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Bakas, Panagiotis
Publications (6 of 6) Show all publications
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
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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 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
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: Proc. 2019 21st European Conference on Power Electronics and Applications (EPE'19 ECCE Europe), IEEE and EPE Association, Genova, Italy, Sep. 2-6, 2019: . Paper presented at 2019 21st European Conference on Power Electronics and Applications (EPE'19 ECCE Europe), Genova, Italy, Sep. 2-6, 2019. Genova, Italy: IEEE and EPE Association
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: Proc. 2019 21st European Conference on Power Electronics and Applications (EPE'19 ECCE Europe), IEEE and EPE Association, Genova, Italy, Sep. 2-6, 2019, Genova, Italy: IEEE and EPE Association , 2019Conference paper, Published paper (Other academic)
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
Genova, Italy: IEEE and EPE Association, 2019
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-262670 (URN)978-9-0758-1530-6 (ISBN)
Conference
2019 21st European Conference on Power Electronics and Applications (EPE'19 ECCE Europe), Genova, Italy, Sep. 2-6, 2019
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: 2019-10-21Bibliographically approved
Heinig, S., Jacobs, K., Ilves, K., Bessegato, L., Bakas, P., Norrga, S. & Nee, H.-P. (2019). Implications of Capacitor Voltage Imbalance on the Operation of the Semi-Full-Bridge Submodule. IEEE transactions on power electronics, 34(10), 9520-9535, Article ID 8598807.
Open this publication in new window or tab >>Implications of Capacitor Voltage Imbalance on the Operation of the Semi-Full-Bridge Submodule
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2019 (English)In: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 34, no 10, p. 9520-9535, article id 8598807Article in journal (Refereed) Published
Abstract [en]

Future meshed high-voltage direct current grids require modular multilevel converters with extended functionality. One of the most interesting new submodule topologies is the semi-full-bridge because it enables efficient handling of DC-side short circuits while having reduced power losses compared to an implementation with full-bridge submodules. However, the semi-full-bridge submodule requires the parallel connection of capacitors during normal operation which can cause a high redistribution current in case the voltages of the two submodule capacitors are not equal. The maximum voltage difference and resulting redistribution current have been studied analytically, by means of simulations and in a full-scale standalone submodule laboratory setup. The most critical parameter is the capacitance mismatch between the two capacitors. The experimental results from the full-scale prototype show that the redistribution current peaks at 500A if the voltage difference is 10V before paralleling and increases to 2500A if the difference is 40V. However, neglecting very unlikely cases, the maximum voltage difference predicted by simulations is not higher than 20-30V for the considered case. Among other measures, a balancing controller is proposed which reduces the voltage difference safely if a certain maximum value is surpassed. The operating principle of the controller is described in detail and verified experimentally on a down-scaled submodule within a modular multilevel converter prototype. It can be concluded that excessively high redistribution currents can be prevented. Consequently, they are no obstacle for using the semi-full-bridge submodule in future HVDC converters.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Keywords
AC-DC power conversion, HVDC converters, HVDC transmission, Power transmission, Fault tolerance, Power system faults
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-240824 (URN)10.1109/TPEL.2018.2890622 (DOI)000474581900016 ()2-s2.0-85068640873 (Scopus ID)
Funder
SweGRIDS - Swedish Centre for Smart Grids and Energy Storage, CPC4
Note

QC 20190107

Available from: 2019-01-03 Created: 2019-01-03 Last updated: 2019-07-31Bibliographically approved
Bakas, P., Ilves, K., Harnefors, L., Norrga, S. & Nee, H.-P. (2018). Hybrid Converter With Alternate Common Arm and Director Thyristors for High-Power Capability. In: 2018 20th European Conference on Power Electronics and Applications (EPE’18 ECCE Europe): . Paper presented at 2018 20th European Conference on Power Electronics and Applications (EPE’18 ECCE Europe).
Open this publication in new window or tab >>Hybrid Converter With Alternate Common Arm and Director Thyristors for High-Power Capability
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2018 (English)In: 2018 20th European Conference on Power Electronics and Applications (EPE’18 ECCE Europe), 2018Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents the basic operating principles of a new hybrid converter that combines thyristors and full-bridge (FB) arms for achieving high active-power capability. This converter consists of a modular multilevel converter (MMC) equipped with additional common arms, which alternate between the upper and lower dc poles. This alternation is achieved by the thyristors that are utilized as director switches and allow the parallel connection of the common arms and the arms of the MMC. The main contributions of this paper are the analysis of the operating principles, the simulation verification of the functionality of the proposed converter, and the comparison of the latter with the full-bridge modular multilevel converter (FB-MMC).

Keywords
HVDC power convertors;thyristors;hybrid converter;modular multilevel converter;converter circuit;HVDC
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-239574 (URN)000450299300042 ()
Conference
2018 20th European Conference on Power Electronics and Applications (EPE’18 ECCE Europe)
Funder
SweGRIDS - Swedish Centre for Smart Grids and Energy Storage, SP8
Note

QC 20181210. QC 20191018

Available from: 2018-11-27 Created: 2018-11-27 Last updated: 2019-10-18Bibliographically approved
Bakas, P., Ilves, K., Okazaki, Y., Harnefors, L., Norrga, S. & Nee, H.-P. Hybrid alternate-common-arm converter with high power capability: Potential and limitations. IEEE transactions on power electronics
Open this publication in new window or tab >>Hybrid alternate-common-arm converter with high power capability: Potential and limitations
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(English)In: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107Article in journal (Other academic) Submitted
Abstract [en]

This paper studies a new hybrid converter thatutilizes thyristors and full-bridge (FB) arms for achieving higherpower capability than the full-bridge (FB) modular multilevel converter (MMC) with reduced semiconductor requirements. The study covers the theoretical analysis of the energy balancing,the dimensioning principles, the maximum power capability, and the limitations imposed by the discontinuous operation of theconverter. Based on the analysis of these aspects, the theoretical analysis is concluded by identifying the design constraints that need to be fulfilled for achieving the maximum power capabilityof the converter. It is concluded that the maximum power capability can be achieved for a certain range of modulation indices and is limited by both the commutation time of the thyristors andthe power angle. Finally, simulation and experimental results that confirm the theoretical analysis and the feasibility of the studied converter are presented and discussed.

Place, publisher, year, edition, pages
IEEE
Keywords
DC-AC power conversion, HVDC transmission, Thyristors
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-262701 (URN)
Funder
SweGRIDS - Swedish Centre for Smart Grids and Energy Storage, SP8
Note

QC 20191018

Available from: 2019-10-18 Created: 2019-10-18 Last updated: 2019-10-21Bibliographically approved
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