Screening attenuation as a parameter of screened cables used in converter systems is one of the indicators of screen efficiency. Catalogue data rarely considers that parameter, especially with the division on frequency bandwidths. Screening efficiency may be deduced by analysis of the cable’s construction and type, but based on this, it may only be roughly estimated. The results of screening attenuation tests in a wide frequency bandwidth for chosen cable types are presented in the article. The methods of cable parameters testing based on standard PN-EN 50289-1-6:2009: Communication cables – Specifications for test methods. Part 1–6: Electrical test methods – Electromagnetic performance, were used. Afterwards, the emission of radiated electromagnetic disturbances of the converter drive was measured. The converter was using chosen cable types, for which screening attenuation was determined. Comparisons of the obtained results were presented and the influence of the screen type and cable parameters on the emission of radiated electromagnetic disturbances was analyzed. The obtained measurement results and presented analysis in the field of electromagnetic compatibility may be useful for designers of converter drive systems.

The paper summarizes the power loss results in induction machines supplied with distorted voltage. The voltage waveform contained the fifth and seventh harmonics components of adjustable level in the range of 0% to 30%. The influence of the harmonic content on the core and windings losses is of particular interest. The paper investigates the additive impacts of basic and additional losses resulting from distorted power supply conditions.

This paper presents the method of total harmonic distortion factor calculation, which could be applied for the salient pole synchronous generator with electromagnetic or permanent magnet excitation. The method takes into account the saturation of the magnetic circuit and actual winding scheme (including winding with fractional value of slots per pole and phase Q). The calculations are based on 2D FEM simulation that produces the radial (normal to stator surface) component of the magnetic flux density in the air gap. Total harmonic distortion factor is determined as a function of the shape of the pole shoe. The analysis is performed at a constant value of equivalent air gap. The task is to find the shape of the pole shoe that guarantees the minimal value of the distortion factor KDIST.

The article presents some of the results of measurements of loads for a selected tram traction substation for a continuous period of time covering sixteen weeks (112 days). Particular attention was paid to overloads occurring in consequent days. The second part of the article presents the analysis of overloads relating to the time interval of 60 minutes in successive days. This analysis was implemented in Matlab using a two-layer feedforward artificial neural network (ANN). The results of the approximation of the analyzed overloads are promising. A continuation of research may lead to the formulation of mathematical equations that might be useful for designers in terms of sufficiently precise calculations of overloads of rectifier units of DC traction substations.

Induction generators are widely used to generate electrical power in small hydraulic applications. The main disadvantage of stand- alone induction generators is the problem of regulating the voltage magnitude and voltage frequency under load variation. This paper investigates a three-phase self-excited induction generator (SEIG) operating under varying load, utilizing the water energy in a small reservoir hydropower plant. The generator excitation is provided by a three-phase capacitor bank and an inverter with Space Vector Pulse Width Modulation (SVPWM). Furthermore, the inverter with a battery controls the active power flow between the generator and the load in order to provide a constant frequency of voltage. The proposed control scheme consists of two PI controllers. The first controls the voltage magnitude by regulating the inverter reactive power, while the second one adjusts the guide vanes of the turbine according to the DC voltage of the battery. The proposed control system has been tested under load step changes. The simulation results of the system, obtained using the Matlab/Simulink software, have demonstrated good control performance.

Electrical machines, such as welding arc devices, negatively affect the quality of electric power in a supply network, which in turn affects the operation of loads connected in parallel. The aim of this paper is to present the results of research confirming the positive effect of a passive L-C filter dedicated for welding devices. The paper demonstrates the effectiveness of the filter, which not only helps to reduce the total voltage distortion, but the reactive power compensation as well. The results confirm that installing a passive controlled L-C filter significantly reduces power losses in elements of the power supply network. The conducted research leads the authors to recommend using such filters in electrical arc devices.

Wykorzystanie metody middlebrook’a do analizy częstotliwościowej układów energoelektronicznych

Kompatybilność elektromagnetyczna przekształtnika energoelektronicznego wykonanego w technologii sic.

Producenci komponentów energoelektronicznych wprowadzają obecnie do swoich produktów węglik krzemu (SiC) a tranzystory MOSFET wykonane w tej technologii, pracujące w szerokim zakresie napięciowym i prądowym są dostępne na rynku. Charakteryzują się one wysoką częstotliwością pracy sięgającą 100 kHz i niskimi stratami przełączania. Technologia węglika krzemu umożliwia budowę przekształtników energoelektronicznych, które charakteryzują się w porównaniu z tradycyjną technologią (Si), wysoką sprawnością, mniejszymi gabarytami, mniejszymi elementami pasywnymi oraz większą tolerancją termiczną. W artykule przeanalizowano aspekt kompatybilności elektromagnetycznej przekształtnika wykonanego w technologii SiC. Zaprezentowano wyznaczone poziomy zakłóceń generowanych przez przekształtnik do sieci zasilającej w zakresie harmonicznych i interharmonicznych. Przedstawiono wyniki zaburzeń elektromagnetycznych przewodzonych generowanych do sieci zasilającej, których zwiększone poziomy mogą utrudniać spełnienie przez przekształtnik odpowiednich wymogów normatywnych oraz mogą wpływać niekorzystnie na pracę urządzeń przyłączonych do tej samej sieci zasilającej. Dodatkowo przeanalizowano poziomy zaburzeń elektromagnetycznych przewodzonych również na wyjściu układu przekształtnikowego, których zwiększone poziomy mogą doprowadzić do problemów w zapewnieniu tzw. kompatybilności wewnętrznej badanego układu lub być źródłem emisji elektromagnetycznej promieniowanej. Przedstawione w artykule wyniki badań i analiz przeprowadzone w szerokim paśmie częstotliwości umożliwiają ocenę zastosowania technologii węglika krzemu (SiC) w układzie przekształtnika w zakresie EMC.

Artykuł przedstawia możliwość zastosowania sygnału strumienia poosiowego w diagnostyce maszyn indukcyjnych małej mocy, pracujących przy zmiennych warunkach obciążenia. Badaniom poddano przypadki niesymetrii wirnika i obwodu stojana dla stanu ustalonego oraz przejściowego. Pomiary laboratoryjne zostały wykonane na zmodyfikowanym silniku, przystosowanym do pomiaru napięcia wprost proporcjonalnego do strumienia unipolarnego, za pomocą wbudowanej cewki w tarczy łożyskowej. Przykłady uzyskanych przebiegów oraz danych liczbowych uzupełniono o wnioski i przegląd dotychczasowej wiedzy z zakresu zastosowania sygnału strumienia poosiowego w diagnostyce maszyn klatkowych.

Artykuł dotyczy anizotropowych właściwości typowych blach prądnicowych. Przyczyną anizotropii magnetycznej takich blach jest występowanie w nich pewnych tekstur. Krótko scharakteryzowano typy tekstur najczęściej występujące w tych blachach. Dla kilku wybranych blach prądnicowych przedstawiono wartości typowych parametrów magnetycznych dla różnych kierunków magnesowania. Zaproponowano metodę uwzględnienia anizotropowych właściwości blach prądnicowych w obliczeniach zmian indukcji podczas przemagnesowania osiowego i obrotowego. Specjalnie dobrana funkcja rozłożenia ziaren w danej blasze pozwala uwzględnić anizotropowe właściwości w obliczeniach zmian indukcji. Przykłady zmian indukcji podczas przemagnesowania osiowego i obrotowego przedstawiono w końcowej części artykułu.

Calculation of power losses in transformer steel sheets is still a significant problem. In some places of cores of a three-phase transformer the flux density is not parallel to the rolling direction; it especially refers to the so-called T-points of the transformer cores. In these places magnetization curves differ from the curve measured for the rolling direction. The paper deals with hysteresis losses, eddy current and excess losses and their dependences on the direction of magnetization processes. Analysis is performed for several frequencies of the magnetization process. Measured power losses of the selected transformer steel sheets are compared with results obtained on the basis of the analytical formulas.

The subject of the paper is to present innovative technological architecture of the power supply system EPS (Electric Power System) in the field of high voltage power HVDC (High Voltage Direct Current) by conducting a critical analysis of the literature as well as an analysis and simulation of its selected component in line with the trend of more electric aircraft MEA (More Electric Aircraft). The considered advanced technologies relate to the architecture of the power supply system HVDC in the high voltage 540V DC (±270 V DC) and 350 V DC, used for advanced aircraft in line with the trend of MEA/ AEA, in particular for military aircraft made by Lockheed Martin (F-22 Raptor, the JSF F-35). Based on the above, the simulation of sample components of the system architecture of high voltage power HVDC has been made, selected from the group of military aircraft in the area of more electric aircraft ’More Electric Aircraft’, which is mainly the domain of advanced military aircraft the JSF (Joint Strike Fighter) F-35 and F-22 Raptor. In the final part, the paper presents the main conclusions arising from the analysis and simulation of selected components of HVDC power system architecture in accordance with the concept of a more electric aircraft.

In the article based on the fundamental laws of physics and mathematics has been formulated mathematical model to analyze the electromagnetic waveforms in electrical power systems with non-linear loads, such as arc furnaces.

In the paper, alternative technologies of electric machines for domestic appliances were discussed. Nowadays, domestic appliances are used on a mass scale. In most households, there are domestic appliances where electric machines are used. Commutator motors are generally used in domestic appliances due to low costs of production. This is one of their few advantages, whereas to their disadvantages can include low energy efficiency and durability, which is limited by the sliding contact of brush-commutator. In consequence, devices equipped with these motors have low efficiency of energy conversion and are very often unreliable. In recent years, the vacuum cleaner became the receiver of relatively high power from the mains. Therefore, vacuum cleaners were covered by EU regulations. An increase of the energy efficiency of domestic appliances where electric machines are used is possible, among others, by introducing energy- saving technologies in electric machines. They are characterized not only by higher energy efficiency, but also by much longer failure-free operation of domestic appliance drive.

Atmospheric icing on traction lines is very important problem because it causes difficulties of using electric vehicles by people and can result to breaking of traction lines. Heating the wire can preventing atmospheric icing.

In the paper, the results of laboratory tests of a surface mounted permanent magnet brushless motor were presented. Two power electronics systems, which are made as inverters for PMSM and BLDC motors, were used. The PMSM inverter supplies the motor with sinusoidal currents and the BLDC inverter supplies the motor with trapezoidal voltage. The motor characteristics and its waveforms were determined when the motor was supplied from the BLDC inverter and the PMSM inverter. A comparison of the influence of the motor supply method on its features and parameters was performed.

This article presents various forms of fuzzy queries with a particular emphasis of two different approaches to the representation of fuzziness, a detailed analysis of these queries and their conversion into standard SQL queries using Oracle 11g XE. The actions discussed above point out to the methods of obtaining fuzzy information from the database that have been easy to implement. A qualitative and quantitative study about the use of fuzzy queries on relational databases has been included in this article, as well. This research takes into account the fact that obtaining this type of information is not supported by any commercial database management system.

The mathematical model of a DC motor control system’s dynamic work with series impulse was designed. Control is performed by thyristor’s ignition angle changing with doubling voltage. The parametric optimization was realized by genetic algorithm. The main genetic operators were crossover and mutation.

The paper summarizes models and methods of data center resource management for SaaS. An approach for the allocation of computing resources for single-tenant SaaS was proposed. Different cases of this problem for excess and lack of computing resources were considered. Those problems belong to the classes of linear and nonlinear Boolean programming. In order to solve the mentioned problems, heuristic and genetic algorithms have been proposed. A comparison of their effectiveness was made.

In this article the methods’ review of a control system’s parametric optimization have been performed. According to the revealed analysis, the genetic algorithms have been chosen as the most appropriate tools for these tasks. Using genetic algorithms, the global optimum could be identified. To demonstrate it the system’s parametric optimization, which consists of controlled three phase half wave rectifier and DC motor with independent excitation has been executed, using a classic genetic algorithm.