AltaLink Geomagnetic Disturbance (GMD) Studies

AltaLink Geomagnetic Disturbance GMD Studies

The sun consistently emits coronal mass ejections, consisting of charged particles. Approximately 3% reach Earth and interact with the Earth’s magnetic field, creating geomagnetic disturbance (GMD) events. During a GMD, this interaction creates varying electrojet currents above the surface of the Earth. The changing geomagnetic field induces voltage potential in transmission lines, creating a geomagnetically induced current (GIC).

A GIC can flow in metallic pipelines, underground cables, communication systems, railways, transmission lines, and in equipment in power transmission and distribution stations resulting in multiple or cascading outages or damage to power systems.

AltaLink determined that GIC studies were required for their system, in accordance with the NERC Standard TPL-007-1, which was created as part of the second stage of FERC Order 779. Teshmont was retained to address implications of a severe geomagnetic disturbance (GMD), and evaluate the level of GICs on the system caused by a GMD. The study included AltaLink’s 500 kV and 240 kV stations in addition to preliminary investigations into the effects of the induced GIC currents in the transformers for the HVDC system.

As a continuation to the above works, Teshmont performed power flow studies to investigate the point of inception of voltage collapse due to the increased reactive power demand during a geomagnetic disturbance. Data and models from the AltaLink GIS studies were used in conjunction with an AC power flow model to determine the magnitudes and orientations of geomagnetic disturbances, the resulting reactive power demand, and the corresponding voltage levels which could result in the collapse of AltaLink’s system.

Teshmont was awarded the 2017 Association of Consulting Engineering Companies (ACEC) Manitoba “Award of Excellence” in the Energy Resource Development category for our work on this project. An Award of Excellence is the highest award possible within a category, and recognizes outstanding achievement in consulting engineering.

At a Glance:

Client: AltaLink
Country: Canada
Geographical Region: North America