The Alberta Electricity Contingency Reserve is a critical grid management system designed to maintain reliable electrical service across the province by responding to unexpected disruptions to the power system. It is managed by the Alberta Electric System Operator (AESO).
Purpose and Function
The contingency reserve serves as an emergency buffer to restore balance between electricity supply and demand following unexpected events that threaten grid reliability. These events can include the sudden loss of a generating unit, loss of wind generation capacity, an unanticipated increase in demand, or the disconnection of interconnections linking Alberta to neighboring jurisdictions like British Columbia and Montana.aeso+2
The reserve is designed to respond within a critical 15-minute window to restore system balance to its pre-disturbance level or reduce area control error to zero. Real power must be delivered to the interconnected electric system within 10 minutes of receiving a directive to deploy contingency reserves.aeso
Two Types of Contingency Reserves
Alberta maintains two distinct types of contingency reserves that work together to maintain grid stability:rodanenergy+1
Spinning Reserve: This is the fastest-acting contingency reserve. Generators, energy storage resources, or large loads providing spinning reserves are synchronized to the grid (operating at reduced power or no-load state). This synchronization allows the reserve to respond extremely quickly to system disturbances. Additionally, spinning reserves provide automatic frequency support to the system through their governor systems, which dynamically respond to frequency changes.aeso+1
Supplemental Reserve: Unlike spinning reserves, supplemental reserve providers are not required to be synchronized to the grid, allowing them to respond with approximately 10 minutes of activation time. This type includes both generators that can start up quickly and large electricity consumers who can implement rapid load curtailment to reduce demand.aeso+1
Sources of Contingency Reserves
Contingency reserves can be deployed from multiple sources:aeso+1
Supply-side resources include generators increasing their output to the interconnected electric system. On the demand side, large electricity consumers can implement controlled load reduction through immediate demand curtailment. Energy storage resources can provide reserves through either charging or discharging modes.aeso
Procurement Process
The AESO procures contingency reserves through competitive bidding via the Alberta Watt-Ex Exchange (operated by Watt-Ex), a third-party clearing house for ancillary services. The AESO is the sole buyer of operating reserves and determines procurement volumes based on reliability standards established by the Western Electricity Coordinating Council (WECC).aeso+1
The AESO procures reserves based on forecasted requirements outlined in the 7-Day Forecast of Operating Reserves Volumes report, published on the AESO website. The system operator can adjust contingency reserve volumes in real-time based on actual system conditions.aeso
Activation and Response Requirements
When the AESO system controller identifies a contingency event, designated providers receive a directive specifying the required real power quantity and response timeframe. Under normal market conditions, a contingency reserve directive remains effective for one hour, though during abnormal market conditions such as supply shortfall events, directives may extend beyond one hour.aeso+2
Providers must maintain the directed power output at specified tolerance levels—typically within 5 megawatts for smaller generators or loads (≤200 MW capability) and 10 megawatts for larger facilities (>200 MW capability).aeso
Regional Cooperation
As a member of the North West Power Pool Reserve Sharing Agreement, the AESO is obligated to provide contingency reserves to neighboring balancing authorities if requested during contingency events. This regional cooperation framework ensures reliability across the broader western North American grid.aeso
The contingency reserve system is essential to Alberta's grid operation, particularly important given the increasing variability introduced by renewable energy sources like wind generation, which cannot guarantee constant output.nrc-publications.canada
- https://www.aeso.ca/assets/Information-Documents/2013-007R-Contingency-Reserve-2024-04-05.pdf
- https://www.aeso.ca/market/market-participation/ancillary-services/operating-reserve/
- https://nrc-publications.canada.ca/eng/view/fulltext/?id=2d7a5190-4522-45d9-a83a-7cfe162cdb4a
- https://rodanenergy.com/how-navigate-aeso-operating-reserves-guide-energy-professionals/
- https://www.aeso.ca/assets/Information-Documents/2013-005R-Operating-Reserve-2024-04-05.pdf
- https://www.aeso.ca/assets/Uploads/2013-007R-Contingency-Reserve-2018-02-3.pdf
- https://www.ashb.com/wp-content/uploads/2020/08/IS-2020-125.pdf
- https://www.sciencedirect.com/science/article/abs/pii/S1040619003001581
- https://jasondoering.substack.com/p/steps-to-darkness-how-electricity
- https://www.linkedin.com/pulse/managing-power-system-variability-operating-jason-doering-p-eng-t2c7c
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