Andrzej Sikorski and Marek Korzeniewski
The aim of the paper is to conduct an analytical study of a new method of induction motor torque and flux direct control with nonlinear controllers.
Abstract
Purpose
The aim of the paper is to conduct an analytical study of a new method of induction motor torque and flux direct control with nonlinear controllers.
Design/methodology/approach
The method is based on the inverter state predictive determination in order to minimize the torque and flux errors.
Findings
The proposed method allows one to eliminate known DTC disadvantages, i.e. the hexagonal flux shape and nonsinusoidal current at a low motor speed, and also secures a decrease of torque and flux pulsation.
Practical implications
This new method enables a more precise reproduction of the motor torque and flux command signals, working with the same sampling frequency of the control processor as in the case of the standard DTC method. The decreased torque pulsations cause a decrease of the motor speed pulsation.
Originality/value
An innovative optimal control method is presented. The correctness of the initial assumptions as well as the expected final results have been verified in practice.
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Andrzej Sikorski and Rafał Grodzki
The aim of the paper is to conduct an analytical study of the two new methods of the permanent magnet synchronous motor torque and flux direct control with the predictive…
Abstract
Purpose
The aim of the paper is to conduct an analytical study of the two new methods of the permanent magnet synchronous motor torque and flux direct control with the predictive non‐linear torque and flux controller.
Design/methodology/approach
The method is based on the prediction of the torque and flux error vector in order to minimize the torque ripple and ensure the constant switching frequency.
Findings
The proposed methods ensure the torque and flux error vector minimization, reduction of the torque ripples, and constant switching frequency without deterioration of the dynamic properties of the standard direct torque control (DTC).
Originality/value
An innovative predictive DTC method is presented. The correctness of the analysis and main assumptions, as well as the expected final results have been verified in simulation.
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Zbigniew Leonowicz, Tadeusz Lobos and Krzysztof Wozniak
The purpose of this paper is to compare the accuracy of tracking the amplitude and frequency changes of non‐stationary electric signals.
Abstract
Purpose
The purpose of this paper is to compare the accuracy of tracking the amplitude and frequency changes of non‐stationary electric signals.
Design/methodology/approach
Short‐time fourier transform (STFT) and S‐transform algorithms were applied to analyze non‐stationary signals originating from switching of capacitor banks in a power system.
Findings
The S‐transform showed possibilities of sharp localization of the basic component, and allowed improvement of tracking dynamism the transient components in comparison to STFT.
Practical implications
S‐transform is a better tool for the analysis of non‐stationary waveforms in power systems and its properties can be used for diagnostic and power quality applications.
Originality/value
The dynamic tracking of the changes in time and frequency of real‐like signals originating from a power system are investigated in this paper.
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POLAND: Defence leadership
Details
DOI: 10.1108/OXAN-ES290853
ISSN: 2633-304X
Keywords
Geographic
Topical
Andrzej Ochrem, Dominika Kułaj, Joanna Pokorska, Justyna Żychlińska-Buczek, Piotr Zapletal, Ewa Drąg-Kozak and Ewa Łuszczek-Trojnar
The aim of the study was to analyse the quality changes in marinated herring meat depending on the moment of adding milk thistle.
Abstract
Purpose
The aim of the study was to analyse the quality changes in marinated herring meat depending on the moment of adding milk thistle.
Design/methodology/approach
One control (C) and two experimental groups were investigated: MH (milk thistle added to a marinade solution) and FH (fillets rubbed with milk thistle before marination). The basic chemical composition, the meat colour, heavy metals concentration, fatty acids profile, quality of lipids and antioxidant capacity were determined.
Findings
The occurrence of Fe, Mn, Cu and Zn was higher in the experimental group than in the control group throughout the marinating process. The peroxide value was higher from the first day in the control group than in the experimental groups. On the last day of the study, the peroxide value in the control group exceeded the maximum acceptable value. The highest level of Thiobarbituric Acid Reactive Substances was determined in the control group on the first day, and the lowest in the FH group. On the first day, the highest percentage of DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical quenching was recorded in the FH group.
Originality/value
The results are the first to find that the addition of milk thistle to herring fillets in marinating process maintains or even improves the quality of the marinades. The process of previously coating the fillets in milk thistle and then marinating achieves a lower peroxide value, higher content of polyunsaturated fatty acids and a higher content of elements such as iron and manganese, which are very valuable for human health.
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POLAND: Kopacz strives to stabilise Civic Platform
Details
DOI: 10.1108/OXAN-ES200209
ISSN: 2633-304X
Keywords
Geographic
Topical
POLAND: Warsaw will enhance its defence capabilities
Details
DOI: 10.1108/OXAN-ES286840
ISSN: 2633-304X
Keywords
Geographic
Topical
Dariusz Zieliński, Piotr Lipnicki and Wojciech Jarzyna
In the dispersed generation system, power electronic converters allow for coupling between energy sources and the power grid. The requirements of Transmission System Operators are…
Abstract
Purpose
In the dispersed generation system, power electronic converters allow for coupling between energy sources and the power grid. The requirements of Transmission System Operators are difficult to meet when the share of distributed energy sources of the total energy balance increases. These requirements allow to increase penetration of distributed generation sources without compromising power system stability and reliability. Therefore, in addition to control of active or reactive power, as well as voltage and frequency stabilization, the modern power electronic converters should support power grid in dynamic states or in the presence of nonlinear distortions. The paper aims to discuss these issues.
Design/methodology/approach
The research methodology used in this paper is based on three steps: Mathematical modelling and simulation studies, Experiments on laboratory test stand, Analyzing obtained results, evaluating them and formulating the conclusions.
Findings
The authors identified two algorithms, αβ-Filter and Voltage Controlled Oscillator, which are able to successfully cope with notch distortions. Other algorithms, used previously for voltage dips, operate improperly when the voltage grid has notching disturbances. This work evaluates six different synchronization algorithms with respect to the abilities to deal with notching.
Research limitations/implications
The paper presents results of the synchronization algorithms in the presence of nonlinear notching interference. These studies were performed using the original hardware-software power grid emulator, real-time d’Space platform and power electronic converter. This methodology allowed us to exactly and accurately evaluate synchronization performance methods in the presence of complex nonlinear phenomena in power grid and power electronic converter. The results demonstrated that the best algorithms were αβ – Filtering and Voltage Controlled Oscilator.
Originality/value
In this paper, different synchronization algorithms have been tested. These included the classical Phase Locked Loop with Synchronous Reference Frame as well as modified algorithms developed by the authors, which displayed high robustness with respect to the notching interference. During the tests, the previously developed original test rig was used, allowing software-hardware emulation of grid phenomena.
Details
Keywords
Inna Blam, Katarína Vitálišová, Kamila Borseková and Mariusz Sokolowicz
The paper aims to analyze actual issues of the corporate social responsibility (CSR) practices in monofunctional towns in Russia, Slovakia and Poland. The process of social…
Abstract
Purpose
The paper aims to analyze actual issues of the corporate social responsibility (CSR) practices in monofunctional towns in Russia, Slovakia and Poland. The process of social investment restructuring is obviously under way in these countries. However, there can be identified a few examples where the dominant employer with the long tradition (from the soviet period, even longer) has initiated and directly influenced by the social policy the local and regional development. The paper analyzes their development during the past decades, with the special emphasis on social issues. It identifies its strengths and weaknesses and defines future research areas.
Design/methodology/approach
The first part of the paper defines the CSR with focus on the social sphere and relationships between local dominant employer, local government and community. Refer to the theory, the paper adopts a case study methodology to explore the specifics of CSR with a focus on monotowns, especially the role of local dominant employer and its relationship with local government and community in three selected post-communist nations – Russia, Slovakia and Poland. The research uses also the secondary data (the strategic documents, statistical data) and own observation during the study visits to the selected cities. The authors analyze the town’s development during the past decades, with the special emphasis on the social issues.
Findings
It is shown that maintenance and development of essential living conditions in many monofunctional towns depends upon the direct participation of large dominating companies. The paper argues that there is a principal difference between the current social policy conducted by these dominant local employers and the policy that was conducted in the past. What is more, most of the engagement of large in the social affairs in monotowns refers to the CSR concept. The paper summarizes the common features and differences in functioning monotowns in selected states, from the perspective of social responsible behaviors of dominant companies, suggests the practical implications and identifies future research areas.
Originality/value
The paper maps the specific kind of social responsibility interconnected with the issue of local and regional development – monotowns in Russia, Poland and Slovakia – in the countries with common political and social history. It brings in the form of case studies the detailed overview of the selected examples from Russia, Ukraine and Poland dealing with the CSR. Based on the collected data, it summarizes the advantages and disadvantage of these towns and opens the new research areas.