HV faults on the underground network account for a large proportion of unplanned outages, where customers may remain off-supply until the fault is found and repaired unless an alternative network arrangement is used to back feed. To help solve this problem, HV Pinpoint aims to develop a methodology for detection and precise location of pre-fault events in the HV underground network. This solution may be used in conjunction with the Pre-Fix NIA project method to provide a more precise defect location, or as an alternative pre-fault method. The intention of this is to reduce the reliance on test van methods, as well as providing a new solution to more easily retrofit sensor on to existing underground cables. 

Benefits

Reduction of fault management costs through:

• Reduced operational staff time spent during the restoration and location phase of the incident when compared to test van methods.
• Accurate, prompt, validated event location requires smaller excavations and surface restatements to find events
• A reduction of CIs/CMLs resulting in a reduction of IIS penalties incurred.

Improved customer service through:

• Proactive pre-fault management will reduce unplanned outages and customers can be adequately prepared and supported throughout necessary planned works
• A systematic reduction in network operation costs may ultimately be reflected in lower bills for customers.  

Reducing our need for PD Mapping 

An analysis of the potential financial benefits of using the method developed in this project as an alternative to Partial Discharge (PD) mapping was undertaken – this is mainly linked to operational cost savings.  

To quantify this, an estimate for the amount of PD mapping required per year if Pre-Fix was rolled out across the business was derived. This was derived as both a lowball estimate and a highball estimate, to get an idea of the range of benefits this project could deliver.

• For the lower estimate, we have assumed that 376 circuit sections need to be PD mapped per year. This was estimated using data from Pre-Fix to suggest 6% have pre-fault activity.
• For the higher estimate, we have assumed that 1000 circuit sections will need to be PD mapped. This is based on historic fault data from 2021 to 2023.

The project will inform us on the equipment cost, and the operational savings when compared to PD mapping.