimped) can be used periodically using specialised OTDRs. We recommend that this is not carried out continuously but on a periodic basis.
Supplier - ADVA
There are a range of findings learnt from the project so far. In the first trial, one of the findings was that while a coherent OTDR can accurately see phase variations across the fibre, it is not very effective in measuring temperature and stress. As such, the measurement concept was extended in the second trial to include specific measurements for temperature and stress.
With the second trial it is possible to identify locations with increased stress on the fibre. The measurement unit provides the distance from the measurement device to the location. However, to find out the geographical location of the fault one needs to correlate the measurement data with geographical data. The fibre has sag and in addition wrap around fibre has a helix factor from the wrapping. These need to be considered to provide accurate geographical information. This is an aspect that will be reviewed more closely in a possible follow-up project.
Dissemination
Year 2022/2023
As the project was in the field trial phase, dissemination is planned once further project progress has been made.
Year 2023/2024
Supplier – EXFO
CIGRE Presentation made in 2023
Project showcased at the Liverpool Energy Innovation Summit NGET stand.
Supplier - ADVA
No dissemination recorded at the moment.
