Wrocław University of Science and Technology
Repozytorium Eny Politechnika WrocławskaNot a member yet
431 research outputs found
Sort by
Układy kondensatorowe - zadania
No full textZadania - układy kondensatorowe, teoria pola, Podstawy Elektrotechniki
Modelowanie procedur przetwarzania rozproszonego w sieciach informatycznych laboratoriów dydaktycznych
Get PDFW referacie przedstawiono adaptację dedykowanego systemu przetwarzania rozproszonego, przeznaczonego do wdrożenia w studenckich laboratoriach-sieciowo komputerowych wydziałów elektrycznych ze szczególnym uwzględnieniem zagadnień z zakresu kursów z cyfrowego przetwarzania sygnałów oraz metod numerycznych w technice. Podstawowym założeniem projektu było przyjęcie formuły maksymalnej zwięzłości semantyki logicznej oraz przenośności oprogramowania pomiędzy różnymi systemami operacyjnymi, uniezależniając tym samym meritum zagadnienia dydaktycznego od platformy systemowo-sprzętowej
Numerical calculation of varistor model for sinusoidal signal
Get PDFZnO varistors are semiconductor devices with highly nonlinear current-voltage characteristic and are widely used as devices for overvoltage protection. Varistor applications range from the use of small varistors to protect electronic components to large varistors for protection of power systems. This paper presents proposed model of ZnO varistor and methodology of its mathematical analysis and simulation. The mathematical analysis of the proposed model makes it possible simulate the current trace on a nonlinear element
Adaptive estimation of wide range frequency changes for power generator protection and control purposes
Get PDFA method and a detailed adaptive algorithm for wide-range frequency change measurement is presented. The method is based on a two-stage operating principle in which the results of a coarse frequency measurement are used for both orthogonal filter adjustment and modifications to the basic algorithm that is applied to fine frequency estimation. The adaptive features ensure good selectivity of the algorithm (in the sense of higher and subharmonic attenuation) within the range 5 to 80Hz. Simulation results presented confirm good accuracy of frequency estimation in the presence of a standard noise level in the input signal, as well as satisfactory frequency tracking properties of the algorithm at relatively high frequency changing rates
Real-time Implementation of Adaptive Amplitude Estimators for Protection and Control Purposes.
Get PDFIn the paper a new fast and adaptive scheme for measurement of signal amplitude for protection and control purposes is presented. The algorithm developed is intended for amplitude tracking of the distorted sinusoidal signals with varying frequency. Wide frequency band features of the estimator are obtained by adaptive on-line changes of the orthogonal filter parameters (data window length) and coefficients in the measurement equations according to the observed actual frequency being tracked with special but simple digital procedure. The developed algorithms have been tested with MATLAB and EMTP-ATP generated signals. Practical implementation of the adaptive scheme on the TMS signal processor is described in the paper. The real-time tests have shown that the time required for execution of all equations of the adaptive estimator within one time-step was equal to 0.14ms, which allows working with the sampling frequency set to 7kHz. That means that real-time application of the adaptive algorithm for estimation of amplitude of both currents and voltages is utterly attainable
Design of an analogue filter
No full textSynthesize a normalized low-pass filter (Butterworth, Chebyshev or other) of order n (3-6). Draw the circuit and give the values of all components. Based on the normalized low-pass filter, design a high-pass or band-pass or band-stop filter at a given 3dB cut-off frequency (frequencies) and terminated with a resistive load of m Ohm
Wavelets and Prony Method for Disturbance Detection in Wind Farms
Get PDFWind generator impact on power quality is crucial for power system operation. This paper presents assessment of transients originated in a power system with fixed speed wind farm. Faults in the power system and switching capacitor bank cause transients. Detailed power quality studies on transients are helpful in better assessment of the phenomena. Prony method and wavelets have been applied to determine signal parameters in different operation modes of wind generation unit
Accurate Location of Faults on Three-Terminal Line with Use of Three-End Unsynchronised Measurements
Get PDFThis paper presents a new fault location algorithm for three-terminal line utilising unsynchronised measurements of three-end currents and voltages. The distributed parameter line model is strictly considered for formulating three subroutines of the algorithm. Efficient procedure for selecting the valid results is introduced. The presented results of the ATP-EMTP evaluation prove the validity of the fault location algorithm and its high accuracy
Simulative Analysis of a New Type Wide Range Estimator of Protection Criterion Values
Get PDFIn the paper a new adaptive estimator of protection criterion values insensitive to wide range power system frequency changes is proposed and analysed. Its operation is based on a coarse calculation of signal frequency and appropriate correction of used orthogonal filters frequency responses as well as adaptation of chosen parameters of the measurement algorithm. The main features of the new method has been compared with standard criterion values estimators both theoretically and by simulations. The proposed estimators assure good accuracy of measurement within the frequency range from 5 to 95 Hz
Application de Revêtements en Silicone sur les Isolateurs en Porcelaine en Pologne
Get PDFSilicone coatings have been used to improve insulating properties of outdoor insulators, under polluted conditions, for over 30 years. In Poland this method was used for the first time in 1995. This paper presents Polish experiences and analyzes the usefulness of such coatings. Changes in pollution emission and their influence on operation and investments of outdoor insulation were taken under consideration. Résumé: Les revêtements en silicone ont été utilisés pour améliorer les propriétés isolantes des isolateurs de types extérieurs sous pollution, depuis plus de 30 années. En Pologne, cette méthode a été utilisée pour la première fois en 1995. Ce papier présente des expériences polonaises et analyse l'utilité de tels revêtements. Les changements dans les émissions de la pollution et leur influence sur l'opération et les investissements d'isolement extérieur ont été pris en considération