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Propagation of Supraharmonics in Low-Voltage Networks
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.ORCID iD: 0000-0001-6074-8633
2022 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The need for measures towards a sustainable use of energy has incited the proliferation of devices and systems for the efficient use of electricity. Energy-efficient appliances, equipment for the electrification of transportation, electricity generators from renewable energy sources, and communication protocols, e.g., for smart metering are sources of supraharmonic distortion in electrical networks. Supraharmonics are voltage and current waveform distortion in the frequency range from 2 up to 150 kHz.

The increase in sources of supraharmonics in the last decades and the propagation of this type of distortion have triggered a variety of unwanted consequences (interference) in the electrical networks. Interference associated to supraharmonics such as audible noise, degradation or failure in the operation of electrical equipment, and breakdown of insulation materials, have been reported around the world. A standardized framework for supraharmonics as a power quality phenomenon that involves both grid operators and equipment manufacturers is needed to limit these interferences. The limits to be set shall not hinder the modernization of the electrical system and the consequential energy transition.

There are gaps in the standardization framework for supraharmonics as a power quality phenomenon. The study of supraharmonics as a power quality parameter should consider variables that affect emission levels and propagation of supraharmonics. At the same time, an assessment of the severity of given supraharmonics levels regarding their consequences is needed to settle realistic reference levels. Deterministic methods have been generally used to study supraharmonic propagation but they might not be suitable when considering many possible scenarios.

This research introduces forefront methods and results on the study of supraharmonics emission, propagation, and consequences. The study has two focal points: 1) to study the impact of the impedance of the grid and low-voltage devices on the emission and propagation of supraharmonics; 2) to assess the severity of propagated supraharmonics in terms of the characteristics of the distortion and the probability of interference. Experimental and theoretical case studies are built to carry out the research. Measured and synthetic signals representative of supraharmonic distortion present in low-voltage networks are used.

The main results of this research are summarized as:

The levels of emitted and propagated supraharmonics depend on the impedance of the grid, the emitting device and the neighboring devices. Resonance can lead to significant levels of supraharmonics anywhere in the grid. The variability and diversity of low-voltage devices lead to high uncertainty in the estimation of their impedance. Stochastic methods are recommended to assess the probability of interference.

Different attributes of supraharmonics are responsible for different interference phenomena. Indications of the severity of supraharmonics attributes are given for three phenomena: audible noise, negative impacton residual current devices, and light flicker of LED lamps.

This research contributes to the establishment of supraharmonics as a power quality phenomenon with standardized solutions. It introduces methods for the assessment of: 1) supraharmonic emission from installations needed to recommend planning levels; 2) supraharmonic propagation in low-voltage networks, and 3) the probability of interference needed to define reference levels.

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 [en]
supraharmonics, waveform distortion, low-voltage, high-frequency harmonics
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electric Power Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-93508ISBN: 978-91-8048-176-2 (print)ISBN: 978-91-8048-177-9 (electronic)OAI: oai:DiVA.org:ltu-93508DiVA, id: diva2:1701931
Public defence
2022-12-05, Hörsal A, Luleå tekniska universitet, Skellefteå, 10:00 (English)
Opponent
Supervisors
Available from: 2022-10-10 Created: 2022-10-07 Last updated: 2023-09-05Bibliographically approved
List of papers
1. Summation law for supraharmonic currents (2–150 kHz) in low-voltage installations
Open this publication in new window or tab >>Summation law for supraharmonic currents (2–150 kHz) in low-voltage installations
Show others...
2020 (English)In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 184, article id 106325Article in journal (Refereed) Published
Abstract [en]

The development of methods to study the propagation of supraharmonics in LV and even MV grids is a current research topic among the power quality community, which has been motivated by the efforts to establish limits for non-intentional supraharmonic emissions and planning levels. The assessment of how much distortion a bulk use of power electronics devices can inject into the grid is necessary before stating emission limits and planning levels for supraharmonics. To address this issue, the development of suitable models that can predict the supraharmonic emission from a low-voltage installation as a whole is required. This article presents a comparison of models for the summation of supraharmonics. An improved model for the summation of supraharmonics is proposed, which is validated experimentally. It is shown that by using the proposed model, predictions of supraharmonic propagation can be accomplished. Furthermore, it is demonstrated experimentally that, with the increasing number of supraharmonic emitting devices, the supraharmonic current distortion injected into a grid by an installation increases up to a maximum value and then decreases due to the capacitive nature of power electronics appliances existing in low-voltage networks.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Supraharmonics, High-frequency distortion, Summation, Power quality
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electric Power Engineering
Identifiers
urn:nbn:se:ltu:diva-78295 (URN)10.1016/j.epsr.2020.106325 (DOI)000525770200038 ()2-s2.0-85082135782 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-02 (alebob)

Available from: 2020-04-02 Created: 2020-04-02 Last updated: 2023-09-05Bibliographically approved
2. Evaluation of Supraharmonic Propagation in LV Networks Based on the Impedance Changes Created by Household Devices
Open this publication in new window or tab >>Evaluation of Supraharmonic Propagation in LV Networks Based on the Impedance Changes Created by Household Devices
Show others...
2020 (English)In: Proceedings of 2020 IEEE PES Innovative Smart Grid Technologies Europe (ISGT-Europe) 26-28 October, 2020, IEEE, 2020, p. 754-758Conference paper, Published paper (Refereed)
Abstract [en]

This paper investigates the characteristics of emission in the frequency range 2-150 kHz (supraharmonics) in time and frequency domain and how it propagates under different scenarios posed by the customer connections and changes in the grid. The analysis is based on measurements performed in a low-voltage installation, considering the simultaneous operation of a set of PV inverters and LED lamps in order to create changes in both impedance and emissions. The results confirm that supraharmonics tend to interact with nearby devices in the customer installation. As the number and constellation of emitting devices change so does the propagation of the supraharmonics. The propagation towards the grid can either increase or decrease with the increasing number of connected devices depending on the ratio between the impedances of the device and the grid impedance. Devices’ technology plays an important role in defining supraharmonic characteristics, emission levels and propagation. Finally, a qualitative analysis of the individual devices’ impedance and discussion of some of the practical aspects is provided.

Place, publisher, year, edition, pages
IEEE, 2020
Keywords
electric power distribution, interaction, LED, lighting, supraharmonics, power quality
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electric Power Engineering
Identifiers
urn:nbn:se:ltu:diva-81459 (URN)10.1109/ISGT-Europe47291.2020.9248928 (DOI)2-s2.0-85097343162 (Scopus ID)
Conference
10th IEEE PES Innovative Smart Grid Technologies Europe (ISGT-Europe 2020), 26-28 October, 2020, Delft, The Netherlands (Virtual)
Note

ISBN för värdpublikation: 978-1-7281-7100-5

Available from: 2020-11-19 Created: 2020-11-19 Last updated: 2023-09-05Bibliographically approved
3. Assessment of Grid Impedance Impact On Supraharmonic Propagation
Open this publication in new window or tab >>Assessment of Grid Impedance Impact On Supraharmonic Propagation
2021 (English)In: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution, Institution of Engineering and Technology, 2021, p. 688-692, article id 0073Conference paper, Published paper (Refereed)
Abstract [en]

Supraharmonic (SH) propagation is determined by the impedance of both the grid and the devices connected to it. Few attempts to characterize this combined dependency have been done. The interest of grid operators is in counteracting the propagation of SHs upstream to maintain power quality. Characterizing the impact of impedance on SH propagation gives information to strategically counteract this propagation to the upstream grid. This paper presents an experimental case study for the assessment of the sensitivity of SH propagation to changes in impedance of the grid at the delivery point. The results are then compared to the changes of SH propagation provoked by the connection of low-voltage (LV) equipment.

Place, publisher, year, edition, pages
Institution of Engineering and Technology, 2021
Keywords
Supraharmonics, Impedance, Propagation, Power quality
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electric Power Engineering
Identifiers
urn:nbn:se:ltu:diva-88911 (URN)10.1049/icp.2021.1816 (DOI)
Conference
26th International Conference and Exhibition on Electricity Distribution (CIRED 2021), Online, September 20-23, 2021
Note

ISBN för värdpublikation: 978-1-83953-591-8 (elektroniskt)

Available from: 2022-01-25 Created: 2022-01-25 Last updated: 2023-09-05Bibliographically approved
4. Modeling and Analysis of Supraharmonic Propagation for Stochastic Studies
Open this publication in new window or tab >>Modeling and Analysis of Supraharmonic Propagation for Stochastic Studies
2022 (English)In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 37, no 6, p. 4899-4910Article in journal (Refereed) Published
Abstract [en]

Supraharmonic (SH) propagation depends on the impedance of both the grid and the devices connected to it. Few attempts to quantify the impact of the customer's load variability have been done. The interest of grid operators is in counteracting the SH propagation upstream to maintain power quality. Quantifying the impact of impedance on supraharmonic propagation gives information to strategically counteract this propagation to the grid. This article presents a method for analysis of SH propagation that uses a stochastic approach to describe the impact of low-voltage (LV) loads. Scenarios of a strong and a weak grid are presented to study the impact of reinforcement grid measures.

Place, publisher, year, edition, pages
IEEE, 2022
Keywords
high-frequency distortion, power distribution, power quality, power system harmonics, supraharmonics
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electric Power Engineering
Identifiers
urn:nbn:se:ltu:diva-90023 (URN)10.1109/tpwrd.2022.3162712 (DOI)000891435100038 ()2-s2.0-85127466907 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-11-28 (joosat);

Available from: 2022-03-31 Created: 2022-03-31 Last updated: 2023-09-05Bibliographically approved
5. Evaluation of the Probability of Supraharmonic Interference in Low-Voltage Networks
Open this publication in new window or tab >>Evaluation of the Probability of Supraharmonic Interference in Low-Voltage Networks
(English)Manuscript (preprint) (Other academic)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:ltu:diva-93506 (URN)
Available from: 2022-10-07 Created: 2022-10-07 Last updated: 2022-10-07
6. Diagnosis of supraharmonics-related problems based on the effects on electrical equipment
Open this publication in new window or tab >>Diagnosis of supraharmonics-related problems based on the effects on electrical equipment
2021 (English)In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 195, article id 107179Article in journal (Refereed) Published
Abstract [en]

Supraharmonics (SH) have proliferated in low-voltage (LV) and medium-voltage (MV) grids due to the increasing use of technologies emitting distortion in the range 2–150 kHz. Currently, no recommended practices to assess the effects of SH on the electrical system exist. The propagation of SH through LV and MV grids leads to interference with the elements for power delivery and end-user equipment, e.g., light flicker, aging of capacitors and cable terminations, audible noise, and interruption of electric vehicle (EV) charging. As such incidents happen more often, the need for guidelines that facilitate the diagnosis of problems related to SH arises. Different features of the SH distortion are responsible for different interferences. This article introduces guidelines for the evaluation of the impact of SH based on the morphology of the interference. The evaluation is performed with easy-to-use methods and formulas directly related to the characteristics of the SH distortion. The adverse effects of SH considered are audible noise, light flicker, tripping of LV residual current devices (RCDs), and MV cable termination failure. This work interests field engineers and researchers facing problems related to SH; it also serves as a guide for further research.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
Acoustic noise, Electromagnetic interference, Leakage currents, Power cable insulation, Power quality, Supraharmonics
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electric Power Engineering
Identifiers
urn:nbn:se:ltu:diva-83472 (URN)10.1016/j.epsr.2021.107179 (DOI)000639725700009 ()2-s2.0-85103242601 (Scopus ID)
Funder
Swedish Transport AdministrationSwedish Energy Agency
Note

Validerad;2021;Nivå 2;2021-04-12 (alebob)

Available from: 2021-04-01 Created: 2021-04-01 Last updated: 2023-09-05Bibliographically approved

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Espin Delgado, Angela

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Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
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  • Other style
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  • en-GB
  • en-US
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  • nn-NO
  • nn-NB
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  • Other locale
More languages
Output format
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