Wydzial Elektryczny

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Karolewski B.,Wydzial Elektryczny | Urbanski P.,University of Lodz
Przeglad Elektrotechniczny | Year: 2017

Cooperation between small renewable power station and the supply system was studied. 3 induction generators, powered by wind turbines or 3 induction motors are working in the power plant. Selected results of the analysis of the system operation made static methods were compared with those obtained by simulation using programs for the system modeling. Voltage drops on the elements of the system in different variants work of machines was studied. The obtained values of short-circuit currents of three-phase and single-phase were also compared. The results obtained by various methods are generally similar, but there are also significant differences between them. © 2017, Wydawnictwo SIGMA - N O T Sp. z o.o. All rights reserved.


On-line dynamic security assessment has grown in popularity in recent years due to the need to deal with the ever-increasing challenges of secured system operation. In on-line security assessment systems, a snapshot of the actual system condition is captured and analytical engines are used to assess security in near-real-time. This has greatly reduced the uncertainties previously introduced by forecasting required in conventional off-line operational studies. Basic on-line VSA systems are now quite mature, and new features and functions are in development including more comprehensive analyses and artificial intelligence that can be used to assist the operators in maintain secure systems. The paper presents a highly automated method identifying voltage control areas, areas prone to voltage instability, and reactive power reserves requirement ensuring voltage stability under all considered contingencies.


Piasecki S.,Warsaw University of Technology | Jasinski M.,Warsaw University of Technology | Rafal K.,Warsaw University of Technology | Korzeniewski M.,Politechnika Biallostocka | Milicua A.,Wydzial Elektryczny
Przeglad Elektrotechniczny | Year: 2011

The paper presents overview of high-order harmonics compensation methods applied for control of grid-connected converter. Two harmonic compensation methods are presented. One based on band-pass filers cooperating with Direct Power Control with Space Vector Modulation (DPC-SVM) is dedicated for renewable energy interface. Second method based on resonant controllers applied in Voltage Oriented Control (VOC) adds an active filtering function to PWM rectifier. Simulation and preliminary experimental results for these two methods are presented.


Glinka T.,Wydzial Elektryczny | Olech W.,Zaklad Pomiarowo Badawczy Energetyki | Glinka M.,BOBRME Komel w Katowicach
Przeglad Elektrotechniczny | Year: 2012

Unit transformer is usually connected directly to synchronous generator. Transformer windings are subject to all perturbations, coming from both generator and power grid. The paper lists different types of possible perturbations and presents example of unit transformer failure which occurred in one of thermal power stations.


Machowski J.,Warsaw University of Technology | Kacejko P.,Wydzial Elektryczny | Robak S.,Warsaw University of Technology | Miller P.,Wydzial Elektryczny | Wancerz M.,Wydzial Elektryczny
Przeglad Elektrotechniczny | Year: 2013

Stability analyses of a power system are conducted at short-term and mid-term planning of transmission network development. Recent years have seen transmission networks working closer and closer to their technical capability. Therefore it is necessary to conduct even a simplified power system stability assessment also at long-term planning. The article shows that very simple criteria of angle stability and voltage stability based on short-circuit power can be used for the sake of long-term planning. The suggested criteria were verified for a real large-scale power system.


The relatively recent fractal theory has disclosed a description of the Word surrounding us different from the classical owe. New tools to describe processes difficult to be examined so far, have been developed. Fractal analysis is used in many areas of science, from biology and medicine to geography and computer science. In the paper an attempt has been made to avail of certain components of this theory, successfully applied in others fields of science, in order to analyze the processes of generating electricity by wind farms. Attention has been focused on examination of similarity and self-similarity. Relationships between power versus wind velocity dependencies and hurst exponent have been checked. Studies on similarity between stochastic time series (wind velocity time dependencies) and generated power for a given wind turbine have been carried out. On the basis of the studies a model has been developed in order to create short-term forecasts of electric energy production in wind farms. A statistical approach has been used, whose main goal is to find a relationship between the processes wind speed - generated energy.


An effect of the way and accuracy of modeling automatic control systems of generating units on parameters of the power system stability evaluation has been investigated. The evaluation parameters are the following: values of the critical short-circuit time tkr, and corresponding to them values of the stability margin kt, and the regulation times t50% and t15%. The obtained results make an attempt to establishing the effect of the way generating units are modeled on the conclusions following from the power system stability analyses.


Borowik L.,Wydzial Elektryczny | Kurkowski M.,Wydzial Elektryczny
Rynek Energii | Year: 2013

The paper presents provisions of EU Directives on energy efficiency equipment used for lighting installations. Attention to recommendations for measurements with meters and transparency of information on energy consumption is paid. It describes the results of audits of lighting installations of premises public buildings and indicates how much data on electricity consumption by the end devices (such as lighting) are insufficient or uncertain. We analyzed requirements for obtaining energy saving methodology. Necessity of power transmission control systems has been indicated. The paper also presents a system developed for the control and monitoring of power and performance of lighting installations equipment.


Piatek Z.,Wydzial Inzynierii i Ochrony Srodowiska | Baron B.,Wydzial Elektryczny | Szczegielniak T.,Wydzial Inzynierii i Ochrony Srodowiska | Kusiak D.,Wydzial Elektryczny | Pasierbek A.,Wydzial Elektryczny
Przeglad Elektrotechniczny | Year: 2013

In this paper, using a definition of a mutual inductance for two conductors of any shape and finite lengths, the new exact closed formula for mutual inductance between two thin tapes whose axes are parallel and whose widths are perpendicular is proposed. In case of direct current (DC) or low frequency (LF) this inductance is given by analytical formula. The mutual inductance between two long thin tapes whose plans are perpendicular to one another is also presented.

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