Change search
Link to record
Permanent link

Direct link
Alternative names
Publications (10 of 10) Show all publications
Laury, J., Abrahamsson, L. & Bollen, M. (2019). A rotary frequency converter model for electromechanical transient studies of 16 (2/3) Hz railway systems. International Journal of Electrical Power & Energy Systems, 106, 467-476
Open this publication in new window or tab >>A rotary frequency converter model for electromechanical transient studies of 16 (2/3) Hz railway systems
2019 (English)In: International Journal of Electrical Power & Energy Systems, ISSN 0142-0615, E-ISSN 1879-3517, Vol. 106, p. 467-476Article in journal (Refereed) Published
Abstract [en]

Railway power systems operating at a nominal frequency below the frequency of the public grid (50 or 60 Hz) are special in many senses. One is that they exist in a just few countries around the world. However, for these countries such low frequency railways are a critical part of their infrastructure.

The number of published dynamic models as well as stability studies regarding low frequency railways is small, compared to corresponding publications regarding 50 Hz/60 Hz public grids. Since there are two main type of low frequency railways; synchronous and asynchronous, it makes the number of available useful publications even smaller. One important reason for this is the small share of such grids on a global scale, resulting in less research and development man hours spent on low frequency grids.

This work presents an open model of a (synchronous-synchronous) rotary frequency converter for electromechanical stability studies in the phasor domain, based on established synchronous machine models. The proposed model is designed such that it can be used with the available data for a rotary frequency converter.

The behaviour of the model is shown through numerical electromechanical transient stability simulations of two example cases, where a fault is cleared, and the subsequent oscillations are shown. The first example is a single-fed catenary section and the second is doubly-fed catenary section.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Low frequency railways, 16 (2/3)  Hz, Modelling, Simulations, Transient stability, Rotary frequency converter, Motor generator set, Multi machine system
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
FOI-portföljer, Äldre portföljer
Identifiers
urn:nbn:se:trafikverket:diva-5727 (URN)10.1016/j.ijepes.2018.10.017 (DOI)000454377000043 ()2-s2.0-85055732778 (Scopus ID)
Projects
Drift av stora kraftsystem med små mängder av fysiskt tröghetsmoment
Funder
Swedish Transport Administration, TRV 2014/39852
Available from: 2023-02-06 Created: 2023-02-06 Last updated: 2023-02-14Bibliographically approved
Abrahamsson, L., Laury, J. & Bollen, M. (2019). Evaluating a constant-current load model through comparative transient stability case-studies of a synchronous-synchronous rotary frequency converter-fed railway. In: 2019 Joint Rail Conference: . Paper presented at ASME/IEEE Joint Rail Conference, 9-12 April, 2019, Snowbird, Utah, USA. ASME Press, Article ID V001T09A003.
Open this publication in new window or tab >>Evaluating a constant-current load model through comparative transient stability case-studies of a synchronous-synchronous rotary frequency converter-fed railway
2019 (English)In: 2019 Joint Rail Conference, ASME Press , 2019, article id V001T09A003Conference paper, Published paper (Other academic)
Abstract [en]

This paper continues the pursuit of getting a deeper understanding regarding the transient stability of low-frequency AC railway power systems operated at 16 2/3 Hz synchronously to the public grid. The focus is set on the impact of different load models. A simple constant-current load model is proposed and compared to a previously proposed and studied load model in which the train’s active power is regulated.

The study and comparison is made on exactly the same cases as and grid as with the already proposed and more advanced load model. The railway grid is equipped with a low-frequency AC high-voltage transmission line which is subjected to a fault. The study is limited to railways being fed by different distributions of RFC (Rotary Frequency Converter) types. Both AT (auto transformer) and BT (booster transformer) catenaries are considered.

The RFC dynamic models are essentially Anderson-Fouad models of two synchronous machines coupled mechanically by their rotors being connected to the same shaft.

The differences in load behaviour between the proposed constant-current load model and the previously proposed and studied voltage-dependent active power load model are analyzed and described in the paper.

Place, publisher, year, edition, pages
ASME Press, 2019
Series
Trafikverkets forskningsportföljer
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
FOI-portföljer, Äldre portföljer
Identifiers
urn:nbn:se:trafikverket:diva-5733 (URN)10.1115/JRC2019-1249 (DOI)
Conference
ASME/IEEE Joint Rail Conference, 9-12 April, 2019, Snowbird, Utah, USA
Projects
Drift av stora kraftsystem med små mängder av fysiskt tröghetsmoment
Funder
Swedish Transport Administration, TRV 2014/39852
Note

ISBN för värdpublikation: 978-0-7918-5852-3

Available from: 2023-02-06 Created: 2023-02-06 Last updated: 2023-02-16Bibliographically approved
Laury, J., Abrahamsson, L. & Bollen, M. (2019). Impact of Reduced Share of Rotary Frequency Converters in a Low Frequency Synchronous Railway Grid: A Transient Stability Study. In: Proceedings of the 2019 Joint Rail Conference2019 Joint Rail Conference. Snowbird, Utah, USA. April 9–12, 2019.: . Paper presented at ASME/IEEE Joint Rail Conference, 9-12 April, 2019, Snowbird, Utah, USA. American Society for Mechanical Engineers (ASME), Article ID V001T09A002.
Open this publication in new window or tab >>Impact of Reduced Share of Rotary Frequency Converters in a Low Frequency Synchronous Railway Grid: A Transient Stability Study
2019 (English)In: Proceedings of the 2019 Joint Rail Conference2019 Joint Rail Conference. Snowbird, Utah, USA. April 9–12, 2019., American Society for Mechanical Engineers (ASME) , 2019, article id V001T09A002Conference paper, Published paper (Other academic)
Abstract [en]

Most low-frequency AC single-phase railway grids have both power-electronic based Static Frequency Converters (SFCs) and electrical-machine based Rotary Frequency Converters (RFCs) connecting them to the three-phase public grid.

Already today, in some such grids, a majority of the power conversion is from SFCs. As railway traffic (and thus power demand) increases, more SFCs are installed for capacity increase, while the number of RFCs remains (almost) constant. Thus, the share of SFCs is expected to increase, and the ratio of installed rotational inertia over installed power to decrease.

This paper investigates how different shares of SFCs affect the transient stability of low-frequency AC railway grids when having a mix of RFCs and SFCs converting three-phase AC power to single-phase AC power. Results from numerical simulations of the interactions that occur between converters when and after the grid is subject to a fault are presented.

The numerical studies show that with an increased share of SFCs there is an increased oscillatory behavior, for example in the voltage magnitude and active power after fault clearance.

Place, publisher, year, edition, pages
American Society for Mechanical Engineers (ASME), 2019
Series
Trafikverkets forskningsportföljer
Keywords
Railroads, Stability, Transients (Dynamics), Alternating current (Electricity), Clearances (Engineering), Computer simulation, Energy conversion, Machinery, Rotational inertia, Traffic
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
FOI-portföljer, Äldre portföljer
Identifiers
urn:nbn:se:trafikverket:diva-5731 (URN)10.1115/JRC2019-1238 (DOI)000488337500049 ()978-0-7918-5852-3 (ISBN)
Conference
ASME/IEEE Joint Rail Conference, 9-12 April, 2019, Snowbird, Utah, USA
Projects
Drift av stora kraftsystem med små mängder av fysiskt tröghetsmoment
Funder
Swedish Transport Administration, TRV 2014/39852
Available from: 2023-02-06 Created: 2023-02-06 Last updated: 2023-02-16Bibliographically approved
Abrahamsson, L., Laury, J. & Bollen, M. (2018). Further studies on the transient stability of synchronous-synchronous rotary frequency converter fed railways with low-frequency AC high-voltage transmission. International Journal of Energy Production and Management, 3(4), 266-276
Open this publication in new window or tab >>Further studies on the transient stability of synchronous-synchronous rotary frequency converter fed railways with low-frequency AC high-voltage transmission
2018 (English)In: International Journal of Energy Production and Management, ISSN 2056-3272, E-ISSN 2056-3280, Vol. 3, no 4, p. 266-276Article in journal (Refereed) Published
Abstract [en]

This paper continues the pursuit of getting a deeper understanding regarding the transient stability of low-frequency AC railway power systems operated at 16 2/3 Hz that are synchronously connected to the public grid. Here, the focus is set on such grids with a low-frequency AC high-voltage transmission line subject to a fault. The study here is limited to railways being fed by different distributions of Rotary Frequency Converter (RFC) types. Both auto transformer (AT) and booster transformer (BT) catenaries are considered. No mixed model configurations in the converter stations (CSs) are considered in this study. Therefore, only interactions between RFCs in different CSs and between RFCs, the fault, and the load can take place in this study. The RFC dynamic models are essentially two Anderson-Fouad models of synchronous machines coupled mechanically by their rotors being connected to the same mechani- cal shaft. Besides the new cases studied, also a new voltage-dependent active power load model is presented and used in this study.

Place, publisher, year, edition, pages
WIT Press, 2018
Keywords
railway, power systems, transient stability, electromechanical dynamics, frequency converters, 162⁄3Hz, synchronous machines, train load modelling
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
FOI-portföljer, Äldre portföljer
Identifiers
urn:nbn:se:trafikverket:diva-5732 (URN)10.2495/EQ-V3-N4-266-276 (DOI)
Projects
Drift av stora kraftsystem med små mängder av fysiskt tröghetsmoment
Funder
Swedish Transport Administration, TRV 2014/39852
Available from: 2023-02-06 Created: 2023-02-06 Last updated: 2023-02-16Bibliographically approved
Laury, J., Abrahamsson, L. & Bollen, M. (2018). Transient Stability of a Rotary Frequency Converter fed railway, interconnected with a parallel low frequency high voltage transmission system. Paper presented at Comprail 2018, 16th International Conference on Railway Engineering Design & Operation, 2-4 July 2018, Lisbon, Portugal. WIT Transactions on the Built Environment, 181, 15-24
Open this publication in new window or tab >>Transient Stability of a Rotary Frequency Converter fed railway, interconnected with a parallel low frequency high voltage transmission system
2018 (English)In: WIT Transactions on the Built Environment, ISSN 1746-4498, E-ISSN 1743-3509, Vol. 181, p. 15-24Article in journal (Refereed) Published
Abstract [en]

Using low frequency High Voltage Transmission systems (HV-T) in parallel with the catenary systemstrengthens the railway system by reducing the total impedance of the railway grid. A consequence ofthe reduced impedance is that converter stations are electrically closer to each other. Inside a converter station, different types of Rotary Frequency Converters (RFCs) are used. It is not wellexplored how different RFCs behaves and interacts with each other during and after a large disturbance, like a short circuit. The dynamics of an RFC are modelled by using the Andersson-Fouad model of a synchronous machine. The study presented in this paper investigates interactions inside and between converter stations, withdifferent types of RFC, for an HV-T system in parallel with a Booster Transformer catenary system. The numerical simulation results show, for instance, that the main power oscillation take place inside aconverter station with mixed configuration of RFC type after fault clearance.

Place, publisher, year, edition, pages
WIT Press, 2018
Keywords
railway, low frequency, 16 (2/3) Hz, transient stability, rotary frequency converter, RFC, high voltage transmission, BT, power oscillations, synchronous
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
FOI-portföljer, Äldre portföljer
Identifiers
urn:nbn:se:trafikverket:diva-5730 (URN)10.2495/CR180021 (DOI)978-1-78466-285-1 (ISBN)
Conference
Comprail 2018, 16th International Conference on Railway Engineering Design & Operation, 2-4 July 2018, Lisbon, Portugal
Projects
Drift av stora kraftsystem med små mängder av fysiskt tröghetsmoment
Funder
Swedish Transport Administration, TRV 2014/39852
Note

Konferensartikel i tidskrift

Available from: 2023-02-06 Created: 2023-02-06 Last updated: 2023-02-16Bibliographically approved
Laury, J., Abrahamsson, L. & Bollen, M. (2018). Transient stability of rotary frequency converter fed low frequency railway grids: The Impact of Different Grid Impedances and Different Converter Station Configurations. In: : . Paper presented at ASME Joint Rail Conference (JRC 2018), Pittsburgh, PA, APR 18-20, 2018. American Society of Mechanical Engineers (ASME), Article ID UNSP V001T09A006.
Open this publication in new window or tab >>Transient stability of rotary frequency converter fed low frequency railway grids: The Impact of Different Grid Impedances and Different Converter Station Configurations
2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

One method of strengthening low frequency AC railway grids is to upgrade Booster Transformer (BT) catenary systems, to Auto Transformer (AT) catenary systems. An AT catenary system has lower equivalent impedance compared to a BT system. Thus, an upgrade makes the existing converter stations electrically closer.

Converter stations may have different types of Rotary Frequency Converters (RFCs) installed in them, and it is not well explored how different RFCs behaves and interact during and after a large disturbance.

Using the Anderson-Fouad model of synchronous machines to describe the dynamics of RFCs, several case studies have been performed through numerical simulations. The studies investigate the interactions within and between converter stations constituted with different RFC types, for BT as well AT catenary systems.

The numerical studies reveal that replacing BT with AT catenary systems, results in a more oscillatory system behaviour. This is seen for example in the power oscillations between and inside converter stations, after fault clearance.

Place, publisher, year, edition, pages
American Society of Mechanical Engineers (ASME), 2018
Series
Trafikverkets forskningsportföljer
Series
Proceedings of the ASME Joint Rail Conference, ISSN 1559-9531, E-ISSN 2160-1380
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
FOI-portföljer, Äldre portföljer
Identifiers
urn:nbn:se:trafikverket:diva-5729 (URN)10.1115/JRC2018-6247 (DOI)000438662100091 ()978-0-7918-5097-8 (ISBN)
Conference
ASME Joint Rail Conference (JRC 2018), Pittsburgh, PA, APR 18-20, 2018
Projects
Drift av stora kraftsystem med små mängder av fysiskt tröghetsmoment
Funder
Swedish Transport Administration, TRV 2014/39852
Available from: 2023-02-06 Created: 2023-02-06 Last updated: 2023-02-16Bibliographically approved
Mahmood, Y. A., Abrahamsson, L., Ahmadi, A. & Verma, A. K. (2016). Reliability Evaluation of Traction Power Capacity in Converter-fed Railway Systems. IET Generation, Transmission & Distribution
Open this publication in new window or tab >>Reliability Evaluation of Traction Power Capacity in Converter-fed Railway Systems
2016 (English)In: IET Generation, Transmission & Distribution, ISSN 1751-8687, E-ISSN 1751-8695Article in journal (Refereed) Submitted
Abstract [en]

A Traction Power Supply System (TPSS) supplies electricity for train propulsion on electrified railways. In many countries, electrified railways have single-phase low-frequency AC power systems fed by frequency converters (FCs). Outages of power will significantly weaken the TPSS, cause operational problems and ultimately lead to traffic disruption in the form of speed reduction, train delays, or cancellations. The aim of this study is to propose an approach to analyse the reliability of power conversion capacity to discover the reasons for ‘loss of load”. The paper assumes train delays are caused by converter outages, shortages of reserve power capacity for unexpected train loads, or a combination of the two. It considers the availability performance of the converter station and evaluates the reliability of the conversion power capacity. It proposes a power-traffic factor (PTF) to aggregate and quantify train power demands. The PTF can be related to the availability of traction power capacity and will identify areas with risks of power shortages. The study finds the shortage in power leading to train delays in some regions of the system is due to a shortage of reserve power capacity

National Category
Other Civil Engineering
Research subject
FOI-portföljer, Strategiska initiativ
Identifiers
urn:nbn:se:trafikverket:diva-5953 (URN)a295cadd-7a75-4579-b7ae-5c2050fd8743 (Local ID)a295cadd-7a75-4579-b7ae-5c2050fd8743 (Archive number)a295cadd-7a75-4579-b7ae-5c2050fd8743 (OAI)
Projects
JVTC
Funder
Swedish Transport Administration, TRV 2011/58769
Note

Upprättat; 2015; 20150224 (yasahm)

Available from: 2016-09-29 Created: 2023-03-02
Laury, J., Abrahamsson, L. & Östlund, S. (2014). OPF for an HVDC feeder solution for railway power supply systems. Paper presented at Conference of 14th International Conference on Railway Engineering Design and Optimization, COMPRAIL 2014. WIT Transactions on the Built Environment, 135, 803-812
Open this publication in new window or tab >>OPF for an HVDC feeder solution for railway power supply systems
2014 (English)In: WIT Transactions on the Built Environment, ISSN 1746-4498, E-ISSN 1743-3509, Vol. 135, p. 803-812Article in journal (Refereed) Published
Abstract [en]

With increasing railway traffic, the demand for electrical power increases. However, railway power systems are often weak causing high transmission losses and large voltage drops. One possible method for strengthening the railway power supply system is to implement a High Voltage Direct Current (HVDC) feeder in parallel to the Overhead Contact Line (OCL). The HVDC feeder is connected to the OCL by converters. This paper describes different properties and characteristics of such an HVDC feeder solution. An AC/DC unified Optimal Power Flow (OPF) model and unit commitment is used to obtain proper control of the converters. The non-linear load flow and converter loss equations, and the binary variables for the unit commitment, lead to an optimization problem of Mixed Integer Non- Linear Programming (MINLP) type. The optimization problem is formulated in the software GAMS, and is solved by the solver BONMIN. In each case, the objective has been to minimize the total active power losses.

Keywords
Electric power systems, Feeding, Integer programming
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
FOI-portföljer, Äldre portföljer
Identifiers
urn:nbn:se:trafikverket:diva-17999 (URN)10.2495/CR140671 (DOI)2-s2.0-84903688956 (Scopus ID)
Conference
Conference of 14th International Conference on Railway Engineering Design and Optimization, COMPRAIL 2014
Projects
Ny effektelektronik i framtidens elektriska järnvägssystem
Funder
Swedish Transport Administration, TRV 2010/92183
Note

QC 20150608

Available from: 2015-06-08 Created: 2024-11-22
Abrahamsson, L., Kjellqvist, T. & Östlund, S. (2012). High-voltage DC-feeder solution for electric railways. IET Power Electronics, 5(9), 1776-1784
Open this publication in new window or tab >>High-voltage DC-feeder solution for electric railways
2012 (English)In: IET Power Electronics, ISSN 1755-4535, E-ISSN 1755-4543, Vol. 5, no 9, p. 1776-1784Article in journal (Refereed) Published
Abstract [en]

For AC railway power supply systems with a different frequency than the public grid, high-voltage AC transmission lines are common, connected to the catenary by transformers. This study suggests an alternative design based on an high-voltage DC (HVDC)-feeder, which is connected to the catenary by converters. Such an HVDC line would also be appropriate for DC-fed railways and AC-fed railways working at a public-grid frequency. The converter stations between the public grid and the HVDCfeeder can be sparsely distributed, not denser than on 100 km distances, whereas the converters connecting the HVDC-feeder to the catenary are distributed denser. Their ratings can be lower than present-day substation transformers or converters, since the power flows can be fully controlled. Despite a relatively low-power rating, the proposed converters can be highly efficient because of the use of medium frequency technology. The proposed feeding system results in lower material usage, lower losses and higher controllability compared with the present solutions. Simulations of the proposed solution show clear advantages regarding transmission losses and voltages compared with conventional systems, especially for cases with weak feeding, and when there are substantial amounts of regeneration from the trains.

Place, publisher, year, edition, pages
Institution of Engineering and Technology, 2012
Keywords
Banutformning
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
FOI-portföljer, Äldre portföljer
Identifiers
urn:nbn:se:trafikverket:diva-17998 (URN)10.1049/iet-pel.2011.0219 (DOI)000317655400018 ()2-s2.0-84880017472 (Scopus ID)
Projects
Ny effektelektronik i framtidens elektriska järnvägssystem
Funder
Swedish Transport Administration, TRV 2010/92183
Note

QC 20130813

Available from: 2024-11-22 Created: 2024-11-22 Last updated: 2024-11-22
Laury, J., Abrahamsson, L. & Bollen, M. Challenges with increased share of power electronic generation in railway power supply systems.
Open this publication in new window or tab >>Challenges with increased share of power electronic generation in railway power supply systems
(Swedish)Manuscript (preprint) (Other academic)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
FOI-portföljer, Äldre portföljer
Identifiers
urn:nbn:se:trafikverket:diva-5734 (URN)
Projects
Drift av stora kraftsystem med små mängder av fysiskt tröghetsmoment
Funder
Swedish Transport Administration, TRV 2014/39852
Available from: 2023-02-06 Created: 2023-02-06 Last updated: 2023-02-16Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2109-060X

Search in DiVA

Show all publications