The Perfect Storm

What happens when an aging distribution network meets a season of particularly nasty weather? This is the story of how one northern European country is solving the problem.

Despite being one of the world’s most technologically advanced nations, Finland’s distribution network is both varied and aging. It’s a problem that’s shared by many nations.

But Finland’s situation is particularly acute. Finland is Europe's most heavily-forested country, where 23 million hectares, or 74 percent of the nation, is covered by trees.

Network meets storm

It wasn’t just one terrible storm. There were four: Asta, Veera, Lahja, and Sylvi all took their toll on the countryside in the summer of 2010.

Finland suffered record warm temperatures, including a new national temperature record of 37.2 degrees Celsius set on July 29. Ground flashes were counted at 170,000, exceeding the long-term average by 30,000.

“In a nation of forests, storms mean fallen trees, and these storms felled over eight million cubic meters of trees,” says Jouni Siniranta, Sales Director for Ensto Utility Networks in Finland. “And for citizens of Finland, fallen trees mean electrical outages.”

An aging network

Finland covers approximately 338,145 square kilometers, making it roughly the size of California. The nation is served by 77 electrical distribution companies, with consumer bases ranging from 757 to 460,000 customers.

Ensto’s Siniranta, who’s worked with Finnish distribution companies for over 20 years in planning, maintenance, and construction, says some regions of Finland have close to all of their electrical cables underground and protected. “But others have most of their cabling in overhead lines, which cut right through the middle of forests, the most susceptible areas during a storm.” And the overhead lines are supported by aging poles, part of the network installed from 1950 to 1970. Downed trees break both lines and poles.

Finland’s 2010 summer storms caused significant outages. Over 35,000 kilometers of distribution network was damaged, and repairs required nearly 200,000 working hours. Due to widespread and large scale damage, the longest outages lasted a full thousand hours, or 41 days.

In 2011, Finland was pummeled by winter storms Hannu and Tapani. Although after the storms most in Finland had their electricity restored in a timely manner, the government of Finland knew it could not stand idly by.

The Electricity Market Act

In 2013, Finland updated its Electricity Market Act, with a focus on the security of supply. The new law included transitional provisions to connect consumers to a weatherproof network that by 2029 no customer in a populated area will be without electricity for more than six hours. More rural areas may not go without electricity for more than 36 hours.

Finland’s 77 distribution companies have selected a variety of compliance strategies. Some have chosen to move from using overhead lines to underground cables. Some are moving substation-to-city lines underground, and remove overhead lines from the center forests to place them roadside where they’re more easily protected and serviced.

The solutions for total compliance with the law will cost close to nine billion euros by 2029.

Towards a smart grid

The new law has another benefit, as well. As long as lines are replaced or updated, intelligence may be added, allowing those connected to participate in the smart grid.

Today, any household can be equipped with a remote-readable smart energy meter. It enables better information about electricity consumption and quality. At the same time, it allows a homeowner to participate in small-scale electricity production which can be sold to the electricity company.

Electricity companies, in turn, are able to balance the load on the power grid, thus enabling the most trouble-free supply of electricity for special events. Also, power grid transmission capacity can be optimized by means of the smart grid.

Ensto’s role: Helping companies comply

Siniranta says Ensto’s role is to provide solutions that help distribution companies make cost-effective investments for the long term, which meet both legal and consumer requirements.

“One quick and efficient solution is to increase automation points and power electronics in the existing distribution network,” he says, “and at the same time build underground cables. We also offer solutions for live line work, allowing work to be done without interruption in electrical service.” In addition to products, Ensto provides Ensto Pro training and certification for installers.

“Ensto has world-class processes, including extensive product testing before anything makes it to market,” says Siniranta. “High-quality products and their proper use ensure a high quality and reliable distribution network that can withstand the beatings of storms.”

Preparing for the future

Finland’s situation with an aging network is certainly not unique, though indeed the nation’s heavy forestation forces it to confront its problems faster.

“Given climate change,” says Siniranta, “we may expect more severe storms wherever we’re located. And in a society that runs on electricity, it’s our responsibility to prepare.”

How to measure an outage

Finland’s energy authority tracks outages with a key index called SAIDI, the System Average Interruption Duration Index, which measures the total duration of interruptions for a group of customers.

SAIDI is composed of two indices, CAIDI and SAIFI, respectively the Customer Average Interruption Duration Index and the System Average Interruption Frequency Index.

The indices serve as valuable tools for comparing electrical utilities performance reliability. Nordic authorities have adapted SAIDI/SAIFI criteria to monitor electricity distribution in their markets, and Ensto solutions are developed to improve SAIDI and SAIFI indices.

Underground networks


Author: Scott Diel