Change search
Refine search result
2345678 201 - 250 of 375
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 201.
    Larsson, Anders
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Mitigation of main factors that limit the introduction of energy‐efficient lighting systems2012Report (Other academic)
    Abstract [sv]

    Detta är slutrapporten från den svenska Energimyndigheten projekt (P31550‐1) "Minskat livslängd av energieffektiv belysning på grund av höga nivåer av elektromagnetiska störningar" som utförs av kraftteknik gruppen vid Luleå Tekniska Universitet. I detta projekt har elektromagnetiska störningar studerats i anläggningar med ett stort antal lysrör med högfrekventa förkopplingsdon (HF‐don). Sådana belysningsanläggningar återfinns i butiker och köpcentra, stora kontor och lagerutrymmen.Projektet har resulterat i ökad kunskap om vågformsdistorsion i frekvensområdet 2 till 150 kHz och spridningen av dessa komponenter inom en belysningsanläggning. Följandekonkreta resultat kan nämnas:Övertoner (under 2 kHz) från en belysningsinstallation är låg jämfört med liknande typer av elektroniska lasterEmission inom frekvensområdet mellan 2 till 150 kHz kan hänföras till rester från om ”switchingen” i HF‐donen och återkommande oscillationer som sker näragrundtonens nollgenomgång Typen av emission från belysningsinstallationer i frekvensområdet 2 till 150 kHz kan delas in i följande:o Smalbandiga komponentero Bredbandiga komponentero Återkommande oscillationerNär belysningen installeras i stora grupper som t.ex. i varuhus så sprids de olikaemissionerna på olika sätt. Resterna från switchingen går framförallt mellanarmaturerna medan de återkommande oscillationerna adderas i amplitud och sprider sig uppåt i nätet mot transformatorn.Anledningen till att resterna från switchingen till största del stannar ibelysningsanläggningen beror på att varje EMC‐filter på AC sidan erbjuder en lågimpedans för dessa komponenter.Rapporten diskuterar också idéer om lämpliga lösningar för att minimera olikaemissioner och om hur man designar belysningsanläggningar och EMC‐filter drivdon.De återkommande oscillationerna kan uppfattas som ett potentiellt problem i stora anläggningar. Det finns även inga tecken ännu att återkommande oscillationer är antingen ett hot eller inte, för den förväntade livslängden hos drivdonen. Här behövs dock ytterligare forskning.

  • 202.
    Larsson, Anders
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Some consequences for the power grid of high densities of electronic equipment2005In: First International Conference on Lifestyle, Health and Technology: June 1-3, 2005 at Luleå University of Technology, Porsön, Luleå, Sweden, Luleå: Luleå tekniska universitet, 2005Conference paper (Refereed)
    Abstract [en]

    This paper will highlight some problems that can arrise when many different power supplies are densley connected to the electric mains. Measurements have been made on sites where numerous electronic devices are connected. The results of these measurements are presented and some of the consequences are discussed.

  • 203.
    Larsson, Anders
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Lundmark, Martin
    Measurement and analysis of high-frequency conducted disturbances2007In: Conference proceedings: 19th International Conference and Exhibition on Electricity Distribution, Vienna, 21 - 24 May 2007, Liege: AIM , 2007Conference paper (Refereed)
    Abstract [en]

    The frequency range above the "traditional" harmonic range up to about 2 to 3 kHz has been under investigation for a while but less attention has been paid to the frequency range slightly above. This paper presents measurements both in laboratory environment and in the field on different types of equipment and general long- term measurement on site in the low voltage network. The general aim of this paper is to increase the knowledge about voltage and current distortion in the frequency range above 2 kHz.

  • 204.
    Larsson, Anders
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Wahlberg, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Lundmark, Martin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Measurements of high-frequency (2-150 kHz) distortion in low-voltage networks2010In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 25, no 3, p. 1749-1757Article in journal (Refereed)
    Abstract [en]

    This paper presents different methods to describe voltage and current distortion in the frequency range 2 to 150kHz. The time-frequency domain was shown to give additional information next to the time- and frequency-domain representations. Measurements of different devices and at different locations showed remnants of the switching frequency of the power electronics as well as lower frequency oscillations around the current zero crossing to be present in voltage and current. The voltage distortion is shown to vary a lot during the day and between locations.

  • 205.
    Larsson, Anders
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gil-de-Castro, Aurora
    University of Cordoba.
    Wahlberg, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Field and laboratory measurements of interference with light equipment due to waveform distortion originating from a large rectifier2015Conference paper (Refereed)
    Abstract [en]

    This paper will present a case study where light in anoffice building is disturbed and do not function properly.From measurements it is shown that a UPS system iscausing distortions. One lamp from the office wasbrought to laboratory where the distortions was repeatedand subjected to the lamp. When doing so the lampshowed the same immunity problem.

  • 206.
    Larsson, Anders
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundmark, Martin
    Bollen, Math
    Distortion of fluorescent lamps in the frequency range 2-150 kHz2006Conference paper (Refereed)
    Abstract [en]

    This paper presents measurements of voltages and currents taken by fluorescent lamps with high-frequency ballast. The results are discussed in time domain, in frequency domain and in time-frequency domain. A number of different high-frequency components are present: recurrent transients, narrow-band time-invariant signals, and time-dependent signals. The increase in distortion with increasing number of lamps is studied as well. The distortion increases about linear with the number of lamps in the frequency range 2-9 kHz but shows only a minor increase or no increase at all in the frequency range 9-150 kHz.

  • 207.
    Larsson, Anders
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundmark, Martin
    Bollen, Math
    Measurement of current taken by fluorescent lights in the frequency range 2-150 kHz2006In: IEEE Power Engineering Society general meeting, 2006: 18 - 22 June 2006, Montreal, QC, Canada, Piscataway, NJ: IEEE Communications Society, 2006Conference paper (Refereed)
    Abstract [en]

    This paper discusses measurements taken on fluorescent lights in the frequency range between 2 and 150 kHz. The presentation of the measurement results form an important part of the paper. The measurement results are presented in time-domain, in the frequency domain and in the time-frequency domain (by means of a "spectrogram"). The latter allows the study of sub-cycle changes in the current spectrum. The current taken by one lamp is compared with the current taken by two, three and four lamps. The relative high-frequency distortion reduced for frequencies above 15 kHz.

  • 208.
    Larsson, Anders
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundmark, Martin
    Bollen, Math
    Wahlberg, Mats
    Rönnberg, Sarah
    Evolution of the harmonic distortion from state-of-the-art computers: 2002 to 20082009In: CIRED 20th International Conference on Electricity Distribution: 8 -11 June 2009, Prague Congress Centre, Prague, Red Hook, NY: Curran Associates, Inc., 2009, p. 164-167Conference paper (Refereed)
    Abstract [en]

    This paper shows trends in harmonic emission by large groups of modern computers over a 7-year period. The measurements were obtained at computer tournaments where almost exclusively the newest types of computers are used. The measurements clearly show that the harmonic distortion is decreasing significantly while the power consumption per computer does not change significantly.

  • 209.
    Larsson, Anders
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wahlberg, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Reduced life-time of lamps: Temperature rise and bad power quality2014Article in journal (Refereed)
    Abstract [en]

    To save energy, many new buildings have modern energy saving lighting installed. In large department or grocery stores the use of fluorescent lamps powered by high frequency electronic ballast is common. There are however consistent reports of large numbers of failures of the electronic ballast of these lamps. The failures of the electronic ballast are due to high temperature or bad power quality. But neither of these reasons has been confirmed as the cause. This paper discusses in general the lifetime of electronic ballast. The paper also presents detailed analysis of results from measurement performed in a grocery store where high instances of failure have been observed. Both temperature and power quality in the harmonic range and 2 to 150 kHz have been included in the measurements

  • 210.
    Larsson, Anders
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wahlberg, Mats
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Lundmark, Martin
    Waveform distortion at computer festivals: 2002 to 20082008In: 2008 13th International Conference on Harmonics and Quality of Power: [ICHQP 2008] ; Wollongong, Australia, 28 September - 1 October 2008, Piscataway, NJ: IEEE Communications Society, 2008Conference paper (Refereed)
    Abstract [en]

    This paper shows measurements of the harmonic emission by large groups of state-of-the-art computers measured at five different occasions from 2002 to 2008. The emission was measured during LAN-festivals where the participants use mainly the newest models of computer. This allows insight in the change in emission of computers during the last 6 years. The results from these measurements show that the distortion level generated by computers is decreasing while the power consumption does not show any significant change.

  • 211.
    Laury, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Abrahamsson, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    A rotary frequency converter model for electromechanical transient studies of 16 (2/3) Hz railway systems2019In: International Journal of Electrical Power & Energy Systems, ISSN 0142-0615, E-ISSN 1879-3517, Vol. 106, p. 467-476Article in journal (Refereed)
    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.

  • 212. Laury, John
    et al.
    Abrahamsson, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Challenges with increased share of power electronic generation in railway power supply systems.In: The Electricity Journal - ElsevierArticle in journal (Refereed)
  • 213. Laury, John
    et al.
    Abrahamsson, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Impact of reduced share of rotary frequency converter in a low-frequency synchronous railway grid: A transient stability study.2019Conference paper (Refereed)
  • 214.
    Laury, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Abrahamsson, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Modified voltage control law for low frequency railway power systems2017In: Proceedings of the 2017 IEEE/ASME Joint Rail Conference, ASME Press, 2017Conference paper (Refereed)
    Abstract [en]

    In today's Swedish and Norwegian low frequency railway power system the voltage at a converter is controlled such that its voltage will drop with increased reactive power output. However, for low frequency railways the influence of active power on voltage is larger compared to public power systems and alternative methods are interesting to investigate. This paper presents a modified voltage control law for increased load sharing between converter stations and reduce the risk for converter overload in low frequency railways power systems. The modified voltage control law is derived mathematically and tested with different droops for two case studies. The results confirms the increased load sharing between the converter stations. The results are analysed and discussed; ideas are presented to counteract some of the negative impacts of the modified voltage control law

  • 215.
    Laury, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Abrahamsson, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Transient Stability of a Rotary Frequency Converter fed railway, interconnected with a parallel low frequency high voltage transmission system2018In: WIT Transactions on the Built Environment, ISSN 1746-4498, E-ISSN 1743-3509, Vol. 181, p. 15-24Article in journal (Refereed)
    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.

  • 216.
    Laury, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Abrahamsson, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Transient stability of rotary frequency converter fed low frequency railway grids: The Impact of Different Grid Impedances and Different Converter Station Configurations2018Conference 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.

  • 217.
    Laury, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Multi-machine transient stability for railways2015In: Computers in Railways XIV Special Contributions: Railway Engineering Design and Optimization / [ed] C.A. Beribba, Southampton: WIT Press, 2015, Vol. 155Conference paper (Refereed)
    Abstract [en]

    This papers concern the replacement of Static Frequency Converters (SFC) by Rotary Frequency Converters (RFC) in Railway Power Supply Systems (RPSS) operating at 16⅔ Hz. There is a need to investigate how such a system behaves with only one or with a small number of RFCs. This is of great importance as SFCs do not contribute to the inertia of the RPSS. Thus, the remaining RFCs have to keep the stability during a large disturbance.Few studies investigate the stability of a RPSS and most of them study only the behaviour of a RFC in a converter station against an infinite bus. However, there are very few studies investigating a system with several RFCs in converter stations. Against this background, the aim of this paper is to present the results of a multi-machine transient stability study with several RFCs. Different cases have been investigated: regenerative braking of a train; a fault in the overhead contact line and a fault in the parallel 132 kV line.For the investigated cases the system with RFCs is stable but oscillations in the rotor angle swing occur due to no damping being modelled in the system.

  • 218.
    Laury, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Abrahamsson, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Transient stability analysis of low frequency railway grids2016In: WIT Transactions on the Built Environment, ISSN 1746-4498, E-ISSN 1743-3509, Vol. 162, p. 213-223Article in journal (Refereed)
    Abstract [en]

    This paper investigates the replacement of Rotary Frequency Converters(RFCs) with Static Frequency Converters (SFCs) in the Swedish synchronous-synchronous Railway Power Supply System (RPSS) operating at1623Hz. Thereis a need to investigate how such a system behaves when RFCs are partly replacedwith SFCs, as the SFCs do not have any physical inertia.Most of the transient stability studies published for synchronous-synchronousRPSS address the behaviour of a single RFC or SFC against an infinite bus.However, there are very few studies investigating a system with several RFCs,SFCs or a mix of both in the same converter station. This paper presents the resultsof a transient stability study with both RFCs and SFCs. The investigated casesconsist of faults at different locations, and present the results when an RFC isreplaced with an SFC in a converter station.

  • 219.
    Laury, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Abrahamsson, Lars
    Kungliga tekniska högskolan, KTH.
    Östlund, Stefan
    Some benefits of a HVDC feeder solution for railways2014Conference paper (Refereed)
  • 220.
    Le, C. D
    et al.
    Chalmers University of Technology, Department of Signals and Systems.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gu, Irene
    Chalmers University of Technology, Department of Signals and Systems.
    A method to evaluate harmonic model-based estimations under non-white measured noise2011In: 2011 IEEE PES Trondheim PowerTech: The Power of Technology for a Sustainable Society, POWERTECH 2011; Trondheim; 19 June 2011 through 23 June 2011, Piscataway, NJ: IEEE Communications Society, 2011Conference paper (Refereed)
    Abstract [en]

    Automatic extracting information from power-system event recordings requires applications of signal-processing estimation techniques whose performance has been verified under white noise. This paper proposes a method to test these techniques under real power-system noise, which is very different from white noise, to evaluate their application feasibility. The first part of the paper describes the evaluation method used to evaluate the techniques in a statistical sense and a method to extract noise from measured power-system recordings. The second part of the paper focuses on the evaluation of a number of harmonic model-based techniques under non-white noise, including: Kalman filter, MUSIC, ESPRIT, and segmentation algorithms. The paper shows that for the Kalman filter, a very high order with high computational burden is necessary only if high frequency components are of interest. The application of MUSIC, ESPRIT, and the segmentation algorithms under natural power-system noise is shown to be feasible.

  • 221.
    Le, C. D
    et al.
    Chalmers University of Technology.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gu, Irene
    Chalmers University of Technology.
    Analysis of power disturbances from monitoring multiple levels and locations in a power system2010In: 14th International Conference on Harmonics and Quality of Power, 2010: ICHQP 2010, 26-29 Sep. 2010, Bergamo, Italy, IEEE Communications Society, 2010Conference paper (Refereed)
    Abstract [en]

    This paper proposes a new methodology for diagnosing the original source and underlying causes of power system disturbances, where voltage and current recordings from different locations of a power system are collected. In the proposed method, disturbances are first pre-classified based on the number of transition segments. The spatial zone of the source of disturbances is coarsely determined from voltage recordings only. Disturbances are then further analyzed and characterized by extracting information from both voltages and currents. Finally more accurate information about the location of the source of disturbances is obtained by different techniques depending on the type of disturbances. Several underlying causes are analyzed and classified by using the proposed features extracted from both voltage and current waveforms. Finally, the location of the source of disturbances is refined once the underlying causes are found. Case studies were performed on a large grid-connected wind farm with disturbances from several underlying causes, including: fault, unit tripping, transformer, capacitor, and cable energizing generated by PSCAD/EMTDC.

  • 222.
    Le, C.D.
    et al.
    Chalmers University of Technology, Department of Signals and Systems.
    Gu, I.Y.H.
    Chalmers University of Technology, Department of Signals and Systems.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Joint causal and anti-causal segmentation and location of transitions in power disturbances2010In: 2010 IEEE Power and Energy Society General Meeting, Piscataway, NJ: IEEE Communications Society, 2010Conference paper (Refereed)
    Abstract [en]

    An important step in power disturbance data analysis is to first partition the disturbance sequence into transition and event segments. One main contribution of the paper is the propose of a new segmentation scheme that jointly uses the causal and anti-causal segmentation. We show that the actual location of a trigger point can be accurately estimated by combining the causal and anti-causal transition segments. Another main contribution is a new method for setting the threshold of detection parameter. From the residuals of Kalman filter, a detection parameter is defined and the threshold for this parameter is computed based on pdf estimates and hypothesis tests on measurement sequences with/without disturbances. Using the proposed segmentation and the statistically-based threshold, we show that transition segments, especially the trigger points, are allocated more accurately. Tests are performed on semi-synthetic disturbance sequences containing step, ramp and multi-stage transition. The proposed method is shown to be able to locate fast transitions with very high accuracy. The performance of segmentation against the point on wave, depth of transition, speed of transition, and polluted noise level are also evaluated.

  • 223.
    Le, Chung D.
    et al.
    Chalmers University of Technology, Department of Signals and Systems.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ride-through of induction generator based wind park with switched capacitor, SVC or STATCOM2010In: 2010 IEEE Power and Energy Society General Meeting, Piscataway, NJ: IEEE Communications Society, 2010Conference paper (Refereed)
    Abstract [en]

    This paper discusses about the ride-through capability of a large induction-generator based wind park with different reactive power support solutions. Three different solutions have been compared and it has been shown that conventional switching of capacitors is able to help the wind park meet the Nordel gird code requirements on low voltage ride-through. The requirements on rating are shown to be the same for an SVC and for a STATCOM. Two aggregation methods for large wind parks have been studied and an error estimation has been made. It is shown that a two-machine model is the smallest one that gives an acceptable error in reactive-power flow. A single-machine model is not appropriate to assess fault-ride-through

  • 224.
    Leborgne, R.C
    et al.
    Chalmers University, Elteknik.
    Olguin, G
    ABB Corporate Research.
    Filho, J.M. Carvalho
    Itajuba Federal University, Brazil.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Differences in voltage dip exposure depending upon phase-to-phase and phase-to-neutral monitoring connections2007In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 22, no 2, p. 1153-1159Article in journal (Refereed)
    Abstract [en]

    Voltage dip indices are estimated for a set of simulated and measured events. The simulated dips are obtained applying the method of fault positions on a large transmission network and the measured dips come from a one-year survey. The indices estimated to compare phase-to-phase and phase-to-neutral dips are SARFI-90, SARFI-70, SARFI-ITIC, and average voltage dip amplitude. Furthermore, the results are analyzed in terms of the cumulative distribution frequency of the voltage dip amplitude. The comparison of phase-to-phase and phase-to-neutral indices indicates that, at transmission level, phase-to-neutral dips are more frequent and more severe than phase-to-phase ones. However, these differences are reduced at the load connection level, where the phase and line voltages show similar performance for the monitored system

  • 225.
    Leborgne, Roberto Chouhy
    et al.
    Federal University of Rio Grande do Sul (UFRGS), Porto Alegre.
    Oliveira, Thiago Clé de
    Itajuba Federal University, Brazil.
    Filho, José Maria de Carvalho
    Itajuba Federal University, Brazil.
    Oliveira, Jeder Francisco de
    CEMIG, Belo Horizonte.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    New approach for power lines performance estimation based on load variation due to voltage sags2011In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 83, no 1, p. 35-40Article in journal (Refereed)
    Abstract [en]

    The power line performance has traditionally been assessed in terms of its efficiency and reliability. The increase of the effect of voltage sags on sensitive loads, maybe located far away from the faulted line, is the reason to carry out a new analysis of power line's performance. A new method to evaluate the power line performance, based on voltage sag indices, is proposed. The voltage sag indices suggested to assess power lines performance are the load variation, the non delivered energy and the total cost due to voltage sags. The proposed power line performance is compared with the traditional performance based on power line outages. The results show that the proposed method can change the assessment of power lines performance and therefore the utility focus for investment.

  • 226.
    Lennerhag, Oscar
    et al.
    STRI AB, Ludvika.
    Ackeby, Susanne
    STRI AB, Ludvika.
    Bollen, Math
    STRI AB, Ludvika.
    Foskolos, Georgios
    MälarEnergi, Västerås.
    Gafurov, Tokhir
    MälarEnergi, Västerås.
    Using measurements to increase the accuracy of hosting capacity calculations2017In: CIRED - Open Access Proceedings Journal, E-ISSN 2515-0855, Vol. 2017, no 1, p. 2041-2044Article in journal (Refereed)
    Abstract [en]

    This study has compared five different methods for calculating the hosting capacity in a distribution grid. The results show a large difference in the obtained hosting capacity depending on the method used. It was found that the use of measurements in the calculations greatly increases the hosting capacity, compared with when using assumptions based on a ‘worst case scenario’, without increasing the risk for the network operator or other customers. It was also found that the statistical index used (i.e. 100, 99, or 95%) has a large impact on the calculated hosting capacity.

  • 227.
    Lennerhag, Oscar
    et al.
    STRI.
    Ackeby, Susanne
    STRI.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Voltage variations due to wind power and solar power at time scales of 10 minutes and less2014Conference paper (Refereed)
  • 228.
    Lennerhag, Oscar
    et al.
    Independent Insulation Group Sweden AB.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Power system impacts of decreasing resonance frequencies2018In: Proceedings of International Conference on Harmonics and Quality of Power, ICHQP, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2018Conference paper (Refereed)
    Abstract [en]

    As the energy system is transitioning to a more sustainable one several of the related changes will affect the power system in different ways. Renewable electricity sources, energy efficiency measures and increased operational flexibility lead to more serious resonances in the electricity network and an increased uncertainty in terms of frequency and damping of those resonances. This could have a large impact on the spread of harmonics and on temporary overvoltages. In this paper, some examples of changes in the grid are presented and their impact on the spread of harmonics and temporary overvoltages, as a consequence of changes in resonances, is discussed.

  • 229.
    Lennerhag, Oscar
    et al.
    STRI.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ackeby, Susanne
    STRI AB.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Spänningsvariationer och intermittent produktion2014Report (Refereed)
  • 230.
    Lennerhag, Oscar
    et al.
    STRI AB.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ackeby, Susanne
    STRI AB.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Very short variations in voltage (timescale less than 10 minutes) due to variations in wind and solar power2015Conference paper (Refereed)
    Abstract [en]

    This paper presents results from a study on variations in voltage magnitude at a timescale less than 10 minutes, due to measured variations in wind and solar production. The variations are compared with the measured variations at several low and medium-voltage sites. It is concluded that individual solar panels are not a concern but that several solar panels connected to the same low-voltage feeder may lead to a noticeable increase in voltage variations at this timescale. Individual wind turbines and wind farms are not expected to lead to a significant increase in voltage variations. The voltage variations do change in character by the introduction of wind and solar power.

  • 231.
    Lennerhag, Oscar
    et al.
    Independent Insulation Group Sweden AB, Ludvika, Sweden.
    Lundquist, Jan
    Independent Insulation Group Sweden AB, Ludvika, Sweden.
    Engelbrecht, Christiaan
    Engelbrecht Consulting B.V., The Netherlands.
    Karmokar, Tanumay
    NKT HV Cables AB, Lyckeby, Sweden.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Engineering Sciences and Mathematics, Luleå University of Technology, Skellefteå, Sweden.
    An Improved Statistical Method for Calculating Lightning Overvoltages in HVDC Overhead Line/Cable Systems2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 16, article id 3121Article in journal (Refereed)
    Abstract [en]

    HVDC cable systems connected to HVDC overhead lines are subject to fast front overvoltages emanating from the line when lightning strikes a shield wire (backflashover) or a pole conductor (shielding failure). Representative fast front overvoltage levels for HVDC cable systems are usually established without considering their statistical characteristics. A statistical method to determine overvoltages related to the acceptable mean time between failure (MTBF) for the cable system was developed previously. The method accounts for the statistical distribution of lightning current magnitudes as well as the attenuation of the overvoltage wave due to corona discharges on the line, since this effect dominates for system voltages up to about ±320 kV. To make the method suitable for higher system voltages as well, this article introduces an improved statistical method which also accounts for surge attenuation through resistive effects, soil ionization, and statistical treatment of overvoltages due to shielding failures. To illustrate the improved method, it is applied to a case study for a ±525 kV DC line. 

  • 232.
    Lennerhag, Oscar
    et al.
    STRI AB, Ludvika.
    Pinares, Gustavo
    STRI AB, Ludvika.
    Bollen, Math
    STRI AB, Ludvika.
    Foskolos, Georgios
    MälarEnergi, Västerås.
    Gafurov, Tokhir
    MälarEnergi, Västerås.
    Performance indicators for quantifying the ability of the grid to host renewable electricity production2017In: CIRED - Open Access Proceedings Journal, E-ISSN 2515-0855, Vol. 2017, no 1, p. 792-795Article in journal (Refereed)
    Abstract [en]

    This study proposes a comprehensive set of performance indicators that should be used when evaluating the hosting capacity (HC) of a system. Descriptions are given for the most relevant phenomena and how they should be quantified and measured. The suggested time resolution for the data has been 1 h, 10 min, and 3 s, based on what is available already in standard meters. The use of 100, 99, or 95 percentile values has an impact on the HC, and there is a need for further discussion with regard to the selection of statistical limits.

  • 233.
    Lin, Yufeng
    et al.
    Department of Electrical and Electronic Engineering, University of Hong Kong.
    Zhong, Jin
    Department of Electrical and Electronic Engineering, University of Hong Kong.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    An optimal power flow based dispatch model for distributed generation embedded network2010In: 9th Conference on Environment and Electrical Engineering, EEEIC 2010, IEEE Communications Society, 2010, p. 101-106Conference paper (Refereed)
    Abstract [en]

    The installation of distributed generation (DG) introduces challenges to distribution systems operation. The distribution network operator needs to schedule DG outputs considering some constraints, such as DG characteristics, reactive power control mode of generators, automatic voltage regulation, compensator and power quality standard, etc. Based on an optimal power flow model, this paper proposes a dispatch model for DG embedded distribution systems. The model is proposed basing on energy prices, weather forecasting and load forecasting. The objective is to minimize the electricity supply cost of the distribution company. The proposed model is tested in the 33-buse system. The results show that DisCo's cost and losses of the distribution system can be reduced by enhancing system operation flexibility

  • 234.
    Lin, Yufeng
    et al.
    Department of Electrical & Electronic Engineering, University of Hongkong.
    Zhong, Jin
    Department of Electrical & Electronic Engineering, University of Hongkong.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Evaluation of dip and interruption costs for a distribution system with distributed generations2008In: 2008 13th International Conference on Harmonics and Quality of Power: [ICHQP 2008] ; Wollongong, Australia, 28 September - 1 October 2008, Piscataway, NJ: IEEE Communications Society, 2008Conference paper (Refereed)
    Abstract [en]

    This paper propose a method to evaluate the dip and interruption costs in the distribution system with distributed generation units (DGs). The game theory is used to allocate the additional cost caused by operating DGs. To evaluate the impacts of DGs on dip and interruption costs, which could be positive impact or negative impact, the operating hours of DGs, the frequencies of the power quality events and the cost of a power quality event are estimated. In this paper, the operation hours of DGs are estimated according to the load duration curve and the operation cost of DGs; the frequencies of power quality events are calculated according to the reliability theory; the cost of a power quality event is evaluated using weighting factors. The additional dip and interruption costs caused by operating DGs are allocated among the DGs using the Shapley value axiom.

  • 235. Lindén, K
    et al.
    Jacobson, B
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundquist, J
    Reliability study methodology for HVDC grids2010Conference paper (Refereed)
  • 236.
    Lu, Shengye
    et al.
    Department of Electrical Engineering, Tampere University of Technology.
    Repo, Sami
    Department of Electrical Engineering, Tampere University of Technology.
    Tjäder, Jonas
    STRI AB, Ludvika.
    Kjellström, Anders
    Luleå tekniska universiet.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Etherden, Nicholas
    Vattenfall AB.
    IEC 61850-based Communication and Aggregation Solution for Demand-Response Application2017In: IEEE PES Innovative Smart Grid Technologies Conference Europe: ISGT Europe 2016,  Ljubljana,  Slovenia,  9-12  October 2016, Piscataway, NJ, 2017, Vol. Part F126485, article id 7856283Conference paper (Refereed)
    Abstract [en]

    This paper presents an IEC 61850 standard-based communication and aggregation solution for Demand-Response application, which allows end devices automatically detected, configured and integrated to the overlying Demand-Response system, thereby greatly increasing the integration efficiency, and making large scale of deployment feasible. This communication solution is dedicated to one community-wide Demand-Response application designed for a residential area near an industrial installation in Sweden. The community-wide Demand-Response application will be briefly explained in the paper, however, the main focus of this paper is the communication solution and IT system implementation for this application. The communication solution is realized by the unconventional use of IEC 61850 standard, and implemented in a hierarchical structure consisting of SCADA, communication gateway and low cost micro processor-based spatial heating controllers

  • 237.
    Lundmark, Martin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Larsson, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Projekt: Minskad livslängd av energieffektiv belysning på grund av höga nivåer av elektromagnetiska störningar2012Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Ett potentiellt hinder mot införandet av energisnål belysningsteknik är en förtätad användning av kraftelektronikbaserade ljuskällor eftersom dessa kan ge en alltför hög generering av ledningsbundna elektromagnetiska störningar. Målet med projektet är att kartlägga hur den elektromagnetiska störnivån förändras vid olika typer av installationsteknik, ökande antal störkällor mm. Delmål är att utveckla befintlig mätteknik och analysmetoder och studera olika elektronikkonstruktioner.

  • 238.
    Lundmark, Martin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Larsson, Anders
    Bollen, Math
    Harmonics and high-frequency emission by small end-user equipment2006Conference paper (Refereed)
    Abstract [en]

    This paper discusses different treatments of harmonics in three phase systems, especially passive and active power factor correction (PFC). The change from harmonics below 2 kHz to above 2 kHz is described. Measurements have been carried out with two types of computer load together with LCD and florescent light driven by electronic ballast: on a large number of devices during a LAN party and on individual devices in the laboratory. Also some aspects of increasing numbers of equipment are illustrated.

  • 239.
    Lundmark, Martin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Larsson, Anders
    Bollen, Math
    High-frequency components in the neutral and protective earth currents due to electronic equipment2007In: Conference proceedings: 19th International Conference and Exhibition on Electricity Distribution : Vienna, 21 - 24 May 2007, Liege: AIM , 2007Conference paper (Refereed)
    Abstract [en]

    This paper addresses the issue of neutral and protective earth currents in the frequency range 2 through 150 kHz. Both theoretical analysis and measurements will be presented. It is concluded that a large part of the high frequency distortion in the phase currents closes via the neutral wire and impacts the terminal voltage for equipment in the other phases. The introduction of HF-harmonics is even more detrimental to the intention with three-phase systems to minimize the currents outside the phase conductors.

  • 240.
    Lundmark, Martin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Larsson, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Projekt: Livslängd av energieffektiv belysning vid höga nivåer av elektromagnetiska störningar2012Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Byte till energisnål belysning är enligt flera forskningsstudier det mest kostnadseffektiva sättet att minska koldioxidutsläpp. Livslängden för belysning måste dock vara tillräckligt lång för att den minskade energianvändningen ska ha en ekonomisk fördel. Det är denna livslängd som ifrågasätts. Den begränsade hållfasthet ”immunitet” som belysning har mot störningar i spänningen kan vara en orsak till den minskade livslängden. Det behövs ny kunskap om detta förhållande för att kunna utveckla testmetoder, sätta gränsvärden på immunitet och kunna öka livslängden på belysningsinstallationer.

  • 241.
    Lundmark, Martin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Larsson, Anders
    Bollen, Math
    Required changes in emission standards for high-frequency noise in power systems2006In: International Journal of Energy Technology and Policy, ISSN 1472-8923, Vol. 4, no 1-2, p. 19-36Article in journal (Refereed)
    Abstract [en]

    This paper discusses some recent developments that make the existing standards on the emission of high-frequency noise in power systems need to be reconsidered. It is shown that it is possible for an equipment to remain below the emission limits while at the same time the disturbance level increases beyond what was intended by the standard document. Further, the change from analog to digital communication and the use of communication via the power system, make that the permitted disturbance levels need to be reconsidered. This paper also contains an example of measured high-frequency noise and proposes a framework for re-coordination of emission and immunity levels.

  • 242.
    Lundmark, Martin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Larsson, Anders
    Bollen, Math
    Unintended consequences of limiting high-frequency emission by small end-user equipment2006In: IEEE Power Engineering Society General Meeting: 18 - 22 June 2006, [Montreal, QC, Canada, Piscataway, NJ: IEEE Communications Society, 2006Conference paper (Refereed)
    Abstract [en]

    This paper discusses some consequences of developments in technologies that may impact the risk of electromagnetic interference and equipment damage despite the equipment complying with the tests according to the product standards. Examples of such technologies are: the change from analogue to digital communication, the fast increase in numbers of power converters having smart switching technology and the use of communication via the power system. The paper discusses upcoming sources of emission, uncertainties in emission level, and changing circumstances. It is shown that it is possible for equipment to remain below the emission limits while at the same time the disturbance level increases beyond what was intended by the standard document. The paper also proposes a framework for addressing the problems due to massive penetration of equipment injecting high-frequency harmonics.

  • 243.
    Lundmark, Martin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah
    Wahlberg, Mats
    Larsson, Anders
    Bollen, Math
    EMC filter common mode resonance2009In: 2009 IEEE Bucharest PowerTech: Bucharest, Romania, 28 June - 2 July 2009 / [ed] Lucian Toma, Piscataway, NJ: IEEE Communications Society, 2009, p. 2312-2317Conference paper (Refereed)
    Abstract [en]

    This paper discusses the possibility that high common mode voltages occur in low-voltage distribution due to oscillations between parallel connected EMC-filters. It is shown that such oscillations may occur in the frequency range between 2 kHz to 150 kHz. Simulations and measurements have been carried out with different types of parallel connected power inlet filter, a common EMC Filter, and the circumstances giving oscillations have been highlighted.

  • 244. Macken, K.J.P
    et al.
    Wallace, I.T
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Reliability assessment of motor drives2006In: 37th IEEE Power Electronics Specialists Conference, PESC '06: 18 - 22 June 2006, [Jeju, Jeju, Korea], Piscataway, NJ: IEEE Communications Society, 2006, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Electric motor drives have seen widespread adoption in many applications. Motor drives reliability has become a driving factor for potential customers whose process up time and power availability are crucial to their business success. Reliability is therefore a key driver in power circuit design for these applications. Two commonly used approaches available to designers to assess the reliability of motor drives are detailed in this paper. The first approach is a failure mode and effect analysis (FMEA). This approach is used to identify and list those component failures and combinations of component failures that result in an interruption of operation. The second approach is a so-called calculation of reliability indices which is performed to quantify the reliability of the system and verify that the design requirements are met. A case study of a redundant multilevel motor drive for multi-mega watt gas compression systems is given to illustrate both approaches

  • 245. Martinez, J A
    et al.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Voltage dip evaluation and prediction tools2009In: ELECTRA, ISSN 1286-1146, no 242, p. 67-72Article in journal (Refereed)
    Abstract [en]

    A voltage dip is a sudden reduction of the voltage below a specified threshold followed by its recovery after a brief interval, which can cause problems on sensitive equipment. The TB introduces the subject of voltage dips and their characterisation, equipment behaviour and mitigation techniques. Furthermore, a review is given of simulation tools and calculation methods that can be used for voltage dip assessment.

  • 246.
    Meyer, Jan
    et al.
    TU Dresden, Institute of Electrical Power Systems and High Voltage Engineering.
    Blanco, Ana Maria
    TU Dresden, Institute of Electrical Power Systems and High Voltage Engineering.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Smith, Jeff W.
    Electric Power Research Institute (EPRI), Power System Studies, Palo Alto, CA.
    CIGRE C4/C6.29: Survey of utilities experiences on power quality issues related to solar power2017In: CIRED - Open Access Proceedings Journal, ISSN 2515-0855, Vol. 2017, no 1, p. 539-543Article in journal (Refereed)
    Abstract [en]

    Owing to the energy policies and the consequent transition to renewable energy sources, the amount of photovoltaic (PV) installations is continuously increasing in many countries. As PV inverters utilise power electronics, its impact on power quality is an important concern for manufacturers, planners, solar power operators and utilities/ network operators. The International council on large electric systems (CIGRE) working group C4/C6.29 has studied many aspects related to PV installations and its impact on power quality. To incorporate the existing experiences with power quality issues related to solar power, an international survey has been conducted by the working group. The survey has found that there is a significant lack of information among utilities/network operators with respect to the possible impact of PV installations on power quality. It is recommended to intensify the monitoring of PV installations in order to obtain sufficient information for a reliable assessment of its impact on power quality.

  • 247.
    Meyer, Jan
    et al.
    Technical University Dresden.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Amaris, Hortensia
    University Carlos III, Madrid.
    Blanco, Ana María
    Technical University Dresden.
    Castro, Aurora Gil de
    University of Cordoba.
    Desmet, Jan
    Ghent University, Kortrijk.
    Klatt, Matthias
    Technical University Dresden.
    Kocewiak, Lukasz
    DONG Energy Wind Power, Fredericia.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Yang, Kai
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Future work on harmonics: some expert opinions part II – supraharmonics, standards and measurements2014Article in journal (Refereed)
    Abstract [en]

    A workshop on power system harmonics was organized in Stockholm in January 2014. On the agenda was among others a discussion on what are the main issues on harmonics at the moment and in the near future. Some of the issues discussed at that workshop are presented in this paper and its companion paper. In this paper the following issues will be addressed: the appearance of emission at higher frequencies (supraharmonics); the need for new and improved standards; measurement issues and data analysis

  • 248.
    Milanovic, J. V.
    et al.
    School of Electrical and Electronic Engineering, The University of Manchester.
    Meyer, J.
    Institute of Electrical Power Systems and High Voltage Engineering, Technische Universitaet Dresden.
    Ball, R. F.
    National Grid, Warwick Technology Park, Warwick.
    Howe, W
    Electric Power Research Institute (EPRI), Boulder, CO.
    Preece, R.
    School of Electrical and Electronic Engineering, The University of Manchester.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Elphick, S.
    Australian Power Quality and Reliability Centre, University of Wollongong.
    Čukalevski, N.
    Institue “Mihailo Pupin,” Belgrade.
    International Industry Practice on Power Quality Monitoring2014In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 29, no 2, p. 934-941Article in journal (Refereed)
    Abstract [en]

    Monitoring of voltages and currents at system buses gives the network operators information about the performance of their network, both for the system as a whole and for individual locations and customers. There is also demand from the customers and the regulatory agencies to provide information on the actual power-quality (PQ) level. Developments in enabling technology have made it possible to monitor at a large scale and to record virtually any PQ parameter of interest. While many network operators are installing monitoring equipment and while more and more monitors are available, there is a lack of knowledge and agreement on a number of aspects of the monitoring process and on processing the recorded data. As a response to this lack of uniformity in approach, data acquisition, and processing, in February 2011, CIGRE and CIRED established the Joint Working Group C4.112: “Guidelines for Power quality monitoring—measurement locations, processing and presentation of data.” In order to identify the current international industry practice on PQ monitoring, the group carried out a survey in 43 countries across the world. This paper summarizes the key findings from 114 responses to the questionnaire and identifies prevalent industrial practice in PQ monitoring around the world.

  • 249.
    Milanovic, Jovica V.
    et al.
    University of Manchester, School of Electrical and Electronic Engineering, The University of Manchester.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Cukalevski, Ninel
    Mihailo Pupin Institute.
    Guidelines for monitoring power quality in contemporary and future power networks – results from CIGRE/CIRED JWG C4.1122014Conference paper (Refereed)
  • 250.
    Morena-Garcia, Isabel
    et al.
    University of Cordoba.
    Gil-de-Castro, Aurora
    University of Cordoba.
    Gu, Irene
    Chalmers University of Technology.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Tests and Analysis of a novel Segmentation method using Measurement Data2015Conference paper (Refereed)
    Abstract [en]

    Fault detection in power systems and its diagnosis are highly relevant issues within a power quality scope. Detailed analysis of disturbance recordings, like voltage dips, requires accurate segmentation methods. A joint causal and anti-causal (CaC) segmentation method has been introduced but only been tested with synthetic signals. In this paper, its performance has been analysed with a set of real measurement signals.

2345678 201 - 250 of 375
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf