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    Transmission Must-Run service

    Transmission Must-Run (TMR) is generation that is required to be online and operating at specific levels in parts of the province's electricity system to compensate for insufficient local transmission infrastructure relative to local demand. TMR is used to ensure reliability until adequate transmission infrastructure is built in that local area.

    Given the location-specific nature of TMR, only specific units in Alberta may be required to provide TMR. The AESO may enter into a contract with these units when long-term requirements for TMR are identified.

    TMR resources

    In order to compensate for the effect that TMR generators may have on pool price, we use a service called Dispatch Down Service (DDS) whereby eligible generators receive a payment for reducing generation levels or dispatching off in proportion to the amount of TMR online when the system marginal price is less than a TMR “reference price." ISO rules Section 204 provides a detailed description of DDS.

    Compensation for unforeseeable TMR 

    When the AESO directs a market participant to provide TMR and a market participant does not have a contract with the AESO to provide the service, then the amount paid as compensation is determined in accordance with section 8 of the AESO tariff.

    In order to receive compensation, the following documents must be submitted to the AESO ( on a timely basis:

    (1) Customer invoice

    a. Indicating the date of the Unforeseen TMR event

    b. Submitted by the legal entity owning the generation that provided the service   

    (2) Calculation spreadsheet (Excel format)

    a. Deemed  values will be used unless necessary supporting material is provided to justify use of actual values

    (3) Signed Officer’s Certificate