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Uncertainty analysis of stochastic dynamic line rating
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.ORCID iD: 0000-0002-2634-8852
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.ORCID iD: 0000-0003-4074-9529
2021 (English)In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 194, article id 107043Article in journal (Refereed) Published
Abstract [en]

This paper presents an uncertainty analysis of lines equipped with dynamic line rating (DLR) that are exposed to operational overloading. Multiple sources of uncertainties are taken in to account to model the line rating probabilistically. The superiority of dynamic rating above static rating is confirmed in this paper. However, it is shown in this paper that when the uncertainties in line rating are not considered, DLR can result in a high probability of undetected overloading. Based on assumptions for the uncertainties in relevant weather parameters, the probability of overloading is calculated for three different loading profiles of a line, for each hour during an eight-year period. Guaranteeing a low probability of overloading, with a deterministic dynamic rating, will require a large margin and result in many hours during which unnecessary measures against overloading will be taken. A stochastic dynamic rating, as introduced in this paper, allows for a more transparent and hour-by-hour trade-off between failure to take measures and unnecessary measures against overloading.

Place, publisher, year, edition, pages
Elsevier, 2021. Vol. 194, article id 107043
Keywords [en]
Dynamic line rating, Electric power transmission, Overloading, Power system protection, Stochastic method
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electric Power Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-82730DOI: 10.1016/j.epsr.2021.107043ISI: 000632386100010Scopus ID: 2-s2.0-85099927161OAI: oai:DiVA.org:ltu-82730DiVA, id: diva2:1524433
Note

Validerad;2021;Nivå 2;2021-02-01 (alebob)

Available from: 2021-02-01 Created: 2021-02-01 Last updated: 2022-04-13Bibliographically approved
In thesis
1. Multiple Aspects of Dynamic Rating in the Power System
Open this publication in new window or tab >>Multiple Aspects of Dynamic Rating in the Power System
2022 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Increased consumption and increased use of renewable energy make overhead lines and transformers more often congested. Dynamic rating (DR) uses a time-depending maximum permissible current instead of a long-term-fixed rating; it is an effective solution to upgrade the capacity of existing grid assets to minimize this congestion. Dynamic line rating (DLR) considers how the weather affects the thermal behavior of the conductor and therewith its rating; environmental parameters as well as conductor characteristics have to be considered. Likewise, dynamic rating of transformers (DTR) relies on a thermal assessment of the hottest spot in the transformer windings. The hot-spot temperature is dependent on the ambient temperature, loading, and transformer’s cooling system.

In this thesis, a number of lesser-studied aspects of DR are studied: stochastic modeling of the rating; relations between protection, reliability and rating; risk assessment for line selection when using DLR; and increased transformer hosting capacity (HC) in the presence of solar photovoltaic (PV).

In the first part of the work, the focus is on the stochastic modeling of DLR and its relation to the protection operation. Actual line rating is considered a random variable in the protection system for a more flexible decision-making. Different sources of uncertainties are modeled using suitable probability density functions. The method allows for a transparent trade-off between the risk of failure to take measures and the risk of unnecessary measures against overload. The results depicts that deterministic DLR could result in high probabilities of overloading or would require large safety margins. While, a stochastic approach will allow for both small margins and appropriate risks.  

A generic model is introduced to consider DLR reliability from two different viewpoints: errors and failures of components that would affect the calculation of the rating; and the impact of a DLR failure on the power system. The qualitative reliability study highlights that it is important to update the protection settings on a real-time basis. 

In the second part of the work, a risk assessment framework is proposed to select the minimum set of overhead lines for DLR implementation. Results show a possible increase of permissible hosting capacity (HC) for electric-vehicle charging by up to 80% (depending on the test system and initial data) with low interruption costs and reduced risk of congestion. Furthermore, the improvement in the transformer HC by using DTR has been quantified. The results indicate that depending on the HC performance indices, the transformer can be loaded beyond the normal operational limits up to 35% to host PV and up to 100% for increased consumption.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2022
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
Dynamic rating, Transmission lines, Overload Protection, Stochastic analysis, Hosting capacity, Transformers
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electric Power Engineering
Identifiers
urn:nbn:se:ltu:diva-90176 (URN)978-91-8048-063-5 (ISBN)978-91-8048-064-2 (ISBN)
Public defence
2022-06-10, Hörsal A, Campus Skellefteå, 97187, Skellefteå and Zoom, 09:00 (English)
Opponent
Supervisors
Available from: 2022-04-13 Created: 2022-04-13 Last updated: 2023-09-05Bibliographically approved

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Hajeforosh, SeyedeFatemehBollen, Math H.J.

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