Each system could prevent over 6,000 customer minutes lost per year
A 22-month trial on 240 km of MV cable, and the business case that took Alliander from 64 systems to a planned 3,000.
Faults located to within 1% of monitored cable length, often far closer
Nine partial-discharge outages prevented, avoiding over 400,000 customer minutes lost
An estimated 6,150 customer minutes lost prevented per system per year
About Alliander
Alliander is one of the largest network operators in the Netherlands, serving more than three million customers through an 87,000 km cable network — around 40,000 km of it medium voltage.
The challenge
A fault anywhere in that network can leave hundreds of thousands of people without power, which is disastrous for them and for the business. Alliander was interested in anything that could reduce cable-related outage time.
The company had followed the technology for more than ten years while its performance and capabilities improved. The arrival of a new generation with a fault-location function was what took it, in Alliander’s words, to a different level — and made a trial worth running.
Our contribution
Sixty-four systems were installed across 240 km of the MV network for 22 months. They went in at various places on the network to monitor different lengths and types of cable, often covering more than one cable section, watching for breakdowns, intermittent faults and the partial discharges that indicate a weak spot.
The benefits
Problems were located to within 1% of the monitored cable length, and often far closer. A breakdown in a 3 km cable was placed within 9 m; the repair was carried out in the standard way, but Alliander estimated that acting on the data directly would have saved almost 15,000 customer minutes lost — a reduction of about 25%.
In another case a series of intermittent faults in a 4 km cable was pinpointed to within 3 m, under 0.1% of length. The section was isolated and switched off, and it broke down on testing. Alliander estimated that fault alone saved around 21,000 customer minutes lost.
Intense partial-discharge activity was identified in a joint on a 13 km cable running between a windfarm and a substation. The joint was replaced and the activity stopped. Across the trial Alliander believes nine partial-discharge-based outages were prevented, avoiding more than 400,000 customer minutes lost.
On that basis Alliander estimates each system could prevent an average of 6,150 customer minutes lost per year — and that is the direct saving only. Because weak spots are identified, parts can be analysed before they fail, which helps develop counter-measures against the next problem. Having seen the impact on SAIFI and SAIDI, Alliander planned 400 systems in the first year, rising to 3,000 across its MV network.
“Reliability is essential for any network operator. Alliander believes that SCG will play a major role in our efforts to continually set new standards for quality of service for our customers.”
Originally published as a DNV case study.
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