Vulnerability Assessment of Power Transformers and Power Systems to Geomagnetic Disturbances

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dc.contributor.advisorRezaei Zare, Afshin
dc.contributor.authorAriannik, Mohamadreza
dc.date.accessioned2024-03-18T18:20:54Z
dc.date.available2024-03-18T18:20:54Z
dc.date.issued2024-03-16
dc.date.updated2024-03-16T10:37:44Z
dc.degree.disciplineElectrical Engineering & Computer Science
dc.degree.levelDoctoral
dc.degree.namePhD - Doctor of Philosophy
dc.description.abstractPowerful solar storms emit plasma that may travel towards the earth. Interactions between the plasma and the earth magnetic field cause geomagnetic disturbances (GMDs), which in turn induce quasi-dc voltage along long conductors in power systems. Assessing the power system resiliency against GMDs requires accurately calculating the induced electric fields and the resultant geomagnetically induced currents (GICs). Offline and online wide-area geomagnetic field monitoring systems are established in this research to estimate GIC flows in power systems accurately. The proposed monitoring systems process the magnetic field signals that are measured at several observatories worldwide. In the offline monitoring system, the magnetic field signals are denoised, and spikes are detected and replaced. The time derivative of the signal is taken by a continuous wavelet transform to prevent amplification of the noises. GICs in a modified IEEE 118-bus benchmark power system are calculated concerning a realistic geomagnetic storm to demonstrate the effectiveness of the proposed signal processing methods. A sliding window is applied in the online monitoring system, and its size is optimized to lower processing time while increasing the signal-to-noise ratio. High amplitude GICs can cause a sharp increase in the hottest-spot temperature of the power transformers. The high temperature allows the formation of gaseous bubbles in the oil-paper insulation and endangers the integrity of the transformer's insulation system. The bubbles include mainly water vapor and emerge in the cavities on the surface of the paper insulation. In the experimental phase of this research, a test setup is created to detect bubbling inception temperature (BIT) for Kraft and thermally upgraded papers (TUPs). The paper samples are dried, prepared at six different moisture levels, and immersed in synthetic ester oil for the experiments. The paper strips are wound around a cartridge heater, and a controller unit raises its temperature at 3 ºC/min and 20 ºC/min rates to detect BIT. The BITs are considered the operational limit on the hottest-spot temperature of the transformers.
dc.identifier.urihttps://hdl.handle.net/10315/41976
dc.languageen
dc.rightsAuthor owns copyright, except where explicitly noted. Please contact the author directly with licensing requests.
dc.subjectElectrical engineering
dc.subjectElectromagnetics
dc.subject.keywordsGeomagnetic field
dc.subject.keywordsGeomagnetically induced current (GIC)
dc.subject.keywordsPower system
dc.subject.keywordsSolar storm
dc.subject.keywordsTransformer
dc.subject.keywordsBubble
dc.subject.keywordsOil-paper insulation
dc.subject.keywordsBubbling inception temperature
dc.subject.keywordsSynthetic ester oil
dc.subject.keywordsThermally upgraded paper
dc.subject.keywordsKraft paper
dc.titleVulnerability Assessment of Power Transformers and Power Systems to Geomagnetic Disturbances
dc.typeElectronic Thesis or Dissertation

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