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Jahn, I., Hohn, F., Chaffey, G. & Norrga, S. (2020). An Open-Source Protection IED for Research and Education in Multiterminal HVDC Grids. IEEE Transactions on Power Systems
Open this publication in new window or tab >>An Open-Source Protection IED for Research and Education in Multiterminal HVDC Grids
2020 (English)In: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679Article in journal (Refereed) Published
Abstract [en]

The integration of large amounts of renewable energy will require multiterminal high-voltage direct-current (MTDC) grids to reliably transport the energy over long distances. However, before building an MTDC grid, a functional protection system design is needed. Realistic and industrial studies are required to validate the functionality of such a system. In addition, further academic research as well as education in the field are needed. This paper presents an open-source, low-cost protection intelligent electronic device (IED) prototype for use in a laboratory environment. In particular, the IED design, its fastest measured performance, example results for different fault scenarios, and an assessment of its use in education are shown. The open-source IED is useful to accelerate industrial and academic research, as well as to enable education in protection for MTDC grids.

National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-267207 (URN)10.1109/TPWRS.2020.2970477 (DOI)
Note

QC 20200206

Available from: 2020-02-04 Created: 2020-02-04 Last updated: 2020-02-06Bibliographically approved
Bessegato, L., Byes, K., Harnefors, L., Norrga, S. & Östlund, S. (2020). Control and Admittance Modeling of an AC/AC Modular Multilevel Converter for Railway Supplies. IEEE transactions on power electronics, 35(3), 2411-2423
Open this publication in new window or tab >>Control and Admittance Modeling of an AC/AC Modular Multilevel Converter for Railway Supplies
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2020 (English)In: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 35, no 3, p. 2411-2423Article in journal (Refereed) Published
Abstract [en]

Modular multilevel converters (MMCs) can be configured to perform ac/ac conversion, which makes them suitable as railway power supplies. In this paper, a hierarchical control scheme for ac/ac MMCs for railway power supplies is devised and evaluated, considering the requirements and the operating conditions specific to this application. Furthermore, admittance models of the ac/ac MMC are developed, showing how the suggested hierarchical control scheme affects the three-phase and the single-phase side admittances of the converter. These models allow for analyzing the stability of the interconnected system using the impedance-based stability criterion and the passivity-based stability assessment. Finally, the findings presented in this paper are validated experimentally, using a down-scaled MMC.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2020
Keywords
Rail transportation, Power supplies, Stability criteria, Admittance, Voltage control, Capacitors, AC, AC converters, current control, frequency-domain analysis, linearization techniques, modular multilevel converters (MMCs), railway engineering, stability
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-267142 (URN)10.1109/TPEL.2019.2930321 (DOI)000507286000019 ()2-s2.0-85077193974 (Scopus ID)
Note

QC 20200217

Available from: 2020-02-17 Created: 2020-02-17 Last updated: 2020-02-17Bibliographically approved
Jahn, I., Hohn, F., Sharifabadi, K., Wang, M., Chaffey, G. & Norrga, S. (2020). Requirements for open specifications in multivendor HVDC protection systems. In: : . Paper presented at IET DPSP 2020, The 15th International Conference on Developments in Power System Protection, Liverpool, 9-12 March 2020.
Open this publication in new window or tab >>Requirements for open specifications in multivendor HVDC protection systems
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2020 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Integrating multiterminal high-voltage direct-current (HVDC) connections into the existing alternating current (AC) power transmission system is a possible solution for transport of large amounts of renewable energy. Protection is considered a key enabler for multiterminal HVDC (MTDC) grids. Designing such a protection system is a challenge, in particular in a multivendor setup. Fault detection during transients might be required to achieve the stringent speed requirements for HVDC protection. This in turn requires knowledge about the expected system behaviour during faults and involves knowledge from all vendors supplying equipment in MTDC grid. Traditionally, HVDC projects are, however, supplied as turn-key solutions and the control and protection systems are the intellectual property of the vendors and not open for the HVDC end-users. This paper aims to provide a starting point on the discussion which information has to be shared between vendorsand HVDC end-users when designing MTDC grid protection. Simulations results show that missing information about certain aspects can lead to a failure of the protection system. A discussion on organization of the available information is added. Open specifications of the used equipment are useful to design safe and reliable MTDC grid protection.

Keywords
HVDC grid protection, multivendor, open specifications
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-270612 (URN)
Conference
IET DPSP 2020, The 15th International Conference on Developments in Power System Protection, Liverpool, 9-12 March 2020
Note

QC 20200313

Available from: 2020-03-10 Created: 2020-03-10 Last updated: 2020-03-13Bibliographically approved
Jahn, I., Bessegato, L., Björk, J., Hohn, F., Norrga, S., Svensson, N., . . . Despouys, O. (2019). A Proposal for Open-Source HVDC Control. In: : . Paper presented at 2019 IEEE PES Innovative Smart Grid Technologies Europe (ISGT-Europe).
Open this publication in new window or tab >>A Proposal for Open-Source HVDC Control
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2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Future multiterminal high-voltage direct-current (HVDC) grids are considered an enabling technology to efficiently integrate large amounts of renewable energy into the existing grid. However, already in today’s existing point-to-point HVDC links, harmonic interaction issues and instabilities related to the controland protection system of the converters have been reported. The converter control software is usually black-boxed and problems are therefore solved in close cooperation with the HVDC vendor. This paper aims to provide a starting point for a discussion onan open-source HVDC control system. In particular, it covers the control design including technical and non-technical aspects. The open-source approach can be useful to solve current as wellas future control-related problems, both in point-to-point links as well as in multiterminal and multivendor HVDC grids.

Keywords
HVDC transmission, Open source software
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-257736 (URN)
Conference
2019 IEEE PES Innovative Smart Grid Technologies Europe (ISGT-Europe)
Note

QC 20190917

Available from: 2019-09-03 Created: 2019-09-03 Last updated: 2019-10-14Bibliographically approved
Johannesson, N. & Norrga, S. (2019). Contribution of travelling wave propagation time to the speed of optical link protections in multi-terminal high-voltage DC systems. IET Generation, Transmission & Distribution, 13(14), 3078-3085
Open this publication in new window or tab >>Contribution of travelling wave propagation time to the speed of optical link protections in multi-terminal high-voltage DC systems
2019 (English)In: IET Generation, Transmission & Distribution, ISSN 1751-8687, E-ISSN 1751-8695, Vol. 13, no 14, p. 3078-3085Article in journal (Refereed) Published
Abstract [en]

During faults in multi-terminal high-voltage DC systems, the disturbance will quickly become evident throughout the entire system. If DC breakers are included in such systems, the entire fault clearing process needs to occur within a few milliseconds. Therefore, DC line protection schemes based on telecommunication have previously been discarded by some authors as their performance is constrained by the communication delay. However, telecommunication-based detection methods offer some very favourable features, one being that selectivity can be achieved without coordination of settings. In this study, several telecommunication-based protection schemes are evaluated with regards to their minimum possible detection time when considering telecommunication delay. It is shown that they perform best during faults located at the remote end of a line, i.e. fault locations that are difficult to reliably detect using single-ended methods. Therefore, it is reasonable that the most reliable protection system will consist of both single-ended and communication-based methods because they complement each other well. Furthermore, it is shown that the travelling wave differential protection offers the shortest theoretical detection time due to the wave propagation delay being included in the formulation.

Place, publisher, year, edition, pages
Institution of Engineering and Technology, 2019
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-255739 (URN)10.1049/iet-gtd.2019.0344 (DOI)000476558800019 ()2-s2.0-85069442033 (Scopus ID)
Note

QC 20190813

Available from: 2019-08-13 Created: 2019-08-13 Last updated: 2019-08-13Bibliographically approved
Bessegato, L., Ilves, K., Harnefors, L., Norrga, S. & Östlund, S. (2019). Control and Admittance Modeling of an AC/AC Modular Multilevel Converter for Railway Supplies. IEEE transactions on power electronics
Open this publication in new window or tab >>Control and Admittance Modeling of an AC/AC Modular Multilevel Converter for Railway Supplies
Show others...
2019 (English)In: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107Article in journal (Refereed) In press
Abstract [en]

Modular multilevel converters (MMCs) can be configured to perform ac/ac conversion, which makes them suitable as railway power supplies. In this paper, a hierarchical control scheme for ac/ac MMCs for railway power supplies is devised and evaluated, considering the requirements and the operating conditions specific to this application. Furthermore, admittance models of the ac/ac MMC are developed, showing how the suggested hierarchical control scheme affects the three-phase and the single-phase side admittances of the converter. These models allow for analyzing the stability of the interconnected system using the impedance-based stability criterion and the passivity-based stability assessment. Finally, the findings presented in this paper are validated experimentally, using a down-scaled MMC. 

Keywords
Modular multilevel converters, ac/ac converters, current control, voltage control, admittance, frequency-domain analysis, linearization techniques, stability, railway engineering.
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-248130 (URN)
Note

QC 20190404

Available from: 2019-04-04 Created: 2019-04-04 Last updated: 2019-08-19Bibliographically approved
Bakas, P., Okazaki, Y., Ilves, K., Norrga, S., Harnefors, L. & Nee, H.-P. (2019). Design considerations and comparison of hybrid line-commutated and cascaded full-bridge converters with reactive-power compensation and active filtering capabilities. In: : . Paper presented at 2019 21st European Conference on Power Electronics and Applications (EPE'19 ECCE Europe).
Open this publication in new window or tab >>Design considerations and comparison of hybrid line-commutated and cascaded full-bridge converters with reactive-power compensation and active filtering capabilities
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2019 (English)Conference paper, Published paper (Other academic)
Abstract [en]

This paper compares two hybrid topologies that combine the line-commutated converter (LCC) with cascaded full-bridge (FB) converters. The latter are utilized for compensating the reactive power and filtering the current harmonics of the LCC. The method that was developed for dimensioning these hybrid topologies is presented in detail. This method is utilized for calculating the arm voltage and current waveforms, which are used to estimate other important quantities, such as conduction losses and energy variations. Finally, the studied converters are compared in terms of voltage/current ratings, semiconductor requirements, conduction losses, and energy variations.

Keywords
Converter circuit, HVDC, Multilevel converters, Thyristor.
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-262671 (URN)978-9-0758-1530-6 (ISBN)
Conference
2019 21st European Conference on Power Electronics and Applications (EPE'19 ECCE Europe)
Funder
SweGRIDS - Swedish Centre for Smart Grids and Energy Storage, SP8
Note

QC 20191018

Available from: 2019-10-17 Created: 2019-10-17 Last updated: 2019-10-18Bibliographically approved
Bakas, P., Okazaki, Y., Ilves, K., Norrga, S., Harnefors, L. & Nee, H.-P. (2019). Design considerations and comparison of hybrid line-commutated and cascaded full-bridge converters with reactive-power compensation and active filtering capabilities. In: 2019 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe: . Paper presented at 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe, 3-5 September 2019. Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>Design considerations and comparison of hybrid line-commutated and cascaded full-bridge converters with reactive-power compensation and active filtering capabilities
Show others...
2019 (English)In: 2019 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe, Institute of Electrical and Electronics Engineers Inc. , 2019Conference paper, Published paper (Refereed)
Abstract [en]

This paper compares two hybrid topologies that combine the line-commutated converter (LCC) with cascaded full-bridge (FB) converters. The latter are utilized for compensating the reactive power and filtering the current harmonics of the LCC. The method that was developed for dimensioning these hybrid topologies is presented in detail. This method is utilized for calculating the arm voltage and current waveforms, which are used to estimate other important quantities, such as conduction losses and energy variations. Finally, the studied converters are compared in terms of voltage/current ratings, semiconductor requirements, conduction losses, and energy variations.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2019
Keywords
Converter circuit, HVDC, Multilevel converters, Thyristor, Active filters, Power electronics, Reactive power, Thyristors, Topology, Converter circuits, Design considerations, Full bridge converters, Line commutated converter (LCC), Multilevel converter, Reactive power compensation, Voltage and current waveforms, Power converters
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-268052 (URN)10.23919/EPE.2019.8915146 (DOI)2-s2.0-85076669919 (Scopus ID)9789075815313 (ISBN)
Conference
21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe, 3-5 September 2019
Note

QC 20200218

Available from: 2020-02-18 Created: 2020-02-18 Last updated: 2020-02-18Bibliographically approved
Bessegato, L., Ilves, K., Harnefors, L. & Norrga, S. (2019). Effects of Control on the AC-Side Admittance of a Modular Multilevel Converter. IEEE transactions on power electronics, 34(8), 7206-7220, Article ID 8514034.
Open this publication in new window or tab >>Effects of Control on the AC-Side Admittance of a Modular Multilevel Converter
2019 (English)In: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 34, no 8, p. 7206-7220, article id 8514034Article in journal (Refereed) Published
Abstract [en]

The stability of a modular multilevel converter connected to an ac grid can be assessed by analyzing the converter ac-side admittance in relation to the grid impedance. The converter control parameters have a strong impact on the admittance and they can be adjusted for achieving system stability. This paper focuses on the admittance-shaping effect produced by different current-control schemes, either designed on a per-phase basis or in the $dq$ frame using space vectors. A linear analytical model of the converter ac-side admittance is developed, including the different current-control schemes and the phase-locked loop. Different solutions for computing the insertion indices are also analyzed, showing that for a closed-loop scheme a compact expression of the admittance is obtained. The impact of the control parameters on the admittance is discussed and verified experimentally, giving guidelines for designing the system in terms of stability. Moreover, recommendations on whether a simplified admittance expression could be used instead of the detailed model are given. The findings from the admittance-shaping analysis are used to recreate a grid-converter system whose stability is determined by the control parameters. The developed admittance model is then used in this experimental case study, showing that the stability of the interconnected system can be assessed using the Nyquist stability criterion.

Place, publisher, year, edition, pages
IEEE Press, 2019
Keywords
Modular multilevel converters, admittance, current control, stability, frequency-domain analysis, linearization techniques.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-238818 (URN)10.1109/TPEL.2018.2878600 (DOI)000469912200014 ()2-s2.0-85055681354 (Scopus ID)
Note

QC 20181113

Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2019-06-26Bibliographically approved
Bakas, P., Ilves, K., Norrga, S., Harnefors, L. & Nee, H.-P. (2019). Hybrid alternate-common-arm converter with director thyristors - Impact of commutation time on the active-power capability. In: 2019 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe: . Paper presented at 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe, 3-5 September 2019, Genova, Italy. Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>Hybrid alternate-common-arm converter with director thyristors - Impact of commutation time on the active-power capability
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2019 (English)In: 2019 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe, Institute of Electrical and Electronics Engineers Inc. , 2019Conference paper, Published paper (Refereed)
Abstract [en]

This paper investigates the impact of the thyristor commutation time on the peak currents and the active-power capability of the hybrid alternate-common-arm converter (HACC). This converter employs director thyristors for the alternate connection of a common arm in parallel to the main arms. The parallel connection enables current sharing among the arms, which allows the HACC to transfer higher output power without increasing the peak arm current. It is shown that the active-power capability of the HACC is doubled for a certain current-sharing factor, which, however, is altered by the thyristor commutation time. Therefore, the impact of the commutation time on the active-power capability of the HACC is investigated theoretically. Finally, this analysis is verified by simulation results.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2019
Keywords
Converter circuit, HVDC, Multilevel converters, Thyristor, Electric connectors, Power converters, Commutation time, Converter circuits, Current-sharing, Multilevel converter, Output power, Parallel connections, Peak currents, Thyristors
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-268051 (URN)10.23919/EPE.2019.8915473 (DOI)2-s2.0-85076682012 (Scopus ID)978-9-0758-1531-3 (ISBN)978-1-7281-2361-5 (ISBN)
Conference
21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe, 3-5 September 2019, Genova, Italy
Note

QC 20200217

Available from: 2020-02-17 Created: 2020-02-17 Last updated: 2020-02-17Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8565-4753

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