As customer reliance on the electricity network increases, and the regulator places more emphasis on customer satisfaction, quality of supply will become even more important to Distribution Network Operators (DNOs). Customers will be particularly impacted by factors that lead to a complete loss of power, whether this is caused by faults on their circuits or increased demand on the system overloading fuses.
One solution for DNOs is to simply respond quicker to customer complaints, ensuring the time customers are impacted becomes shorter. Although this solution is potentially achievable in the short term, the number of issues that will arise on the network will only become greater over time as more electric vehicles are purchased and heat pumps are installed. Furthermore, analysis of National Fault and Interruption Reporting Scheme (NaFIRS) data has shown that on average across GB up to 50% of faults at the LV level are permanent when they first become noticeable and cannot be remedied by a fuse alone in the first instance . Given this, a reactive approach to fault response impacts quality of supply for customers, drives up operational costs for repeat visits to replace fuses, increases emergency works including unplanned excavations and cause DNOs to significantly underperform against their potential in terms of regulatory measures for Customer Interruptions (CIs) and Customer Minutes Lost (CMLs) . Therefore, the most efficient solution is to take a more proactive approach and prevent the faults from occurring in the first place – easy, right?
It’s well established that most LV faults don’t appear overnight, they tend to develop over a long period of time. Similarly, demand tends to gradually increase on a circuit as time goes on. By deploying monitoring solutions that predict when faults are likely to have an impact, and when demand on a circuit is likely to present a capacity issue, Network Operators will have the foresight and time to address developing problems before customers become aware of an issue. But what does this mean in practical terms for the teams managing the networks on a daily basis?
Traditionally, asset management and operations have been viewed as two disciplines, with the long-term assessment of cables and network health coming under the domain of asset managers. But with the mass deployment of monitoring solutions across the distribution network, we believe asset management and operations will overlap and experience the mutual benefits that LV monitoring can offer.
When we dive a little deeper, we can see historic principles of asset management focused on the age of the asset, with the view that assets typically get worse as they get older. Thanks to advanced monitoring solutions which have been developed to identify the signals of early life faults and cable degradation, we now know this isn’t actually the case. Many old cables have been found to be functioning satisfactorily, with many newer cables degrading at a faster rate.
Early in the stages of cable degradation, fault activity is limited to very low-level bursts of current as sparking between conductors takes place when the right environmental conditions are present. Each burst of fault activity further worsens the conditions of the cable, leading to the slow development of the fault until destructive arcing between the conductors starts to take place and customer supplies are interrupted before the fault eventually becomes permanent. A secondary impact of the arcing activity is that the cable between the substation and the fault is increasingly stressed and then damaged by the high fault currents – leading to further faults on this cable.
Advanced LV monitors such as PRESense , can uniquely identify very low-level fault activity early in the development lifecycle and use this data to quantify cable health, as well as to provide locations on the cable network for these faults. This cable health indexing allows asset managers to target overlay and cable replacements to the sections of the network which are showing poorer health as opposed to the traditional method of simply going by the age of the cable.
With the benefits for asset management teams clear, we now look at the benefits for operations teams. The early life asset prioritisation strategy eliminates the worst-performing cables, therefore easing the future burden on operational teams. Operational teams will have fewer faults to address and, in any case, will know the location of many of these faults before they impact customers.
Despite this, there will always instances of faults developing and degrading more quickly, for example when there has been third-party interference with the cable. Thankfully an LV monitoring solution which identifies faults early in the cycle will also identify these types of faults, allowing immediate action to be taken, therefore reducing the impact on customers.
This proactive management approach is easily in reach for many DNOs with the right LV monitoring strategy and solution in place. Some of our clients have already adopted this proactive approach to network management and are reaping the benefits.
By proactively repairing faults, clients can reduce the time spent off supply by 40-60% significantly reducing the impact on customers. They can gain a 50% increase in operational efficiencies by enabling planned proactive repairs versus emergency excavations. The number of site visits can be reduced by up to a factor of 4 when used as part of a proactive fault repair strategy. Finally, DNOs can gain a 3-5-fold increase in observable faults which translates to a significant increase in IIS benefits.
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