High-ohmic earth faults triggered Corona inspection
Dala Energi has been a customer of dLab for many years, where the collaboration is characterized by an open and close dialogue regarding making the power grid smarter, a transition where technology and quality management interact. Among other things, Dala Energi was a pioneer in using the hardware-independent solution from dLab that analyses disturbance information from existing protection relays in the primary substation.
At dLab we are keen on collecting and sharing how our user community are benefiting from the installations they have. Over the years, it has become apparent that especially the high ohmic earth faults detected by the dLab system play an important role in detecting imminent problems with assets. And we have repeatedly reported successful results, and this case is yet another one.
Unplanned maintenance activities are costly and in many other ways unwanted. By working proactively transforming tomorrow’s unplanned outages to a planned maintenance activity today can not only save money but is a matter of workplace safety and customer satisfaction.
There are of course many incidents that are impossible to foresee such as thunderstrikes or sabotage, but there are many situations where it, in-fact, is possible to detect early warnings of imminent problems. In particular degrading components and other assets in the power grid.
How did Dala utilize the dLab information?
In May 2022, the dAnalyzer in dLab’s dInsight Analytics Platform started to indicate high-ohmic earth faults in a feeder in one of the primary substations. A recurring event that eventually caused Dala Energi to start investigating further. As they are using a ring distribution system, they could start moving loads to an adjacent feeder and track the movement of the earth fault, leading to a quick identification of the affected section of the feeder. As a second step, Dala Energi decided to do further inspections of secondary substations in the identified section with the help of a portable PD measurement device.
In one of the substations with four feeders, PD activity was detected on the busbar insulator, which was replaced together with a few other components. After this action, the recurrent faults disappeared.
“It feels safe to know that dLab’s system constantly supervises our grid reliably and notify us when something is deviating from normal. In this case we could with a few actions quickly pin-point the problem for further investigation, which in turn led us to a proactive component replacement before failure happened”, says Hans Fernlund, grid engineer at Dala Energi.
One of dLab’s major focus is to help DSOs to optimize their outage management strategy. And one step in this direction is the upcoming grid health index that will further assist in enabling a proactive maintenance work and investment need identification.