Wyniki 1-4 spośród 4 dla zapytania: authorDesc:"Mirosław SZMAJDA"

Models of disturbances in power networks for testing frequency methods used in measurements of power quality

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W artykule przedstawiono systematykę zakłóceń, pojawiających się w sieci elektroenergetycznej związanych z niskoczęstotliwościowymi zaburzeniami przewodzonymi, do których należą zakłócenia związane z jakością energii elektrycznej. Zaprezentowano również propozycję bazy sygnałów testowych będących pomocnych w badaniach nowych, alternatywnych do DFT, metod częstotliwościowych przetwarzania sygnałów, koniecznych do obliczeń niektórych parametrów jakości energii elektrycznej. (Modele zakłóceń w sieci elektroenergetycznej z uwzględnieniem pomiarów jakości energii). Abstract. This article presents the systematics of disturbances occurring in power networks, connected with low frequency conducted disturbances including disturbances related to the quality of electrical power. It also provides a proposal of test signals basis that may be useful in testing new, alternative frequency methods of signal processing, necessary for calculation of some parameters of power quality. Słowa kluczowe: jakość energii elektrycznej, systematyka zakłóceń, modele testowe zakłóceń. Keywords: Power quality, systematics of disturbances, testing models of disturbances. Introduction Recently, the increased development of measuring tools for test and analysis of electrical power quality has been observed. The tools include both measuring equipment and methods of signal analysis. In such measuring systems, time analysis (e.g. for calculation of voltage deviations) and frequency analysis (e.g. for calculation of THD parameter) are used as main analyses. Most frequency analyses use discrete Fourier transform (DFT). However, that analysis provides incorrect results for testing e.g. transient overvoltages. Therefore, as an alternative to DFT, scientists search for other analyses that could guarantee proper measurement of such types of disturbances. Adaptation of various methods of signal analysis for the purpose of calculating power quality parameters requires determin[...]

Mechanisms of electric arc detection based on current waveform spectrum and incremental decomposition analysis DOI:10.15199/48.2016.11.15

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This paper presents two methods that enable arc detection, these are frequency analysis FFT and incremental decomposition of current increase in time. Both methods enable arc detection and provide additional information as compared to currently existing commercial solutions. Streszczenie. W artykule zaprezentowano dwie metody umożliwiające wykrywanie występowania łuku elektrycznego: analizę częstotliwościową FFT oraz metodę badania rozkładu przyrostów prądu w czasie. Obydwie metody umożliwiają detekcję łuku oraz dostarczają dodatkowych informacji w stosunku do istniejących obecnie rozwiązań komercyjnych. (Metody detekcji łuku elektrycznego w oparciu o analizę widmową oraz przyrostową przebiegu prądowego). Keywords: electric arc, signal processing, spectrum analysis, incremental decomposition. Słowa kluczowe: łuk elektryczny, przetwarzanie sygnałów, analiza widmowa, analiza przyrostowa. Introduction Formation of electric arc is a highly disadvantageous phenomenon that appears increasingly in electric installations. This phenomenon can occur in both the renewable energy installations [1÷5] and in the railway electric traction [6÷9]. The negative effects of electric arc can be experienced in households, where micro-power photovoltaic or wind energy systems have been used, as well as in industrial power systems [10÷16]. On the basis of the above, it can be concluded that the scale of this phenomenon is very extensive. In order to protect electrical installations from occurrence of electric arc, methods based on detection of sudden voltage drop and light-emission of electric arc are currently applied. Further, research is being carried out into current waveforms spectral analysis [17], which provides additional information on the load nature and the distortion degree of nonlinear receivers’ network. Some kind of analyses might be taken from power quality measuring methodology [18]. In addition, studies are conducted into altern[...]

Systemy pomiarowe jakości energii elektrycznej

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W artykule przedstawiono systematykę urządzeń do badania jakości energii elektrycznej biorąc pod uwagę różne aspekty konfiguracji hardwarowej oraz softwarowej. Dokonano krótkiej charakterystyki systemów pod kątem mocy obliczeniowych zastosowanych mikroprocesorów oraz oprogramowania. Przedstawiono najnowocześniejsze trendy w dziedzinie aplikacji procesorów sygnałowych w pomiarach jakości energii elektrycznej oraz pokazano sposób zastosowania dedykowanego systemu czasu rzeczywistego DSP/BIOS. Abstract. The systematics of power quality measurement systems considering different aspects of software and hardware configuration was presented in the article The short characteristic of the systems considering computational power of processors and software (firmware) was performed. The modern t[...]

Use of incremental decomposition and spectrogram in vibroacoustic signal analysis in knee joint disease examination DOI:10.15199/48.2018.07.41

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Joint dysfunctions are the most common disorders in human locomotor system. Complex biomechanical environment makes the knee joint particularly susceptible to such disorders [5]. Although X-ray has a number of advantages and is still a basic form of assessment of the articular system, this method presents some limitations that significantly reduce its clinical relevance [6]. On the other hand, access to more sensitive and specific imaging methods (e.g. MRI) is significantly limited due to high costs. In addition, it should be noted that these methods allow only for structure evaluation, without the assessment of the joint function [1]. Vibroarthrography (VAG) is an experimental method for assessing the function of articular structures. This method bases on recording mechanical vibrations generated by moving articular cartilaginous surfaces, which under physiological conditions reduce the coefficient of friction [2, 3]. However, in the course of various disorders within the articular system the cartilage structures are damaged or the changes in their biomechanical characteristics appear. This results in increased friction and increased vibrations corresponding to the degree of damage to the joint [2]. Because of its non-invasive character and relatively low cost, VAG method appears to be a promising diagnostic tool that can be used in clinical conditions. However, it is necessary to develop algorithms that classify individual disorders with respect to generally accepted diagnostic criteria. Therefore, the aim of this paper is to use the incremental decomposition and spectrograms in the analysis of vibroarthrography signals representing different levels of cartilaginous disorders within the knee joint. Measurement methodology The VAG signal was recorded using the 4513B-002 accelerometer sensor and the Brüel & Kjær Nexus 2692-C signal amplifier connected to an analogue-to-digital converter and a PC. The sensor was attac[...]

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