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  • 1.
    Abid, Fahim
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Busatto, Tatiano
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Intermodulation due to interaction of photovoltaic inverter and electric vehicle at supraharmonic range2016Inngår i: 2016 17th International Conference on Harmonics and Quality of Power, Piscataway. NJ, 2016, s. 685-690, artikkel-id 7783471Konferansepaper (Fagfellevurdert)
    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.

  • 2.
    Abrahamsson, Lars
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Laury, John
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Evaluating a constant-current load model through comparativetransient stability case studies of a synchronous-synchronous rotary frequencyconverter fed railway2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper continues the pursuit of getting a deeperunderstanding regarding the transient stability of lowfrequencyAC railway power systems operated at 162⁄3 Hzsynchronously to the public grid. The focus is set on theimpact of different load models. A simple constant-currentload model is proposed and compared to a previously proposedand studied load model in which the train’s activepower is regulated.The study and comparison is made on exactly the samecases as and grid as with the already proposed and moreadvanced load model. The railway grid is equipped witha low-frequency AC high-voltage transmission line whichis subjected to a fault. The study is limited to railwaysbeing fed by different distributions of RFC (Rotary FrequencyConverter) types. Both AT (auto transformer) andBT (booster transformer) catenaries are considered.The RFC dynamic models are essentially Anderson-Fouad models of two synchronous machines coupled mechanicallyby their rotors being connected to the same shaft.The differences in load behaviour between the proposedconstant-current load model and the previously proposedand studied voltage-dependent active power load model areanalyzed and described in the paper.

  • 3.
    Abrahamsson, Lars
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Laury, John
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Further studies on the transient stability of synchronous-synchronous rotary frequency converter fed railways with low-frequency AC high-voltage transmission2018Inngår i: International Journal of Energy Production and Management, ISSN 2056-3272, E-ISSN 2056-3280, Vol. 3, nr 4, s. 266-276Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 4.
    Abrahamsson, Lars
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Serrano Jimenez, Daniel
    University Carlos III.
    Laury, John
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    AC cables strengthening railway low frequency AC power supplysystems2017Inngår i: ASME/IEEE 2017 Joint Rail Conference, ASME Press, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In present-day railway power supply systems using an AC frequency lower than the one in the public power system of 50/60 Hz, high voltage overhead transmission lines are used as one measure of strengthening the railway power supply system grids. This option may be economically beneficial, compared to strengthening the grid purely by increasing the density of converter stations or increasing the cross section areas of the overhead catenary wires. High voltage AC transmission lines in the railway power supply system allow larger distances between converter stations than would otherwise be possible for a given amount of train traffic. Moreover, the introduction of AC transmission lines implies reduced line losses and reduced voltage level fluctuations at the catenary for a given amount of train traffic. However, due to the increased public and government resistance for additional overhead high voltage AC transmission lines in general, different alternatives will be needed for the future improvements and strengthening of railway power systems. For a more sustainable transport sector, the share and amount of railway traffic needs to increase, in which case such a strengthening becomes inevitable. Earlier, usage of VSC-HVDC transmission cables has been proposed as one alternative to overhead AC transmission lines. One of the main benefits with VSC-HVDC transmission is that control of power flows in the railway power systems is easier and that less converter capacity may be needed. Technically, VSC-HVDC transmission for railway power systems is a competitive solution as it offers a large variety of control options. However, there might be other more economical alternatives reducing the overall impedance in the railway power system. In public power systems with the frequency of 50/60 Hz, an excess of reactive power production in lowly utilized cables imposes an obstacle in replacing overhead transmission lines with cables. In low frequency AC railway power system, the capacitive properties are less significant allowing longer cables compared to 50/60 Hz power systems. Moreover, in converter-fed railways, some kind of reactive compensation will automatically be applied during low-load. At each converter station, voltage control is already present following the railway operation tradition. Therefore, in this paper, we propose AC cables as a measure of strengthening low-frequency AC railway power systems. The paper compares the electrical performances of two alternative reinforcement cable solutions with the base case of no reinforcement. The options of disconnecting or toggling the cables at low load as well as the automatic reactive compensation by converter voltage control are considered. Losses and voltage levels are compared for the different solutions. Investment costs and other relevant issues are discussed.

  • 5.
    Alvarez, Manuel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Zhong, Jin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Gil-de-Castro, Aurora
    University of Cordoba, Electronics and Electronic Technology Area, University of Cordoba.
    A Smart Distribution Toolbox for Distribution System Planning2015Konferansepaper (Fagfellevurdert)
    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.

  • 6.
    Alvarez, Manuel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    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 Planning2018Inngår i: 2018 IEEE International Conference on Environment and Electrical Engineering and 2018 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), 2018, artikkel-id 8493874Konferansepaper (Fagfellevurdert)
    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.

  • 7.
    Alvarez Perez, Manuel Alejandro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bermúdez, Juan
    Universidad Simón Bolívar.
    Zhong, Jin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. The University of Hong Kong.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    A Generic Storage Model Based on a Future Cost Piecewise-Linear Approximation2019Inngår i: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 10, nr 1, s. 878-888Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 8.
    Alvarez Perez, Manuel Alejandro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bermúdez, Juan
    Universidad Simón Bolívar.
    Zhong, Jin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    A Hydro-Reservoir Generic Storage Model for Short-Term Hydrothermal Coordination2017Inngår i: IEEE PES PowerTech Manchester 2017: towards and beyond sustainable energy systems, 2017, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, artikkel-id 7980882Konferansepaper (Fagfellevurdert)
    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.

  • 9.
    Alvarez Perez, Manuel Alejandro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bermúdez, Juan
    Department of Energy Conversion and Transport, Simón Bolívar University.
    Zhong, Jin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Reservoir-Type Hydropower Equivalent Model Based on a Future Cost Piecewise Approximation2018Inngår i: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 155, s. 184-195Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 10.
    Alvarez Perez, Manuel Alejandro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Cossent, Rafael
    Universidad Pontificia de Comillas.
    Zhong, Jin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Regulatory Matters Affecting Distribution Planning With Distributed Generation2017Inngår i: CIRED - Open Access Proceedings Journal, E-ISSN 2515-0855, Vol. 2017, nr 1, s. 2869-2873Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 11.
    Alvarez Perez, Manuel Alejandro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Cossent, Rafael
    Universidad Pontificia de Comillas.
    Zhong, Jin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Remuneration Assessment of a VPP Providing Distribution Capacity Services2017Inngår i: IEEE PES PowerTech Manchester 2017: towards and beyond sustainable energy systems, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, artikkel-id 7980881Konferansepaper (Fagfellevurdert)
    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.

  • 12.
    Andersson, Marcus
    et al.
    Luleå tekniska universitet.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lundmark, Martin
    Larsson, Anders
    Wahlberg, Mats
    Bollen, Math
    Interfering signals and attenuation: potential problems with communication via the power grid2006Inngår i: Proceedings of Nordic Distribution and Asset Management Conference: NORDAC 2006, 2006Konferansepaper (Fagfellevurdert)
    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.

  • 13.
    Axelberg, Peter
    et al.
    Unipower AB, Alingsås.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Gu, Irene Y.H.
    Chalmers University of Technology.
    A measurement method for determining the direction of propagation of flicker and for tracing a flicker source2005Inngår i: CIRED: 18th International Conference on Electricity Distribution Turin, 6-9 June 2005, 2005, s. 505-508Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper describes a new and highly efficient measurement method (algorithm) that determines how flicker propagates throughout the network and also traces the dominant flicker source. The fundamental principle of the method is to use the fact that a flicker source produces an amplitude modulation in the voltage and current waveforms. The low frequency variations in voltage and current that cause flicker are retrieved in a demodulation and filtering process. By first multiplying the low frequency variations in voltage and current and then integrate, a new quantity, flicker power, is achieved. The sign and the magnitude of flicker power give the direction to the flicker source as well as tracing the dominating flicker source.

  • 14.
    Axelberg, Peter G V
    et al.
    Unipower.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Gu, Irene Y H
    Chalmers University of Technology.
    Efficient trace of flicker sources by using the quantity of flicker power2008Inngår i: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 23, nr 1, s. 465-471Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Industries that produce flicker are often placed close to each other and connected to the same power grid system. This implies that the measured flicker level at the point of common coupling (PCC) is a result of contribution from a number of different flicker sources. In a mitigation process it is essential to know which one of the flicker sources is the dominant one. Therefore this paper proposes a method to determine the flicker propagations and trace the flicker sources by using flicker power measurements. Flicker power is considered as a quantity containing both sign and magnitude. The sign determines if a flicker source is placed downstream or upstream with respect to a given monitoring point and the magnitude is used to determine the propagation of flicker power throughout the power network and to trace the dominant flicker source. This paper covers the theoretical background of flicker power and describes a novel method for calculation of flicker power that can be implemented in a power network analyzer. Also a conducted field test based on the proposed method is described in the paper.

  • 15.
    Axelberg, P.G.V.
    et al.
    Unipower AB, Alingsås.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    An algorithm for determining the direction to a flicker source2006Inngår i: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 21, nr 2, s. 755-760Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes an algorithm for calculating the direction to a flicker source with respect to a monitoring point. The proposed algorithm is based on sampling of both the voltage and current. The low-frequency fluctuations in voltage and current are recovered from the input signals by demodulation, and passed through a bandpass filter as described in IEC 61000-4-15. A new quantity - flicker power - is defined from the output signals of the two filters. The direction to a flicker source is obtained from the sign of this flicker power. The proposed algorithm has been validated by simulations and several field measurements

  • 16. Axelberg, P.G.V
    et al.
    Gu, I.Y.H
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Automatic classification of voltage events using the support vector machine method2007Inngår i: Conference proceedings: 19th International Conference and Exhibition on Electricity Distribution : Vienna, 21 - 24 May 2007, Liege: AIM , 2007Konferansepaper (Fagfellevurdert)
  • 17. Axelberg, P.G.V
    et al.
    Gu, I.Y.H
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Performance test of a support vector machine used for classification of voltage disturbances2006Inngår i: 12th International Conference on Harmonics and Quality of Power, 2006Konferansepaper (Fagfellevurdert)
  • 18.
    Axelberg, P.G.V
    et al.
    University College of Borås.
    Gu, I.Y.H
    Chalmers University of Technology.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Support vector machine for classification of voltage disturbances2007Inngår i: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 22, nr 3, s. 1297-1303Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The support vector machine (SVM) is a powerful method for statistical classification of data used in a number of different applications. However, the usefulness of the method in a commercial available system is very much dependent on whether the SVM classifier can be pretrained from a factory since it is not realistic that the SVM classifier must be trained by the customers themselves before it can be used. This paper proposes a novel SVM classification system for voltage disturbances. The performance of the proposed SVM classifier is investigated when the voltage disturbance data used for training and testing originated from different sources. The data used in the experiments were obtained from both real disturbances recorded in two different power networks and from synthetic data. The experimental results shown high accuracy in classification with training data from one power network and unseen testing data from another. High accuracy was also achieved when the SVM classifier was trained on data from a real power network and test data originated from synthetic data. A lower accuracy resulted when the SVM classifier was trained on synthetic data and test data originated from the power network.

  • 19.
    Axelsson, Urban
    et al.
    Vattenfall Research & Development.
    Holm, Anders
    Vattenfall Research & Development.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Yang, Kai
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Propagation of harmonic emission from the turbines through the collection grid to the public grid2013Inngår i: 22nd International Conference and Exhibition on Electricity Distribution (CIRED 2013): Stockholm, Sweden, 10 - 13 June 2013, Red Hook, NY: Curran Associates, Inc., 2013, artikkel-id 650Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper addressed the harmonic emission from a large off-shore wind farm. An overview is given of the issues, where a distinction is made between frequencies below and above 2 kHz. Three different approaches are presented: a simplified mathematical model; a more detailed mathematical model; and measurements at the point of connection for an off-shore wind farm. It is concluded from both models and measurements that the emission is small for frequencies above a few kHz. However, specific resonances at higher frequencies involving the power transformers, when coinciding with switching frequencies or harmonics of switching frequencies, could result in high emission even at these high frequencies. Studies, including the propagation through the collection grid, are needed with the connection of any wind park to the grid.

  • 20.
    Axelsson, Urban
    et al.
    Vattenfall Research & Development.
    Holm, Anders
    Vattenfall Research & Development.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Yang, Kai
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Propagation of harmonic emission from the turbines through the collection grid to the public grid2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper addresses the harmonic emission from a large off-shore wind farm. An overview is given of the issues, where a distinction is made between frequencies below and above 2 kHz. Three different approaches are presented: a simplified mathematical model; a more detailed mathematical model; and measurements and the point of connection for an off-shore wind farm. It is concluded from both models and measurements that the emission is small for frequencies above a few kHz. However, specific resonances at higher frequencies involving the power transformers, when coinciding with switching frequencies or harmonics of switching frequencies, could result in high emission even at these high frequencies.

  • 21.
    Bagheri, Azam
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Additional information from voltage dips2016Inngår i: 17th International Conference on Harmonics and Quality of Power, Piscataway, NJ, 2016, s. 326-332, artikkel-id 7783434Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents some methods to extract additional information from voltage dip recordings, beyond residual voltage and duration. Additionally it discusses some issues related to the massive amount of data obtained from modern measurements that, is referred to as Big Data. The paper proposes some Deep Learning based algorithms as good candidates to extract complex features from big data as a step towards additional information. The applications of the information include predicting individual equipment performance, fault type and location, protection operation, and overall load behavior. Individual equipment and overall load include production as well as consumption

  • 22.
    Bagheri, Azam
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Characterizing three-phase unbalanced dips through the ellipse parameters of the space phasor model2018Inngår i: 2017 IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT-Europe 2017: proceedings, New York: Institute of Electrical and Electronics Engineers (IEEE), 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper verifies the potential of ellipse parameters as voltage dip characteristics. The space-phasor model (SPM) of three phase voltages is generally in form of an ellipse in the complex plane. Mathematical relations are derived between the single-event characteristics (Characteristic Voltage; PN factor and Dip Type), and the ellipse parameters (semi-major axis, Semi-minor axis and major axis direction). The relations are validated by applying them to several actual recorded voltage dips and synthetic voltage dips.

  • 23.
    Bagheri, Azam
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Developments in voltage dip research and its applications, 2005-20152016Inngår i: 17th International Conference on Harmonics and Quality of Power, Piscataway, NJ, 2016, s. 48-54, artikkel-id 7783428Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a review of literature on voltage dips, from several points of view, throughout the last decade. It also summarizes the results related to voltage dip mitigation in both AC and DC power systems whereas it shows the remaining challenges that requires further research on voltage dips.

  • 24.
    Bagheri, Azam
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Simple diagnostic technique of switch failure modes of VSI power converter2018Inngår i: 2017 IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT-Europe 2017: proceedings, New York: Institute of Electrical and Electronics Engineers (IEEE), 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a diagnostic method to detect switch failure of PWM power converters. The proposed method uses space phasor model (SPM) of three voltages measured at terminal of the power converter, then it applies principal component analysis to detect and localize the failure mode. The SPM results in one unique rotated ellipse or semi ellipse for every failure mode of every faulty leg. The quadrants occupied by the ellipse or semi ellipse also determine the faulty switch location in the leg. The proposed method is validated through comprehensive simulations.

  • 25.
    Bagheri, Azam
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Space Phasor Model Based Monitoring of Voltages in Three Phase Systems2018Inngår i: Proceedings of International Conference on Harmonics and Quality of Power, ICHQP, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper proposes a method for monitoring of voltages in three-phase systems using parameters of the ellipse, correspondent to the space phasor model of three-phase voltages. Three main parameters, semi-minor axis, semi-major axis and rotating angle of the ellipse are calculated as single-cycle characteristics. Once these characteristics exceed predefined threshold values, different voltage events are detected. Given whole event data the parameters of the corresponding ellipse are calculated as ‘single-event characteristics’. The proposed method is applied to different measured voltage waveforms. The simulation results confirm that the ellipse parameters are a good basis for both detecting and characterizing voltage events.

  • 26.
    Bagheri, Azam
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Gu, Irene Y.H.
    Signal Processing group, Chalmers University of Technology.
    Big data from smart grids2018Inngår i: 2017 IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT-Europe 2017: proceedings, New York: Institute of Electrical and Electronics Engineers (IEEE), 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper gives a general introduction to “Big Data” in general and to Big Data in smart grids in particular. Large amounts of data (Big Data) contains a lots of information, however developing the analytics to extract such information is a big challenge due to some of the particular characteristics of Big Data. This paper investigates some existing analytic algorithms, especially deep learning algorithms, as tools for handling Big Data. The paper also explains the potential for deep learning application in smart grids.

  • 27.
    Bagheri, Azam
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Gu, Irene Y.H.
    Chalmers University of Technology.
    Improved characterization of multi-stage voltage dips based on the space phasor model2018Inngår i: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 154, s. 319-328Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper proposes a method for characterizing voltage dips based on the space phasor model of the three phase-to-neutral voltages, instead of the individual voltages. This has several advantages. Using a K-means clustering algorithm, a multi-stage dip is separated into its individual event segments directly instead of first detecting the transition segments. The logistic regression algorithm fits the best single-segment characteristics to every individual segment, instead of extreme values being used for this, as in earlier methods. The method is validated by applying it to synthetic and measured dips. It can be generalized for application to both single- and multi-stage dips.

  • 28.
    Bagheri, Azam
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Gu, Irene Y.H.
    Department of Electrical Engineering, Chalmers University of Technology.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Balouji, Ebrahim
    Department of Electrical Engineering, Chalmers University of Technology.
    A Robust Transform-Domain Deep Convolutional Network for Voltage Dip Classification2018Inngår i: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 33, nr 6, s. 2794-2802Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper proposes a novel method for voltage dip classification using deep convolutional neural networks. The main contributions of this paper include: (a) to propose a new effective deep convolutional neural network architecture for automatically learning voltage dip features, rather than extracting hand-crafted features; (b) to employ the deep learning in an effective two-dimensional transform domain, under space-phasor model (SPM), for efficient learning of dip features; (c) to characterize voltage dips by two-dimensional SPM-based deep learning, which leads to voltage dip features independent of the duration and sampling frequency of dip recordings; (d) to develop robust automatically-extracted features that are insensitive to training and test datasets measured from different countries/regions.

    Experiments were conducted on datasets containing about 6000 measured voltage dips spread over seven classes measured from several different countries. Results have shown good performance of the proposed method: average classification rate is about 97% and false alarm rate is about 0.50%. The test results from the proposed method are compared with the results from two existing dip classification methods. The proposed method is shown to out-perform these existing methods.

  • 29.
    Bahramirad, S
    et al.
    ComEd, Chicago.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Khodaei, A
    University of Denver, Colorado.
    Smart distribution applications – some contributions to P18542014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Rapid and wide-spread deployment of newtechnologies in the electric power distribution network under theconcept of smart grids has resulted in a growing need to newstandards and guidelines specifically designed to addressemerging technological challenges and further streamline the useof new technology. This document is prepared as part of theactivities to develop the IEEE Power and Energy Society’s“smart distribution application guide”, to give guidance toutilities and network operators in the use of new technology inelectric power distribution. The document will provide adescription of the available new technology based on itsapplication, followed by a more detailed description of thetechnologies and associated supporting solutions. The topicsdiscussed in this document include improving the reliability ofsupply, improving the power quality, improving the efficiency ofdistribution-system operation, increasing hosting capacity fornew production or for new consumption, and allowing marketfunctioning and participation of all network users. This papercontains some examples of texts as they are currently beingdiscussed within the smart distribution working group

  • 30.
    Bahramirad, Shay
    et al.
    ComEd, Chicago.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Khodaei, Amin
    University of Denver, Colorado.
    Clark, George Larry
    Alabama Power.
    Svachula, Jospeh
    ComEd, Chicago.
    Simard, Georges
    SIMARD SG Inc..
    Smart Distribution Application Guide – IEEE Project P18542014Konferansepaper (Fagfellevurdert)
  • 31.
    Balouji, Ebrahim
    et al.
    Department of Electrical Engineering, Chalmers University of Technology.
    Gu, Irene Y.H.
    Department of Electrical Engineering, Chalmers University of Technology.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bagheri, Azam
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Nazari, Mahmood
    Department of Electrical Engineering, Chalmers University of Technology.
    A LSTM-based deep learning method with application to voltage dip classification2018Inngår i: Proceedings of International Conference on Harmonics and Quality of Power, ICHQP, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, a deep learning (DL)-based method for automatic feature extraction and classification of voltage dips is proposed. The method consists of a dedicated architecture of Long Short-Term Memory (LSTM), which is a special type of Recurrent Neural Networks (RNNs). A total of 5982 three-phase one-cycle voltage dip RMS sequences, measured from several countries, has been used in our experiments. Our results have shown that the proposed method is able to classify the voltage dips from learned features in LSTM, with 93.40% classification accuracy on the test data set. The developed architecture is shown to be novel for feature learning and classification of voltage dips. Different from the conventional machine learning methods, the proposed method is able to learn dip features without requiring transition-event segmentation, selecting thresholds, and using expert rules or human expert knowledge, when a large amount of measurement data is available. This opens a new possibility of exploiting deep learning technology for power quality data analytics and classification.

  • 32.
    Barakou, Fani
    et al.
    Eindhoven University of Technology, The Netherlands.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Mousavi-Gargari, S.
    TenneT TSO B.V, The Netherlands.
    Lennerhag, Oscar
    STRI AB, Sweden.
    Wouters, Peter A A F
    Eindhoven University of Technology, The Netherlands.
    Steennis, E. Fred
    Eindhoven University of Technology, The Netherlands.
    Impact of Load Modeling on the Harmonic Impedance seen from the Transmission Network2016Inngår i: 17th International Conference on Harmonics and Quality of Power, Piscataway, NJ, 2016, s. 283-288, artikkel-id 7783466Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Traditionally when studying harmonics at transmis-sion system level the medium and low voltage grid is modeledwith either an equivalent short-circuit impedance or a fixed PQload (based on the powerflow) directly at the secondary side ofthe transmission transformer. However the recent replacement ofconventional loads with electronic loads as well as the extendeduse of power electronics in LV level will result in reductionof damping and increase of household capacitance which maychange the harmonic impedance seen from the upstream network(MV or HV) both in the dominant frequency and magnitude.In this paper a HV feeder is modeled in detail starting fromthe transmission transformer up to the household equipmentto investigate whether changes in the type of load affect theimpedance seen from the HV. The simulations are performedusing software package PSCAD/EMTDC.

  • 33.
    Barakou, Fani
    et al.
    Eindhoven University of Technology.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Mousavi-Gargari, S.
    TenneT TSO BV, Arnhem.
    Wouters, P.A.A.F.
    Eindhoven University of Technology.
    Steenis, E.F.
    Eindhoven University of Technology.
    Downstream network modeling for switching transients in EHV networks containing cables2017Inngår i: IEEE PES PowerTech Manchester 2017: towards and beyond sustainable energy systems, 2017, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, artikkel-id 7980800Konferansepaper (Fagfellevurdert)
    Abstract [en]

    For the study of switching transients in Extra High Voltage (EHV) networks it is common practice to model a relatively small part of the EHV network. The downstream network is either disregarded or modeled as a parallel RC or RL circuit, based on the powerflow, directly at the secondary side of the transmission transformer. In this paper an investigation for the extent and model type of the downstream network (below 380 kV) is performed. A detailed model for an example downstream network is developed. Different simplifications and equivalent models are compared in frequency domain and in time domain, during cable energization. The impact of the lower voltage network on both the maximum overvoltage and the harmonic content during energization is assessed. Moreover, components that are of major importance are identified and proper equivalent models for the downstream network are proposed. Simulation results show that in particular the type of the 150 kV network (underground cable or overhead line) affects greatly both the maximum overvoltage and the harmonic content during energization. On the other hand, the parameters of end customer loads have only minor effect.

  • 34.
    Basu, Supratim
    et al.
    Bose Research (P) Ltd., Bangalore.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    A novel common power factor correction scheme for homes and offices2005Inngår i: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 20, nr 3, s. 2257-2263Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper explores the approach of having a common Power Factor Correction circuit for domestic and commercial loads. This leads to lower harmonic distortion without the need to install (expensive) active rectifiers in each end-user device. The need for power-factor correction as well as a number of design options is discussed in this paper. The design and cost estimation of a common Power Factor Correction scheme and some reliability issues are discussed

  • 35.
    Beek, Jaap van de
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Larsson, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Eriksson, Mats
    Arctos Labs Scandinavia AB.
    Can Solar Power Help Providing Broadband Cellular Coverage in Extreme-Rural Sweden?2016Rapport (Annet vitenskapelig)
  • 36.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    CIGRE/CIRED/UIE Joint Working Group C4.110, voltage dip immunity of equipment in installations: main contributions2010Konferansepaper (Fagfellevurdert)
  • 37.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Consumer electronics and the power grid: what are they doing to each other?2013Inngår i: Proceedings 2013 IEEE third International Conference on Consumer Electronics - Berlin (ICCE-Berlin) / [ed] Petra Friedrich, Piscataway, NJ: IEEE Communications Society, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Consumer electronic devices mostly get their energy from the electric power grid. Such devices might be continuously connected to the grid (like televisions) or only connected to charge the batteries (like cell phones). The amount of energy taken from the grid is not reduced by using devices powered by batteries. Instead, the electrical energy consumption is more likely increased due to the losses in the conversion process and because there are more opportunities to use the device.

  • 38.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Impacts of small units for electricity generation2005Inngår i: First International Conference on Lifestyle, Health and Technology: June 1-3, 2005 at Luleå University of Technology, Porsön, Luleå, Sweden, Luleå: Luleå tekniska universitet, 2005Konferansepaper (Fagfellevurdert)
  • 39.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Is there a place for power quality in the smart grid?2014Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper contains some thoughts on the relations between power quality and smart grids. It includes some of the, in our opinion, important research and development activities that are needed within power quality as part of the transition to the smart grid.

  • 40.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Overvoltages due to wind power: hosting capacity, deterministic and statistical approaches2008Inngår i: Electrical Power Quality and Utilization, ISSN 1234-6799, Vol. 3, nr 2, s. 2-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper introduces methods to quantify the impact of wind power and other types of distributed generation on the overvoltage risk. The so-called hosting capacity approach, introduced in the very first issue of this magazine, is used as the basic approach. Both a deterministic and a statistical approach are introduced. The deterministic approach is suitable for generation with a constant production most of the time. However, it is shown that a deterministic approach could easily result in an unnecessary barrier against the introduction of wind power. For any method used to determine the hosting capacity, a serious discussion is needed about overvoltage indices and objectives.

  • 41.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    The smart grid: Adapting the power system to new challenges2011Bok (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    This book links the challenges to which the electricity network is exposed with the range of new technology, methodologies and market mechanisms known under the name "smart grid." The main challenges will be described by the way in which they impact the electricity network: the introduction of renewable electricity production, energy efficiency, the introduction and further opening of the electricity market, increasing demands for reliability and voltage quality, and the growing need for more transport capacity in the grid. Three fundamentally different types of solutions are distinguished in this book: solutions only involving the electricity network (like HVDC and active distribution networks), solutions including the network users but under the control of the network operator (like requirements on production units and curtailment), and fully market-driven solutions (like demand response). An overview is given of the various solutions to the challenges that are possible with new technology; this includes some that are actively discussed elsewhere and others that are somewhat forgotten.Linking the different solutions with the needs of the electricity network, in the light of the various challenges, is a recurring theme in this book.

  • 42.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Voltage dip immunity of equipment and installations2010Inngår i: Electra, ISSN 0212-6222, nr 249, s. 51-56Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This document covers methods to improve the voltage-dip immunity of installations, starting from a detailed description of voltage dips, an overview of the knowledge on equipment immunity, and global voltage-dip statistics. The economics of voltage-dip immunity are discussed. Recommendations for immunity testing are given. A systematic method for designing and improving the immunity of an industrial process is introduced.

  • 43.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Voltage sags2007Inngår i: Electric Power Engineering Handbook: 1. Electric power generation, transmission and distribution, Boca Raton: CRC Press, 2007, 2 edKapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
  • 44.
    Bollen, Math
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bahramirad, Shay
    ComEd, Chicago.
    Khodaei, Amin
    University of Denver, Colorado.
    Meyer, Jan
    Dresden University of Technology.
    Langella, Roberto
    Seconda Università di Napoli.
    Hasler, Jean-Philippe
    ABB Corporate Research.
    Zavoda, Francisc
    IREQ.
    Liu, Juncheng
    Xian Boyu Electrical Co.
    Volt-var control and power quality (CIGRE/CIRED C4.24)2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper summarizes the state of discussions in CIGRE/CIRED joined working group C4.24, concerning expected impacts on the power quality of future methods for volt-var-control in the distribution grid. The positive impacts include the reduction of the number of overvoltage and undervoltages and also a reduction of voltage unbalance, when some control schemes are applied. Potential negative impacts include an increased number of short-duration undervoltages, rapid voltage changes, flicker, and voltage transients; a higher risk of harmonic resonances; and increased emission of supraharmonics. All these potential impacts are discussed in the paper.

  • 45.
    Bollen, Math
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bengtsson, C
    Nielsen, L.H
    Larsen, P.H
    Mikkelsen, S.D
    Application of regulated shunt reactor for off-shore wind farms2007Konferansepaper (Fagfellevurdert)
  • 46.
    Bollen, Math
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Beyer, Y
    Styvactakis, E
    Trhulj, J
    Vailati, R
    Friedl, W
    A European benchmarkning of voltage quality regulation2012Inngår i: 15th International Conference on Harmonics and Quality of Power (ICHQP), IEEE Communications Society, 2012, s. 45-52Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Council of European Energy Regulators has been publishing Benchmarking Reports on the Quality of Electricity Supply since 2001. For the 2011 edition of the Benchmarking Report the 29 member countries of CEER were joined by the 9 NRA's from the Energy Community and the NRA from Switzerland. This paper contains the main results, findings and recommendations on voltage quality from the 2011 edition.

  • 47.
    Bollen, Math
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Castel, Romain
    CRE.
    Friedl, Werner
    E-Control.
    Villa, Ferruccio
    AEEG.
    Baumann, Philippe
    Elcom.
    Esteves, Jorge
    ERSE.
    Larzeni, Samuele
    AEEG.
    Ström, Lars
    EI.
    Beyer, Yvonne
    NMA.
    Faias, Sergio
    ERSE.
    Trhulj, Jasmina
    AERS.
    Guidelines for good practice on voltage quality monitoring2013Inngår i: 22nd International Conference and Exhibition on Electricity Distribution (CIRED 2013): Stockholm, Sweden, 10 - 13 June 2013, Red Hook, NY: Curran Associates, Inc., 2013, artikkel-id 349Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Guidelines are given for setting up and running a voltage quality monitoring programme. These guidelines are published jointly by CEER and ECRB and contain among others recommendations on the number and location of monitors, on disturbances to be monitored and indices to be calculated, on reporting of the results and on financing of the programme. It is concluded that voltage quality monitoring programs are important tools for voltage quality regulation and that all other possible applications should be kept in mind when setting up such a programme. It is also concluded that such programmes should be funded through the network tariffs; that the results should be made available regularly and that diversification of indices and methods is to be avoided.

  • 48. Bollen, Math
    et al.
    Chen, Y
    Etherden, Nicholas
    STRI AB.
    Risk analysis of alternatives to N-1 reserves in the network2013Inngår i: 22nd International Conference and Exhibition on Electricity Distribution (CIRED 2013): Stockholm, Sweden, 10 - 13 June 2013, Red Hook, NY: Curran Associates, Inc., 2013, artikkel-id 280Konferansepaper (Fagfellevurdert)
  • 49.
    Bollen, Math
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Cundeva, S
    Etherden, Nicholas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Yang, Kai
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Considering the needs of the customer in the electricity network of the future2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The main purpose of the electric power system and the electricity network (power grid) is to supply electrical energy to the consumers. The interest of those consumers is in the price of electricity and in the performance of the delivery of the electrical energy. For the electricity producers, the aim of the grid is to enable the transport of electricity from them to the consumers. Also for the producers the importance is in costs and performance. Performance of the grid is typically divided into two parts: continuity of supply and voltage quality.The appearance of the smart grid, introduced as the use of new technology, methodology or market principles, to address new challenges, impacts continuity of supply and voltage quality. Such challenges include new types of production, new types of consumption, and electricity markets, but also increasing demands by customers on continuity of supply and voltage quality.This paper discusses a number of examples of new thinking for addressing the challenges that the power system has to cope with.An alternative approach for overload protection of subtransmission grids will be proposed, where the “smartness” is in the fact that the overload protection does not remove the overloaded component but the cause of the overload. Upon detection of an overload, the protection disconnects part or whole of curtailable customers to reduce the current through the lines to a level below the overload limit. As a result subtransmission lines can be operated without any reserve, so that more customers can be connected for the same costs while at the same time the continuity of supply for the non-curtailable customers is not impacted.The limits set to the hosting capacity by the risk of overvoltages due to distributed generation can be removed either by new technology (curtailment of production) or by allowing occasional overvoltages. An example will be provided to show the probability of an overvoltage occurring with a low-voltage customer when increasing amounts of wind power are connected to a medium-voltage feeder.An example of the measured emission from wind turbines will be presented. Allowing higher levels of non-characteristic harmonics is a possible alternative for strict emission limits on new installations.The provided examples of the use of new technology and/or new ways of thinking are part of the transition to the smart grid. Such new thinking in combination with new technology will be an important element in the transition to the future electricity network i.e. the “smart grid”. With any design or operation issue of the power system it remains important to always keep the main aims of the power system in mind: to maintain acceptable continuity of supply and voltage quality for all network users at a reasonable price.

  • 50.
    Bollen, Math
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Cundeva, S
    University Sts. Cyrill and Methodias, Skopje.
    Gordon, J.M R
    Djokic, S. Z
    University of Edinburgh.
    Stockman, K
    Ghent University.
    Milanovic, J. V
    University of Manchester.
    Neumann, R
    Qualitrol, Belfast.
    Ethier, G
    Hydro-Québec Research’s Institute.
    Voltage dip immunity aspects of power-electronics equipment: Recommendations from CIGRE/CIRED/UIE JWG C4.1102011Inngår i: 2010 14th International Power Electronics and Motion Control Conference (EPE/PEMC 2010): Ohrid, Macedonia, 6 - 8 September 2010, Piscataway, NJ: IEEE Communications Society, 2011, s. 803-810Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents some of the results from an international working group on voltage-dip immunity. The working group has made a number of recommendations to reduce the adverse impact of voltage dips. Specific recommendations to researchers and manufacturers of powerelectronic equipment are: considering all voltage dip characteristics early in the design of equipment; characterize performance of equipment by means of voltage-dip immunity curves; and made equipment with different immunity available

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