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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. Source


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. Source


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. Source


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. Source


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. Source

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