Literatura científica selecionada sobre o tema "Short-Circuit fault (SCF)"

Like the widely-used semiconductor switch, Insulated Gate Bipolar Transistors (IGBTs) are subject to many failures and degradation in power electronic converters. In Short Circuit Fault (SCF), as the most reported failures in IGBTs, drastic, sudden temperature rise, and peak SCF current are widespread failures owing to a relatively long delay of the protection subsystem. This paper proposes a protection strategy to limit the junction temperature rise by limiting the SCF current by adding a small value resistor in the IGBT emitter. Second, it reduces the SCF current to a value much less than the saturated current. With the proposed control approach, sudden temperature rise during SCF is controlled, preventing significant failure in IGBTs. The extension of the permissible SCF time is achieved even for the cases with temporary arcs. A simple control loop activates in the SCF condition and does not create slow transients for the IGBT. The results of this paper are validated through simulation and experiment.

Short circuit fault (SCF) in stator coils is one of the most common types of electrical faults. The expansion of this fault leads to the permanent demagnetization of the magnet, and causes irreparable damage to the machine in a short period. With the development of artificial intelligence technologies and various machine learning and deep learning techniques, an increase in fault detection accuracy has been achieved. In this paper, permanent magnet synchronous motor (PMSM) is investigated under normal mode and fault conditions, namely SCF in winding loops, phase to phase SCF and open circuit fault of one of the phases. Group Model of Data Handling deep neural network (GMDH-DNN) is used to produce a SCF detection model. Results of simulating the proposed method and the data extracted from the PMSM reveals that the accuracy rate of SCF detection in the winding loops of the PMSM in the proposed method is equal to 99.2%, which constitutes an improvement of 1.7% compared to other existing methods such as conditional generative adversarial network (CGAN). Moreover, simulating other existing methods - namely support vector machine (SVM), k nearest neighbors (KNN), C4.5, multi-layer perceptron (MLP), recursive deep neural network (RDNN) and long short-term memory networks (LSTM) – and comparing them with the proposed method, unveil that the accuracy of the proposed method for SCF detection in winding loops overweigh those of aforesaid existing methods.

The effects of the wind/PV grid-connected system (GCS) can be categorized as technical, environmental, and economic impacts. It has a vital impact for improving the voltage in the power systems; however, it has some negative effects such as interfacing and fault clearing. This paper discusses different grounding methods for fault protection of High-voltage (HV) power systems. Influences of these grounding methods for various fault characteristics on wind/PV GCSs are discussed. Simulation models are implemented in the Alternative Transient Program (ATP) version of the Electromagnetic Transient Program (EMTP). The models allow for different fault factors and grounding methods. Results are obtained to evaluate the impact of each grounding method on the 3-phase short-circuit fault (SCF), double-line-to-ground (DLG) fault, and single-line-to-ground (SLG) fault features. Solid, resistance, and Petersen coil grounding are compared for different faults on wind/PV GCSs. Transient overcurrent and overvoltage waveforms are used to describe the fault case. This paper is intended as a guide to engineers in selecting adequate grounding and ground fault protection schemes for HV, for evaluating existing wind/PV GCSs to minimize the damage of the system components from faults. This research presents the contribution of wind/PV generators and their comparison with the conventional system alone.

<p>The stability analysis is one of the most important elements to describe the performance of AC drive systems under both dynamic and steady-state operating circumstances. This is particularly essential because electric motors operate over a wide range of speeds and utilize complex control systems such as field-oriented control (FOC). This study establishes a small-signal stability analysis (SSSA) in a 1-horsepower vector-controlled Y-connected three-phase induction motor (YCTPIM) drive during an insulated gate bipolar transistor short-circuits failure (IGBT-SCF). In the beginning, a vector control system that is based on the indirect rotor FOC (IRFOC) method is described for post-fault functioning of the YCTPIM while the IGBT-SCF is taking place. After that, a small-signal model of the system that has been provided is explored. This model is based on a voltage-current model, and it is constructed by linearizing the non-linear dynamic equations of the system. During IGBT-SCF, an IRFOC strategy as well as SSSA operations are carried out on the 1-HP, 380 V, and YCTPIM. In this research, both analytical and simulation-based methodologies are applied.</p>

This article is about the detection of a partial inter-turn short-circuit fault in a brushless motor with permanent magnets (BLPMM). The detection of a single inter-turn short circuit is a difficult issue. The authors of this article tested the sensitivity of the tested powertrain damage detection method. The diagnostic method developed for BLPMM allows for any configuration of the motor winding. A number of analysed configurations have been applied for the combined star–delta connection (YΔ). For the combined star–delta connection Y/Δ, the problem of partial short circuit at two locations was analysed. In the first case, this was the short-circuit winding phenomena in the star part (SC1). In the second case, the short circuit was connected in part to the delta (SC2). A mathematical model has been developed that takes into account both the type of connection and the chance of a partial short circuit of the coil. Based on numerical calculations, the sensitivity of diagnostic methods is designated for both cases. Furthermore, the impact of partial short circuits on motor performance was also examined. The effect of a partial inter-turn short-circuit fault on motor parameters was also determined. Laboratory verification was carried out.

In this paper, a new concept of short-circuit current (SCC) reduction for power distribution systems is presented and analyzed. Conventional fault current limiters (FCLs) are connected in series with a circuit breaker (CB) that is required to limit the short-circuit current. Instead, the proposed scheme consisted of the parallel connection of a current-controlled power converter to the same bus intended to reduce the amplitude of the short-circuit current. This power converter was controlled to absorb a percentage of the short-circuit current from the bus to reduce the amplitude of the short-circuit current. The proposed active short-circuit current reduction scheme was implemented with a cascaded H-bridge power converter and tested by simulation in a 13.2 kV industrial power distribution system for three-phase faults, showing the effectiveness of the short-circuit current attenuation in reducing the maximum current requirement in all circuit breakers connected to the same bus. The paper also presents the design characteristics of the power converter and its associated control scheme.

This paper investigates the influence of stator flux barriers on the short-circuit current (SCC) and braking torque of a dual three-phase permanent magnet (PM) synchronous machine. By optimizing the position and width of stator flux barriers, the machine has a lower amplitude of short-circuit current and brake torque when the short-circuit fault occurs. First, the SCC and braking torque are analytically derived. The amplitude of SCC is proportional to the PM flux linkage and inversely proportional to the inductance. The braking torque is proportional to the square of the PM flux linkage and inversely proportional to inductance. Then, the equivalent magnetic circuit model of flux barriers is established. Its influence on flux linkage and inductance is analyzed, and the improvement mechanism of output torque and fault tolerance is revealed. Furthermore, the flux barriers’ width is optimized by finite element analysis and the theoretical analysis is verified. Finally, experiments on the prototype machine are carried out for the validation.

This paper proposes a practical approach to estimate the symmetrical short-circuit current (SCC) levels in overcurrent protection devices (OCPDs) installed on radial feeders for any penetration level of inverter-based distributed energy resources (DERs). The proposed method restores the lost phase protection coordination by estimating SCC values and changing the TMS of OCPDs accordingly. The method is validated by comparing the results with simulations on the IEEE 34-Node Test Feeder using MATLAB/Simulink, which shows an average error of 1.5% and a maximum error of 3.0%. For a 100% penetration level, the SCC variation through OCPDs installed on the main fault trunk (MFT) exceeds ± 10%, leading to compromised phase protection coordination. The SCC flowing reversely through OCPDs on lateral branches and the fault on the MFT could cause improper tripping. Higher SCC levels are estimated and measured for fault impedances equal to zero. The phase protection is restored by changing the TMS of OCPDs using the estimated values. The study proposes two phase protection schemes to accommodate inverter-based DERs injecting 1.2 pu and 2.0 pu of SCC for a 100% penetration level. This study contributes to improving the protection coordination of distribution networks with high penetration levels of DERs. The findings have practical implications for distribution system operators and planners to maintain safe and reliable operation of distribution feeders.

The paper builds up a wind farm simulation model by DIgSILENT software, and analyses the short-circuit current (SCC) characteristics of doubly-fed induction generators (DFIGs) and wind farm. Simulation analysis shows that DFIGs have different SCC characteristics compared with synchronous generators. The wind farm only provides little fault current when symmetrical fault occurs in the grid; while under asymmetrically grounding fault, the SCC in wind farm side mainly includes zero-sequence current, which shows that the wind farm has weak power characteristic. After integrating the wind farm into the power grid, sensitivity of current-based protection, transformer differential protection as well as phase selection element will be influenced at some extent. Some countermeasures to reduce the impacts of wind power integration on protection are proposed based on the analysis of the impacts of wind farm on protection.

Recently, deep learning has provided a new opportunity to achieve high precision and real-time parameter identification of the doubly-fed induction generator (DFIG) in the event of short-circuit fault. However, deep learning algorithms based on data training are facing the challenge of relying on a large amount of training data and poor generalization performance. In order to improve these shortcomings, we embed the forward calculation model of three-phase short-circuit current (SCC) into the neural network, and propose an unsupervised neural network which can realize high-precision parameter identification. The network only needs to convert the short circuit current curve into a two-dimensional gray level map to complete the precise training of the network without real labels, which effectively improves the fitting ability of the network for inverse problems. The simulation results show that the proposed method can achieve high precision identification of DFIG parameters both within and outside the domain, and verify the high precision identification and generalization ability of unsupervised networks.

Les hacheurs élévateurs à quatre phases parallèles et à commandes entrelacées (4IBC) sont largement utilisés dans les véhicules électriques à hydrogène (FCEVs) afin d’adapter la tension de la pile à combustible (PAC) au bus DC, assurer la tolérance aux défauts et réduire les ondulations de courant de la PAC. Etant donné que le poids et le volume constituent de réelles contraintes dans ces applications, la topologie du hacheur élévateur à quatre phases parallèles couplées inversement en cascade cyclique (4IBC-IC) a été adoptée. L’objectif de cette thèse consiste à améliorer la disponibilité des convertisseurs DC/DC, qui constitue une préoccupation majeure dans l’électronique de puissance. Dans ce contexte, un contrôle tolérant aux défauts de type court-circuit (SCF) et de type circuit ouvert (OCF), a été développé. La méthode de diagnostic proposée se base sur la mesure de la valeur moyenne des courants des inductances pour pouvoir identifier la phase en défaut, l’isoler et reconfigurer les signaux de commandes des phases saines. La régulation de la tension de sortie et des courants de phases est assurée par des correcteurs PI. Cette approche a été validée par simulation sur Matlab/Simulink et en simulation virtuelle en temps réel (VHIL) sur le logiciel Typhoon. Ces principaux résultats démontrent l'efficacité et la robustesse de cette approche à maintenir un fonctionnement optimal en mode sain et défaillant, sans générer de fausses détections.En raison des difficultés rencontrées pour obtenir des inductances couplées, la validation expérimentale de l’approche proposée a été validée sur un convertisseur 4IBC classique. Le contrôle tolérant aux défauts (FTC) a été exécuté et intégré sur La MicroLabBox DS1202 en utilisant une implémentation mixte entre son processeur et sa carte FPGA. Les résultats expérimentaux valident l’efficacité des résultats de simulation. Cette approche ne nécessite pas de capteurs supplémentaires, ni de temps d'échantillonnage élevé et elle est facile à mettre en œuvre. Elle peut facilement être intégrée aux contrôles existants et peut même être étendue à d'autres topologies de convertisseurs multi-phases.Afin de remédier aux limitations du correcteur PI, une amélioration des boucles de régulations a été proposée en utilisant des contrôleurs non-linéaires, qui sont robustes aux perturbations et aux variations et permettent d'améliorer la dynamique du convertisseur. Cette approche repose sur le contrôle par platitude de la tension de sortie et le contrôle par mode glissant pour la régulation des courants de phases. La particularité de cette amélioration est l'utilisation d'un observateur pour estimer la tension d'entrée et le courant de charge, afin d'optimiser judicieusement le nombre de capteurs sans utiliser de capteurs supplémentaires. L'approche de diagnostic proposée est également intégrée et communique les informations de présence de défauts avec les boucles de régulation et avec l'observateur afin d'optimiser le fonctionnement du convertisseur en mode défaillant. Les résultats de simulation montrent la robustesse de cette approche face aux variations et aux perturbations. Ces contributions améliorent la disponibilité et la robustesse des convertisseurs DC/DC et renforcent la position des FCEVs en tant qu'option viable et prometteuse pour le transport durable
Fuel cell electric vehicles (FCEVs) are seen as potential solutions and represent one of the most recent advances in the field of transport to reduce CO2 emissions. As the fuel cell is the main power source, a boost converter is required to increase its low voltage and adapt it to the DC bus voltage. The four-phase interleaved DC/DC boost converter with inverse cyclic cascade coupled inductors (4IBC-IC) has been confirmed as the most suitable architecture for fuel cell electric vehicles. Not only does it improve efficiency and reduce the converter’s size, but it also helps to extend the fuel cell's lifespan by reducing input current ripple. Since semiconductors are very fragile components, they can fail and degrade fuel cell system performance. Even if the converter architecture is fault-tolerant, it requires a fault-tolerant controller to ensure optimal operation in the event of disturbances or faults. In this context, a signal-based fault-tolerant control is proposed in this thesis to diagnose both short-circuit fault (SCF) and open-circuit-fault (OCF). Once the fault is detected, it is isolated by the control unit and the converter architecture is then reconfigured according to the fault location to ensure optimal operation. PI correctors are implemented to ensure the regulation of the output voltage and phase currents. Due to the unavailability of coupled inductors, this approach has been validated experimentally on a classical four-phase interleaved boost converter (4IBC) test bench using the MicroLabBox DS1202 with its processor and internal FPGA board to implement the fault-tolerant control.Simulation, on Matlab/Simulink and virtual hardware simulation (VHIL), and experimental results validate the robustness of the proposed fault-tolerant control. It is easy to implement and can quickly identify faults without the need for additional sensors. It operates efficiently without requiring high sampling rates, addressing one of the key limitations of signal-based methods. Given its simplicity of implementation, the proposed method can be easily integrated into existing controls and can even be extended to other multilevel converter topologies.To improve the robustness of the control unit, a novel fault-tolerant robust control approach has been proposed by replacing the traditional PI controllers with flatness-based and sliding mode controllers while incorporating an observer. The observer plays a key role in accurately estimating the input voltage and load current, ultimately ensuring high robustness against disturbances. A judicious optimization of the number of sensors is thus achieved, minimizing the cost and the probability of measurement errors. Simulation results in the Matlab/Simulink environment confirm the effectiveness of this approach. This significant contribution strengthens the reliability and robustness of DC/DC converters with coupled inductors and consolidates the position of the FCEVs as a promising sustainable mobility solution

The operation of electrical and electronic equipment may be affected by disturbances in the supply network. Voltage dips and short interruptions are common disturbances that involve sudden reduction of the supply voltage below a certain voltage level followed by restoration after a short interval. They are usually caused by faults in the electricity supply network such as presence of short circuit or by sudden large variation in electric loading. These unwanted electromagnetic interferences may cause malfunctioning of or even damage to the equipment. Therefore, it is important to conduct voltage dips and short interruptions immunity tests on electrical and electronic products. Voltage dips and short interruptions generators are key equipment for conducting immunity tests and these generators need to be verified. This paper describes a computer aided system developed by the Standards and Calibration Laboratory (SCL) for verification of voltage dips and short interruptions generators in accordance with the international standard IEC 61000-4-11 (2004-03). The parameters that can be calibrated are: ratios of the residual voltages to the rated voltage; the rise time, fall time, overshoot and undershoot of the switching waveform; and the accuracy of the phase angle at switching. A specially built adapter is used to convert the high voltage output waveforms of the generators to lower level signal to be acquired by a digital oscilloscope. An in-house developed software then analyses the captured signal to calculate the required parameters. The paper also discusses the uncertainty evaluations for the measured parameters.