Wrocław University of Science and Technology
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431 research outputs found
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Analysis of Distorted Waveforms in Power Converter Systems
Full text linkThe paper presents a method of determining the frequency developed and based on the Prony model. The method was derived for those cases in which the process contains two dominant harmonics and noise. Additionally, in order to improve the accuracy of the method, median filtering was applied. The presented methods can be useful for practical applications in power systems, like the control systems of frequency converters
Wykorzystanie pakietu FILTR'96 w dydaktyce i projektowaniu cyfrowych filtrów FIR
Full text linkW artykule przedstawiono przykładową realizację zadania dydaktycznego w ramach prowadzonych kursów z bloku przedmiotowego "Cyfrowe Przetwarzanie Sygnałów". Zaprezentowano temat aplikacyjny wykorzystujący autorskie, nowe koncepcje projektowania filtrów FIR. Szczególną uwagę zwrócono na aspekty przetwarzania i identyfikacji w czasie rzeczywistym zakłóconych sygnałów okresowych. Zasygnalizowano możliwość praktycznego zastosowania filtrów nierekursywnych w zagadnieniach automatyki pomiarowej, których współczynniki wyznaczane są z uwzględnieniem tzw. Kryterium Fazy Optymalnej (KFO). Stwierdzono, że w ogólnym przypadku kryterium KFO pozwala na zmniejszenie wartości charakterystyki amplitudowej (oraz błędów kwantyzacji) bez zwiększania stopnia filtru
New Digital Algorithms for On-line Determination of Symmetrical Components in Power Systems
Full text linkUsing the Fourier method the Kalman theory and the Walsh functions, non-recursive algorithms for the on-line determination of the basic waveforms of the symmetrical components in three-phase power systems are introduced, investigated and compared. The circular rotating phasors of the symmetrical components are calculated from the orthogonal components instead of the three original signals. The numerical operations required for the on-line calculation can be reduced by one third. The developed algorithms combine the suppression of higher frequencies and the separation of the symmetrical positive- and negative-sequence components
Control and Grid Synchronization for Distributed Power Generation Systems
No full textOverview--- Main DPGS structures, PV and fuel cell (FC) system, Classification of wind turbine (WT) systems with regard to the use of power electronics, Control structures for grid-side converter , Characteristics of control strategies under grid fault conditions , Grid synchronization method
Reliability and Renewable Sources
No full textReliability in electrical power system Renewable Sources. Energy production from waste water. Electricity generation from supplied drinking water. Problematic Largest Hydropower Project. Wind Turbine Cylinders with Spiral Fin
Waveform Distortions due to AC/DC converters feeding DC arc furnaces
Full text linkThe line-commutated converters cause significant harmonic distortions in electrical power systems. They can operate as a six-pulse converter or configured in parallel arrangement for high-pulse operation; twelve pulse converters are usually used for DC arc furnaces. The DC arc furnaces can cause time varying power quality disturbances in the feeding network, mainly waveform distortion and voltage fluctuations. In this paper the problem of the waveform distortion assessment of these important disturbing loads is taken into account. The study is performed using computer simulations based on Power System Blockset, that is a tool of Matlab®, and using a chaos-based model for simulating the dc arc
Proceedings of the 8. International Conference on Environment and Electrical Engineering, Karpacz, Poland, 10-13. May 2009
No full textThe aim of the Conference is to promote a Forum, where people involved with electrical power systems may exchange their experiences and present solutions found for actual and future problems.
Topics: A. Renewable energy sources 1. Wind energy, wind turbines 2. Solar energy 3. Photovoltaic cell technology 4. Hydro energy 5. Ocean energy: tidal and wave 6. Biomass 7. Biofuels B. Nuclear energy C. Energy storage 1. Electrochemical batteries 2. New generation batteries 3. Ultracapacitors D. Hydrogen based sources 1. Hydrogen transport and storage systems 2. Fuel cell 3. Hydrogen generation with fossil fuels and carbon sequestration and capture E. Power Systems 1. Power Quality 2. Design, Control and Management 3. Protection 4. RAM (Reliability, Availability,Maintainability) 5. Grid integration of renewable energy sources 6. Management of MV/LV distribution grids with Distributed/Renewable Generation F. Components 1. Generators for wind turbines 2. Hydro turbines 3. Electrical generators 4. Power electronic converters for renewables 5. Hydrogen combustion G. Regulatory, legal and economic aspects 1. Investment and support schemes-Tax support schemes 2. Integration of renewables in electricity markets 3. Certificate systems H. Environmental aspects and Pollution I. Signal Processing 1. Circuits and systems theory and applications 2. Nonlinear aspects of power systems 3. Signal processing and identification J. Innovative educational method
Power Quality Analysis of Grid-Connected Wind Turbine System
Full text linkIn this paper time-frequency methods have been investigated for complex investigations of transient states in wind power plants. Application of parallel processing in time and frequency domain brought new findings in description of wind power plants working under transient conditions. Proposed algorithms represents standard Short-Time Fourier Transform (STFT) as well as alternative methods associated with Cohen’s class, called Choi-Williams Distribution (CWD). In order to explore advantages and disadvantages of the method several experiments were performed using model of squirrel-cage induction machine connected directly to the grid. Investigated phenomena concerns power distortion caused by faults in comparison with influence of the wind speed
New solution to the problem of bipolar injection in insulator and semiconductor devices
Full text linkA problem of the space charge transport with two mobilities is presented. It is found that interactions between carriers can be described by the n(p) relationships. Three stable states of the charged capacitor occur. The stability problem is studied by the first approximation method. The laws of Ohm, Fowler-Nordheim, Schottky and Child are obtained
Power Quality in Industry - Problems and Solutions
No full textLecture based on ABB Power Quality Semina