Remote wind power generation creates challenges for the electrical transmission system. Developing a transmission system plan robust enough to accommodate the scattered locations of wind interconnections required new lines for power transfer.
The rural, treeless plains of southern Alberta, Canada, epitomize the perfect breezy locale for a wind farm. And in Alberta, there’s no lack of interest in wind generation development. The Alberta Electric System Operator (AESO) has received requests for 11,500 megawatts (MW) of wind power interconnection, 7,500 MW of which is spread across the province’s southern region. However, the archetypal rural location of southern Alberta has fewer power consumers than its urban counterparts and lacks the transmission system needed to transport the potential surplus power generation to load centers in Calgary, Edmonton and beyond.
AESO is currently connected to 500 MW of wind power, all from southern Alberta, and forecasts that wind generation in the province will increase to 2,000 MW to 3,900MW within the next 10 years — 1,700 MW to 3,200 MW of which is anticipated in the southern region. In order to accommodate this growth in wind generation, AESO turned to Burns & McDonnell to develop a comprehensive 10-year transmission plan.
“Our challenge for this project was to develop a transmission system plan robust enough to accommodate the scattered locations of wind interconnection requests, flexible enough handle a potential fivefold expansion and cost-effective enough to start implementing now without overbuilding,” says Feuerborn.
Burns & McDonnell compiled a team of experts to contemplate a range of transmission system arrangements that would meet Alberta’s needs now and in the future. One alternative considered was the installation of direct current (DC) transmission lines parallel to existing alternating current (AC) lines. DC transmission would allow Alberta to transfer a set amount of power to specified locations that can use southern Alberta’s surplus wind energy. But considering that all wind interconnection requests won’t come to fruition, the current size of Alberta’s transmission system and the cost of DC technology, this alternative becomes economically unfeasible.
The solution that AESO proposed to its stakeholders and that Burns & McDonnell found to best meet Alberta’s transmission needs is a 240-kV looped system implemented in stages. The looped system involves stringing double-circuit towers with a single-circuit 240-kV AC transmission line until the second 240-kV circuit is required by newly constructed wind generation. This approach avoids additional land impact, has the flexibility to accommodate the uncertain size and location of wind generation in the province and leaves room for future expansion. With this system, AESO will be able to economically interconnect with the 2,700 MW of new wind generation in southern Alberta by its target date in 2017.
The first stage of the 10-year, $1.83 billion transmission system plan — a $750 million, 1,700 MW system expansion — will progress once regulatory approvals are obtained. The second and third stages will remain on hold until Alberta’s wind power needs exceed the capacity expansion from stage one.
“Integrated transmission planning can be even more effective if it spans jurisdictions of electric councils, states, provinces and even nations, connecting us all,” says Kiah Harris, Burns & McDonnell Business & Technology Services Group principal. “We need one integrated plan for the transmission grid similar to how our administration planned the national highway system. The competing interests of stakeholders will always be a barrier to such holistic transmission planning. But an independent consultant, like Burns & McDonnell, without a vested interest in the politics of crossing jurisdictions could create a situation where we all benefit.”
For more information, contact Scott Feuerborn, 816-822-3907.