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Stator current signal crossing for fault diagnosis of self-excited induction generators
Get PDFThis paper presents a novel method for modelling and diagnosis of electrical and mechanical faults in fixed-Speed Self-Excited Induction Generators (SEIGs) operating in autonomous mode in a small-scale wind energy system. The proposed method is validated using the finite element method. After the selection of the magnetising capacitors, the self-excitation process is performed under no-load conditions. Once the stator voltage is established, a symmetrical three-phase load is connected. The fault detection method introduced here is called Stator Current Signal Crossing (SCSC). The SCSC extracts a new signal from the stator currents, that enables the detection of stator inter turn shortcircuits, broken rotor bars, and dynamic eccentricity faults in SEIGs. A spectral analysis of SCSC using the Fast Fourier Transform (FFT) algorithm is used to precisely locate the induced fault components. What sets this fault-tracking method apart from its predecessors is its exceptional ability to detect faults of any magnitude by analysing the modulation of the SCSC signal. These faults are directly identified by the presence of distinct harmonics, each indicative of a specific type of fault. This study also focuses on the SEIG in a wind energy system, whereas previous works have mainly addressed the induction machine in motor mode. In contrast, previous methods involved analysing a single current signal and isolating specific harmonics from a wide frequency range. The effectiveness of the proposed fault detection method and the self-excitation process are illustrated by simulation results and spectral analysis
New Technology and Logistics on the Railway
No full textThe conference New Technology and Logistics on the Railway was held in Prague, in May 5, 2022.
The 5th year of the Student Scientific Conference 2022 follows up on the previous Student Scientific Conferences with railway topics organized by the Faculty of Transportation Sciences in 2016, 2017, 2020 and 2021. The main topic of this year\u27s Student Scientific Conference is again the railway digitization, which is the main content of the Intelligent Transport Systems on Railways (ITS-R) project and the technological development of ITS-R in the Railways 4.0 project. Digitization, in addition to the management and security part, concerns passengers (internet access, etc.), information and check-in technologies, logistics and dispatching applications. The field of logistics is associated with the optimization of timetables and schedules, especially dynamic optimization responding to current anomalies and delays on the railway network, requiring the application of information technology such as big data, artificial intelligence, massive parallel (distributed) calculations and simulations etc. With the deployment of new technologies, it will be necessary to change the approach to training of dispatchers and drivers, so an integral part of the railway system is training based on the principles of simulators (e.g. locomotive simulators, of course with the ETCS system). Vehicle maintenance, infrastructure and their innovation, whether conventional lines or planned VRT, must also be an important part of the railway system.
Main participants were students of master\u27s and doctoral study programs from CTU in Prague, BUT Brno, University of Pardubice, VŠB-TU Ostrava and the University of West Bohemia, who are engaged in research in the field rail transport. The announced thematic areas of the conference covered the above-mentioned issues: Railways 4.0 - ETCS, digitization, Optimization in railway traffic management, Railway infrastructure innovation, Modern rolling stock, Environment and railways, New directions in maintenance, Logistics and management.
The Student Scientific Conference in 2022 was held under the patronage of the Dean of the Faculty of Transportation Sciences prof. Ing. Ondřej Přibyl, Ph.D.
Scientific committee:Josef Jíra (Czech Technical University in Prague - Faculty of Transportation Sciences)Tomáš Brandejský (Czech Technical University in Prague - Faculty of Transportation Sciences)Antonín Blažek (Enteria a.s.)Martin Jacura (Czech Technical University in Prague - Faculty of Transportation Sciences)Aleš Hába (University of Pardubice – Faculty of Transport Engineering)Zdeněk Kaufmann (SIZI)Martin Král (SŽ, s.o.)Petr Kolář (SŽ, s.o.)Jaroslav Grim (SIZI)Martin Leso (Czech Technical University in Prague - Faculty of Transportation Sciences)Petr Nachtigall (University of Pardubice – Faculty of Transport Engineering)Otto Plášek (Brno University of Technology – Faculty of Civil Engineering)Jindřich Sadil (Czech Technical University in Prague - Faculty of Transportation Sciences)Richard Svoboda (Brno University of Technology – Faculty of Civil Engineering)Lukáš Týfa (Czech Technical University in Prague - Faculty of Transportation Sciences)Jaroslav Vašátko (VUZ, a.s.)Jakub Vágner (University of Pardubice – Faculty of Transport Engineering)Jan Řezníček (Czech Technical University in Prague - Faculty of information technology)Jiří Chludil (Czech Technical University in Prague - Faculty of information technology)
Local organizing committee:Vít Fábera, Ph.D. - předsedaJitka ŘezníčkováJitka JírováJan ZelenkaLukáš SvobodaJitka Řezníčková Jr.Jan Řezníček
Guarantor of the peer review process:prof. Ing. Josef Jíra, CSc
Optical Investigation of a Spark Gap for DC Protection around Current Zero
Get PDFThe applied experimental setup consists of a pair of fixed electrodes forming a short gap in air. The electrodes are connected with a thyristor forming a parallel current path. Once the thought flashover ignited arc has burnt a given time in the range of several hundreds of microseconds, the thyristor will be fired causing a commutation of the current in the semiconductor path. Hence, the current through the electrode gap will be reduced. The extinguishment of the arc permits the creation of a current zero in the gap. The focus of the experimental work is set to the analysis of the arc plasma during the DC phase and its distinction in the current extinction phase (current zero). High speed camera observation and optical emission spectroscopy are carried out and combined with the electrical measurements
Survey of user needs and the impact of parking prices on drivers’ motivation to use parking spaces in the capital city of Prague
Get PDFThe paper deals with the possibilities of implementing dynamic tariff regulation of on-street parking spaces in the capital city of Prague. Achieving optimal results is conditioned by the implementation of advanced technologies, but at the same time, the dynamic tariff regulation must follow the applicable legislation and, above all, be accepted by drivers. For this reason, the paper briefly discusses the technical and legislative possibilities of implementation, and most attention is paid to the conducted survey of user needs. The survey investigates the impact of parking prices on drivers’ motivation to park their vehicles in the area
Analysis of objective eye tracking data used for vehicle assessment
Get PDFThis paper describes the application of eye tracking technology in the automotive industry in the context of vehicle assessment in customer clinics. The paper presents the mentioned technology, the applied experimental methodology and selected results. In particular, the hypotheses that were expressed during the research of the topic and during the preparation of the experiment are answered. In this way, the innovative technology of eye tracking can be used to reflect the "voice of the customer" in the vehicle design
Development of advanced driving simulator for driving schools
Get PDFThis paper describes development of an innovative advanced driving simulator (ADS), that will be implemented into the driver education process as a method to improve education of students and thus their readiness to enter everyday traffic. ADS will allow the driving school students to get more practice in general vehicle control, unusual situation solving and use of modern assistant systems, as well as objectively evaluate student’s skills by the instructor. As a conclusion, expected outcomes of innovative simulator design and results validation possibilities are discussed
Local defect formation in short glass fibre reinforced polymers – micro-mechanical simulations and interrupted in-situ experiments
Get PDFDiscontinuous fibre reinforced polymers are widely used in various industry sectors and often replace conventional materials, due to lower production costs and their lightweight structure. For improvement of the component design, detailed knowledge of the failure mechanisms are necessary. To better understand the defect formation and thus the micro-mechanics, the strain behaviour in single fibres was analysed by micro-mechanical simulations of Representative Volume Elements (RVE). Therefore, selected fibres – similar orientated as in the real structure – were chosen for detailed analysis. Additionally, the defect formation next to selected fibres was investigated by X-ray computed tomography (CT). Furthermore, the critical fibre length was estimated based on the protruding fibre length of the fracture surface. Overall the simulation results correspond to theory. However, the detailed local inspection of the experimental volume data showed a rather strong influence of neighbouring fibres
Electrical and Optical Investigation of an Electric Arc in Hydrogen for short gaps
Get PDFHydrogen or mixtures containing hydrogen represent attractive gases for low-voltage switching devices because of increased arc quenching behaviour. However, fundamental electrical properties of arcs in hydrogen are still not well known. In this paper, first results of a study of a DC switching arc in pure hydrogen at 1 bar between graphite electrodes are presented for low currents of 8 and 16 A. The arc voltage and current are measured during contact separation. High-speed images of the arc are processed to determine the arc length considering the high arc dynamics with erratic elongations and jumps of the electrode attachment. The arc voltage dependence on the length results in a typical sheath voltage of approximately 23 V and mean electric fields in the arc column of 18.7 V/mm at 8 A and 10.8 V/mm at 16A
Simulative Comparison of Radiation Model Parameterizations for Direct Current Arcs in a Busbar Setup
Get PDFThe influence of different methods for calculating mean absorption coefficients on the mean arc voltage and velocity of an arc moving in air along parallel busbars is investigated in a numerical arc simulation. The radiation model used is the discrete ordinate method. Planck, hybrid and Rosseland mean calculations for a three- and six-band selection are discussed. Compared with the experimental results from a published paper, the Planck mean for six bands shows the most promising results
The footbridge Jesípek – application of radar interferometry for dynamic response evaluation
Get PDFRecent advances in radar systems have led to the development of radar interferometry (RI) methods for contactless vibration monitoring of large-scale structures, i.e. bridges, water tower reservoirs, and factory chimneys. Interferometric radars are devices capable to measure with 200 Hz sampling frequency and relative movement precision of 0.1 mm up to 0.01 mm. The major part of this paper describes an in-situ footbridge experiment near Hradec Králové. Radar interferometry devices were deployed along with ordinary techniques compounded by accelerometers, wiring, and acquisition station. Experiment was focused on the evaluation of basic dynamic structural properties such as natural frequencies and mode shapes. A lot of attention was also given to the result comparison of these measurement methods. Test results have confirmed the applicability of RI for bridge vibration monitoring