Effects of DC Bias on Power Transformers Tutorial for CIGRE SC A2

Summary

There has been growing concern in the electric power industry regarding the impact of Geomagnetically Induced Currents (GIC), or DC-quasi currents, which have caused, and may continue to cause, overheating of large numbers of power transformers in certain regions of the world, potentially leading to large-scale, long-duration system blackouts. Similarly, other sources of DC bias, depending on the associated parasitic DC levels, may also affect transformers. These include applications involving power electronic components, HVDC systems, and DC transmission or traction systems.
The scope of this Working Group was to address the effects of DC bias (including GIC) on power transformers and reactors and to explore methods for assessing the transformers' ability to withstand these impacts. As a result of this work, the published Technical Brochure was developed as a guide for assessing the effects of DC bias on power transformers for the engineering community. It is based on eight comprehensive, systematically written chapters, each covering a specific topic, including the state of the art, effect of DC/GIC on power transformers, modeling, testing, power system studies, design considerations, monitoring, mitigation, and accessory considerations, all structured to form a complete technical report.

Additional informations

Video

Speakers

William A. RADASKY, Dietrich BONMANN, Johannes RAITH, Patil KRISHNAT, Dejan SUSA, Gary HOFFMAN

Keywords

Power Transformers, Geomagnetic Disturbances, GMD, Geomagnetic Currents, DC Bias, GIC/DC signatures, Core saturation, Magnetization current, Hot spot temperature, Reactive power, Design Review, Monitoring, Mitigation, Site testing, Laboratory testing, 5 limb core, 3 limb core, Structural parts, Eddy current, Losses, Core, Unbalanced MMF, Modelling, Stray Losses, Winding Losses, Core Losses, Noise, Sound, Vibration, Design Review, Power system