Keeping the lights on

Two weeks ago, a widespread power outage impacted half of our membership. Approximately 30,000 members in our core areas of Palmer and Wasilla lost power during rush hour. What was the cause? A tree made contact with one of our transmission lines between the Eklutna hydroelectric plant and Palmer substation, creating a surge that tripped off two of our major substations and seven additional substations in between.

How can one tree have such a large impact? Here is how.

In other grids throughout the developed world and in the Lower 48, a tree through the transmission line would not have had such significant impact. What’s the difference? Unfortunately, the reliability and redundancy of our electric infrastructure in our service area is inadequate for the new demands we all place on it.

When MEA’s system was originally constructed, there was probably 10 percent of the population served as is now on the system. There are only two sources for MEA’s power — the Teeland substation on KGB Road, carrying power from Chugach Electric, and the Eklutna hydroelectric link, following the Old Glenn Highway. Any disturbance on either connection will overload a part of the system, and the protective systems will intervene and shut off the load.

Similar to the fuse box in your house, upon interruption, substations must each be re-energized. This is what happened to the system during last week’s outage. Fortunately, power was restored fairly quickly. Members near Palmer and Butte had to wait longer while the transmission line was repaired before the line and substations could be re-energized.

The majority of our infrastructure was built between 1940 and 1960, when MEA’s load was significantly less than it is today. Now we have more than 4,000 miles of lines and other infrastructure that were designed and built to serve a fraction of our growing load.

To decrease our vulnerability to such outages, MEA must bring our system up to standards that will allow us to deliver power with high reliability and redundancy. Here are a few things we are planning:

Looped vs. Radial Design

Systems with fully developed electrical networks are traditionally created in loops. So if a section of the loop is damaged, it can be isolated and the power replaced within moments by isolating the damaged area and feeding power from the other side of the loop. The majority of the MEA service area is equipped with long radial feeds (single lines of power). When a section is damaged, it simply cuts everyone off beyond that segment until repairs can be made. Creating looped circuits will decrease our vulnerability and outage inconveniences.

Redundancy

Each substation must handle its own peak load plus that of an adjacent substation. This allows a section of line or an entire substation to be taken offline and the corresponding customers switched to a different power source if repairs are required or substation capability exceeded. Currently, many of our substations are unable to achieve these basic criteria as the number of members and our power demands have outgrown our aging infrastructure.

Alaska Railbelt Cooperative Transmission and Electric Company

MEA and our partner Railbelt utilities recognize these shortcomings in our system. Individually and through the Generation and Transmission coop organization, Alaska Railbelt Cooperative Transmission and Electric Company, we have plans to improve how we deliver power. Just like roads, airports, schools and other public infrastructure, our grid system is the electric highway that must grow to meet the demands of our businesses and homes.

We at MEA know that very few things are as important to our members and the economic vitality of the Valley as reliable, sustainable and economical energy. It is our mission to do that for you.

Joe Griffith is general manager of Matanuska Electric Association, and President of the Alaska Railbelt Cooperative Transmission and Electric Company.