Dorsey Station powers Manitoba and beyond

Hey there, time traveller!
This article was published 20/11/2017 (2952 days ago), so information in it may no longer be current.

Anytime you switch on a light or turn your oven on, you are using electricity coming from Dorsey Converter Station in the RM of Rosser.

The Manitoba Hydro station sits on about 33 hectares of land adjacent to PR 221. Driving past, you can see part of the huge network of towers that bring in high voltage direct current (HVDC) from five hydroelectric generating stations along the Nelson River in northern Manitoba. The HVDC is converted into alternating current at Dorsey Station, and then distributed across the province and, depending on market conditions, to inter-connecting systems in Saskatchewan, Ontario and into the U.S.

A map hanging in the lobby of Dorsey Station’s main office building shows how the station links up with electrical systems as far south as Texas. This allows power to be exported when market conditions are favorable.

Dorsey’s department manager Tim Navitka said Dorsey supplies about 70 per cent of Manitoba Hydro’s total electrical output. The station usually runs at maximum capacity during the winter’s peak heating period.

“We’re pretty close to 100 per cent capacity,” he said. Manitoba Hydro’s Riel Converter Station, now under construction in the RM of Springfield, will add capacity as it links to the new Bipole III transmission system.

Built in 1968, Dorsey Converter Station was named after University of Manitoba professor John Dorsey, who taught electrical engineering from 1912 to 1952 and was well known for his work on the transmission of electricity. The first transmission to Dorsey Station came from the Bipole I system in June 1972. Bipole II was completed in May 1985.

The Nelson River HVDC transmission lines accommodate two bipolar transmission systems called Bipole I and Bipole II. Over 4,100 steel towers that average 38 metres in height and are placed in two lines carry HVDC to Dorsey over a distance of about 900 kilometres. The Bipole I line starts at Radisson Converter Station in Gillam while Bipole II begins 42 kilometres northwest at Henday Converter Station.

“You can see the transmission towers located close to Highway 6,” Navitka said.

This huge network is regularly inspected and maintained by Manitoba Hydro staff who use aerial surveillance and specialized vehicles to reach the towers, some of which stand in isolated areas in northern Manitoba. Navitka said a lot of the maintenance is done in the winter months as travel is then easier in northern Manitoba.

According to Manitoba Hydro, direct current is used for long distance transmission is because it offers certain advantages over alternating current. These include less energy loss and a lower cost for transmission line construction.

Dorsey’s HVDC switchyard directs the current to valve halls in converter buildings that stretch for over a quarter of a mile housing equipment manufactured in England and newer equipment from Germany. The valves switch on and off to convert direct current to alternating current.
Navitka said the valve arrays at Dorsey are connected to the floor because, unlike locations in other parts of the country and world, Manitoba is unlikely to experience an earthquake that could damage the equipment. However, the Riel Converter Station will follow the modern technique of suspending the valve arrays from the ceiling.

This type of valve system is also used to convert electricity from solar and wind-powered sources, he said.

A second switchyard contains 12 230-kilovolt lines that serve Manitoba customers and connect with systems in Saskatchewan, Ontario and the U.S. Another 500 kV line serves the U.S.

Navitka said Manitoba Hydro exports power when there is an excess supply within Manitoba and demand and price merit it. There is no way to store excess electricity.

While the huge transmission towers appear to be highly resilient, Navitka said, in 1996 a sudden burst of high wind toppled two towers at once, leaving transmission lines lying across Highway 6 and disrupting the entire Manitoba Hydro network for about a week.

More recently a farmer was baling hay on land next to a hydro tower when he accidentally backed into the tower and damaged it.

The new Bipole III HVDC line will reduce risk within Manitoba Hydro’s system, Navitka said.
Much of the equipment at Dorsey Station is showing its age. Navitka said staff are trained to be able to repair the equipment and will continue to do so as long as parts are available.

In 2000, 112 people worked at Dorsey and that number has decreased to 82. Navitka said some of these employees will spend part of their work week at the Riel Station when it opens next spring.

Dorsey Station has its own fire and emergency crew, but it works in conjunction with the RM of Rosser fire department that has its fire hall just up the road from Dorsey Station’s entrance.

Navitka said employees can eat at a cafeteria run by a private contractor. There is a system in place to keep employees housed and fed if they are storm-stayed.

“We once had staff stuck here for three days,” he said.

The RM of Rosser has benefited from taxes paid by Manitoba Hydro for Dorsey Station and other properties within the municipality. The 2017 Rosser financial plan shows that approximately $532,000 was levied in taxes.