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    Transmission outages are sometimes necessary for work purposes, and are planned carefully. Our System Controllers manage these outages with an operational plan for different contingencies.

    Each week, the AESO creates a report of planned transmission outages for market participants. The following explains the different kinds of outage reports we create.

    Long-range significant transmission outages

    This report lists outage requests from transmission facility owners (TFOs). While the AESO hasn’t necessarily approved these requests, they still cover a 24-month period beyond the approved outages. With this information, TFOs can coordinate outages between each other, and stakeholders stay aware of what's happening to the grid.

    If the outage request is considered significant, the appropriate TFO must give long-range notice of the request so we can adequately assess and coordinate it. An outage is significant if it affects the following:

    • Transmission facility operating at 240 kV or greater
    • Intertie
    • Element connecting facilities owned by two or more different legal owners
    • Element connecting a generating unit or an aggregated generating facility to the grid
    • Cutplane limit
    • High-voltage direct current facilities
    • The limiting, or reduction, of a synchronous condenser, static VAr compensator, static compensator or other similar dynamic device

    A transmission outage may need adjustments to generation, either more or less, to maintain reliable system operation. If so, the adjustments to generation typically happen in the hour before the scheduled transmission outage, and in the hour after the element returns to service.

    View the long-range outages report.

    Approved outages

    After approval, the TFOs receive a report on their outages. Updated on Wednesday, it includes all transmission outages 69 kV or greater approved by us for the following operating week (Saturday to Friday).

    View the approved outages report.

    24-month supply and demand graphs

    Updated on regular business days, these graphs show the available supply compared with expected demand over a rolling 24-month window. You’ll see information on forecast load and required reserves, and supply which includes scheduled generator outages, reductions to intertie capabilities and derates (including those from transmission outages). This information helps market participants plan for generator and intertie outages.

    View the 24-month supply and demand graphs.

    Daily outage, monthly outage and seven days hourly available capability reports

    These reports show outages and availability for generating units. The daily and monthly outage reports use the difference between maximum capability and available capability as submitted by pool participants. The 7 days hourly available capability report calculates availability percentages as the sum of available capability divided by total maximum capability.

    All three reports update at regular intervals as shown by their time stamp. Aggregated by fuel type, the reports don't identify any specific generating unit.

    Read the outage reports here:

    Available transfer capability report

    This report presents the current and anticipated available transfer capabilities for the interties to Saskatchewan and British Columbia. With this information, we create market awareness of Alberta’s import/export conditions. The report covers a period that changes on an hour-by-hour basis, and can go out as far as 13 months.

    View the available transfer capability report.

    For more information on transmission outages and intertie capability, contact Eric Viray, Manager, Operations Coordination, at: