Ancillary Services
Ancillary services (AS) are services required to ensure that electricity can be transmitted reliably, efficiently, and securely across Alberta’s interconnected transmission system.
These services include operating reserve (OR), transmission must run (TMR), black start, and load shed scheme services (LSS).
The AESO is mandated through the Alberta Electric Utilities Act to procure ancillary services. The Act defines ancillary services as follows;
“those services required to ensure that the interconnected electric system is operated in a manner that provides a satisfactory level of service with acceptable levels of voltage and frequency”
The AESO is committed to using a fair, efficient and openly competitive procurement process for ancillary services, whenever possible*
* Note that some ancillary services are location specific and thus only specific generators are considered necessary to provide them.
The Ancillary Services Participant Manual provides an overview of the following ancillary services procured by the AESO's Commercial Services group.
Operating Reserves (OR)
Operating reserves are generator capacity the System Controller can call on or load that can be reduced with short notice to maintain system reliability. This is required when there is an unexpected imbalance between supply and demand due to the failure of a generator or transmission line.
Transmission Must Run Service (TMR)
TMR is generation required to be online and operating at specific levels in particular parts of the Alberta Integrated Electrical System (AIES) to compensate for insufficient local transmission infrastructure relative to local demand. The AESO contracts with generators in areas where TMR is required.
Black Start Services
The AESO contracts for black start service with generators that are able to restart their generation facility with no outside source of power. In the event of a system-wide black-out, black start providers are called upon to re-energize the transmission system and provide start-up power to generators who can not self start. The AESO contracts with generators in areas where black start services are required.
Load Shed Scheme Services (LSS)
Load shed schemes allow the AESO to automatically trip off a large electrical consumer(s) to instantly reduce demand when an unexpected system event occurs. The AESO contracts with large consumers of electricity to provide load shed schemes.