| 1. |
- Gutiérrez Ballesteros, Elena, et al.
(författare)
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Temperature and voltage distortion analysis in LED lamps
- 2019
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Ingår i: CIRED 2019 Proceedings. - : AIM.
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Konferensbidrag (refereegranskat)abstract
- Measurements in electrical and thermal parameters of LED lamps over time have been studied. To get comparable results between lamps, for compliance testing and benchmarking, measurements after stabilization are recommended. Two cases have been tested in the lab: stabilization with sinusoidal voltage waveform and stabilization with distorted voltage waveform both with and without external cooling of the lamp, giving four tests for each LED lamp.The parameters tested were illuminance, active power and temperature of the LED lamps. Based on the results for voltage variations, no significant difference of the parameters studied have been observed. On the other hand, according to the results about environmental thermal variations (emulated using forced ventilation) it is concluded that the illuminance increases with low temperatures, and in addition, in greater percentage than the active power consumed, since the low temperatures would decrease the temperatures of thermal stabilization of LED lamps.
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| 2. |
- Ravindran, Vineetha, 1987-, et al.
(författare)
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Characterization of the impact of PV and EV induced voltage variations on LED lamps in a low voltage installation
- 2020
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Ingår i: Electric power systems research. - : Elsevier. - 0378-7796 .- 1873-2046. ; 185
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Tidskriftsartikel (refereegranskat)abstract
- Photovoltaic (PV) systems, Electric vehicles (EV) and LED lamps have gained significant popularity in our current society. It is therefore common to find customer installations with all three operating together. PV and EV are known sources of voltage variations on the grid. The impact of these voltage variations on LED lamps situated in close proximity to PV or EV in a low voltage installation, in terms of overvoltage, undervoltage, and rapid voltage changes is systematically studied in a laboratory environment in this paper. Such variations can cause malfunctioning of the lamp based on its immunity and tolerance level or be disturbing to the end-user based on the intensity of variations and rate of recurrence of being subjected to such variations. In this work, the observed impacts on LED lamps are illustrated as 15 different cases. The scope of this work is to identify the possible impacts due to voltage variations induced by PV and EV systems on LED lamps and the potential problems that could happen long term due to recurrent subjection of such voltage variations.
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| 3. |
- Sakar, Selcuk, et al.
(författare)
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Immunity Test of LED Lamps Based on IEC 61000-4-19 and Unexpected Consequence
- 2018
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Ingår i: Proceedings of International Conference on Harmonics and Quality of Power, ICHQP. - Piscataway, NJ : Institute of Electrical and Electronics Engineers (IEEE). - 9781538605172
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Konferensbidrag (refereegranskat)abstract
- ED lighting technology is the most efficient way oflighting service and its usage has increased rapidly. Although,LED lamps are potential victim and source of electromagneticinterference in the frequency range between 2 kHz and 150 kHz(“supraharmonics”). Therefore, immunity test for this frequencyrange is necessary to analyze its performance variations. In thisstudy, Test profiles described in IEC 61000-4-19 have beenapplied to LED lamps and the results have been analyzedaccording to implemented algorithm that uses the relative lightintensity variation index. The results show that bothsupraharmonics and modulation of the test profiles can reveallight flicker. In addition, some potential drawbacks of thestandard have been found that deviation of the mains’ frequencyis also another factor causes intermodulation/nonsynchronizationon the applied test signal, so this can be seen aslight flicker. This issue better be clarified with more details in theIEC 61000-4-19, particalulary for lighting equipment.
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| 4. |
- Sakar, Selcuk, et al.
(författare)
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Increasing PV hosting capacity in distorted distribution systems using passive harmonic filtering
- 2017
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Ingår i: Electric power systems research. - : Elsevier. - 0378-7796 .- 1873-2046. ; 148, s. 74-86
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Tidskriftsartikel (refereegranskat)abstract
- Adding new capacity expansion alternatives using distributed generation (DG) technologies, particularly penetration of renewable energy, has several economical, and technical advantages such as the reduced system costs, the improved voltage profile, lower line loss and enhanced system’s reliability. However, the DG units may lead to power quality, energy efficiency, and protection problems in the system when their penetration exceeds a particular value, generally called as the system’s hosting capacity (HC) in the literature. In this paper, the HC determination of a distorted distribution system with Photovoltaic (PV)-based DG units is handled as an optimization problem by considering over and under voltage limitations of buses, current carrying capabilities of the lines, and harmonic distortion limitations as constraints. It is seen from simulation results that the HC is dramatically decreased with the increment of the load’s nonlinearity level and the utility side’s background voltage distortion. Accordingly, a C-type passive filter is designed to maximize the harmonic-constrained HC of the studied system while satisfying the constraints. The results indicate that higher HC level can be achieved using the proposed filter design approach compared to three conventional filter design approaches as voltage total harmonic distortion minimization, line loss minimization and power factor maximization.
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| 5. |
- Sakar, Selcuk, et al.
(författare)
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Integration of large- scale PV plants in non-sinusoidal environments : Considerations on hosting capacity and harmonic distortion limits
- 2018
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 82:1, s. 176-186
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Tidskriftsartikel (refereegranskat)abstract
- Distributed generation (DG) penetration in a system may affect power quality, and energy efficiency, if it exceeds a particular value, known as the system's hosting capacity (HC). In this work, a comprehensive overview of hosting capacity and harmonic distortion limits is presented and discussed. The highest allowable penetration level of photovoltaic (PV)-based distributed generation units, hosted on typical industrial distribution systems, was analyzed in terms of the three power quality and energy efficiency performance parameters, namely bus voltage limits, line ampacities, and harmonic distortion limits. The analytical results show that the system's HC decreases with increase in utility side's background voltage distortion and load side's nonlinearity values. The HC level was affected more by the nonlinearity of the load side than by the utility side's background voltage distortion. Therefore, a single-tuned passive filter is suggested for maximizing the system's limited HC. Further, an optimization algorithm was developed to find simultaneously the system's HC and the parameters of the proposed filter, by considering the three performance parameters as constraints. The proposed filter design was found to attain a better level of HC than what can be obtained with a traditional filter design, based on current demand distortion minimization.
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| 6. |
- Sakar, Selcuk, et al.
(författare)
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Interferences in AC-DC LED Drivers Exposed to Voltage Disturbances in the Frequency Range 2 kHz - 150 kHz
- 2019
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Ingår i: IEEE transactions on power electronics. - : IEEE. - 0885-8993 .- 1941-0107. ; 34:11, s. 11171-11181
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Tidskriftsartikel (refereegranskat)abstract
- LED lamps are both potential victims and sources of electromagnetic disturbances in the frequency range between 2 kHz and 150 kHz (“supraharmonics”). Immunity tests for this frequency range are important due to possible performance degradation of light intensity with LED lamps. In this paper, the impact of supraharmonics (SHs) on light intensity from LED lamps has been analyzed. LED lamps have been exposed to supraharmonic test profiles based on IEC 61000-4-19. Three phenomena that impact light intensity metrics have been observed and explained by models: (1) earlier conduction/later blocking caused by supraharmonic voltage, (2) intermittent conduction depending on the supraharmonic impedance of the LED driver and (3) reverse-recovery current of the diodes at higher frequency. It is observed that impact on the light intensity metrics shows up around the beginning and end of the conduction period. The results reveal that the profile of the supraharmonic voltage could cause deviations in the modulation depth and the average light intensity. The immunity of LED lamps against SHs shall be further studied and discussed by research groups and standard committees.
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| 7. |
- Sakar, Selcuk, et al.
(författare)
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Interharmonic Emission in AC–DC Converters Exposed to Nonsynchronized High-Frequency Voltage Above 2 kHz
- 2021
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Ingår i: IEEE transactions on power electronics. - : IEEE. - 0885-8993 .- 1941-0107. ; 36:7, s. 7705-7715
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Tidskriftsartikel (refereegranskat)abstract
- More and more devices connected to low voltage networks inject currents in the frequency range above 2 kHz up to 150 kHz, so called supraharmonics. Supraharmonics can appear as synchronized or nonsynchronized to the power system frequency. A device exposed to a fixed supraharmonic frequency are here shown to generate interharmonics when the power system frequency deviates from the ideal 50/60 Hz. Resulting interharmonic frequency and magnitude are determined by three factors, the frequency at which a supraharmonic component exist, the voltage magnitude of that component, and the deviation from 50/60 Hz of the power system frequency. Formation of interharmonics is confirmed in a functional model and validated through the measurements and numerical simulations.
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| 8. |
- Sakar, Selcuk, et al.
(författare)
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Light Intensity Behavior of LED Lamps within theThermal Stabilization Period
- 2018
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Ingår i: Proceedings of International Conference on Harmonics and Quality of Power, ICHQP. - Piscataway, NJ : Institute of Electrical and Electronics Engineers (IEEE). - 9781538605172
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Konferensbidrag (refereegranskat)abstract
- Visible changes in the light intensity of lamps, referredto as flicker, are quantified based on definitions such asnormalized gain factor and relative light intensity variation.However, those values also change depending on the time after anLED lamp has been switched on. An experiment has been carriedout to analyze this phenomenon. A new metric, a “thermalstabilization time”, has been proposed to identify the time toreach steady state light intensity. Although rare, the change inlight intensity can reach up to 68% during the thermalstabilization time. Consequently, acquiring data at differentintervals can lead to incorrect estimation of critical metrics.Stabilization is an essential factor that should be taken intoconsideration in LED lamps’ measurement. It is recommended bythe authors that 60-minute operation is required before acquiring data.
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| 9. |
- Sakar, Selcuk, et al.
(författare)
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Light intensity immunity performance of LED street lamps under power quality disturbances
- 2019
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Ingår i: CIRED 2019 Proceedinga. - : AIM.
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Konferensbidrag (refereegranskat)abstract
- An increasing application of LED street lamps brings out an important question regarding their immunity against power quality disturbances. The behaviour of commonly used lighting equipment such as incandescent lamps, compact fluorescent lamps (CFL), and gas-discharge lamps is known. However, knowledge on immunity of LED based lighting equipment is still limited, particularly in street lighting aspect. In this paper, immunity of LED street lamps is determined for voltage dips, short interruptions, voltage fluctuations and supraharmonics. A series of experiments has been performed with respect to test levels defined in IEC 61000-4-11, IEC 61000-4-15 and IEC 61000-4-19. Voltage dips and short interruptions cause higher short-term light flicker severity values that might lead to unintended consequences for car drivers and pedestrians. Interharmonics can result in light flicker, but the impact is very limited, only one lamp exceeds the limits. Supraharmonics impact the current but have minor impact on the visible light. The supraharmonic current can be 25 times nominal. This could decrease the lifetime of equipment
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| 10. |
- Sakar, Selcuk, et al.
(författare)
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Modelling and Analysis of DC-link Capacitors Subjected to High Frequency Conducted Disturbances in Electronic Equipment
- 2022
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Ingår i: IEEE transactions on power electronics. - : IEEE. - 0885-8993 .- 1941-0107. ; 37:5, s. 5949-5956
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Tidskriftsartikel (refereegranskat)abstract
- Occurrence of high frequency emission due to increasing use of power electronic based equipment challenges the functioning of equipment, e.g., malfunctions of equipment, audible noise or performance/lifetime degradation of dc-link capacitor. When subjected to a high frequency voltage distortion, an AC-DC converter draws intermittent current of the same frequency, this is referred to as 'intermittent conduction'. In this paper, a link between intermittent conduction and dc-link capacitor current has, for the first time, been constituted through a mathematical expression. Based on this, a model that can quantify the impacts on dc-link capacitor and calculate maximum allowed voltage in the frequency range of 2-150 kHz, so called 'supraharmonics' (SHs), has been proposed for avoiding degradations. Besides modelling, a testing technique is implemented where maximum allowed voltage can be identified for an equipment under test (EUT). The result shows that dc-link capacitor's stress can be managed under the SHs if maximum SH voltages are respected. The proposed model gives a better understanding of SH impacts on dc-link capacitor and the mechanisms behind. The study has been limited to equipment that draws input current lower than 16 A as they exhibit more non-linear characteristic and longer zero-crossing which results in intermittent conduction.
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