The Experts below are selected from a list of 2298 Experts worldwide ranked by ideXlab platform
Ranko Goic - One of the best experts on this subject based on the ideXlab platform.
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Lightning Overvoltage Protection of Step-Up Transformer Inside a Nacelle of Onshore New-Generation Wind Turbines
Energies, 2021Co-Authors: Petar Sarajcev, Antun Meglic, Ranko GoicAbstract:This paper presents an electromagnetic transient analysis of lightning-initiated Overvoltage stresses of the step-up transformers installed inside a nacelle of onshore, multi-megawatt, new-generation wind turbines. The increase in the wind turbine (WT) nominal power output, necessitated introducing the step-up transformer into the nacelle. A transformer installed inside a nacelle is subjected to completely different Overvoltage stresses from those present if it were installed at the base of the WT tower. This has serious repercussions on its Overvoltage Protection (i.e., selection and installation of surge arresters) and insulation coordination. Furthermore, the Overvoltage Protection of medium-voltage cables (inside the tower) is also problematic when considering their length, proximity to the tower wall, and their screen grounding practices, and needs to be tackled in conjunction with that of the step-up transformer. This paper presents detailed models for the various components of the latest-generation WTs, intended for fast-front transient analysis and assembled within the EMTP software package. We further present the comprehensive results of the lightning-transient numerical simulations, covering both upward and downward (first and subsequent) strikes, their analysis, and recommendations for the optimal selection of medium-voltage surge arresters for the step-up transformers installed inside a nacelle.
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Assessment of lightning current parameters suitable for wind turbine Overvoltage Protection analysis: Assessment of lightning current parameters for wind turbines
Wind Energy, 2011Co-Authors: Petar Sarajcev, Ranko GoicAbstract:A selection procedure for determining the lightning current parameters, suitable for wind turbine Overvoltage Protection analysis, will be presented in this paper. It will be based on the mathematical model that accounts for the wind turbine geometry, keraunic level, statistical distribution of lightning current parameters and correlation between statistical variables defining lightning current waveshape. Theoretical analysis will be backed up by the most recent propositions of parameters that define statistical distributions and thereafter applied on the concrete wind turbine example. Subsequently, obtained results would provide insight into the selection procedure for the lightning current parameters (i.e., amplitude, front duration, wave duration and polarity), associated with lightning stroke incidence to wind turbines. Emphases will be given to the modern new-generation wind turbines. This selection procedure could be subsequently applied in the analysis (and design) of the wind turbine and wind farm Overvoltage Protection, with emphasis on the so-called back-surge phenomenon. Copyright © 2011 John Wiley & Sons, Ltd.
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A review of current issues in state-of-art of wind farm Overvoltage Protection
Energies, 2011Co-Authors: Petar Sarajcev, Ranko GoicAbstract:This paper elaborates on several important outstanding issues in the state-of-art of Overvoltage Protection selection for modern wind farms. The lack of experience with this still-new technology, together with the inherent complexity of wind farm electrical systems, entails several unresolved issues pertinent to the topic of Overvoltage Protection, particularly in relation to lightning-initiated surges. Firstly, several aspects of the wind turbine lightning incidence, along with the issues related to the selection of lightning current parameters (pertinent to the wind farm Overvoltage Protection), are addressed in this paper. Secondly, several issues in the state-of-art models of the wind farm electrical systems—for the lightning surge analysis—are addressed and discussed. Here, a well-known ElectroMagnetic Transients Program (EMTP) software package is often employed, with all of its benefits and some limitations. Thirdly, the metal-oxide surge arrester energy capability and the issues related to the selection of the surge arrester rated energy—in relation to the direct lightning strikes to wind turbines—is addressed. Finally, some general considerations concerning the Overvoltage Protection selection for wind farm projects, particularly regarding the installation of the metal-oxide surge arresters, are provided as well.
Petar Sarajcev - One of the best experts on this subject based on the ideXlab platform.
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Lightning Overvoltage Protection of Step-Up Transformer Inside a Nacelle of Onshore New-Generation Wind Turbines
Energies, 2021Co-Authors: Petar Sarajcev, Antun Meglic, Ranko GoicAbstract:This paper presents an electromagnetic transient analysis of lightning-initiated Overvoltage stresses of the step-up transformers installed inside a nacelle of onshore, multi-megawatt, new-generation wind turbines. The increase in the wind turbine (WT) nominal power output, necessitated introducing the step-up transformer into the nacelle. A transformer installed inside a nacelle is subjected to completely different Overvoltage stresses from those present if it were installed at the base of the WT tower. This has serious repercussions on its Overvoltage Protection (i.e., selection and installation of surge arresters) and insulation coordination. Furthermore, the Overvoltage Protection of medium-voltage cables (inside the tower) is also problematic when considering their length, proximity to the tower wall, and their screen grounding practices, and needs to be tackled in conjunction with that of the step-up transformer. This paper presents detailed models for the various components of the latest-generation WTs, intended for fast-front transient analysis and assembled within the EMTP software package. We further present the comprehensive results of the lightning-transient numerical simulations, covering both upward and downward (first and subsequent) strikes, their analysis, and recommendations for the optimal selection of medium-voltage surge arresters for the step-up transformers installed inside a nacelle.
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Assessment of lightning current parameters suitable for wind turbine Overvoltage Protection analysis: Assessment of lightning current parameters for wind turbines
Wind Energy, 2011Co-Authors: Petar Sarajcev, Ranko GoicAbstract:A selection procedure for determining the lightning current parameters, suitable for wind turbine Overvoltage Protection analysis, will be presented in this paper. It will be based on the mathematical model that accounts for the wind turbine geometry, keraunic level, statistical distribution of lightning current parameters and correlation between statistical variables defining lightning current waveshape. Theoretical analysis will be backed up by the most recent propositions of parameters that define statistical distributions and thereafter applied on the concrete wind turbine example. Subsequently, obtained results would provide insight into the selection procedure for the lightning current parameters (i.e., amplitude, front duration, wave duration and polarity), associated with lightning stroke incidence to wind turbines. Emphases will be given to the modern new-generation wind turbines. This selection procedure could be subsequently applied in the analysis (and design) of the wind turbine and wind farm Overvoltage Protection, with emphasis on the so-called back-surge phenomenon. Copyright © 2011 John Wiley & Sons, Ltd.
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A review of current issues in state-of-art of wind farm Overvoltage Protection
Energies, 2011Co-Authors: Petar Sarajcev, Ranko GoicAbstract:This paper elaborates on several important outstanding issues in the state-of-art of Overvoltage Protection selection for modern wind farms. The lack of experience with this still-new technology, together with the inherent complexity of wind farm electrical systems, entails several unresolved issues pertinent to the topic of Overvoltage Protection, particularly in relation to lightning-initiated surges. Firstly, several aspects of the wind turbine lightning incidence, along with the issues related to the selection of lightning current parameters (pertinent to the wind farm Overvoltage Protection), are addressed in this paper. Secondly, several issues in the state-of-art models of the wind farm electrical systems—for the lightning surge analysis—are addressed and discussed. Here, a well-known ElectroMagnetic Transients Program (EMTP) software package is often employed, with all of its benefits and some limitations. Thirdly, the metal-oxide surge arrester energy capability and the issues related to the selection of the surge arrester rated energy—in relation to the direct lightning strikes to wind turbines—is addressed. Finally, some general considerations concerning the Overvoltage Protection selection for wind farm projects, particularly regarding the installation of the metal-oxide surge arresters, are provided as well.
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Assessment of lightning current parameters suitable for analysis of HV substation Overvoltage Protection
2010 30th International Conference on Lightning Protection (ICLP), 2010Co-Authors: Petar SarajcevAbstract:This paper will present theoretical and mathematical background of the process which aims at evaluation of lightning current parameters suitable for the analysis of high voltage transformer station Overvoltage Protection. It is a well appreciated fact that the analysis of Overvoltage Protection for the high voltage substation stems from the backflashover analysis on several first neighboring towers of the incoming overhead transmission line. Statistical distribution of lightning current parameters is employed in the process of deriving analytical expression which expresses a probability of lightning current with specific parameters (striking several first towers as seen from the substation) being exceeded only once during the specified time frame. A typical numerical example will corroborate the analysis with concrete results.
Bernd Deutschmann - One of the best experts on this subject based on the ideXlab platform.
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Investigation of SPICE Models for Overvoltage Protection Devices With Respect to Fast Transients
2019Co-Authors: Susanne Bauer, Werner Renhart, Christian Turk, Christoph Maier, Gunter Winkler, Oszkar Biro, Bernd DeutschmannAbstract:Models of Overvoltage Protection devices, such as transient voltage suppressor diodes (TVS-diodes) are largely available in circuit analyzer tools. For this letter, the widely used circuit simulation tool LTspice was employed and during the course of investigating the simulation of such Protection devices in the context of electrical fast transient phenomena, especially electrical fast transients (EFT/BURST) and electrostatic discharge (ESD), certain existing diode-model types can present inaccuracies when predicting the disturbances generated by those devices. Presumably this is the case regarding the model of the junction capacitances, especially for the cutoff region, since the implementation follows a linear extrapolation and therefore differs from the real behavior of the Protection device under test. This letter deals with the investigation of a simulation setup and occurring limitations for the analysis of the transient behavior. It should give some encouragement to always consider given model-limitations and how they can affect the simulated results and also if the applicability for certain investigations is provided.
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Investigation of Spice Models for Overvoltage Protection Devices with Respect to Fast Transients
2018 IEEE Symposium on Electromagnetic Compatibility Signal Integrity and Power Integrity (EMC SI & PI), 2018Co-Authors: Susanne Bauer, Werner Renhart, Oszkar Biroo, Christian Turk, Christoph Maier, Gunter Winkler, Bernd DeutschmannAbstract:Models of Overvoltage Protection devices such as voltage suppressor diodes (TVS) are available for the most part in circuit analyzer tools. During the course of investigating the simulation of such Protection devices via LTspice in the context of fast transient phenomena some assumptions of those existing models can present problems. This is the case regarding the model of the junction capacitances, especially for the cutoff region when predicting the disturbances generated by those devises.
Volker Hinrichsen - One of the best experts on this subject based on the ideXlab platform.
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Overvoltage Protection of inverter-fed drives with the help of energy varistors - Dimensioning rules for consideration of different cable types
2009 Twenty-Fourth Annual IEEE Applied Power Electronics Conference and Exposition, 2009Co-Authors: A. Rocks, Volker HinrichsenAbstract:This contribution deals with Overvoltage Protection in inverter-fed drives by varistors. Several kinds of Overvoltage in combination with very low rise times impose extreme dielectric stress on the insulation of electrical machines. With varistors it is possible to decrease these Overvoltages in combination with an extended rise time of the impulses occurring at the machine terminal. During this service the varistor has to withstand the power losses and has to dissipate heat into the surrounding medium. The operation mode of the varistor strongly depends on the basic parameters like pulse frequency, rise time of the impulses at the inverter, applied cable, size of the motor etc. Here correlations between the voltage-current characteristic (U-I characteristic) of the varistor, the maximum occurring voltage steepness and the applied cable type are given in order to be able to carry out detailed dimensioning for different application cases.
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Effect of varistors for Overvoltage Protection in inverter-fed drives on the voltage distribution in the stator winding
Conference Record of IEEE International Symposium on Electrical Insulation, 2008Co-Authors: A. Rocks, Volker HinrichsenAbstract:The use of varistors for Overvoltage Protection in inverter-fed drives can be a promising alternative to common solutions like filters. In this contribution the varistor's influence on the voltage distribution in the stator winding is presented under certain aspects such as cable type and varistor type. The results of different measurements are shown and the main aspects are discussed. It is shown voltage amplitudes and voltage distribution can be affected positively to increase life time of the winding insulation of the machine.
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Overvoltage Protection of inverter-fed drives with the help of energy varistors — dimensioning and lifetime considerations
2008 Twenty-Third Annual IEEE Applied Power Electronics Conference and Exposition, 2008Co-Authors: A. Rocks, Volker HinrichsenAbstract:This contribution deals with Overvoltage Protection in inverter-fed drives by varistors. Several kinds of Overvoltages in combination with very short rise times impose extreme dielectric stress on the insulation of electrical machines. With varistor discs it is possible to limit these Overvoltages in combination with an increased rise time of the impulses occurring at the machine terminal. During this service the varistor has to withstand the power losses and to dissipate the resulting heat to the surrounding medium. Here, currents and power losses are focused in order to get better understanding of the mechanisms that lead to a reduction of the Overvoltage at the machine terminal. Finally, a proposal for an accelerated aging procedure will be made that takes the given service conditions into account. First results are presented, and the chances of this application for Overvoltage Protection will be discussed as well.
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Application of varistors for Overvoltage Protection of machine windings in inverter-fed drives
2007 IEEE International Symposium on Diagnostics for Electric Machines Power Electronics and Drives SDEMPED, 2007Co-Authors: A. Rocks, Volker HinrichsenAbstract:This contribution deals with Overvoltage Protection in inverter-fed drives by varistors. Several kinds of Overvoltage in combination with very low rise times impose extreme dielectric stress on the insulation of electrical machines. Here a novel approach of Overvoltage Protection in inverter-fed drives is presented. After a discussion of the origins of the Overvoltages and of Overvoltage limitation by varistors in general, the dimensioning for the particular application, which is quite unusual for varistors, will be presented. Two special cases of actual Overvoltages are addressed. Oscillograms are analyzed, and comparisons of measurements and calculations are made as well. Finally, possible applications for certain cases are discussed.
Dev Paul - One of the best experts on this subject based on the ideXlab platform.
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Transient Overvoltage Protection of shore-to-ship power supply system
IEEE Transactions on Industry Applications, 2011Co-Authors: Dev Paul, Vahik HaddadianAbstract:It is known that an unpredictable threat of transient Overvoltage exists in a power system. Therefore, transient Overvoltage Protection analysis, commonly known as insulation coordination, should be performed to design cold-ironing power systems. This paper provides a review of the transient surge environment, transient Overvoltage analysis, and the application of metal–oxide surge arresters at specific locations within the shore-to-ship power supply system to enhance transient Overvoltage Protection to minimize equipment damage.
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transient Overvoltage Protection of shore to ship power supply system
Petroleum and Chemical Industry Technical Conference, 2010Co-Authors: Dev Paul, Vahik HaddadiaAbstract:It is known that unpredictable threat of transient Overvoltage exits in a power system, therefore; transient Overvoltage Protection analysis; commonly known as insulation coordination should be performed to design cold-ironing power system. This paper provides a review of the transient surge environment, transient Overvoltage analysis and application of metal-oxide surge arresters at specific locations within the shore-to-ship power supply system to enhance transient Overvoltage Protection.
