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  • 1.
    Augustin, Tim
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electric Power and Energy Systems.
    Parekh, Mrunal
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Magnusson, Jesper
    ABB.
    Becerra Garcia, Marley
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. ABB.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electric Power and Energy Systems.
    Thomson-Coil Actuator System for Enhanced Active Resonant DC Circuit Breakers2022In: IEEE Journal of Emerging and Selected Topics in Power Electronics, ISSN 2168-6777, E-ISSN 2168-6785, Vol. 10, no 1, p. 800-810Article in journal (Refereed)
    Abstract [en]

    Enhanced active resonant (EAR) dc circuit breakers (DCCBs) are a promising set of recently proposed DCCB concepts. As other DCCBs, EAR DCCBs still require a fast mechanical switch. The requirements on the actuator of the mechanical switch depend on the DCCB concept and the dc grid and are derived here for an EAR DCCB. Thomson-coil actuators (TCAs) can open and close mechanical switches sufficiently fast to satisfy the requirements. This work studies experimentally a TCA system with active damping for an off-the-shelf industrial vacuum interrupter used as mechanical switch in an EAR DCCB. The prototype is explained in detail, and extensive measurement results are presented, showing that active damping must be perfectly timed to be effective. A novel Thomson-coil (TC) driver is proposed and studied experimentally, which operates the TCA more efficiently by recycling energy during the actuation. Moreover, the novel TC driver reduces the capacitive storage by 50% and allows for faster recharging with lower charging current. Finally, the autoreclosing and proactive commutation operation of the TCA system and the interruption capability of the prototype EAR DCCB are demonstrated experimentally.

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  • 2. Bissal, A.
    et al.
    Eriksson, A.
    Magnusson, Jesper
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Engdahl, G.
    Hybrid multi-physics modeling of an ultra-fast electro-mechanical actuator2015In: Actuators, ISSN 2076-0825, Vol. 4, no 4, p. 314-335Article in journal (Refereed)
    Abstract [en]

    The challenges of an HVDC breaker are to generate impulsive forces in the order of hundreds of kilonewtons within fractions of a millisecond, to withstand the arising internal mechanical stresses and to transmit these forces via an electrically-insulating device to the contact system with minimum time delay. In this work, several models were developed with different levels of complexity, computation time and accuracy. Experiments were done with two mushroom-shaped armatures to validate the developed simulation models. It was concluded that although the electromagnetic force generation mechanism is highly sensitive to the mechanical response of the system, the developed first order hybrid model is able to predict the performance of the breaker with good accuracy.

  • 3.
    Bissal, Ara
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Comparison of two Ultra-fast actuator concepts2012In: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 48, no 11, p. 3315-3318Article in journal (Refereed)
    Abstract [en]

    In this paper, two different types of ultra-fast electromechanical actuators are compared using a multi-physical finite element simulation model that has been experimentally validated. They are equipped with a single-sided Thomson coil (TC) and a double-sided drive coil (DSC), respectively. The former consists of a spirally-wound flat coil with a copper armature on top, while the latter consists of two mirrored spiral coils that are connected in series. Initially, the geometry and construction of each of the actuating schemes are discussed. Subsequently, the theory behind the two force generation principles are described. Furthermore, the current, magnetic flux densities, accelerations, and induced stresses are analyzed. Moreover, mechanical loadability simulations are performed to study the impact on the requirements of the charging unit, the sensitivity of the parameters, and evaluate the degree of influence on the performance of both drives. Finally, it is confirmed that although the DSC is mechanically more complex, it has a greater efficiency than that of the TC.

  • 4.
    Bissal, Ara
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Electric to Mechanical Energy Conversion of Linear Ultra-Fast Electro-Mechanical Actuators Based on Stroke Requirements2014In: Electrical Machines (ICEM), 2014 International Conference on, IEEE conference proceedings, 2014, p. -515Conference paper (Refereed)
    Abstract [en]

    The operational efficiency of ultra fast actuators usedas drives in high voltage direct current breakers are at best5 %. To boost their efficiency, the design of the energizing circuitis crucial. A multi-physics finite element method (FEM) modelcoupled with a SPICE circuit model that is able to predict theperformance of the actuator with an accuracy of at least 95 % hasbeen developed and verified experimentally. Several variants ofprototypes and models have been simulated, built, and tested.It was shown that one of the main problems leading to lowefficiencies is the stroke of the drive. However, there is a possibilityto increase the efficiency of the electric to mechanical energyconversion process of the studied Thomson (TC) and double sidedcoils (DSC) to a maximum of 54 % and 88 % respectively iftheir stroke is minimized. This can be done at the expense ofincreasing the complexity and the cost of the contact system bydesigning a switch with several series connected contacts that isencapsulated in a medium with a high dielectric strength. Anotherproposed solution is to design a current pulse with a rise timethat is considerably shorter than the mechanical response time ofthe system. Parametric variations of capacitances and chargingvoltages show that the TC and the DSC can achieve efficienciesup to 15 % and 23 % respectively. Regardless of the chosenmethod, the DSC has a superior efficiency compared to a TC.

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  • 5.
    Bissal, Ara
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Electric to Mechanical Energy Conversion of Linear Ultrafast Electromechanical Actuators Based on Stroke Requirements2015In: IEEE transactions on industry applications, ISSN 0093-9994, E-ISSN 1939-9367, Vol. 51, no 4, p. 3059-3067Article in journal (Refereed)
    Abstract [en]

    The operational efficiency of ultrafast actuators used as drives in high-voltage direct-current breakers is at best 5%. To boost their efficiency, the design of the energizing circuit is crucial. A multiphysics finite-element method model coupled with a SPICE circuit model that is able to predict the performance of the actuator with an accuracy of at least 95% has been developed and verified experimentally. Several variants of prototypes and models have been simulated, built, and tested. It was shown that one of the main problems leading to low efficiencies is the stroke of the drive. However, there is a possibility to increase the efficiency of the electric to mechanical energy conversion process of the studied Thomson coil (TC) and double-sided coil (DSC) to a maximum of 54% and 88%, respectively, if their stroke is minimized. These efficiencies are idealistic, and these were obtained with clamped armature studies. The efficiency of the actuator can be increased at the expense of increasing the complexity and the cost of the contact system by designing a switch with several series-connected contacts that is encapsulated in a medium with a high dielectric strength. Another proposed solution is to design a current pulse with a rise time that is considerably shorter than the mechanical response time of the system. Parametric variations of capacitances and charging voltages show that the TC and the DSC can achieve efficiencies up to 15% and 23%, respectively. Regardless of the chosen method, the DSC has a superior efficiency compared to a TC.

  • 6.
    Bissal, Ara
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Optimal Energizing Source Design for Ultra-Fast Actuators2013Conference paper (Refereed)
    Abstract [en]

    One of the key enabling technologies for multi-terminal HVDCgrids is the existence of a breaker that can operate withina few milliseconds. A lot of research has been done to builddifferent ultra-fast drives to actuate the electric contacts ofthese breakers. What they all have in common is an operationalefficiency of at best 5 %. Capacitor banks are discharged throughspirally shaped flat coils to generate ultra-fast repulsive forces. Tooptimize the efficiency of the drive, the design of the energizingcircuit is crucial. The aim of this paper is to optimize theenergizing source and provide a deep explanation of the effectof the chosen capacitance and charging voltage for two actuatorconcepts, the Thomson coil (TC) and the double sided coil (DSC)for different stroke requirements. An experimentally validatedmulti-physics finite element method (FEM) simulation model is applied.

  • 7.
    Bissal, Ara
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Salinas, Ener
    ABB AB Corporate Research, Sweden.
    Loadability and scaling aspects of Thomson based ultra-fast actuators2012In: Actuator 2012, 2012Conference paper (Refereed)
    Abstract [en]

    In this paper, an ultra-fast single-sided Thomson based actuator is studied. The actuator is comprised of a flat spiral-shaped coil with a conductive armature in its proximity. This armature is mechanically loaded with a uniform mass distribution over its cross section. The energizing source consists of a capacitor bank that is discharged through the actuator coil resulting in a high magnetic pressure within fractions of a millisecond. The coil is dimensioned to withstand the temperature rise.

    An experimentally validated multi-physical finite element model is used to perform simulations by varying the mechanical load to explore the performance of the actuator topology. The obtained currents, induced forces, stresses, and accelerations of the armature are then analyzed in an attempt to develop scaling techniques that can predict for example velocity and efficiency. Finally, the results of the scaling techniques are presented and compared to each other.

  • 8.
    Bissal, Ara
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. ABB AB Corporate Research, Sweden.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. ABB AB Corporate Research, Sweden.
    Salinas, Ener
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Multiphysics modeling and experimental verification of ultra-fast electro-mechanical actuators2015In: International journal of applied electromagnetics and mechanics, ISSN 1383-5416, E-ISSN 1875-8800, Vol. 49, no 1, p. 51-59Article in journal (Refereed)
    Abstract [en]

    In this paper, a multi-physics computational tool has been developed to accurately model and build high performance ultra-fast actuators. The research methodology is based on a finite element method model coupled with a circuit model. Electromagnetic, thermal, mechanical, and algebraic equations are implemented in Comsol Multiphysics and verified with laboratory experiments of a built prototype. A simplified model is preferred as long as its underlying assumptions hold. However, in the presence of large current and force densities, nonlinearities such as deformations may occur. Such phenomena can only be captured by the use of the developed comprehensive multi-physics simulation model. Although this model is computationally demanding, it was shown to have an accuracy of at least 95% when compared with experiments.

  • 9.
    Bissal, Ara
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Salinas, Ener
    ABB AB Corporate Research, Sweden.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Eriksson, Anders
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    On the Design of Ultra-Fast Electromechanical Actuators: A Comprehensive Multi-Physical Simulation Model2012In: Sixth International Conference on Electromagnetic Field Problems and Applications (ICEF), 2012, IEEE conference proceedings, 2012, p. 1-4Conference paper (Refereed)
    Abstract [en]

    In this paper, a simulation of an ultra-fast electromechanical drive was performed by using a two-dimensional axi-symmetric multi-physical finite element model. The aim of this paper is to primarily show that the following model can be used to simulate and design those actuators with good accuracy, secondly, to study the behavior and sensitivity of the system and thirdly, to demonstrate the potential of the model for industrial applications. The simulation model is coupled to a circuit and solves for the electro-magnetic, thermal, and mechanical dynamics utilizing a moving mesh. The actuator under study is composed of a spiral-shaped coil and a disk-shaped 3mm thick copper armature on top. Two numerical studies of such an actuator powered by 2640 J capacitor banks were performed. It is shown that forces up to 38 kN can be achieved in the range of 200 μs. To add credibility, a benchmark prototype was built to validate this experimentally with the use of a high speed camera and image motion analysis.

  • 10.
    Bissal, Ara
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. ABB Corporate Research.
    Salinas, E.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    On the design of a linear composite magnetic damper2015In: 2015 IEEE International Magnetics Conference, INTERMAG 2015, IEEE conference proceedings, 2015Conference paper (Refereed)
    Abstract [en]

    In recent years, ultra-fast actuators have become key elements in the development of high voltage direct current (HVDC) breakers for multiterminal grids which represent a huge progress in modern power transmission [1]. After fulfilling their operation these actuators need to be decelerated using controllable forces to avoid deforming vital components incorporated in the system. In this paper, a dedicated damper is proposed based on a magnet array that induces eddy currents in a composite metal tube resulting in an efficient braking response. Several topologies are investigated by simulations and experiments. The theory behind eddy current damping is explained in [2]. The main requirements for such dampers are reliability, robustness, and ease of construction. The expected durability of these kind of dampers is longer than the breaker itself which guarantees extremely good reliability within HVDC systems.

  • 11.
    Bissal, Ara
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Salinas, Ener
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    On the Design of a Linear Composite Magnetic Damper2015In: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 51, no 11, article id 8003305Article in journal (Refereed)
    Abstract [en]

    High-voltage direct current (HVdc) breakers are the key components in the realization of multiterminal HVdc grids. In the presence of fault current, these breakers should be able to deliver impulsive forces to swiftly open the metallic contacts. After the acceleration phase, the moving armature should be decelerated using controllable forces to avoid plastically deforming fragile components integrated in the system. In this paper, finite-element method-based simulation models, complimented with small-scale and large-scale experimental prototypes, were utilized to benchmark different damping topologies. It was found that a Halbach-based configuration can deliver a damping force that is almost two and a half times larger than its sequel. Its sequel, composed of vertically stacked oppositely oriented magnets, is easier to assemble and is also capable of generating a considerable damping force. Finally, it has been shown that both these schemes, inserted in a composite tube, have a potential to be used as dampers in HVdc breakers.

  • 12. Corea-Araujo, Javier A.
    et al.
    Martinez-Velasco, Juan A.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Optimum design of hybrid HVDC circuit breakers using a parallel genetic algorithm and a MATLAB-EMTP environment2017In: IET Generation, Transmission & Distribution, ISSN 1751-8687, E-ISSN 1751-8695, Vol. 11, no 12, p. 2974-2982Article in journal (Refereed)
    Abstract [en]

    The optimum design of power system components is becoming a relevant topic in power system studies. Genetic algorithms (GAs) are considered as a proper approach for optimisation problems in which non-linear elements are involved. Several trends are presently leading GAs to a new level; for instance, its combination with parallel computing can facilitate the solution of problems where individual evaluations of the fitness function require an important computational effort. This study presents a procedure based on a MATLAB-EMTP application and the usage of a multicore environment for the optimum selection of hybrid high-voltage DC (HVDC) circuit breaker parameters; the goal is to obtain a transient response of the hybrid design with voltages, currents and fault clearance times within specified limits.

  • 13.
    Doddapaneni, Venkatesh
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Bissal, Ara
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Edin, Hans
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Gati, Rudolf
    EFFECT OF POLYMER BASED NANOCOMPOSITES ON THE ELECTRICAL ARCS IN AIR2015In: 2015 42ND IEEE INTERNATIONAL CONFERENCE ON PLASMA SCIENCES (ICOPS), ISSN 0730-9244Article in journal (Other academic)
  • 14.
    Doddapaneni, Venkatesh
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Bissai, A.
    Edin, Hans
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Gati, R.
    Spectroscopic investigations of the ablated species from the polymers exposed to electric arcs in air2015In: 2015 3rd International Conference on Electric Power Equipment - Switching Technology, ICEPE-ST 2015, Institute of Electrical and Electronics Engineers (IEEE), 2015, p. 337-340Conference paper (Refereed)
    Abstract [en]

    Polymeric walls have been widely used in the last decades to improve the arc interruption process in electrical switching applications. This improvement is achieved by the evaporation (ablation) of the polymeric walls due to the highly energetic radiation generated by the electrical arcs. This experimental study deals with polymeric walls that are exposed to the electrical arcs generated between a 5 mm air gap with prospective current of 1.4 kA. In this paper, two different techniques are discussed aiming at the identification of the dominant ablated species produced during the arc interruption process, namely Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis coupled with Fourier transform infrared analysis of evolved gases (EGA). In addition, the morphological and chemical changes on the surface of the exposed polymeric walls are analyzed by microscopical techniques.

  • 15.
    Hou, Yining
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Liljestrand, Lars
    Impact on voltage rise of PV generation in future swedish urban areas with high PV penetration2014In: ENERGYCON 2014 - IEEE International Energy Conference, IEEE Computer Society, 2014, p. 904-911Conference paper (Refereed)
    Abstract [en]

    There have been a large amount of statements from different countries, claiming that the integration of photovoltaic generation in the distribution grids can eventually impact the power quality and pose challenges for the distribution system operator. In Sweden, the level of penetration of small scale distributed generation is still low and no such problems have been observed. This study is conducted to investigate the voltage levels in an urban distribution grid when the level of photovoltaic generation is increased. The study is done by modeling the Swedish urban area by PSCAD. The aspects of the model include network design of a real distribution grid, everyday load, photovoltaic generation based on real data, photovoltaic penetrations at different levels and considers the current regulations in Sweden. The results indicate that there are no problems with overvoltages even with a high penetration of photovoltaic generation. Instead the risk of over-current through the installed cables seems to be a greater limitation. The loading of the distribution transformers is decreased due to the mix of commercial and domestic loads in the local grid.

  • 16.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    On the design of hybrid DC-breakers consisting of a mechanical switch and semiconductor devices2015Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The interest of using direct current in networks for both transmission and distribution of power is increasing due to the higher efficiency compared to the alternating current used today. As no natural zero crossings exist in direct current, the interruption of fault currents becomes a challenge. Several circuit breaker topologies have been proposed to fulfill the requirements for DC grids. One such topology is the hybrid DC-breaker consisting of three parallel branches: a mechanical switch, a semiconductor branch, and a metal oxide varistor.

    The current interruption in the hybrid DC-breaker is made in three steps. A mechanical switch carries the nominal current with low losses during normal operation. When the breaker is tripped to interrupt the current, the mechanical switch is opened and commutates the current into the semiconductor branch. This branch will then conduct the current as the mechanical switch regains its voltage withstand. The semiconductors turn off and force the current into the varistor branch where the magnetic energy is absorbed and the current is forced to zero.

    This thesis is based on simulations and experiments to obtain design rules for such a DC-breaker. It has been shown that several aspects needs to be considered. Simulations are performed with several different models to obtain the requirements of each of the components in the DC-breaker.

    First of all, the choice of the semiconductor is important. There are a number of components available in the market, but typically they are optimized for fast switching applications like inverters rather than circuit breaker applications that only requires one single switching. Due to the high current and voltage ratings and the easy control, the IGBT seems to be the best choice among the commercially available components.

    Simulations on the mechanical switch show that there is an optimal combination of opening time and arc voltage of the to obtain a successful commutation into the semiconductor branch. The actuator is a key component since a relatively low increase in performance of the actuator drive circuit, significantly decreases the requirement of the other components in the DC-breaker.

    A significant part of the work has been put on the voltage transient during the turn-off of the semiconductor. As the current is forced into the varistor branch, the stray inductance in that loop will result in an over-voltage due to the high current derivative. A new type of snubber has been investigated using another varistor mounted close to the semiconductor. It has been shown that the function of the varistor snubber can be divided into two regions depending on the ratio between the snubber and the main varistor. If the ratio is high enough, the energy absorbed in the snubber varistor is only a few percent of the total energy.

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    Licentiate Thesis
  • 17.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Studies on Current Commutation in Hybrid DC-breakers2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Compared to conventional AC-circuit breakers, a DC-breaker has to act fast and force the current down to zero. Many different DC-breaker topologies are available, and this thesis is focused on the hybrid DC-breaker comprising a mechanical switch and high power semiconductors.

    The main part of this thesis is focused on the current commutations in the hybrid DC-breaker. The two current commutations: from the mechanical switch to the semiconductor branch, and from the semiconductor to the metal oxide varistor, have completely different characteristics. When the mechanical switch opens, the metallic contacts separate and an electric arc is formed. As the voltage across the arc is higher than the voltage across the semiconductors, the current is pushed over to the semiconductor branch. The undesired stray inductance in the loop limits the current derivative and slows down the commutation. As the contacts keep separating, the arc voltage increases and eventually all current is conducted by the semiconductor and the arc ceases.

    For a hybrid DC-breaker, the worst case is a solid ground fault, as the fast rising current results in high current levels and makes the commutation from the mechanical switch to the semiconductor both difficult and slow. However, the fast rise of the current can be used to enhance the commutation by using coupled inductors in the two parallel branches. When the fault current rises in the semiconductor branch, the mutual coupling of the inductors causes the current in the mechanical switch to decrease and helps the commutation. The result is that the commutation time decreases with decreasing fault impedance, and makes the solid ground fault easier to handle.

    The commutation from the semiconductor to the metal oxide varistor is controlled by the turn-off of the semiconductor. When the semiconductor is turned off, it pulls the current down to zero with a rather constant current derivative regardless of the surrounding circuit and the system current is taken over by the metal oxide varistor. Hence, any inductance in the commutation loop will result in an over-voltage proportional to this inductance on top of the varistor voltage. By connecting a smaller metal oxide varistor, as a snubber, close to the semiconductor, the over-voltage can be controlled and the commutation from the snubber to the metal oxide varistor will be driven by the voltage difference between the two varistors.

    It is shown that for a 12 kV DC-system, a possible design of the mechanical switch in the hybrid DC-breaker comprises two contact gaps in series and opens with a velocity of 11 m/s. It has been experimentally verified that when starting the commutation at 4 kA, the commutation takes less than 700 us and is over before the switch has opened 1 mm.

    The thesis also contains proposed designs for an 80 kV DC-breaker that can be used as a modular solution for higher system voltages. For this higher voltage, the design will be a choice of the combination between the number of contact gaps in series and the opening velocity of the mechanical switch.

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    Jesper Magnusson - Studies on Current Commutation in Hybrid DC-breakers
  • 18.
    Magnusson, Jesper
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Bissai, Ara
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Martinez, J. A.
    Liljestrand, L.
    Experimental study of the current commutation in hybrid DC-breakers2015In: 2015 3rd International Conference on Electric Power Equipment - Switching Technology, ICEPE-ST 2015, Institute of Electrical and Electronics Engineers (IEEE), 2015, p. 506-511Conference paper (Refereed)
    Abstract [en]

    To interrupt a current in a DC system where the feeding voltage is higher than a few kilovolt is a challenge. One popular solution today is the hybrid DC-breaker where a semiconductor is bypassed by a mechanical switch in normal operation to decrease the on-state losses. This paper presents an experimental study of the commutation from the mechanical switch to a parallel diode and IGBT. Three sets of tests were performed with six different current levels between 50 and 450 A. The test circuit consists of a capacitor bank as an energy source, a current limiting inductor, and the breaker. As the pre-charged capacitor bank is discharged through the current limiting inductor, the current will rise linearly, similar to the fault current in a stiff DC system. It was seen that with a very low stray inductance in the commutation loop, the commutation occurs in some ten microseconds just after the contact separation. Due to the small contact separation, the contacts might regain metallic contact again, causing the commutation to stop until the contacts separate again and the arc reignites. Longer arcing times were studied by introducing a larger inductance in the commutation loop. For currents of some hundred amperes, the arc voltage is fairly independent of the current level, but increases with increasing contact separation resulting in an increasing current derivative and a faster commutation. Finally the commutation and interruption of a current in a hybrid DC-breaker with an IGBT was demonstrated.

  • 19.
    Magnusson, Jesper
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Bissal, Ara
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Juan A, Martinez
    Universitat Politècnica de Catalunya.
    Design Aspects of a Medium Voltage Hybrid DC Breaker2014In: 5th IEEE/PES Innovative Smart Grid Technologies Europe (ISGT EUROPE) 2014, 2014Conference paper (Refereed)
    Abstract [en]

    With increased demands on energy efficiency and stability, the use of direct current (DC) will have a natural place in the future smart grid. Today DC is mostly used in high voltage, high power transmission over large distances and in low voltage systems where the demands on reliability are high, e.g. data centres. New applications as wind farm collection grids and a desire to replace over-head lines with cables opens possibilities for DC distribution grids in medium voltage.The use of DC grids will require the development of DC breakers to handle fault in the grid. This paper presents the design aspects of a hybrid DC breaker for a medium voltage application. Since the hybrid topology consists of a mechanical switch as well as semiconductor components and metal oxide varistors, the design must handle trade-offs in performance and cost both for each part and also between the different components.

  • 20.
    Magnusson, Jesper
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Bissal, Ara
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Saers, Robert
    Zhang, Zichi
    Liljestrand, Lars
    On the Use of Metal Oxide Varistors as a Snubber Circuit in Solid-State Breakers2013In: 2013 4th IEEE/PES Innovative Smart Grid Technologies Europe, ISGT Europe 2013, IEEE , 2013, p. 6695454-Conference paper (Refereed)
    Abstract [en]

    When solid-state switches are used in DC-breaker topologies, the turn-off operation can cause transient over-voltages that might harm the semiconductor itself. The over-voltage is caused by the combination of the very rapid current decrease of a solid-state switch and an undesired stray inductance in the parallel MOV-branch. The authors have proposed a possible solution where a smaller MOV is connected close to the solid-state switch to limit the over-voltage. This way, the over-voltage protection can be separated from the energy absorption task of the MOV. A small scale test set-up has been used to show that the peak voltage across the breaker is fully determined by the inner MOV. It is also shown that the performance can be increased by changing the U-I-characteristics of the outer MOV by adding several components in parallel.

  • 21.
    Magnusson, Jesper
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Universitat Polotècnica de Catalunya.
    Martinez-Velasco, Juan A.
    Bissal, Ara
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Optimal design of a medium voltage hybrid fault current limiter2014In: 2014 IEEE International Energy Conference, ENERGYCON, IEEE Computer Society, 2014, p. 431-438Conference paper (Refereed)
    Abstract [en]

    The connection of distributed generation increases the short circuit power which in turn might exceed the ratings of the installed circuit breakers. A solution is to limit the available short circuit power by increasing the grid impedance, but since there is a constant strive for lower losses and higher power transfer capabilities, this is not desired. The application of a fault current limiter (FCL) that can limit the current before the first peak enables a power system with high short circuit power and low short circuit current. This can increase the stability of the grid and reduce the requirements of other equipment. This work presents a simulation model to be used as an aid in the design of a hybrid FCL for a 12 kV AC system. The proposed model combines a transient analysis circuit model with an optimization module to obtain multiple sets of possible design parameters. The design is not straight forward since there is a trade-off between several of the design parameters.

  • 22.
    Magnusson, Jesper
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Saers, R.
    Liljestrand, L.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Separation of the energy absorption and overvoltage protection in solid-state breakers by the use of parallel varistors2014In: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 29, no 6, p. 2715-2722Article in journal (Refereed)
    Abstract [en]

    Hybrid and solid-state breakers offer new possibilities in the power grid by enabling faster switching, and by simplifying dc breaking. However, they consists of expensive power electronic components that are sensitive to overvoltage transients and require energy absorbing elements mounted in parallel. At turn-off, the rapidly decreasing current in the power electronic switch and the presence of an inherent stray inductance leads to hazardous overvoltage transients across the breaker. This paper investigates the possibility to split the overvoltage protection and energy absorption into two separate components. By optimizing the voltage ratio between two varistors, one can dimension a small electronics varistor for overvoltage protection and a large power electronics varistor for energy absorption. With this setup the power electronics varistor is allowed to be in a circuit with a large stray inductance and can thus be placed further away without causing an uncontrolled overvoltage. It is shown both in circuit simulations as well as in a small-scale experiment that if the voltage ratio between the two varistors is large enough, the inner varistor only has to absorb 1-2% of the system energy.

  • 23. Martinez, Juan A.
    et al.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    EMTP Modeling of Hybrid HVDC Breakers2015In: 2015 IEEE POWER & ENERGY SOCIETY GENERAL MEETING, IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    HVDC meshed systems offer several advantages in front of their HVAC counterparts. However, the lack of fast, low-losses and reliable circuit breaker technology has postponed their implementation. A recently proposed hybrid breaker design can alter this situation. The new hybrid HVDC breaker offer a fast low-loss operation that can be easily adapted to high-power high-voltage DC applications. This paper presents the implementation and testing of an HVDC breaker model based on the new design. Simulation results are included to illustrate the operation of the new device when running as a fault-current limiter.

  • 24. Martinez-Velasco, Juan A.
    et al.
    Magnusson, Jesper
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Parametric analysis of the hybrid HVDC circuit breaker2017In: International Journal of Electrical Power & Energy Systems, ISSN 0142-0615, E-ISSN 1879-3517, Vol. 84, p. 284-295Article in journal (Refereed)
    Abstract [en]

    The hybrid circuit breaker design offers a fast low-loss operation that can be of paramount importance for the development of future meshed HVDC systems. This paper summarizes the main results obtained from a parametric analysis based on a simplified representation of both the circuit breaker and the test system. The main goals are to investigate the operation of the new device when running as a fault-current limiter and find out the influence that some breaker and system parameters (e.g. prospective short-circuit current in the test system, operation time of the mechanical switch, cable length, fault position, rated voltage of arrester) can have on the overcurrents and overvoltages that will occur during breaker operation. The results derived from this study can be useful for choosing some breaker parameters and to lesser extent for improving the breaker design.

  • 25.
    Parekh, Mrunal
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Bissal, Ara
    Magnusson, Jesper
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. ABB AB Corporate Research, Västerås 722 26, Sweden.
    Engdahl, Göran
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Design of a linear Halbach magnetic damper2018In: International journal of applied electromagnetics and mechanics, ISSN 1383-5416, E-ISSN 1875-8800, Vol. 59, no 2, p. 1-9Article in journal (Refereed)
    Abstract [en]

    Ultra-fast circuit breakers are operated with fast electromagnetic actuators. They can generate a sufficient impulse force to swiftly open electrical contacts in a couple of milliseconds. Opening of the contacts with high velocities implies a need for a timely and controllable damping. An efficient damping mechanism then is crucial to attain an appropriate actuation performance and secure a long lifetime. In this paper a finite element model of a Halbach magnet array based magnetic damper and a corresponding experimental prototype is described. A parametric study is performed to understand the effect of load mass and incoming velocities. It was found that the magnetic field modulation plays an important role on the damping performance. A uniform and high radial component of the magnetic flux density is necessary in order to achieve high damping force. The radial magnetic field can be controlled via thickness and magnetization direction of the ring magnets that are used to create the Halbach magnet array.

  • 26.
    Parekh, Mrunal
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Bissal, Ara
    ABB AB Corporate Research, Västerås, Sweden.
    Magnusson, Jesper
    ABB AB Corporate Research, Västerås, Sweden.
    Engdahl, Göran
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Study of a linear Halbach passive magnetic damper2017In: 2017 IEEE International Magnetics Conference, INTERMAG 2017, Dublin, Ireland: IEEE conference proceedings, 2017, article id 8008035Conference paper (Refereed)
    Abstract [en]

    High voltage ultra-fast circuit breakers are operated with fast actuators. They are capable of generating impulsive force to swiftly open electrical contacts in a couple of milliseconds. Opening of the contacts with high velocities implies a need for a timely and controllable damping. An efficient damping mechanism then is crucial to attain an appropriate actuation performance and secure a long lifetime. In this paper a finite element model of a Halbach magnet array based magnetic damper and a corresponding experimental prototype is described. It was found that a uniform and high radial component of the magnetic flux density is necessary in order to achieve high damping force. The radial magnetic field can be controlled via thickness and magnetization direction of the ring magnets which are used to create the Halbach magnet array. Finally, it is also shown that the concept provides a frictionless collision free damping demonstrating its potential to be used in fast circuit breakers.

  • 27.
    Parekh, Mrunal
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Electrical Engineering and Computer Science (EECS).
    Magnusson, Jesper
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. ABB AB Corporate Research, Västerås.
    Engdahl, Göran
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Study of an Electromagnetic Damping Actuator2018In: VDE Conference Proceedings on Actuator 18, 2018, p. 475-478, article id P25Conference paper (Refereed)
    Abstract [en]

    Current commutation switches for HVDC devices are operated with Ultra-fast electromagnetic actuators. They can generate hundreds of kilo-newton force and swiftly open electrical contacts in a couple of milliseconds. An efficient damping mechanism then is crucial to attain an appropriate actuation performance and secure a long lifetime. In this article an electromagnetic Halbach damping actuator was studied. A numerical model based on FEA is used to calculate its damping constant and retardation time down to stand still velocity.

  • 28.
    Parekh, Mrunal
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Magnusson, Jesper
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. ABB.
    Engdahl, Göran
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Becerra Garcia, Marley
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Arc Characteristics of Ultra-Fast Opening Switching Contacts in Hybrid Breakers2021In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 36, no 5, p. 2872-2880Article in journal (Refereed)
    Abstract [en]

    A mechanical switch can be used instead of a power electronic load commutation switch to reduce losses during normal power flow in standard hybrid DC breakers. The success of current commutation in such hybrid breakers depends on the arc voltage across the contacts of the mechanical switch. The behaviour of rapidly elongated arcs generated during the opening of an ultra-fast mechanical switch in the air is studied here. The voltage-current characteristics of the generated arcs are obtained for contact opening velocities of 6, 11 and 21 m/s. It is found that the arc voltage at a given current and contact separation increases with contact opening velocity. It is shown that stationary, zero-contact-velocity characteristics can not be used to accurately quantify the voltage build-up in fast elongating arcs in hybrid breakers. A best-fitting black-box the equation for the dynamic arc characteristics is presented for the tested velocities. The obtained voltage-current characteristics are used as input to simulate the current commutation process in a 12 kV hybrid DC circuit breaker case-study. Different scenarios of current commutation failure related to the arc voltage build-up are identified. It is shown that these failures scenarios can be avoided by increasing the contact opening velocity.

1 - 28 of 28
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