Electricity transmission network reliability remains high in 2017

Reliability figures for the Elering-managed electricity transmission network in 2017 were considerably better than the average of the targets set in recent years.

There were 117 outages on the transmission network last year. In the previous ten years, the average annual number of outages was 193.

The largest number of outages in 2017 – 42 – were caused by environmental conditions, vegetation, and lightning. There were 29 trips caused by equipment malfunction, 15 due to errors caused by staff, and eight connected to other human-related activities.

Only 44 megawatt-hours of electricity did not reach clients due to malfunctions. This amount is equal to the average annual consumption of approximately four private houses. The average figure of undelivered energy for the previous ten years is 150 megawatt-hours per year, and last year’s figure is less than a third of this.

Nearly half of the undelivered energy was due to a single event, the tripping at the Volta substation in Põhja-Tallinn, which was caused by the combination of several problems.

Reliability, the internationally used indicator for electricity network reliability assessment, was at its highest level ever last year in the Elering grid: 99.9999994 per cent, or, in other words, only 0.0000006 per cent of energy was not transmitted to customers throughout the year.

The year 2018 has also started well in terms of reliability. January’s windy weather has not caused any outages in Elering’s transmission network.