Energy system resilience to extreme disruptions: reexamining impacts and their assessment

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School of Science | Doctoral thesis (article-based) | Defence date: 2024-06-13
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Date

2024

Department

Teknillisen fysiikan laitos
Department of Applied Physics

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Mcode

Degree programme

Language

en

Pages

78 + app. 111

Series

Aalto University publication series DOCTORAL THESES, 106/2024

Abstract

The functioning of modern societies relies on an undisrupted energy supply, which is subject to a large number and variety of physical and nonphysical threats. The most severe disruptions, despite their rarity, are responsible for a major share of disrupted supply. Furthermore, cost-driving factors depend on disruption severity, which calls for knowledge about the magnitude of unprecedented but possible future disruptions. This work starts with a broad mapping of the landscape of threats to energy systems, later narrowed down to extreme weather threats and vulnerabilities of the Finnish electricity system. As the largest cause of electricity supply interruptions in Finland, windstorms are chosen for impact modeling in the rest of this thesis. To capture the magnitude of unprecedented windstorm impacts, a new fragility-based spatio-temporal impact model was developed with a unique combination of national scale and medium voltage grid detail. The development of this model necessitated rethinking relevant aspects and suitable approaches and the development of new methods across multiple impact chain steps. The most significant new modeling contribution is the synthetic grid generation method utilizing distribution grid operator (DSO) specific data in a country with many relatively small DSOs. This generation method combines spatially mapped grid component data with assumed standard feeder topology. The second most distinct methodological contribution is severity-dependent fixing time distribution derivation using a two-level fitting procedure. The first level of this procedure includes fitting fixing time distributions of faults in a storm and calm periods considered meteorologically independent events. The model is applied to Finland's three most impactful historical and historically unprecedented but meteorologically plausible windstorm cases. The model recreates lost load profiles for historical windstorms with errors of around 20%, despite omitting many windstorm impact driving environmental factors. The historically unprecedented windstorm's wind gust field is obtained by scaling the field of the historically most impactful windstorm upwards by 24%, a value obtained with the extreme-value-theory-based method. The lost load from 24% higher wind gust speeds increases tenfold. Impacts are limited by the significant cabling of powerlines done since 2011, which, despite high costs, would largely pay off during the unprecedented windstorm. That said, the cost of such an event requires a reevaluation of cost rates considering time dependency, critical services, and impacts on smaller economy and population segments.

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Supervising professor

Lund, Peter D., Prof., Aalto University, Department of Applied Physics, Finland

Thesis advisor

Lund, Peter D., Prof., Aalto University, Department of Applied Physics, Finland

Keywords

resilience, energy system, windstorm, synthetic system, faults and repairs

Other note

Parts

  • [Publication 1]: Justinas Jasiūnas, Peter D. Lund, Jani Mikkola. Energy system resilience – A review. Renewable and Sustainable Energy Reviews, 150, 2021.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202108048097
    DOI: 10.1016/j.rser.2021.111476 View at publisher
  • [Publication 2]: Justinas Jasiūnas, Peter D. Lund, Jani Mikkola, Liinu Koskela. Linking socio-economic aspects to power system disruption models. Energy, 222, 2021.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202102262073
    DOI: 10.1016/j.energy. 2021.119928 View at publisher
  • [Publication 3]: Justinas Jasiūnas, Tatu Heikkinen, Peter D. Lund, Ilona Láng-Ritter. Resilience of electric grid to extreme wind: Considering local details at national scale. Reliability Engineering and System Safety, 232, 2023.
    DOI: 10.1016/j.ress.2022.109070 View at publisher
  • [Publication 4]: Justinas Jasiūnas, Ilona Láng-Ritter, Tatu Heikkinen, Peter D. Lund. Electricity load lost in the largest windstorms – is the fragility-based model up to the task? Energies, 2023.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202308114714
    DOI: 10.3390/en16155678 View at publisher
  • [Publication 5]: Justinas Jasiūnas, Ilona Láng-Ritter, Tatu Heikkinen, Peter D. Lund. Modeling the unprecedented but plausible: Windstorm impacts on electric grid. Submitted to Applied Energy in 2023

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https://urn.fi/URN:ISBN:978-952-64-1831-5

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[diss] Perustieteiden korkeakoulu / SCI