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  • 51.
    Nömm, Jakob
    et al.
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    An Analysis of Frequency Variations and its Implications on Connected Equipment for a Nanogrid during Islanded Operation2018In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, article id en11092456Article in journal (Refereed)
    Abstract [en]

    Frequency, voltage and reliability data have been collected in a nanogrid for 48 weeks during islanded operation. Frequency values from the 48 week measurements were analyzed and compared to relevant limits. During 19.5% of the 48 weeks, the nanogrid had curtailed the production due to insufficient consumption in islanded operation. The curtailment of production was also the main cause of the frequency variations above the limits. When the microgrid operated on stored battery power, the frequency variations were less than in the Swedish national grid. 39.4% of all the interruptions that occurred in the nanogrid are also indirectly caused by the curtailment of solar production. Possible solutions for mitigating the frequency variations and lowering the number of interruptions are also discussed.

  • 52.
    Nömm, Jakob
    et al.
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    An analysis of voltage quality in a nanogrid during islanded operation2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 4, article id 614Article in journal (Refereed)
    Abstract [en]

    Voltage quality data has been collected in a single house nanogrid during 48 weeks of islanded operation and 54 weeks of grid-connected operation. The voltage quality data contains the voltage total harmonic distortion (THD), odd harmonics 3 to 11 and 15, even harmonics 4 to 8, voltage unbalance, short-term flicker severity (Pst) and long-term flicker severity (Plt) values, and voltage variations at timescales below 10 min. A comparison between islanded and grid-connected operation values was made, were some of the parameters were compared to relevant grid standard limits. It is shown that some parameters exceed the defined limits in the grid-standards during islanded operation. It was also found that the islanded operation has two modes of operation, one in which higher values of the short circuit impedance, individual harmonic impedance, harmonic voltage distortion and voltage unbalance were reached.

  • 53.
    Nömm, Jakob
    et al.
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Harmonic Voltage Measurements in a Single House Microgrid2018In: 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]

    The harmonic voltage distortion have been measured in a single house microgrid in Sweden. The microgrid can operate in both islanded mode and grid connected mode. A comparison of the voltage harmonic magnitudes has been made between the two operation states and also against relevant standards. Both the 10 minute average and the 3 second average values are presented in the paper. The harmonic voltage magnitudes are higher during island mode and the difference between the 10 minute value and 3 second value is also greater compared to when the microgrid is connected to the grid. At some instances the magnitudes of both total harmonic distortion and of individual harmonics exceed the limits described in the standards.

  • 54.
    Ravindran, Vineetha
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Busatto, Tatiano
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Comparison of a non-parametric and parametric method for interharmonic estimation in PV systems2019Conference paper (Refereed)
    Abstract [en]

    A comparative analysis of ‘Desynchronized processing technique’ (non-parametric) and ‘Sliding window ESPRIT method’ (parametric) for interharmonic estimation in PV systems is carried out. Both methods were applied to field measurements and semi-measured signals to test their feasibility under different conditions. In Desynchronized processing technique, in the second stage of estimation, a Short-term Fourier transform was used to address the time-varying nature of interharmonics. In Sliding window ESPRIT method, the signal subspace dimension was fixed in all analysed cases. An adaptive algorithm was used to find the best rank of the Hankel matrix and apt order of the filter to ensure stability. A set of critical parameters affecting the performance of these methods in interharmonic estimation are identified. This paper emphasizes the significance of using appropriate methods for accurate interharmonic estimation and also demonstrates through the illustrated results that different inferences can be drawn for the same measurements analysed using different methods.

  • 55.
    Ravindran, Vineetha
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Busatto, Tatiano
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Meyer, Jan
    Technische Universität, Dresden, Germany.
    Charactizations of interactions between PV and Energy efficient lighting (LED) in a mixed installation.2019Conference paper (Refereed)
    Abstract [en]

    The possible interactions between grid-tied powerelectronicbased PV systems and energy efficient LEDlighting systems in terms of current and voltage, fordifferent combinations of the inverter and LED lamp typesunder different grid conditions, are studied in a laboratoryenvironment. In this paper, the interactions arecharacterized in terms of the power quality disturbanceslike harmonics, interharmonics, supraharmonics,overvoltage, undervoltage, and rapid voltage changes.

  • 56.
    Ravindran, Vineetha
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Busatto, Tatiano
    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.
    Meyer, Jan
    Institute of Electrical Power Systems and High Voltage Engineering, Technische Universitaet Dresden, Dresden, Germany.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Time-varying interharmonics in different types of grid-tied PV inverter systems2019In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208Article in journal (Refereed)
    Abstract [en]

    Widely existing circuit topologies and inverter control strategies for PV systems allow customer flexibility but also introduce different kinds of interharmonics into the grid. A complete understanding of interharmonics from PV systems, with reasons behind their origin, remains needed. In addition, the timevarying nature of interharmonics and the potential impacts on other equipment are yet to be understood. In this paper, laboratory and field measurements are presented of seven different inverter types at multiple locations. A comprehensive analysis is performed to understand the existence, persistence, and propagation of interharmonics in PV systems on the DC side as well as grid side for different power levels. The origins of the interharmonics are established with experimental evidence and through a comparative analysis. A rural low voltage 6 customer network, with two different impedance profiles caused by the installation of PV, is considered to show the potential impact on customer voltage. To address the time-varying nature of interharmonics, a sliding window ESPRIT method is preferred over FFT based methods

  • 57.
    Ravindran, Vineetha
    et al.
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Interharmonics in PV systems: A Review of analysis and estimation methods; considerations for selection of an apt method2019In: IET Renewable Power Generation, ISSN 1752-1416, E-ISSN 1752-1424, Vol. 13, no 12, p. 2023-2032Article, review/survey (Refereed)
    Abstract [en]

    A comprehensive reviewing of existing interharmonic analysis and estimation methodologies irrespective of application is carried out. The paper is enlisting the characteristics of an appropriate method to analyse and estimate interharmonics in PV systems, and linking these characteristics with the features of the reviewed methodologies. The distinctive characteristics of interharmonic emissions related to PV systems are therefore presented. The various methodologies are classified, summarized, and a checklist is prepared to emphasize the areas to be paid attention to while establishing an apt method for interharmonic analysis in PV systems. The priorities for selection of a method by a practicing engineer vary case by case. This paper will serve as a guideline for selection and further development of a suitable method for interharmonic analysis in a PV included power system.

  • 58.
    Ravindran, Vineetha
    et al.
    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.
    Busatto, Tatiano
    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.
    Inspection of Interharmonic emissions from a Grid-tied PV Inverter in North Sweden2018In: 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]

    The main objective of the paper is to investigate theexistence of interharmonic emissions from an MPPT drivengrid-connected PV inverter, identify their severity andpersistence. The presence of interharmonics in the measuredcurrent from a PV installation is linked to direct and diffusedsolar irradiation as well as a high ramping rate of theirradiation causing variations in both active and reactive power.The paper sets forth a set of observations and inferences, whichis an appendage to the ongoing research on the power qualityaspects of solar power. Three different case studies areevaluated in detail using signal processing tools like STFT andFFT.

  • 59.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Activity: Trends in Harmonics below and above 2 kHz2011Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Tutorial

  • 60.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Emission and interaction from domestic installations in the low voltage electricity network, up to 150 kHz2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis work has focused on conducted emission (up to 150 kHz) from common lowvoltage appliances. The emphasis has been on equipment that contributes to a sustainable energy system: photovoltaic (PV) installations and energy-saving lamps (LED lamps). The frequency components present in the grid in addition to the fundamental 50 Hz component can be divided into harmonics (up to 2 kHz in a 50 Hz system) and supraharmonics (2 kHz to 150 kHz). These frequency components are partly the effect of normal operation of equipment due to power-electronic converters and the switching technique used. Power line communication, PLC, is an important source of frequency components in the range 9 to 95 kHz. Even though from an equipment viewpoint there is no difference between a signal used for communication and a signal that is a residue from a switching circuit, PLC is a useful signal for operation of the grid and for communication with electricity meters. The amplitude of the communication signal is in in almost all cases higher than the emission from any other equipment connected to the grid.Understanding the different types of interaction between PLC and end-user equipment has been a major part of this work. Five types of interaction have been identified; some negative for PLC, some negative for end-user equipment. An important conclusion from this part of the work is that loss of communication with PLC, as is often reported with remote reading of electricity meters, is not due to emission by end-user equipment but due to the EMC filter of the end-user equipment providing a low-impedance path. The understandings acquired from the work with PLC have been applied to other types of emission as well. Supraharmonics from individual devices, above about 10 kHz, flow mainly to neighboring devices, not into the grid. This behavior was found by laboratory experiments and confirmed by other studies as well. A circuit-theory model has been developed that explains this behavior. The EMC filters are shown to be the main cause of this behavior. Other configurations of those filters may result in a larger flow of emission towards the grid.One type of appliance that has been introduced recently is the LED lamp. LED lamps come in different designs with different emission spectra. A possible distinction is between lamps with high levels of low-order harmonics (up to a few 100 Hz) and those with high levels of supraharmonics. Restricting the emission in the lower frequency range, through standardization, could result in higher distortion levels at higher frequencies. Replacement of incandescent lamps by CLF and LED lamps is not expected to result in a noticeable increase in harmonic voltage and current levels in the grid. This has been shown through several laboratory experiments and field experiments.Emission from PV inverters is low at low-order harmonics, this have been shown by a number of measurements both on single phase connected installations, so called rooftop installations and larger, three phase connected installations (20 kW). In addition to emission in the low frequency range, PV inverters emit at their switching frequency, e.g. around 16 kHz. The emission at this frequency is shown to vary by a factor of 5 or more, depending on the presence of neighboring equipment. This was shown by measurements and has been explained by a circuit-theory model. This thesis work has resulted in further understanding on the emission from PV panels and energy-saving lamps and on the propagation of conducted emission from common household appliances. This work is an important contribution to the research on distortion of voltage and current in the frequency range 2 to 150 kHz.

  • 61.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Power line communication and customer equipment2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In Sweden, the change from manual meter reading at irregular intervals, to automatic remote meter reading at predefined instants was completed in July 2009. This change is ongoing or largely completed in a number of other European countries as well. Several methods for communication between the meter and the network operator are in use. In Sweden power-line communication is used for communication with about half of the meters. The frequency range between 9 and 95 kHz contains, in addition to communication signals, conducted emission from end-user equipment connected to the power grid. Electronic components in end-user equipment can also in other ways affect the characteristic of the power lines as a communication media.The aim of this thesis is to give an overview of how power line communication in the frequency range 9 to 95 kHz can interact with modern energy saving end-user equipment. Potential problems concerning this interaction have been identified.Results presented in this thesis are based on a large number of measurements of voltage and current distortions due to connected loads and due to power line communication.A total of five different ways of interaction between power-line communication and end-user equipment are identified in this thesis. As a spin-off from this work, also new aspects of the interaction between end-user equipment have been identified.

  • 62.
    Rönnberg, Sarah
    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.
    Emission from four types of LED lamps for frequencies up to 150 kHz2012In: 15th International Conference on Harmonics and Quality of Power (ICHQP), IEEE Communications Society, 2012, p. 451-456Conference paper (Refereed)
    Abstract [en]

    This paper shows the results of measurements performed on a quantity of different light emitting diode based energy saving lamps (LED's).

  • 63.
    Rönnberg, Sarah
    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.
    Estimating system indices for short interruptions from data obtained by a limited number of monitors2017In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 146, p. 63-70Article in journal (Refereed)
    Abstract [en]

    This paper presents an estimation of the number of monitoring locations needed to get an accurate estimation of system indices for short interruptions. The study uses data from 11 Swedish distribution network operators, where the number of short interruptions is available for every single costumer. The error range in the estimated system parameters is obtained as a function of the number of monitor locations by obtaining mean and spread of the estimations from 10 000 randomly-selected sets of monitor locations.

    To obtain a rough estimation of the system average or 95-percentile (error margin less than 50%), about 200 monitors are needed. For system 99-percentile, about 400 monitors are needed. For a reasonably accurate estimation, with an error margin less than 10%, a few thousand monitors are needed for both system average and system 95-percentile. Several thousand monitors are needed for the system 99-percentile. The paper also presents some system statistics for the 11 distribution network operators and compares the requirements with recommendations given by the Council of European Energy Regulators.

  • 64.
    Rönnberg, Sarah
    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.
    Measurements of primary and secondary emission in the supraharmonic frequency range, 2-150 kHz2015Conference paper (Refereed)
    Abstract [en]

    This paper presents an analysis of current emission from low-voltage devices in the frequency range from 2 to 150 kHz. Measurements on an installation with a photovoltaic (PV) inverter together with common household appliances are presented. It is shown to be important to distinguish between emission driven by a certain device (“primary emission”) and emission driven by other devices (“secondary emission”). Measurements show that primary emission can be strongly impacted by neighbouring devices. Moreover it is shown that supraharmonic currents flow between connected appliances and measurements of supraharmonic distortion should be performed on site, inside the installation.

  • 65.
    Rönnberg, Sarah
    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.
    Power quality issues in the electric power system of the future2016In: Electricity Journal, ISSN 1040-6190, E-ISSN 1873-6874, Vol. 29, no 10, p. 49-61Article in journal (Refereed)
    Abstract [en]

    With the advent of new electricity production modes, power electronics, LED lamps and underground cables, new types of disturbances will appear, including an increase in distortion between 2 kHz and 150 kHz that is referred to as ‘supraharmonics.’ A shift of resonances to lower frequencies may partly compensate for the increased emissions at higher frequencies, but the transfer of disturbances will become less predictable. Equipment immunity also is likely to become less predictable.

  • 66.
    Rönnberg, Sarah
    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.
    Solar power in northern Scandinavia, its impact on the grid and methods to mitigate this impact2013In: 2013 4th IEEE/PES Innovative Smart Grid Technologies Europe (ISGT EUROPE): Copenhagen, Denmark, 6-9 Oct 2013, Piscataway, NJ: IEEE Communications Society, 2013Conference paper (Refereed)
    Abstract [en]

    This paper presents results from measurements of solar-power production in the north of Scandinavia; studies of the impact on the grid when larger amounts of solar power are installed, and methods to mitigate this grid impact. It is shown that solar power has limited contribution to reducing the peak loading of the grid. Large amounts of solar power will even increase the peak loading. Curtailment is shown to be an appropriate way of allowing more solar energy to be injected into the grid without additional grid investment. It is important however to use the right control method (“soft curtailment”) as otherwise production will decrease with increasing installed capacity. It is also shown in the paper that unacceptable voltage variations can occur when large installations are connected to weak parts of the grid. The availability of hourly metering data is an important contribution to integration studies.

  • 67.
    Rönnberg, Sarah
    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.
    Solar power plants in the north of Europe: Power quality, hosting capacity and smart solutions to increase the hosting capacity2013Report (Other academic)
  • 68.
    Rönnberg, Sarah
    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.
    Amaris, Hortensia
    University Carlos III, Madrid.
    Chang, Gary W.
    National Chung Cheng University, Taiwan.
    Gu, Irene Y.H.
    Chalmers University of Technology.
    Kocewiak, Łukasz Hubert
    DONG Energy Wind Power, Fredericia.
    Meyer, Jan Christian
    Technische Universitaet Dresden.
    Olofsson, Magnus
    Swedish Energy Institute.
    Ribeiro, Paulo F.
    Federal University of Itajubá, Brazil.
    Desmet, Jan
    Gent University, Campus Kortrijk.
    On waveform distortion in the frequency range of 2 kHz–150 kHz: Review and research challenges2017In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 150, p. 1-10Article in journal (Refereed)
    Abstract [en]

    The frequency range between 2 and 150 kHz has recently gained significant attention, triggered by standardization needs and increased emission in this wide frequency range. This paper gives an overview of the state-of-the-art concerning these so-called supraharmonics, and noticeably indicates the research challenges associated with waveform distortion in this frequency range, with emphasis on the following aspects: emission; propagation; interference; measurements; standardization; modelling and simulation.

  • 69.
    Rönnberg, Sarah
    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.
    Gil-de-Castro, Aurora
    University of Cordoba.
    Harmonic distortion from energy-efficient equipment and production in the low-voltage network2014Report (Other academic)
  • 70.
    Rönnberg, Sarah
    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.
    Langella, Roberto
    Department of Industrial and Information Engineering, University of Campania "Luigi Vanvitelli".
    Zavoda, Francisc
    IREQ, Varennes.
    Hasler, Jean-Philippe
    ABB Substations, Västerås.
    Ciufo, Philip
    University of Wollongong.
    Cuk, Vladimir
    Eindhoven University of Technology.
    Meyer, Jan Christian
    Technische Universitaet Dresden.
    The expected impact of four major changes in the grid on the power quality: a review2017In: Cigre Science & Engineering, ISSN 2426-1335, Vol. 8, p. 5-13Article in journal (Refereed)
  • 71.
    Rönnberg, Sarah
    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.
    Emission from small scale PV-installations on the low voltage grid2014In: The Renewable Energies and Power Quality Journal (RE&PQJ), ISSN 2172-038X, E-ISSN 2172-038X, no 12, article id 427Article in journal (Refereed)
  • 72.
    Rönnberg, Sarah
    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.
    Grid impact from PV-installations in northern Scandinavia2013In: 22nd International Conference and Exhibition on Electricity Distribution (CIRED 2013): Stockholm, Sweden, 10 - 13 June 2013, Red Hook, NY: Curran Associates, Inc., 2013, article id 1036Conference paper (Refereed)
    Abstract [en]

    The use of solar panels is becoming more popular in Sweden. Parts of Scandinavia have many sun hours and the cold temperatures are advantageous as they lead to higher efficiencies and longer lifetimes of the solar cells. Except during the darkest time of the year (Nov-Feb) PV is a suitable complement for power production also in the northern parts of Scandinavia, especially when using a proper tracking system In this paper power quality issues concerning the connection of photovoltaic systems will be discussed. Emission up to 25 kHz will be presented as well as voltage variations caused by the production. Measurements from three phase connected plants (20 kW) and from smaller (up to 2.5 kW) single phase connected plants are shown. The harmonic emission from PV-plants is reasonable low and somewhat constant with regards to the production. Some residue from the switching of the inverter can be found typical at a few kHz.

  • 73.
    Rönnberg, Sarah
    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.
    Lundmark, Martin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    An overview of the origin and propagation of Supraharmonics (2-150 kHz)2014Conference paper (Refereed)
  • 74.
    Rönnberg, Sarah
    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.
    Wahlberg, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Emission from different types of energy efficient lamps at frequencies up to 150 kHz2012Conference paper (Refereed)
  • 75.
    Rönnberg, Sarah
    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.
    Nömm, Jakob
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Power Quality measurements in a single house microgrid2017In: CIRED - Open Access Proceedings Journal, ISSN 2515-0855, Vol. 2017, no 1, p. 818-822Article in journal (Refereed)
    Abstract [en]

    Power quality measurements have been performed during 1 year in a small-scale microgrid in Sweden. The microgrid consists of one residential house that can operate in grid-connected or grid-disconnected (islanded) modes. During the year the microgrid was disconnected from the main grid most of the time.

  • 76.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Wahlberg, Mats
    Power quality issues due to electronic lighting2010Conference paper (Refereed)
    Abstract [en]

    With the interest to reduce electrical energy consumption there is an upcoming shift from the traditional incandescent lamps to more energy efficient types of lighting. This has raised a concern of a possible adverse effect on the power grid as we replace a resistive load with an electronic one. The main concerns include harmonic distortion, losses in the grid, and displacement power factor (cos ). A set of measurements have been made in order to determent how a shift in lamps would affect a number of power quality parameters. The measurements have been conducted on a typical household base load consisting of a mix of lamps, TV, computers, heat and kitchen equipment. The measurements have been performed in the laboratory so as to have complete control over the load. A typical consumption pattern has been defined however so as to make the measurements both realistic and reproducible. In the initial stage the installation contains only incandescent lamps; in the final stage all incandescent lamps are replaced with a more energy efficient alternative. A second set of measurements have been made in a medium size hotel, with a load of over 500 incandescent lamps. The power quality has been monitored before, during and after all the lamps were replaced by 40 W equivalent LED lamps. This paper will focus on harmonic distortion up to 9 kHz as well as the affect a shift in lamps will have on the displacement power factor and on losses in the distribution grid.

  • 77.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gil de Castro, Aurora
    Electronics Technology, University of Cordoba.
    Moreno-Muñoz, Antonio
    University of Cordoba.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Garrido, Joaquin
    University of Cordoba.
    Solar PV inverter supraharmonics reduction with random PWM2017In: 2017 11th IEEE International Conference on Compatibility, Power Electronics and Power Engineering, CPE-POWERENG 2017, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 644-649, article id 7915248Conference paper (Refereed)
    Abstract [en]

    The international standardization community is currently reviewing the supraharmonics distortion limits. These are harmonics which fall in the frequency range 2 to 150 kHz. Power electronics has consolidated as a ubiquitous technology, which also plays a critical role in this subject. Broadly speaking, these HF components are due to the normal operation of electronic converters and the switching techniques employed. The paper presents measurements of waveform distortion from several illustrative facilities and loads. Recent studies indicate that future problems to distribution grids may include supraharmonics. Grid-tie inverters are an origin of waveform distortion, still in this frequency range, but, can also be the pillar to mitigate it, when methodologies like random pulse with modulation or modular multilevel converter are properly applied

  • 78.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gil-De-Castro, A.
    Departamento de Ingeniería Electrónica y de Computadores, Universidad de Córdoba, Campus de Rabanales, Edificio Leonardo da Vinci, Córdoba, España.
    Medina-Gracia, R.
    Departamento de Ingeniería Electrónica y de Computadores, Universidad de Córdoba, Campus de Rabanales, Edificio Leonardo da Vinci, Córdoba, España.
    Supraharmonics in European and North American Low-Voltage Networks2018In: 2018 IEEE International Conference on Environment and Electrical Engineering and 2018 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), 2018, article id 8493930Conference paper (Refereed)
    Abstract [en]

    This paper presents the measurement and characterization of voltage supraharmonic emission (in the frequency range 2–150 kHz) at different European and North American low-voltage networks. This knowledge is needed to be able to better predict the impact of new equipment on the voltage and current distortion in the low-voltage network. This work presents a discussion serving as a guide for future standardization of voltage supraharmonic levels, as it presents an overview of real values measured in the power grid in different countries.

  • 79.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gil-de-Castro, Aurora
    University of Cordoba.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Moreno-Munoz, Antonio
    University of Cordoba.
    Romero-Cavadal, Enrique
    University of Extremadura, Badajoz.
    Supraharmonics from Power Electronics Converters2015In: 9th International Conference on Compatibility and Power Electroncis (CPE 2015): Costa da Caparica, 24-26 June 2015, Piscataway, NJ: IEEE Communications Society, 2015, p. 539-544Conference paper (Refereed)
    Abstract [en]

    This paper summarizes the state of part of the discussions in CIGRE/CIRED/IEEE joined working group C4.24, especially where it concerns supraharmonics. There is an increasing interest from the international smart grid standard-setting community in knowledge about harmonics distortion in the frequency range 2 to 150 kHz, referred to as supraharmonics. The paper presents measurements of waveform distortion from several illustrative installations and loads. The reduction of emission in the lower-frequency ranges appears to result in an increase in supraharmonic emission by equipment. Power electronics has emerged as a ubiquitous technology, which plays a critical role in almost any areas. Power electronics converter is an important source of waveform distortion, but, as stated in this paper, power electronics can also be the key to mitigate distortion, when the proper technology is employed.

  • 80.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology.
    Gutiérrez Ballesteros, Elena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gil de Castro, Aurora
    University of Cordoba.
    Westman, Malin
    Skellefteå Kraft.
    Brodin, Magnus
    Skellefteå Kraft.
    Long-term power quality measurements in medium voltage networks2019In: CIRED conference proceedings, 2019, article id 652Conference paper (Refereed)
  • 81.
    Rönnberg, Sarah
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Schanen, Jean-Luc
    Grenoble Electrical Engineering Lab.
    A simple model for interaction between equipment at a frequency of some tens of kHz2011In: Proceedings of CIRED 21st International Conference on Electricity Distribution, 2011Conference paper (Refereed)
    Abstract [en]

    This paper presents a simple model to explain the spread of high-frequency current between different devices and into the grid. The model is also used to show the aggregation between devices. The model is used to predict the amplitude modulation of the voltage and current ripple due to the small frequency differences between devices. The results from the model confirm earlier measurement results.

  • 82.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundmark, Martin
    Andersson, Marcus
    Luleå tekniska universitet.
    Larsson, Anders
    Bollen, Math
    Wahlberg, Mats
    Skellefteå Kraft AB.
    Attenuation and noise level: potential problems with communication via the power grid2007In: Conference proceedings: 19th International Conference and Exhibition on Electricity Distribution : Vienna, 21 - 24 May 2007, Liege: AIM , 2007, article id 0186Conference paper (Refereed)
    Abstract [en]

    This paper will give examples of the potential problems associated with remote-meter reading via the power grid and describe some of the technologies available. Examples will be given of practical cases in which the communication channel does not function in the intended way. Three potential problems with communication via the power grid are identified in the paper:The noise level is too high for the information to reach the receiverThe attenuation at the frequencies used for communication is too high. Several cases have been identified where this made communication impossible. Certain types of end-user equipment cause a large attenuation of the communication signal, so that a too small amount of the signal reaches the receiverInterference with other equipment. A flicker problem was found due to a modulated 100-Hz signal used for communication

  • 83.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wahlberg, Mats
    Bollen, Math
    Harmonic emission before and after changing to LED and CFL: Part I: Laboratory measurements for a domestic customer2010In: 14th International Conference on Harmonics and Quality of Power (ICHQP), Piscataway, NJ: IEEE Communications Society, 2010Conference paper (Refereed)
    Abstract [en]

    This paper presents an investigation after the impact on a number of power-quality parameters due to the change from incandescent lamps to energy saving lamps like CFL and LED. The measurements were conducted in a full-scale laboratory model with ordinary household equipment connected, thus simulating an ordinary domestic customer. Incandescent lamps have been replaced in stages by CFL and LED lamps. The CFL's and LED lamps will contribute to an increase in current distortion but the amplitude of the harmonics is quite low so the change of lighting will only have a minor effect on the total current harmonic distortion. It is also shown that the (total) power factor is not a good indicator to compare the impact of different loads on the system.

  • 84.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wahlberg, Mats
    Bollen, Math
    Harmonic emission before and after changing to LED and CFL: Part II: Field Measurements for a hotel2010In: 14th International Conference onHarmonics and Quality of Power (ICHQP), Piscataway, NJ: IEEE Communications Society, 2010Conference paper (Refereed)
    Abstract [en]

    This paper shows the results of measurements performed with a medium-sized hotel in the North of Sweden. The harmonic emission and other parameters were measured before, during and after a replacement of all incandescent lamps with energy saving lamps, both compact fluorescent lamps (CFL's) and light emitting diodes (LED's). it was not possible to see any major difference in harmonic spectrum before and after the replacement. The reduction in power factor that was observed was completely due to the reduction in active power.

  • 85.
    Rönnberg, Sarah
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Harmonic emission before and after changing to LED lamps: Field measurements for an urban area2012In: 15th International Conference on Harmonics and Quality of Power (ICHQP), IEEE Communications Society, 2012, p. 552-557Conference paper (Refereed)
    Abstract [en]

    The paper presents measurements performed in an urban area in the north of Sweden with two individual houses and on LV side of the distribution transformer supplying these two and ten more houses. Measurements of harmonic and interharmonic groups were performed before and after replacing all existing (mainly incandescent) lamps in all 12 houses with LED lamps. The total power of all lamps was reduced from approximately 2300 W to approximately 450 W, per house. All new lamps were low-power-factor lamps. The paper shows the variations of the most important harmonics with time and relevant spectra before and after the replacement. The emission during the evening hours is studied in specific detail. Despite the low power factor of the individual lamps, no change in emission due to the lamps has been observed, neither for any of the two individual houses nor the distribution transformer supplying all 12 houses

  • 86.
    Rönnberg, Sarah
    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.
    Interaction between narrowband power-line communication and end-user equipment2011In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 26, no 3, p. 2034-2039Article in journal (Refereed)
    Abstract [en]

    This paper discusses some of the electromagnetic-compatibility issues concerning the use of power lines for communication. Based on a series of measurements performed in a laboratory environment and in the field, five different types of interactions between communication and end-user equipment are distinguished. Measurement examples are shown for several of these types. It is concluded that the creation of a low-impedance path by end-user equipment is the main cause of interference.

  • 87.
    Rönnberg, Sarah
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Laboratory and field measurements of harmonic emission from energy-efficient lamps2011In: Proceedings of CIRED 21st International Conference on Electricity Distribution, 2011, article id 0172Conference paper (Refereed)
    Abstract [en]

    This paper presents measurements of the harmonic current distortion before and after the replacement of all incandescent lamps with compact fluorescent and LED lamps. Measurements were performed in the laboratory for a physical full-scale model of a residential customer; field measurements were performed for a hotel. In all cases the lamps used were low-power-factor ones (0.6 power factor). The emulated domestic customer showed a small increase in harmonic emission; for the hotel no difference in emission was noticeable before and after the replacement.

  • 88.
    Rönnberg, Sarah
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Total conducted emission from a customer in the frequency range 2 to 150 kHz with different types of lighting2011In: Proceedings of CIRED 21st International Conference on Electricity Distribution, 2011, article id 0173Conference paper (Refereed)
    Abstract [en]

    Harmonic studies in almost all cases are limited to the frequency range up to 2 or 2.5 kHz. In the frequency range above 2 kHz, almost no standards exist and measurements are rare. This paper presents measurements of the emission from a total installation in the frequency range 2 to 150 kHz. A physical model (electrically full-scale) of a domestic customer was built in the laboratory. Field measurements were performed on a medium-sized hotel. The impact of different types of lighting is shown to be small.

  • 89.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wahlberg, Mats
    Bollen, Math
    Larsson, Anders
    Lundmark, Martin
    Measurement of interaction between equipment in the frequency range 9 to 95 kHz2009In: CIRED 20th International Conference on Electricity Distribution: (CIRED 2009) ; Prague, Czech Republic, 8 - 11 June 2009, Red Hook, NY: Curran Associates, Inc., 2009, p. 231-234Conference paper (Refereed)
    Abstract [en]

    A number of measurements have been performed on a full-scale electric model of a house to study equipment emission and impedances in the frequency range 9-95 kHz. Most equipment forms a much lower impedance path that the grid. The result is that conducted disturbances in this frequency range mainly flow between individual devices instead of between devices and the grid. It is also shown that the input impedance of equipment can be highly time dependent at a time scale below one cycle of the power-system frequency.

  • 90.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wahlberg, Mats
    Bollen, Math
    Lundmark, Martin
    Equipment currents in the frequency range 9-95 kHz, measured in a realistic environment2008In: 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]

    A number of measurements have been performed on a full-scale electric model of a house to examine how enduser equipment affect the impedance in the frequency range 9-95 kHz. It is shown that the impedance level for the grid itself is fairly high and that it decreases when end-user equipment is connected. End-user equipment can be divided in to different categories, loads for which impedance is constant over time (for one cycle) and frequency and loads for which impedance varies over time, frequency or both. The measurements indicate that currents in high frequencies travel between loads at a much higher degree than between the load and the transformer.

  • 91.
    Rönnberg, Sarah
    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
    Lundmark, Martin
    Nätpåverkan av lågenergibelysning2009Report (Other academic)
  • 92.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wahlberg, Mats
    Bollen, Math
    Lundmark, Martin
    Åkerlund, John
    Boije, Christer
    Nätpåverkan av lågenergibelysning: populär version2009Report (Other (popular science, discussion, etc.))
  • 93.
    Rönnberg, Sarah
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wahlberg, Mats
    Larsson, Anders
    Bollen, Math
    Lundmark, Martin
    Interaction between equipment and power line communication: 9-95 kHz2009In: 2009 IEEE Bucharest PowerTech Proceedings / [ed] Mircea Eremia, IEEE Communications Society, 2009Conference paper (Refereed)
    Abstract [en]

    This paper presents detailed measurements of currents flowing between modern electronic devices in a domestic environment. The results shown in this paper cover the frequency range 9 to 95 kHz, being the frequency band dedicated to power-line communication by network operators. Large differences exist between different devices, even when they are of the same type. It is also shown that the voltage waveform and the emission by other equipment have a significant impact on the current flowing between a device and the grid. An important conclusion from the measurements is that the high-frequency currents mainly flow between neighbouring devices.

  • 94.
    Rönnberg, Sarah
    et al.
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gil-de-Castro, Aurora
    Waveform distortion: a comparison of photovoltaic and wind power2014Article in journal (Refereed)
    Abstract [en]

    The paper presents measurements of waveform distortion from six solar-power installations and three wind-power installations. The main emphasis is on the emission of low-order odd harmonics as a function of active-power production. It is concluded that the emission levels are low, that there is in most cases just a weak correlation with active power production, and that every installation is unique. Next to that the paper contains a discussion on the emission of supraharmonics (mainly 16 kHz in the case shown). Both for low-order harmonics and for supraharmonics, there is a need for the development of suitable models explaining the emission, including any relation with active-power production

  • 95.
    Sakar, Selcuk
    et al.
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Immunity Test of LED Lamps Based on IEC 61000-4-19 and Unexpected Consequence2018In: 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]

    ED lighting technology is the most efficient way oflighting service and its usage has increased rapidly. Although,LED lamps are potential victim and source of electromagneticinterference in the frequency range between 2 kHz and 150 kHz(“supraharmonics”). Therefore, immunity test for this frequencyrange is necessary to analyze its performance variations. In thisstudy, Test profiles described in IEC 61000-4-19 have beenapplied to LED lamps and the results have been analyzedaccording to implemented algorithm that uses the relative lightintensity variation index. The results show that bothsupraharmonics and modulation of the test profiles can reveallight flicker. In addition, some potential drawbacks of thestandard have been found that deviation of the mains’ frequencyis also another factor causes intermodulation/nonsynchronizationon the applied test signal, so this can be seen aslight flicker. This issue better be clarified with more details in theIEC 61000-4-19, particalulary for lighting equipment.

  • 96.
    Sakar, Selcuk
    et al.
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Interferences in AC-DC LED Drivers Exposed to Voltage Disturbances in the Frequency Range 2 kHz - 150 kHz2019In: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 34, no 11, p. 11171-11181Article in journal (Refereed)
    Abstract [en]

    LED lamps are both potential victims and sources of electromagnetic disturbances in the frequency range between 2 kHz and 150 kHz (“supraharmonics”). Immunity tests for this frequency range are important due to possible performance degradation of light intensity with LED lamps. In this paper, the impact of supraharmonics (SHs) on light intensity from LED lamps has been analyzed. LED lamps have been exposed to supraharmonic test profiles based on IEC 61000-4-19. Three phenomena that impact light intensity metrics have been observed and explained by models: (1) earlier conduction/later blocking caused by supraharmonic voltage, (2) intermittent conduction depending on the supraharmonic impedance of the LED driver and (3) reverse-recovery current of the diodes at higher frequency. It is observed that impact on the light intensity metrics shows up around the beginning and end of the conduction period. The results reveal that the profile of the supraharmonic voltage could cause deviations in the modulation depth and the average light intensity. The immunity of LED lamps against SHs shall be further studied and discussed by research groups and standard committees.

  • 97.
    Sakar, Selcuk
    et al.
    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.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Light Intensity Behavior of LED Lamps within theThermal Stabilization Period2018In: 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]

    Visible changes in the light intensity of lamps, referredto as flicker, are quantified based on definitions such asnormalized gain factor and relative light intensity variation.However, those values also change depending on the time after anLED lamp has been switched on. An experiment has been carriedout to analyze this phenomenon. A new metric, a “thermalstabilization time”, has been proposed to identify the time toreach steady state light intensity. Although rare, the change inlight intensity can reach up to 68% during the thermalstabilization time. Consequently, acquiring data at differentintervals can lead to incorrect estimation of critical metrics.Stabilization is an essential factor that should be taken intoconsideration in LED lamps’ measurement. It is recommended bythe authors that 60-minute operation is required before acquiring data.

  • 98.
    Schwanz, Daphne
    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.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Obalans från enfasanslutna solpaneler2015Report (Refereed)
  • 99.
    Schwanz, Daphne
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Möller, Friedemann
    Technische Universität Dresden.
    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.
    Meyer, Jan Christian
    Technische Universität Dresden.
    Stochastic Assessment of Voltage Unbalance due to Single-Phase-Connected Solar Power2016In: 2016 17th International Conference on Harmonics and Quality of Power, Piscataway, NJ, 2016, p. 95-103, article id 7783353Conference paper (Refereed)
    Abstract [en]

    A stochastic method is presented in this paper to estimate the future voltage unbalance in a low-voltage distribution network with high-penetration of single-phase photovoltaic inverters (PVIs). Location and phase allocation of the PVIs are considered as input parameters for the stochastic simulation. The method has been applied to three different low-voltage networks: two in Sweden and one in Germany. In the Swedish networks, for 6-kW single-phase PVIs, it is likely that the contribution from single-phase photovoltaic inverters to the voltage unbalance exceeds 1%. The 2% value is unlikely to be exceeded. In the German network, for 4.6-kW single-phase PVIs the voltage unbalance is between 1.35% and 2.62%. The risk of high voltage unbalance can be reduced by a combination of controlled distribution over the phases and reduction of the maximum size for a single-phase PVI

  • 100.
    Schwanz, Daphne
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Möller, Friedemann
    Technische Universität Dresden.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Meyer, Jan
    Institute of Electrical Power Systems and High Voltage Engineering, Technische Universitaet Dresden, Technical University Dresden, Dresden University of Technology.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Stochastic Assessment of Voltage Unbalance due to Single-Phase-Connected Solar Power2017In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 32, no 2, p. 852-861, article id 7488998Article in journal (Refereed)
    Abstract [en]

    A stochastic method is presented in this paper to estimate the future voltage unbalance in a low-voltage distribution network with high-penetration of single-phase photovoltaic inverters (PVIs). Location and phase allocation of the PVIs are considered as input parameters for the stochastic simulation. The method has been applied to three different low-voltage networks: two in Sweden and one in Germany. In the Swedish networks, for 6-kW single-phase PVIs, it is likely that the contribution from single-phase photovoltaic inverters to the voltage unbalance exceeds 1%. The 2% value is unlikely to be exceeded. In the German network, for 4.6-kW single-phase PVIs the voltage unbalance is between 1.35% and 2.62%.The risk of high voltage unbalance can be reduced by a combination of controlled distribution over the phases and reduction of the maximum size for a single-phase PVI.

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