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  • 1.
    A. Oliveira, Roger
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    S. Salles, Rafael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah K.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Deep Learning for Power Quality with Special Reference to Unsupervised Learning2023In: 27th International Conference on Electricity Distribution (CIRED 2023), IEEE, 2023, p. 935-939, article id 10417Conference paper (Refereed)
  • 2.
    Abid, Fahim
    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.
    Intermodulation due to interaction of photovoltaic inverter and electric vehicle at supraharmonic range2016In: 2016 17th International Conference on Harmonics and Quality of Power, Piscataway. NJ, 2016, p. 685-690, article id 7783471Conference paper (Refereed)
    Abstract [en]

    Advent of power electronic switching is introducing more and more non-linear loads in the low voltage grid. Besides harmonic current generation in the frequency range below 2 kHz, these non-linear loads are also responsible for current emission in the range of 2 kHz to 150 kHz, commonly known as supraharmonic emission. Supraharmonic currents mainly flow between nearby appliances and heavily influence the overall emission of neighboring devices. This paper presents an analysis of supraharmonic interaction between a photovoltaic inverter and an electric vehicle. It has been noticed that intermodulation distortion arises as a result of interaction between different switching frequencies used by the devices. Later, additional household equipment were added to photovoltaic and electric vehicle to observe their effect on intermodulation distortion. All the measurements were conducted in a controlled laboratory environment imitating a domestic customer.

  • 3.
    Ahmed, Kazi Main Uddin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Sutaria, Jil
    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.
    Electrical Energy Consumption Model of Internal Components in Data Centers2019In: Proceedings of: 2019 IEEE PES Innovative Smart Grid Technologies Europe (ISGT-Europe), IEEE, 2019, article id 331Conference paper (Refereed)
    Abstract [en]

    In the context of modern information technology (IT) industry, cloud computing is gaining popularity for big data handling. Therefore, IT service providers like Google, Facebook and Amazon are expanding their technical resources by building data centers to improve the data processing and data storage facilities under cloud service pattern. However, data centers consume a large amount of electrical energy. In recent years, a lot of research has been done to reduce the electrical energy consumption of data centers by high performance computing. However, very few researchers have focused on the electrical energy consumption by the electrical components inside the data center. In this paper, a component based electrical energy consumption modelling approach is presented to identify the losses of different components as well as their interactions to the total electrical energy consumption of the data center. The electrical energy consumption models of servers and other components are presented as a function of server utilization.

  • 4.
    Alvarez, Manuel
    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.
    Zhong, Jin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gil-de-Castro, Aurora
    University of Cordoba, Electronics and Electronic Technology Area, University of Cordoba.
    A Smart Distribution Toolbox for Distribution System Planning2015Conference paper (Refereed)
    Abstract [en]

    The distribution system planner should be able to coordinate smart grid solutions in order to find cost effective expansions plans. These plans should be able to deal with new added system uncertainties from renewable production and consumers while guaranteeing power quality and availability of supply. This paper proposes a structure for distribution systems planning oriented to help the planner in deciding how to make use of smart solutions for achieving the described task. Here, the concept of a system planning toolbox is introduced and supported with a review of relevant works implementing smart solutions. These are colligated in a way that the system planner can foresee what to expect with their combined implementation. Future developments in this subject should attempt to theorize a practical algorithm in an optimization and decision making context.

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  • 5.
    Alvarez, Manuel
    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.
    Frías, Pablo
    Comillas Pontifical University, Madrid, Spain.
    Cossent, Rafael
    Comillas Pontifical University, Madrid, Spain.
    Jabr, Rabih
    American University of Beirut, Beirut, Lebanon.
    Zhong, Jin
    The University of Hong Kong, Hong Kong, China.
    A Capacity Mechanism Design for Distribution Network Expansion Planning2018In: 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 8493874Conference paper (Refereed)
    Abstract [en]

    Capacity remuneration mechanisms have been originally oriented to ensure availability and continuity of supply on the power generation pool. Equivalent generation-based capacity mechanisms could be implemented to enhance and prolong the usability of the distribution grid. In particular, such capacity mechanisms would provide an alternative to traditional expansion options leading to investment deferral. In this work, a distribution capacity mechanism to fit within a distribution network planning methodology will be proposed and discussed. The capacity mechanism will be outlined following similar guidelines as for the design of capacity mechanisms used in the energy only market. The result of the design is a volume based capacity auction for a capacity-constrained system, oriented to both the active and the reactive power provision.

  • 6.
    Alvarez Perez, Manuel Alejandro
    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.
    Bermúdez, Juan
    Universidad Simón Bolívar.
    Zhong, Jin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. The University of Hong Kong.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    A Generic Storage Model Based on a Future Cost Piecewise-Linear Approximation2019In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 10, no 1, p. 878-888Article in journal (Refereed)
    Abstract [en]

    This work presents a generic storage model (GSM) inspired by the scheduling of hydraulic reservoirs. The model for steady state short-term (ST) operational studies interlaces with the long-term (LT) energy scheduling through a piecewise-linear Future Cost Function (FCF). Under the assumption that a Stochastic Dual Dynamic Programming (SDDP) approach has been used to solve the energy schedule for the LT, the FCF output from that study will be processed to obtain an equivalent marginal opportunity cost for the storage unit. The linear characteristic of a segment of the future cost function (FCF) will allow a linear modeling of the storage unit production cost. This formulation will help to coordinate the renewable resource along with storage facilities in order to find the optimal operation cost while meeting end-point conditions for the long-term plan of the energy storage. The generic model will be implemented to represent a battery storage and a pumped-hydro storage. A stochastic unit commitment (SUC) with the GSM will be formulated and tested to assess the day-ahead scheduling strategy of a Virtual Power Plant (VPP) facing uncertainties from production, consumption, and market prices.

  • 7.
    Alvarez Perez, Manuel Alejandro
    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.
    Bermúdez, Juan
    Universidad Simón Bolívar.
    Zhong, Jin
    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 Hydro-Reservoir Generic Storage Model for Short-Term Hydrothermal Coordination2017In: IEEE PES PowerTech Manchester 2017: towards and beyond sustainable energy systems, 2017, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7980882Conference paper (Refereed)
    Abstract [en]

    This work presents a linear solution for the short-term hydro-thermal scheduling problem linked to long-term conditions through a piecewise-linear Future Cost Function (FCF). Given end-point conditions to conform long-term water releases, and given actual reservoir conditions, a segment of a pre-built piecewise future cost function will be chosen. The linear characteristic of the FCF segment will allow a linear modeling of the hydro-power plant, in a similar fashion as a thermal unit with an equivalent marginal opportunity cost. A short-term hydro thermal coordination problem will be formulated considering parallel and cascaded hydro-reservoirs. Three study cases involving different reservoir configurations and scenarios will be computed to test the model. The results of this model mimics coherently the future-cost hydro-thermal coordination problem for the different configurations tested. Given similarities with other forms of energy storage, a new theoretical model for generic storage will be proposed and discussed.

  • 8.
    Alvarez Perez, Manuel Alejandro
    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.
    Bermúdez, Juan
    Department of Energy Conversion and Transport, Simón Bolívar University.
    Zhong, Jin
    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.
    Reservoir-Type Hydropower Equivalent Model Based on a Future Cost Piecewise Approximation2018In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 155, p. 184-195Article in journal (Refereed)
    Abstract [en]

    The long-term (LT) scheduling of reservoir-type hydropower plants is a multistage stochastic dynamic problem that has been traditionally solved using the stochastic dual dynamic programming (SDDP) approach. This LT schedule of releases should be met through short-term (ST) scheduling decisions obtained from a hydro-thermal scheduling that considers uncertainties. Both time scales can be linked if the ST problem considers as input the future cost function (FCF) obtained from LT studies. Known the piecewise-linear FCF, the hydro-scheduling can be solved as a one-stage problem. Under certain considerations a single segment of the FCF can be used to solve the schedule. From this formulation an equivalent model for the hydropower plant can be derived and used in ST studies. This model behaves accordingly to LT conditions to be met, and provides a marginal cost for dispatching the plant. A generation company (GENCO) owning a mix of hydro, wind, and thermal power will be the subject of study where the model will be implemented. The GENCO faces the problem of scheduling the hydraulic resource under uncertainties from e.g. wind and load while determining the market bids that maximize its profit under uncertainties from market prices. A two-stage stochastic unit commitment (SUC) for the ST scheduling implementing the equivalent hydro model will be solved.

  • 9.
    Alvarez Perez, Manuel Alejandro
    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.
    Cossent, Rafael
    Universidad Pontificia de Comillas.
    Zhong, Jin
    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.
    Regulatory Matters Affecting Distribution Planning With Distributed Generation2017In: CIRED - Open Access Proceedings Journal, E-ISSN 2515-0855, Vol. 2017, no 1, p. 2869-2873Article in journal (Refereed)
    Abstract [en]

    Under the present European directive concerning common rules for the internal market in electricity, distribution companies are not allowed to own distributed generation (DG) but encouraged to include it as a planning option to defer investment in traditional grid reinforcements. Distribution system operators (DSOs) have used the provision of capacity contracted to DG as a viable alternative under current regulatory arrangements. Here, the topics bonding DSOs and DG owners under the present regulation will be explored and a planning structure that considers distribution capacity contracts as a planning option will be proposed. This will serve as a road map for DSOs to implement its preferred planning tools in an optimisation context, considering costs of investment, reliability, operation, and capacity provision while complying with current regulation.

  • 10.
    Alvarez Perez, Manuel Alejandro
    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.
    Cossent, Rafael
    Universidad Pontificia de Comillas.
    Zhong, Jin
    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.
    Remuneration Assessment of a VPP Providing Distribution Capacity Services2017In: IEEE PES PowerTech Manchester 2017: towards and beyond sustainable energy systems, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7980881Conference paper (Refereed)
    Abstract [en]

    A Distribution System Operator (DSO) might consider a capacity contract as a planning alternative to defer grid investments. A Virtual Power Plant (VPP) might be able to provide such capacity and change its production as requested by the DSO. This article presents an assessment of the impact of this type of distribution capacity contract (DCC) on VPP's remuneration. This assessment is done by comparing the optimal production / bidding strategy which maximize its profit, under presence or absence of these contracts. The impact of intermittent generation and storage while evaluating these scenarios will be investigated as well. A stochastic unit commitment will be used to determine the VPP's strategy under uncertainties from wind power, load, market prices, and the requested power by the DSO. The model showed that the VPP involvement in distribution capacity contracts can improve its remuneration when certain types of Distributed Energy Resources (DER) are used to provide the service.

  • 11.
    Andersson, Marcus
    et al.
    Luleå University of Technology.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundmark, Martin
    Larsson, Anders
    Wahlberg, Mats
    Bollen, Math
    Interfering signals and attenuation: potential problems with communication via the power grid2006In: Proceedings of Nordic Distribution and Asset Management Conference: NORDAC 2006, 2006Conference paper (Refereed)
    Abstract [en]

    This paper will give a general overview of the potential problems associated with remote-meter reading via the power grid and describe some of the technologies available. A comparison will be made between the power grid as a communication channel and other, dedicated and shared, channels. Examples will be given of practical cases in which the communication channel does not function in the intended way.

    Download full text (pdf)
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  • 12.
    Blanco, Ana Maria
    et al.
    Institute for Electrical Power Systems and High Voltage Engineering, Technische Universität Dresden.
    Gupta, Manish
    Malaviya National Institute of Technology, Jaipur .
    Gil de Castro, Aurora
    Departamento de Arquitectura de Computadores, El ectrónica y Tecnología Electrónica, Universidad de Córdoba.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Meyer, Jan
    Institute for Electrical Power Systems and High Voltage Engineering, Technische Universität Dresden.
    Impact of flat-top voltage waveform distortion on harmonic current emission and summation of electronic household appliances2018In: The Renewable Energies and Power Quality Journal, ISSN 2172-038X, Vol. 1, no 16, p. 698-703, article id 437Article in journal (Refereed)
    Abstract [en]

    Electronic household appliances are non-linear loads and emit harmonics into the low voltage networks. Usually, these loads are simply modelled by constant current source models, which only represent the harmonic emission of the appliances for a single supply voltage distortion, mostly sinusoidal conditions. Measurements have shown that the harmonic currents emitted by electronic devices can significantly depend on the circuit topology and the existing supply voltage distortion. This paper studies the impact of supply voltage distortion, which can be typically found in public low voltage networks (so-called flat-top voltage waveform), on the harmonic current emission of individual devices with different circuit topologies as well as the impact of supply voltage distortion on the harmonic summation of these devices.

    Download full text (pdf)
    fulltext
  • 13.
    Bollen, Math
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Cundeva, S.
    University Sts. Cyrill and Methodias, Skopje.
    Rönnberg, Sarah
    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.
    Yang, Kai
    Yao, L
    Areva T and D, Technology Centre, Stafford.
    A wind park emitting characteristic and non-characteristic harmonics2010In: 2010 14th International Power Electronics and Motion Control Conference (EPE/PEMC 2010): Ohrid, Macedonia, 6 - 8 September 2010, Piscataway, NJ: IEEE Communications Society, 2010, p. S14-22-S14-26Conference paper (Refereed)
    Abstract [en]

    This paper shows measurements of the emission of harmonics by a small windpark. The spectrum consists of the characteristic harmonics associated with six-pulse converters and a broadband spectrum covering frequencies at which emission normally is not present. These frequencies are caused by the switching pattern of the power-electronics converters. Similar spectra have been reported by other authors and for other types of modern converters. Whereas the actual emission is small, the presence of emission at non-characteristic frequencies could result in voltage distortion limits being exceeded.

  • 14.
    Bollen, Math
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Das, Ratan
    IcaPower LLC, Dover, DE.
    Djokic, Sasa Z.
    University of Edinburgh, School of Engineering and Electronics, University of Edinburgh.
    Ciufo, Phil
    University of Wollongong.
    Meyer, Jan
    Institute of Electrical Power Systems and High Voltage Engineering, Technische Universitaet Dresden, Technical University Dresden, Dresden University of Technology.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Zavoda, Francisc
    IREQ, IREQ/HQ, Hydro-Québec Research’s Institute.
    Power Quality Concerns in Implementing Smart Distribution-Grid Applications2017In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 8, no 1, p. 391-399, article id 7527692Article in journal (Refereed)
    Abstract [en]

    This paper maps the expected and possible adverse consequences for power quality of introducing several smart distribution-grid technologies and applications. The material presented in this paper is the result of discussions in an international CIGRE-CIRED joint working group. The following technologies and applications are discussed: microgrids; advanced voltage control; feeder reconfiguration; and demand-side management. Recommendations are given based on the mapping.

  • 15.
    Bollen, Math
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gil de Castro, Aurora
    The University of Cordoba, Cordoba, Spain.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Characterization methods and typical levels of variations in rms voltage at the time scale between 1 second and 10  minutes2020In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 184, article id 106322Article in journal (Refereed)
    Abstract [en]

    Voltage magnitude deviation from its nominal value varies over a range of time scales. This paper concentrates on the range between 1 s and 10 min as part of the long-term aim of obtaining a complete picture of voltage magnitude variations at time scales below ten minutes. Time series of voltage with 1-s time resolution are obtained at 57 locations around the world. The main contributions of the paper are: the definition of additional indices in the sub-10-minute time scale from the 1-s rms voltages; statistics on the values of these indices for different locations; identifying the need for further research through a set of recommendations to the research community. It is shown, among others, that for the available data set, the voltage typically varies between 0.5 V and 5 V within a 10-min window; a range exceeding 1 or 2 V is common; a range exceeding 5 V is uncommon.

    The need for the indices proposed in this paper is justified as equipment connected to the grid is changing and to help managing and for storing the huge amount of data resulting from power-quality measurements at many sites during several years.

  • 16.
    Bollen, Math
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    GIL DE CASTRO, Aurora
    University of Cordoba, Spain.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Typical harmonic levels and spectra with low-voltage customers2019In: CIRED 2019 Proceedings, AIM , 2019, article id 366Conference paper (Refereed)
    Abstract [en]

    This paper presents levels of harmonic voltage distortion with low-voltage customers during 2017 and 2018. Measurements were obtained over a period between one hour and one day per location. Results are presented for the harmonics in the phase-to-neutral voltage at 163 locations; the highest 10-minute values per location have been used for presenting the results. For harmonics in the neutral-to-ground voltage, 1-second values at 88 locations have been used. The harmonic levels showed to be well below the limits in EN 50160 and IEC 61000-2-2 for almost all locations and for all harmonics with exception of harmonics 9, 15 and 21. The dominating frequencies at most locations are harmonics 5 and 7.

  • 17.
    Bollen, Math H J
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah K
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Schwanz, Daphne
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Eirgrid, Dublin, Ireland.
    Nakhodchi, Naser
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ravindran, Vineetha
    Harmonics and Wind Power Installations2021In: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution, IEEE, 2021, p. 648-652, article id 0028Conference paper (Refereed)
  • 18.
    Bollen, Math
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hooshyar, Hossein
    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.
    Spread of high frequency current emission2013In: 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 209Conference paper (Refereed)
    Abstract [en]

    This paper investigates the spread of the high frequency current emission between devices of different size and the grid. The impact of the EMC filter, either LCL or CLC configuration, has been considered from a simplified model. The high frequency current emission, produced by a large device, can potentially cause a relatively large current flowing through a nearby small device. An important conclusion from the study is that current amplification can occur due to harmonic resonances between different types of filters.

    Download full text (pdf)
    FULLTEXT01
  • 19.
    Bollen, Math
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Meyer, Jan
    Dresden University of Technology.
    Amaris, Hortensia
    University Carlos III, Madrid.
    Blanco, Ana María
    Technical University Dresden.
    Gil-de-Castro, Aurora
    University of Cordoba.
    Desmet, Jan
    Ghent University.
    Klatt, Mattias
    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 I – wind and solar power2014In: International Conference on Harmonics and Quality of Power. Proceedings: , Proceedings - International Conference on Harmonics and Quality of Power, ISSN 1540-6008, p. 904-908, article id 6842870Article 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. The results of this discussion are summarized in this paper and some of the issues are discussed in more detail in this paper and in its companion paper. This paper discusses emission from wind and solar power as well as advantages and disadvantages of active and passive filters.

  • 20.
    Bollen, Math
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Mulenga, Enock
    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.
    Etherden, Nicholas
    Vattenfall R&D, Power Technology, Sweden.
    Hosting Capacity of the Grid for Photovoltaic Installations: a Stochastic Approach Applied to Single-phase Connections2018In: DIGITAL PROCEEDINGS: 8th Solar Integration workshop: International workshop on Integration of Solar Power into Power Systems, Energynautics GmbH, 2018, article id SIW18-46Conference paper (Refereed)
    Abstract [en]

    This paper discusses the voltage rise due to PV installations connected to a low-voltage network. The connection of individual installations is studies for both single-phase and three-phase connection. A stochastic method is presented to estimate the hosting capacity. This method is illustrated for random and coordinated connection of single-phase installations. It is shown, in a number of ways, that the installation of large (e.g. 6 kW) single-phase connected units can easily result in unacceptable overvoltages.

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    fulltext
  • 21.
    Bollen, Math
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Olofsson, Magnus
    Elforsk.
    Larsson, Anders
    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.
    Lundmark, Martin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Standards for supraharmonics (2 to 150 kHz)2014In: IEEE Electromagnetic Compatibility Magazine, ISSN 2162-2264, Vol. 3, no 1, p. 114-119Article in journal (Refereed)
    Abstract [en]

    There is a serious interest from the international standard-setting community in knowledge about voltage and current distortion in the frequency range 2 to 150 kHz, referred to as supraharmonics. At the same time, research is ongoing at a number of locations, but the knowledge about supraharmonics remains limited. This paper compares some of the properties of harmonics and supraharmonics. An increase in supraharmonics for individual devices is observed in association with a decrease in harmonic emission (i.e. below 2 kHz). A proposal is made for setting limits in this frequency range. The proposal is based on existing standards and is meant to be for discussion. The authors strongly encourage an open discussion about the proposed limits. There are a number of differences between harmonics and supraharmonics that are not covered by the proposed set of limits. A substantial amount of further research is needed to extend the standard framework for supraharmonics such that this can be covered by standards

  • 22.
    Bollen, Math
    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.
    A Measurement-Based Definition of Phase-Angle for Negative-Sequence Unbalance2020In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 35, no 5, p. 2561-2564Article in journal (Refereed)
    Abstract [en]

    This letter proposes a measurement-based definition for the phase-angle of the negative-sequence voltage that fits in the general approach used in the IEC standard for power-quality measurements, IEC 61000-4-30. The definition is based on an expression that is obtained during a derivation of the classical expression for calculating the negative-sequence voltage from the rms values of the three line-to-line voltages. The definition can be applied to the 10/12 cycle, 150/180-cycle and 10-minute values.

  • 23.
    Bollen, Math
    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.
    Hosting Capacity of the Power Grid for Renewable Electricity Production and New Large Consumption Equipment2017In: Energies, E-ISSN 1996-1073, Vol. 10, no 9, article id 1325Article in journal (Refereed)
    Abstract [en]

    After a brief historical introduction to the hosting-capacity approach, the hosting capacity is presented in this paper as a tool for distribution-system planning under uncertainty. This tool is illustrated by evaluating the readiness of two low-voltage networks for increasing amounts of customers with PV panels or with EV chargers. Both undervoltage and overvoltage are considered in the studies presented here. Probability distribution functions are calculated for the worst-case overvoltage and undervoltage as a function of the number of customers with PV or EV chargers. These distributions are used to obtain 90th percentile values that act as a performance index. This index is compared with an overvoltage or undervoltage limit to get the hosting capacity. General aspects of the hosting-capacity calculations (performance indices, limits, and calculation methods) are discussed for a number of other phenomena: overcurrent; fast voltage magnitude variations; voltage unbalance; harmonics and supraharmonics. The need for gathering data and further development of models for existing demand is emphasised in the discussion and conclusions

  • 24.
    Bollen, Math
    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.
    Modelling and simulation issues resulting from extended measurements2015In: 2015 IEEE Power & Energy Society General Meeting: 26-30 July 2015, Denver CO, Piscataway, NJ: IEEE Communications Society, 2015, article id 7285961Conference paper (Refereed)
    Abstract [en]

    Presents a collection slides covering the following topics: supraharmonics propagation; measurement modeling; grid supply terminals; device terminals; secondary emission; primary emission; voltage measurement and capacitor

  • 25.
    Bollen, Math
    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.
    Nya lågspänningslaster och störningar i frekvensområdet 2 till 150 kHz: resultat från forskningsprojektet vid Luleå tekniska universitet, samt en kartläggning av behovet på ytterligare forskning2011Report (Other academic)
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    fulltext
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    FULLTEXT02
  • 26.
    Bollen, Math
    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.
    Primary and Secondary Harmonics Emission: Harmonic interaction - A set of definitions2016In: 2016 17th International Conference on Harmonics and Quality of Power, Piscataway, NJ: IEEE Computer Society, 2016, p. 703-708, article id 7783333Conference paper (Refereed)
    Abstract [en]

    This paper proposes a set of definitions to simplify the discussion about the different contributions to the harmonic currents at the terminals of a device or an installation. Definitions are given, and explained, for 'primary harmonic emission', 'secondary harmonic emission', and 'harmonic interaction'

  • 27.
    Bollen, Math
    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.
    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, Energy Science.
    Lundmark, Martin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Harmonic emission from installations with energy-efficient lighting2011In: Proceeding of the International Conference on Electrical Power Quality and Utilisation, EPQU, Piscataway, NJ: IEEE Communications Society, 2011, p. 797-802Conference paper (Refereed)
    Abstract [en]

    This paper presents the results from a number of measurements of the harmonic emission from installations that contain a large number of energy-efficient lamps. Two of the measurements concern the replacement of incandescent lamps with CFL and LED; the other measurement concerns an installation with up to 48 fluorescent lamps with high-frequency ballasts. The paper also contains a discussion on why the (total) power factor is not a good measure to quantify the performance of lamps or installations containing large numbers of lamps

  • 28.
    Bollen, Math
    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.
    Wahlberg, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Laboratory and field measurements of the power factor and the harmonic emission from energy-efficient lamps2011Conference paper (Refereed)
  • 29.
    Bollen, Math
    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.
    Zavoda, Francisc
    IREQ, IREQ/HQ, Hydro-Québec Research’s Institute.
    CIGRE/CIRED C4.24 – power quality in the future grid – first introduction2014Conference paper (Refereed)
    Download full text (pdf)
    FULLTEXT01
  • 30.
    Bollen, Math
    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.
    Zavoda, Francisc
    IREQ (HQ), Varennes.
    Langella, Roberto
    Second University of Naples.
    Djokic, Sasa
    University of Edinburgh.
    Cuifo, Philip
    University of Wollongong.
    Meyer, Jan Christian
    Technische Universitaet Dresden.
    Cuk, Vladimir
    Eindhoven University of Technology.
    Consequences of Smart Grids for Power Quality Overview of the Results from CIGRE Joint Working Group C4.24/CIRED2018In: 2017 IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT-Europe 2017: proceedings, New York: Institute of Electrical and Electronics Engineers (IEEE), 2018Conference paper (Refereed)
    Abstract [en]

    This paper gives an overview of the expected unintended (negative) consequences for power quality of several on-going developments in the power system. Four developments directly related to smart-grid technology are covered: microgrids; advanced voltage control; feeder reconfiguration; and demand-side management. Four developments indirectly related are also covered: new sources of electricity production; increased used of active power-electronic converters; shift from overhead lines to cables; and new types of lighting. The paper summarizes the discussions in an international working group and presents the main findings are recommendations.

  • 31.
    Bollen, Math
    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.
    Zavoda, Francisc
    IREQ.
    Zhong, Jin
    University of Hongkong.
    Djokic, Sasa
    University of Edinburgh.
    Das, Ratan
    ABB.
    Halpin, Mark
    Auburn University Montgomery, Alabama.
    CIGRE/CIRED working group C4.24 – power quality and EMC issues associated with future electricity networks – status report2015Conference paper (Refereed)
    Abstract [en]

    This paper gives a status report of joint working group C4.24. Next to an overview of the different activities started, more details are given of the work done on voltage dips, new sources of emission, feeder reconfiguration, demand side management and power quality and economics.

    Download full text (pdf)
    FULLTEXT01
  • 32.
    Bollen, Math
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Yao, Liangzhong
    Areva T and D, Technology Centre, Stafford.
    Rönnberg, Sarah
    Wahlberg, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Harmonic and interharmonic distortion due to a windpark2010In: IEEE Power and Energy Society General Meeting, Piscataway, NJ: IEEE Communications Society, 2010Conference paper (Refereed)
    Abstract [en]

    This paper discusses two aspects of the impact of windparks on the waveform distortion in the power system: emission and resonances. The paper gives a general overview of the emission and shows measurement results from a small but modern windpark connected to a 10-kV feeder and estimates the need for network strength to limit the resulting voltage distortion. The paper also gives a general overview of harmonic resonances associated with windparks and illustrates this by means of two numerical examples. Important conclusions from this paper are than harmonic resonances are more likely to be a concern that the emission from windparks, and that the interharmonic emission and the emission at non-characteristic harmonics are more prominent than with existing installations.

  • 33.
    Busatto, Tatiano
    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.
    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.
    Including Uncertainties from Customer Connections in Calculating Low-Voltage Harmonic Impedance2019In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 34, no 2, p. 606-615Article in journal (Refereed)
    Abstract [en]

    A method is proposed in this paper to determine the harmonic impedances in low-voltage networks in a stochastic way. The consequences of resonances for harmonic propagation and stability of power converters are summarized. By using Monte Carlo simulation, the method includes the uncertainties in customer impedances, specifically due to electronic loads and local generation. The uncertainty in customer impedance is included by considering probability distribution for the resistive, inductive and capacitive parts of the impedance. The concept of transfer impedance is used for phase-to-neutral connections. A method is developed and applied to two existing low-voltage networks in Sweden. Results show that, for these two networks, the resonant frequencies decrease around 28 % once PV panels are installed. The paper includes a discussion of some of the practical aspects of applying the proposed method.

  • 34.
    Busatto, Tatiano
    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.
    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.
    Supraharmonics Emission Assessment of Multi-level Converters Applied for Photovoltaic Grid-Connected Inverters2017In: The Renewable Energies and Power Quality Journal, ISSN 2172-038X, Vol. 1, no 15, p. 143-148, article id 252Article in journal (Refereed)
    Abstract [en]

    Topologies for different DC-AC converters used on grid-connected photovoltaic (PV) inverters are analysed and compared within this paper. The main focus is to evaluate the supraharmonic emission in the frequency range 2 to 150 kHz. For this study three topologies are evaluated: Neutral Point Clamped (NPC), the Cascaded H-bridge (CHB) and the Flying Capacitor (FC). To approximate the operation closer to a real scenario, the converters are analysed under the presence of voltage waveform distortion in the power supply. The simulation is performed using PSpice for the converters and Simulink for the grid. The characterization is made by the quantification of harmonics and supraharmonics, and also by the frequency domain analysis of the output current. Finally, a comparison of the chosen technologies is carried out, given a better understanding on the elements which exert influence on this type of emission.

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    252-17-Busatto
  • 35.
    Busatto, Tatiano
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ravindran, Vineetha
    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.
    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.
    Measurements on an experimental laboratory setup with PV Inverters and a Large Number of LED Lamps2018Report (Other academic)
  • 36.
    Busatto, Tatiano
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ravindran, Vineetha
    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.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math H. J.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Meyer, Jan
    Institute of Electrical Power Systems and High Voltage Engineering, Technische Universität Dresden, Dresden, Germany.
    Experimental Harmonic Analysis of the Impact of LED Lamps on PV Inverters Performance2019In: 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM), IEEE, 2019Conference paper (Refereed)
    Abstract [en]

    It is known for instance that voltage waveform distortion and network impedance have a significant impact on PV inverter current emissions. Because this, much research is still required to better understand their behavior and impact when multiple common household devices are placed to operate together in the same low-voltage installation. In particular, this paper addresses the harmonic impact of LED lamps on PV inverters performance considering different technologies and number of lamps. The analysis has been carried out with different scenarios considering two types of LED lamps, with and without power factor correction feature, and three different PV inverter technologies. The evaluation of the impacts is simply performed by frequency and time domain analysis, establishing the correlation between the devices current harmonics. The results obtained from the experiments have shown that LED lamps are prone to add a significant impact on the PV inverter current harmonics, and this impact is mainly dependent on the devices used technology.

  • 37.
    Busatto, Tatiano
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ravindran, Vineetha
    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.
    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
    Electric Power Engineering, Technische Universität Dresden.
    Deviations between the commonly-used model and measurements of harmonic distortion in low-voltage installations2020In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 180, article id 106166Article in journal (Refereed)
    Abstract [en]

    Harmonic analysis studies of modern power systems commonly employ Norton and Thévenin equivalents at harmonic frequencies for the nonlinear devices. This approach neglects the so-called nonlinear interaction phenomenon. This paper addresses the difference between the results from the commonly-used model and the actual harmonic distortion measured in a low-voltage installation. A number of indices are introduced to quantify the nonlinear interaction. These indices allow a quantification of the extent to which the commonly-used model is also to predict harmonic voltages and currents in a modern low-voltage installation. The proposed model and the subsequent mathematical analysis are illustrated through measurements from different combinations of PV inverters and LED lamps using different technologies. The results show that deviation is dependent on the used technology, network impedance, and source voltage waveform. Other findings are that nonlinear interaction happens mainly in the low harmonic orders and impacts are more perceived on the harmonics phase angle. Possible explanations for these observations are discussed.

  • 38.
    Busatto, Tatiano
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sara K.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math H. J.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Harmonic Analysis of Electric Vehicle Charging on the Distribution System Network with Distributed Solar Generation2020In: The Renewable Energies and Power Quality Journal, ISSN 2172-038X, Vol. 18, p. 103-108, article id 240Article in journal (Refereed)
    Abstract [en]

    Electric vehicle chargers and solar photovoltaic inverters are two types of household loads that can potentially impact the power quality of the grid. This paper presents a view of the consequences that the connection of these two nonlinear loads into a low-voltage installation can create on voltage harmonic distortion. The analysis considers the combined impact on network impedance and current harmonic distortion. First, the network impedance for phase-to-neutral connections is obtained considering the uncertainty in customer impedance. For this, a Monte Carlo simulation and the concept of transfer impedance are used. Second, based on real measurements, the current harmonic distortion of these two nonlinear loads are used to calculate the resulting voltage distortion at any bus of interest in the network. The analysis is applied to an existing low-voltage network in Sweden. Based on the study case, results show that some harmonics may increase by about 83 % as a function of the penetration of electric vehicles and photovoltaic installations.

  • 39.
    Busatto, Tatiano
    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.
    Comparison of Models of Single-Phase Diode Bridge Rectifiers for Their Use in Harmonic Studies with Many Devices2022In: Energies, E-ISSN 1996-1073, Vol. 15, no 1, article id 66Article in journal (Refereed)
    Abstract [en]

    Harmonic modeling of low-voltage networks with many devices requires simple but accurate models. This paper investigates the advantages and drawbacks of such models to predict the current harmonics created by single-phase full-bridge rectifiers. An overview is given of the methods, limiting the focus to harmonic analysis. The error of each method, compared to an accurate numerical simulation model, is quantified in frequency and time domain considering realistic input scenarios, including background voltage distortion and different system impedances. The results of the comparison are used to discuss the applicability of the models depending on the harmonic studies scale and the required level of detail. It is concluded that all models have their applicability, but also limitations. From the simplest and fastest model, which does not require a numerical solution, to the more accurate one that allows discontinuous conduction mode to be included, the trade-off involves accuracy and computational complexity.

  • 40.
    Busatto, Tatiano
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah K.
    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.
    Stability Analysis of PFC Converters Under Different Source Impedances and Its Consequences on Zero-Crossing Distortion2022In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 37, no 4, p. 3235-3244Article in journal (Refereed)
    Abstract [en]

    In the presence of multiple power converters in a power system the total current may exhibit zero-crossing distortion in the form of recurrent damped oscillations with high magnitude. These oscillations are synchronized with the power system frequency. This paper presents a comprehensive analysis of the input current of single-phase ac-dc converters fitted with power factor correction (PFC) controllers. Emphasis is given on the impacts of the source impedance, and on how the number of converters connected to a common coupling point (PCC) impacts the PFC controller’s performance. A system model is developed followed by simulation and measurements in a real installation with electronic ballasts used to drive fluorescent lighting tubes. Results show that the recurrent damped oscillations originating from PFC controllers are close to the harmonic range and with a very low level of cancellation between devices. The magnitude therefore increases proportionally with the number of devices. As the source impedance increases, instability may occur. Possible explanations for these observations are discussed.

  • 41.
    de Oliveira, Roger Alves
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Nakhodchi, Naser
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    De Souza Salles, Rafael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah K.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Deep Learning Graphical Tool Inspired by Correlation Matrix for Reporting Long-Term Power Quality Data at Multiple Locations of an MV/LV Distribution Grid2023In: 27th International Conference on Electricity Distribution (CIRED 2023), IEEE, 2023, p. 609-613, article id 10324Conference paper (Refereed)
  • 42.
    de Oliveira, Roger Alves
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ravindran, Vineetha
    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.
    Deep Learning For Pattern Recognition Of Interharmonics In Time-Series And Spectrograms2021In: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution, 2021, p. 738-741Conference paper (Refereed)
    Abstract [en]

    This work applies an unsupervised deep feature learning to finding patterns of interharmonics. The main objectives of this work are to provide an additional graphical tool to handle two distinct data inputs: (a) individual interharmonics components in time-series; (b) broadband spectrum by employing spectrograms. Both data inputs are analysed employing an autoencoder based on convolutional neural networks followed by clustering. The application of the method results in the most common patterns in time-series or spectrograms. Two study cases are presented by applying the method to measurements from solar installations in Finland and Sweden. The results show the usefulness of the method to recognize interharmonics in a single frequency and broadband spectrum.

  • 43.
    de Oliveira, Roger Alves
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ravindran, Vineetha
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah K.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math H.J.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Deep Learning Method With Manual Post-Processing for Identification of Spectral Patterns of Waveform Distortion in PV Installations2021In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 12, no 6, p. 5444-5456Article in journal (Refereed)
    Abstract [en]

    This paper proposes a deep learning (DL) method for the identification of spectral patterns of timevarying waveform distortion in photovoltaic (PV) installations. The PQ big data with information on harmonic and/or interharmonics in PV installations is handled by a deep autoencoder followed by feature clustering. Measurements of voltage and current from four distinct PV installations are used to illustrate the method. This paper shows that the DL method can be used as a starting point for further data analysis. The main contributions of the paper include: (a) providing a novel DL method for finding patterns in spectra; (b) guiding the manual post-processing based on the patterns found by the DL method; and (c) obtaining information about the emission from four PV installations.

  • 44.
    de Oliveira, Roger Alves
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah K.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math H. J.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Third Harmonic and its Relation to Solar Elevation Angle in a PV Installation with Solar Tracking Systems2022In: 2022 20th International Conference on Harmonics & Quality of Power (ICHQP) Proceedings: “Power Quality in the Energy Transition”, IEEE, 2022Conference paper (Refereed)
    Abstract [en]

    This paper shows an application of a deep learning method to a solar installation with a solar tracking system. The method consists of a deep autoencoder followed by clustering. The deep learning method allows defining the most dominant component in harmonic spectra during long-term measurements. Power Quality measurements were accessed over two years in 3ϕ PV installation of 6 kVA with 2-axis tracking in northern Sweden. The deep learning results indicate that the third harmonic of current is the component that changes most over the two years. This paper demonstrates that there is a correlation between the daily and seasonal variations of the third harmonic with the solar elevation angle at the location. The main conclusion for this cause was associated with the operation of the solar tracking systems which are based on single-phase motors. The paper also discusses the possibility of correlation of the third harmonic with cloud coverage, snow on the panels, and reactive power unbalance.

  • 45.
    de Oliveira, Roger Alves
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Salles, Rafael S.
    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.
    de Carli, Miguel P.
    Eletrobras at the Generation Departmen in Florianópolis, Brazil.
    Leborgne, Roberto Chouhy
    Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
    Harmonic Anomalies due to Geomagnetically Induced Currents as a Potential Cause of Protection Mal-Trips at the South Atlantic Anomaly Area2024In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208Article in journal (Refereed)
  • 46.
    De Souza Salles, Rafael
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah K.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Interharmonic Analysis for Static Frequency Converter Station Supplying a Swedish Catenary System2022In: 2022 20th International Conference on Harmonics & Quality of Power (ICHQP) Proceedings: “Power Quality in the Energy Transition”, IEEE, 2022Conference paper (Refereed)
    Abstract [en]

    The paper aims to present a waveform distortion analysis focused on interharmonics in measurements from a 70 kV busbar feeding a traction supply substation with four static frequency converters (SFC). The substation supplies a Swedish catenary system from 50 Hz public grid to 15 kV 16 ⅔ Hz. The paper assesses the interharmonics for different scenarios regarding the point of a connection configuration between the traction substation and the upstream grid, as well as a change in the number of SFCs connected in the substation. The IEC 61000-4-7 grouping method and spectrograms were used to illustrate the issue. The significant presence of interharmonics calls attention to the subject in railway application. The total indexes help to evaluate the broad picture of the phenomena. The work contributes to the waveform distortion and interharmonics in railway systems studies.

  • 47.
    De Souza Salles, Rafael
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah K.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Mariscotti, Andrea
    Department of Electrical, Electronics and Telecommunication, Engineering and Naval Architecture (DITEN), University of Genova, Genova, Italy.
    Waveform Distortion Emission Assessment on Pantograph Measurements from Low-Frequency Railway Electrification2022In: 2022 20th International Conference on Harmonics & Quality of Power (ICHQP) Proceedings: “Power Quality in the Energy Transition”, IEEE, 2022Conference paper (Refereed)
    Abstract [en]

    The paper aims to provide a waveform distortion assessment on pantograph current measurements. The data analyzed is regarding a 15 kV 16.7 Hz catenary system from Switzerland. The paper provides a characterization of the rolling stock emission content for different operation modes during a commercial utilization of the vehicle, approaching traditional harmonics, interharmonic and supraharmonic phenomena. In addition, the work provides an adaptation on the interharmonic processing proposed by the IEC 61000-4-7 regarding the 16.7 Hz fundamental frequency. The results contribute to the waveform distortion emission on pantograph measurements subject and railway systems investigation in general.

  • 48.
    Espin Delgado, Angela
    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.
    Assessment of Grid Impedance Impact On Supraharmonic Propagation2021In: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution, Institution of Engineering and Technology, 2021, p. 688-692, article id 0073Conference paper (Refereed)
    Abstract [en]

    Supraharmonic (SH) propagation is determined by the impedance of both the grid and the devices connected to it. Few attempts to characterize this combined dependency have been done. The interest of grid operators is in counteracting the propagation of SHs upstream to maintain power quality. Characterizing the impact of impedance on SH propagation gives information to strategically counteract this propagation to the upstream grid. This paper presents an experimental case study for the assessment of the sensitivity of SH propagation to changes in impedance of the grid at the delivery point. The results are then compared to the changes of SH propagation provoked by the connection of low-voltage (LV) equipment.

  • 49.
    Espin Delgado, Angela
    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.
    Modeling and Analysis of Supraharmonic Propagation for Stochastic Studies2022In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 37, no 6, p. 4899-4910Article in journal (Refereed)
    Abstract [en]

    Supraharmonic (SH) propagation depends on the impedance of both the grid and the devices connected to it. Few attempts to quantify the impact of the customer's load variability have been done. The interest of grid operators is in counteracting the SH propagation upstream to maintain power quality. Quantifying the impact of impedance on supraharmonic propagation gives information to strategically counteract this propagation to the grid. This article presents a method for analysis of SH propagation that uses a stochastic approach to describe the impact of low-voltage (LV) loads. Scenarios of a strong and a weak grid are presented to study the impact of reinforcement grid measures.

  • 50.
    Espin Delgado, Angela
    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.
    Ravindran, Vineetha
    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.
    Summation law for supraharmonic currents (2–150 kHz) in low-voltage installations2020In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 184, article id 106325Article in journal (Refereed)
    Abstract [en]

    The development of methods to study the propagation of supraharmonics in LV and even MV grids is a current research topic among the power quality community, which has been motivated by the efforts to establish limits for non-intentional supraharmonic emissions and planning levels. The assessment of how much distortion a bulk use of power electronics devices can inject into the grid is necessary before stating emission limits and planning levels for supraharmonics. To address this issue, the development of suitable models that can predict the supraharmonic emission from a low-voltage installation as a whole is required. This article presents a comparison of models for the summation of supraharmonics. An improved model for the summation of supraharmonics is proposed, which is validated experimentally. It is shown that by using the proposed model, predictions of supraharmonic propagation can be accomplished. Furthermore, it is demonstrated experimentally that, with the increasing number of supraharmonic emitting devices, the supraharmonic current distortion injected into a grid by an installation increases up to a maximum value and then decreases due to the capacitive nature of power electronics appliances existing in low-voltage networks.

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