Western Power Distribution trials smart auto-reclosers on GB networks

Network operator Western Power Distribution demonstrates detection of multiple auto-reclose trip events, opening the way for incentivised reductions.

The initiative undertaken as part of the OHL (overhead line) Power Pointer project has delivered a sensor-based solution offering centralised recording of circuit breaker trip operations and short interruptions.

This is likely to be particularly useful for older switching equipment, which is not connected to a SCADA network, and a key for boosting network visibility.

Rural overhead feeders are susceptible to intermittent faults, such as can be caused by tree branches or cracked insulators with resultant interruptions to customers.

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Estimates are that up to 80% of interruptions on Britain’s distribution networks are short, lasting less than three minutes.

With the rural nature of its customer base, Western Power Distribution was experiencing a significant number of temporary faults along its feeder and spur lines. In turn these often created permanent outages, requiring the dispatch of a repair crew and increased operation and maintenance costs.

Reducing short term interruptions

The goal of the project, which was launched in 2019 and ran through May 2022, was to reduce the number of such interruptions with circuit breakers with auto-reclose sequences, with their potential to detect transient events of short duration and to help prevent them from becoming permanent outages.

The solution implemented in a clip-on sensor for overhead lines – named the ‘smart navigator’ – was deployed at several locations on Western Power Distribution’s networks and comprises a counter system to record circuit breaker trip operations on a per phase basis. Transient (and permanent) faults are captured in a series of additional counters, where a fault event (overcurrent, or earth fault) results in an incremental change to the counter for each compromised phase.

In addition to the individual counters which record activity on a per phase, there is a logic sequence which reviews the events and increments counters on a per set (all three phases, i.e. per circuit) basis, thereby reporting short interruptions and permanent interruptions ‘per incident’.

The findings of the field trials demonstrate that the detection of auto-recloser operation has been successful across multiple trial locations, the utility states in its final report. Some technical irregularities were discovered in algorithms for the recording of faults in the transient and permanent fault counters, which will be updated in an ‘over the air’ firmware upgrade.

The OHL Power Pointer project was funded by Ofgem through its Network Innovation Allowance mechanism to trial a device capable of self-powering operation and providing real-time voltage, current, directional power flow, conductor temperature and fault activity information.

Western Power Distribution concludes that the technology readiness level (TRL) of the auto-recloser detection solution increased from TRL5 to TRL7 over the course of the project. Further, it could be used to support the delivery of a regulatory mechanism for incentivising reductions of short interruptions – the lack of robust data across all the network operators preventing an introduction so far.