Elering sets all-time low for number of failures in power grid

The electricity transmission network administered by Elering experienced 86 outages last year, which is the lowest figure ever.

Elering has achieved a significant reduction in the number of outages of transmission system equipment in recent years. In 2017, there were 117 such failures, and a year before that, 100. The average number of annual outages due to failures in the period 2007-2018 was 174.

“What is noteworthy is the fact that for the first time, we did not have a single failure due to trees falling on transmission network lines in bad weather. This shows that the intensive line clearance trimming project that spanned several years has borne fruit,” said the chairman of the Elering management board, Taavi Veskimägi.

The greatest number of outages last year – 12 – was caused by thunderstorms. The next most frequent cause was bird and other animal activity, ageing of equipment, human error and contaminant build-up on insulators.

Another significant indicator that characterizes the reliability of the power grid is the amount of energy not served. Energy not served to consumers as a result of failures was just 18.5 megawatt-hours. This is a very small quantity compared to the total volume of electricity transmitted. “The amount of energy that was not transmitted during the year was a mere 0.000225 per cent of the power that did flow through the lines. It is similar to the amount of energy used by two homes with ground-source heat pumps over a year’s time. Only in 2015 was the figure lower. The average for the last 10 years is 145 megawatt-hours,” said Veskimägi.

The ageing of equipment had the greatest impact on energy not served. Production errors, installation and configuration errors, errors in construction or maintenance and birds and other animals were among the other causes of such failures.

Last year, uptime for the Estonia-Finland power connection EstLink 2 was 98.45 of all hours in the year. The same figure for the older EstLink connection was 92.66 per cent. The availability of EstLink 1 was affected by a November failure in the Espoo converter station in Finland, which took 21 days to repair.