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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 range2016Ingår i: 2016 17th International Conference on Harmonics and Quality of Power, Piscataway. NJ, 2016, s. 685-690, artikel-id 7783471Konferensbidrag (Refereegranskat)
    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.
    Busatto, Tatiano
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    On the Interaction Between Efficient Light Bulbs and Photovoltaic Systems in Low-Voltage Networks2018Rapport (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Thanks to the continuous technological development, from time-to-time, new devices emerge in the market to improve our daily life in several ways. Two of these technologies are addressed in this work, in the power quality context on consumption and generation, and in their integration with the electric power system.

    The first refers to the energy efficient lamps, which are massively represented by the LED lamps, found in almost every household, industry or commercial installation.The second is about photovoltaic (PV) power generation, which is less in numbers compared to the first, but still presents a continuous growing in popularity and already a substantial amount in terms of installed capacity. Both technologies have benefits to the environment. LED lamps are more efficient compared to earlier technologies, helping to reduce the global power consumption. PV generation allows producing electricity from an environment friendly source.

    Research and development result in continuous improvements in both technologies. Also, phenomena related to compatibility with grid and performance for individual devices are reasonably well understood.However, there is no such general understanding on the electrical interactions between these two devices (i.e between LED lamps and PV inverters). For instance, it is still not clear how the control from both LED lamps and PV inverters are affected under parallel operation, or how the performance and lifetime changes due the mutual impact the devices have on each other.

    This half-way report addresses a number of issue related to the electrical interactions between PV generation and LED lamps in low-voltage networks; specifically with respect to harmonics and supraharmonics.

    Power quality analysis has been performed in the time and frequency-domain covering different frequencies ranges. Investigation methodology includes the use of simulation and measurements in realistic scenarios, in a controllable laboratory environment. For this, a set of LED lamps and PV Inverters currently found in the market are used to characterize the operation of the devices in terms of current emission and equivalent impedance.

    For the LED lamps, primary current emission is evaluated and correlated with the different circuit topologies. The impedance characterization is performed by invasive measurement methods described in the literature, in combination with a proposed method for estimation of the internal capacitances. For the latter, a non-invasive capacitance measurement is presented, followed by experimental measurements. Some of the results show that the equivalent input capacitances of LED lamps are a few tens of nF. Furthermore, from the circuit analysis, some of the most common topologies in terms of EMI filters topologies, and AC/DC converters are revealed.

    Regarding PV inverters, simulations for different topologies and modulation strategies are performed under external influence from the source supply. Characterization of the grid variations and its impact on inverters is performed through quantification of harmonics and supraharmonics.Some of the results have revealed the low-order harmonics sensitivity when the source supply is not purely sinusoidal, besides dependence of the supraharmonic emissions on the inverter topology. Additionally, the study includes a set of PV inverters impedance measurements in order to understand the common association with the rest of the system.

    As a third part, the influence of the low-voltage network impedance is examined. From simulation of real networks, the network impedance is analyzed and of the results are discussed with respect to resonances for harmonic propagation and stability of power converters. A method was developed to determine the harmonic impedances in low-voltage networks in a stochastic way by using Monte Carlo simulation with the customer impedance as the random variable. The method is applied to two existing low-voltage networks in Sweden. Results show the variation of resonant frequencies as a function of the PV penetration, besides the uncertainties in network impedance for the individual customer connections.

    Finally, preliminary results from a study case to investigate the interaction between PV inverters and LED lamps is presented. Emission and propagation of power quality disturbances for different equipment combinations and operating conditions are analyzed and results discussed. Results have revealed the harmonic interdependency and its consequences for the total harmonic distortion, next to interactions in the supraharmonic range. This work presents several findings and a comprehensive discussion serving as a guideline for future work on interaction analysis and its consequences for devices in the low-voltage network.

  • 3.
    Busatto, Tatiano
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Abid, Fahim
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Larsson, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Singh, Gaurav
    Department of Electrical and Computer Engineering, Clemson University.
    Interaction between Grid-Connected PV systems and LED Lamps: Directions for Further Research on Harmonics and Supraharmonics2016Ingår i: 2016 17th International Conference on Harmonics and Quality of Power, Piscataway, NJ, 2016, s. 193-197, artikel-id 7783479Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper discusses different approaches to investigate the interaction through harmonics, interharmonics, supraharmonics, and light flicker, between photovoltaic (PV) inverters and LED lamps in low-voltage installations. Single grid-connected power generators and electronic loads like LED lamps can be easily characterized in terms of harmonics in a given range of frequency. This subject is relatively well understood, and specific standards for measuring and restricting emissions are already established to ensure a low probability of interference. However, when connected together, source and load exhibit behavior that requires further study and understanding. This work presents a discussion serving as a guide for future work on analysis of losses and other impacts of the disturbances regarding this specific load and source interaction. The following are taken into account: the nonlinearity of LED loads and PV converters; the technologies and methods used in control; and the changes in power flow caused by load and power production variations

  • 4.
    Busatto, Tatiano
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Larsson, Anders
    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.
    Including Uncertainties from Customer Connections in Calculating Low-Voltage Harmonic Impedance2019Ingår i: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 34, nr 2, s. 606-615Artikel i tidskrift (Refereegranskat)
    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.

  • 5.
    Busatto, Tatiano
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Larsson, Anders
    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.
    Supraharmonics Emission Assessment of Multi-level Converters Applied for Photovoltaic Grid-Connected Inverters2017Ingår i: The Renewable Energies and Power Quality Journal (RE&PQJ), ISSN 2172-038X, E-ISSN 2172-038X, Vol. 1, nr 15, s. 143-148, artikel-id 252Artikel i tidskrift (Refereegranskat)
  • 6.
    Busatto, Tatiano
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Ravindran, Vineetha
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Larsson, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Estimation of the Consumer Electronics Capacitance for Harmonic Resonance Studies by a Non-Invasive Measurement Method2018Ingår i: Proceedings of International Conference on Harmonics and Quality of Power, ICHQP, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2018, , s. 6Konferensbidrag (Refereegranskat)
    Abstract [en]

    Harmonic resonances in distribution systems are mainly between network inductances and shunt capacitances from capacitor banks and consumer loads. In this paper, particular attention is devoted to the evaluation of capacitances from domestic equipment, serving as a reference for resonance frequency studies. The assessment is performed by simulation and measurements of common low power electronic loads. From the analysis of EMI filters topologies used in AC/DC converters, a non-invasive capacitance measurement estimation method is presented. The method is verified after correlating capacitances with the resonance frequencies obtained from a frequency sweep method. From experimental measurements, the results show that the equivalent shunt capacitances for a set of 24 LED lamps are between 10 and 135 nF.

  • 7.
    Busatto, Tatiano
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Ravindran, Vineetha
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Larsson, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Measurements on an experimental laboratory setup with PV Inverters and a Large Number of LED Lamps2018Rapport (Övrig (populärvetenskap, debatt, mm))
  • 8.
    Busatto, Tatiano
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Ravindran, Vineetha
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Larsson, Anders
    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.
    Meyer, Jan
    Electric Power Engineering, Technische Universität Dresden.
    Deviations between the commonly-used model and measurements of harmonic distortion in low-voltage installations2020Ingår i: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 180, artikel-id 106166Artikel i tidskrift (Refereegranskat)
    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.

  • 9.
    Busatto, Tatiano
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Ravindran, Vineetha
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Larsson, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Jan, Meyer
    Technische Universität Dresden.
    Experimental Harmonic Analysis of the Impact of LED Lamps on PV Inverters Performance2019Ingår i: 11th Internation Conference on Electric Power Quality and Supply Reliability, Estonia, June 12-15, 2019., 2019Konferensbidrag (Refereegranskat)
    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

  • 10.
    Ravindran, Vineetha
    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.
    Comparison of a non-parametric and parametric method for interharmonic estimation in PV systems2019Konferensbidrag (Refereegranskat)
    Abstract [en]

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

  • 11.
    Ravindran, Vineetha
    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.
    Meyer, Jan
    Technische Universität, Dresden, Germany.
    Charactizations of interactions between PV and Energy efficient lighting (LED) in a mixed installation.2019Konferensbidrag (Refereegranskat)
    Abstract [en]

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

  • 12.
    Ravindran, Vineetha
    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.
    Meyer, Jan
    Institute of Electrical Power Systems and High Voltage Engineering, Technische Universitaet Dresden, Dresden, Germany.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Time-varying interharmonics in different types of grid-tied PV inverter systems2019Ingår i: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 13.
    Ravindran, Vineetha
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Busatto, Tatiano
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Inspection of Interharmonic emissions from a Grid-tied PV Inverter in North Sweden2018Ingår i: Proceedings of International Conference on Harmonics and Quality of Power, ICHQP, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

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

  • 14.
    Schwanz, Daphne
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Busatto, Tatiano
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Larsson, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    A stochastic study of harmonic voltage distortion considering single-phase photovoltaic inverters2018Ingår i: Proceedings of International Conference on Harmonics and Quality of Power, ICHQP, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, the hosting capacity considering harmonic distortion is estimated for single-phase-connected photovoltaic inverters (PVIs) in low-voltage distribution networks. A stochastic approach is used to calculate the harmonic voltage distortion with each customer in the network. The method has been applied to a 6-customer network for the connection of 2.5-kW single-phase PVIs with and without harmonic voltage background. From the results, it was observed that the contribution from 2.5 kW single-phase photovoltaic inverters to the individual harmonic distortion will not cause the established limits to be exceeded. Also, that the harmonic voltage background is often dominating and should be continuously observed.

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